Bug Summary

File:src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
Warning:line 638, column 19
Called C++ object pointer is null

Annotated Source Code

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clang -cc1 -cc1 -triple amd64-unknown-openbsd7.0 -analyze -disable-free -disable-llvm-verifier -discard-value-names -main-file-name AddressSanitizer.cpp -analyzer-store=region -analyzer-opt-analyze-nested-blocks -analyzer-checker=core -analyzer-checker=apiModeling -analyzer-checker=unix -analyzer-checker=deadcode -analyzer-checker=cplusplus -analyzer-checker=security.insecureAPI.UncheckedReturn -analyzer-checker=security.insecureAPI.getpw -analyzer-checker=security.insecureAPI.gets -analyzer-checker=security.insecureAPI.mktemp -analyzer-checker=security.insecureAPI.mkstemp -analyzer-checker=security.insecureAPI.vfork -analyzer-checker=nullability.NullPassedToNonnull -analyzer-checker=nullability.NullReturnedFromNonnull -analyzer-output plist -w -setup-static-analyzer -mrelocation-model pic -pic-level 1 -fhalf-no-semantic-interposition -mframe-pointer=all -relaxed-aliasing -fno-rounding-math -mconstructor-aliases -munwind-tables -target-cpu x86-64 -tune-cpu generic -debugger-tuning=gdb -fcoverage-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -resource-dir /usr/local/lib/clang/13.0.0 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/AMDGPU -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Analysis -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ASMParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/BinaryFormat -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitcode -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Bitstream -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /include/llvm/CodeGen -I /include/llvm/CodeGen/PBQP -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IR -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Coroutines -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData/Coverage -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/CodeView -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/DWARF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/MSF -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/PDB -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Demangle -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/JITLink -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ExecutionEngine/Orc -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenACC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Frontend/OpenMP -I /include/llvm/CodeGen/GlobalISel -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/IRReader -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/Transforms/InstCombine -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/LTO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Linker -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/MC/MCParser -I /include/llvm/CodeGen/MIRParser -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Object -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Option -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Passes -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ProfileData -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Scalar -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/ADT -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Support -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/DebugInfo/Symbolize -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Target -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Utils -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/Vectorize -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include/llvm/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Target/X86 -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include/llvm/Transforms/IPO -I /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/include -I /usr/src/gnu/usr.bin/clang/libLLVM/../include -I /usr/src/gnu/usr.bin/clang/libLLVM/obj -I /usr/src/gnu/usr.bin/clang/libLLVM/obj/../include -D NDEBUG -D __STDC_LIMIT_MACROS -D __STDC_CONSTANT_MACROS -D __STDC_FORMAT_MACROS -D LLVM_PREFIX="/usr" -D PIC -internal-isystem /usr/include/c++/v1 -internal-isystem /usr/local/lib/clang/13.0.0/include -internal-externc-isystem /usr/include -O2 -Wno-unused-parameter -Wwrite-strings -Wno-missing-field-initializers -Wno-long-long -Wno-comment -std=c++14 -fdeprecated-macro -fdebug-compilation-dir=/usr/src/gnu/usr.bin/clang/libLLVM/obj -ferror-limit 19 -fvisibility-inlines-hidden -fwrapv -D_RET_PROTECTOR -ret-protector -fno-rtti -fgnuc-version=4.2.1 -vectorize-loops -vectorize-slp -fno-builtin-malloc -fno-builtin-calloc -fno-builtin-realloc -fno-builtin-valloc -fno-builtin-free -fno-builtin-strdup -fno-builtin-strndup -analyzer-output=html -faddrsig -D__GCC_HAVE_DWARF2_CFI_ASM=1 -o /home/ben/Projects/vmm/scan-build/2022-01-12-194120-40624-1 -x c++ /usr/src/gnu/usr.bin/clang/libLLVM/../../../llvm/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
1//===- AddressSanitizer.cpp - memory error detector -----------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8//
9// This file is a part of AddressSanitizer, an address sanity checker.
10// Details of the algorithm:
11// https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm
12//
13// FIXME: This sanitizer does not yet handle scalable vectors
14//
15//===----------------------------------------------------------------------===//
16
17#include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
18#include "llvm/ADT/ArrayRef.h"
19#include "llvm/ADT/DenseMap.h"
20#include "llvm/ADT/DepthFirstIterator.h"
21#include "llvm/ADT/SmallPtrSet.h"
22#include "llvm/ADT/SmallVector.h"
23#include "llvm/ADT/Statistic.h"
24#include "llvm/ADT/StringExtras.h"
25#include "llvm/ADT/StringRef.h"
26#include "llvm/ADT/Triple.h"
27#include "llvm/ADT/Twine.h"
28#include "llvm/Analysis/MemoryBuiltins.h"
29#include "llvm/Analysis/TargetLibraryInfo.h"
30#include "llvm/Analysis/ValueTracking.h"
31#include "llvm/BinaryFormat/MachO.h"
32#include "llvm/IR/Argument.h"
33#include "llvm/IR/Attributes.h"
34#include "llvm/IR/BasicBlock.h"
35#include "llvm/IR/Comdat.h"
36#include "llvm/IR/Constant.h"
37#include "llvm/IR/Constants.h"
38#include "llvm/IR/DIBuilder.h"
39#include "llvm/IR/DataLayout.h"
40#include "llvm/IR/DebugInfoMetadata.h"
41#include "llvm/IR/DebugLoc.h"
42#include "llvm/IR/DerivedTypes.h"
43#include "llvm/IR/Dominators.h"
44#include "llvm/IR/Function.h"
45#include "llvm/IR/GlobalAlias.h"
46#include "llvm/IR/GlobalValue.h"
47#include "llvm/IR/GlobalVariable.h"
48#include "llvm/IR/IRBuilder.h"
49#include "llvm/IR/InlineAsm.h"
50#include "llvm/IR/InstVisitor.h"
51#include "llvm/IR/InstrTypes.h"
52#include "llvm/IR/Instruction.h"
53#include "llvm/IR/Instructions.h"
54#include "llvm/IR/IntrinsicInst.h"
55#include "llvm/IR/Intrinsics.h"
56#include "llvm/IR/LLVMContext.h"
57#include "llvm/IR/MDBuilder.h"
58#include "llvm/IR/Metadata.h"
59#include "llvm/IR/Module.h"
60#include "llvm/IR/Type.h"
61#include "llvm/IR/Use.h"
62#include "llvm/IR/Value.h"
63#include "llvm/InitializePasses.h"
64#include "llvm/MC/MCSectionMachO.h"
65#include "llvm/Pass.h"
66#include "llvm/Support/Casting.h"
67#include "llvm/Support/CommandLine.h"
68#include "llvm/Support/Debug.h"
69#include "llvm/Support/ErrorHandling.h"
70#include "llvm/Support/MathExtras.h"
71#include "llvm/Support/ScopedPrinter.h"
72#include "llvm/Support/raw_ostream.h"
73#include "llvm/Transforms/Instrumentation.h"
74#include "llvm/Transforms/Instrumentation/AddressSanitizerCommon.h"
75#include "llvm/Transforms/Instrumentation/AddressSanitizerOptions.h"
76#include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
77#include "llvm/Transforms/Utils/BasicBlockUtils.h"
78#include "llvm/Transforms/Utils/Local.h"
79#include "llvm/Transforms/Utils/ModuleUtils.h"
80#include "llvm/Transforms/Utils/PromoteMemToReg.h"
81#include <algorithm>
82#include <cassert>
83#include <cstddef>
84#include <cstdint>
85#include <iomanip>
86#include <limits>
87#include <memory>
88#include <sstream>
89#include <string>
90#include <tuple>
91
92using namespace llvm;
93
94#define DEBUG_TYPE"asan" "asan"
95
96static const uint64_t kDefaultShadowScale = 3;
97static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
98static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
99static const uint64_t kDynamicShadowSentinel =
100 std::numeric_limits<uint64_t>::max();
101static const uint64_t kSmallX86_64ShadowOffsetBase = 0x7FFFFFFF; // < 2G.
102static const uint64_t kSmallX86_64ShadowOffsetAlignMask = ~0xFFFULL;
103static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
104static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 44;
105static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
106static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
107static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
108static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
109static const uint64_t kRISCV64_ShadowOffset64 = 0xd55550000;
110static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
111static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
112static const uint64_t kFreeBSDKasan_ShadowOffset64 = 0xdffff7c000000000;
113static const uint64_t kNetBSD_ShadowOffset32 = 1ULL << 30;
114static const uint64_t kNetBSD_ShadowOffset64 = 1ULL << 46;
115static const uint64_t kNetBSDKasan_ShadowOffset64 = 0xdfff900000000000;
116static const uint64_t kPS4CPU_ShadowOffset64 = 1ULL << 40;
117static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
118static const uint64_t kEmscriptenShadowOffset = 0;
119
120// The shadow memory space is dynamically allocated.
121static const uint64_t kWindowsShadowOffset64 = kDynamicShadowSentinel;
122
123static const size_t kMinStackMallocSize = 1 << 6; // 64B
124static const size_t kMaxStackMallocSize = 1 << 16; // 64K
125static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
126static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
127
128const char kAsanModuleCtorName[] = "asan.module_ctor";
129const char kAsanModuleDtorName[] = "asan.module_dtor";
130static const uint64_t kAsanCtorAndDtorPriority = 1;
131// On Emscripten, the system needs more than one priorities for constructors.
132static const uint64_t kAsanEmscriptenCtorAndDtorPriority = 50;
133const char kAsanReportErrorTemplate[] = "__asan_report_";
134const char kAsanRegisterGlobalsName[] = "__asan_register_globals";
135const char kAsanUnregisterGlobalsName[] = "__asan_unregister_globals";
136const char kAsanRegisterImageGlobalsName[] = "__asan_register_image_globals";
137const char kAsanUnregisterImageGlobalsName[] =
138 "__asan_unregister_image_globals";
139const char kAsanRegisterElfGlobalsName[] = "__asan_register_elf_globals";
140const char kAsanUnregisterElfGlobalsName[] = "__asan_unregister_elf_globals";
141const char kAsanPoisonGlobalsName[] = "__asan_before_dynamic_init";
142const char kAsanUnpoisonGlobalsName[] = "__asan_after_dynamic_init";
143const char kAsanInitName[] = "__asan_init";
144const char kAsanVersionCheckNamePrefix[] = "__asan_version_mismatch_check_v";
145const char kAsanPtrCmp[] = "__sanitizer_ptr_cmp";
146const char kAsanPtrSub[] = "__sanitizer_ptr_sub";
147const char kAsanHandleNoReturnName[] = "__asan_handle_no_return";
148static const int kMaxAsanStackMallocSizeClass = 10;
149const char kAsanStackMallocNameTemplate[] = "__asan_stack_malloc_";
150const char kAsanStackMallocAlwaysNameTemplate[] =
151 "__asan_stack_malloc_always_";
152const char kAsanStackFreeNameTemplate[] = "__asan_stack_free_";
153const char kAsanGenPrefix[] = "___asan_gen_";
154const char kODRGenPrefix[] = "__odr_asan_gen_";
155const char kSanCovGenPrefix[] = "__sancov_gen_";
156const char kAsanSetShadowPrefix[] = "__asan_set_shadow_";
157const char kAsanPoisonStackMemoryName[] = "__asan_poison_stack_memory";
158const char kAsanUnpoisonStackMemoryName[] = "__asan_unpoison_stack_memory";
159
160// ASan version script has __asan_* wildcard. Triple underscore prevents a
161// linker (gold) warning about attempting to export a local symbol.
162const char kAsanGlobalsRegisteredFlagName[] = "___asan_globals_registered";
163
164const char kAsanOptionDetectUseAfterReturn[] =
165 "__asan_option_detect_stack_use_after_return";
166
167const char kAsanShadowMemoryDynamicAddress[] =
168 "__asan_shadow_memory_dynamic_address";
169
170const char kAsanAllocaPoison[] = "__asan_alloca_poison";
171const char kAsanAllocasUnpoison[] = "__asan_allocas_unpoison";
172
173const char kAMDGPUAddressSharedName[] = "llvm.amdgcn.is.shared";
174const char kAMDGPUAddressPrivateName[] = "llvm.amdgcn.is.private";
175
176// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
177static const size_t kNumberOfAccessSizes = 5;
178
179static const unsigned kAllocaRzSize = 32;
180
181// Command-line flags.
182
183static cl::opt<bool> ClEnableKasan(
184 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
185 cl::Hidden, cl::init(false));
186
187static cl::opt<bool> ClRecover(
188 "asan-recover",
189 cl::desc("Enable recovery mode (continue-after-error)."),
190 cl::Hidden, cl::init(false));
191
192static cl::opt<bool> ClInsertVersionCheck(
193 "asan-guard-against-version-mismatch",
194 cl::desc("Guard against compiler/runtime version mismatch."),
195 cl::Hidden, cl::init(true));
196
197// This flag may need to be replaced with -f[no-]asan-reads.
198static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
199 cl::desc("instrument read instructions"),
200 cl::Hidden, cl::init(true));
201
202static cl::opt<bool> ClInstrumentWrites(
203 "asan-instrument-writes", cl::desc("instrument write instructions"),
204 cl::Hidden, cl::init(true));
205
206static cl::opt<bool> ClInstrumentAtomics(
207 "asan-instrument-atomics",
208 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
209 cl::init(true));
210
211static cl::opt<bool>
212 ClInstrumentByval("asan-instrument-byval",
213 cl::desc("instrument byval call arguments"), cl::Hidden,
214 cl::init(true));
215
216static cl::opt<bool> ClAlwaysSlowPath(
217 "asan-always-slow-path",
218 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
219 cl::init(false));
220
221static cl::opt<bool> ClForceDynamicShadow(
222 "asan-force-dynamic-shadow",
223 cl::desc("Load shadow address into a local variable for each function"),
224 cl::Hidden, cl::init(false));
225
226static cl::opt<bool>
227 ClWithIfunc("asan-with-ifunc",
228 cl::desc("Access dynamic shadow through an ifunc global on "
229 "platforms that support this"),
230 cl::Hidden, cl::init(true));
231
232static cl::opt<bool> ClWithIfuncSuppressRemat(
233 "asan-with-ifunc-suppress-remat",
234 cl::desc("Suppress rematerialization of dynamic shadow address by passing "
235 "it through inline asm in prologue."),
236 cl::Hidden, cl::init(true));
237
238// This flag limits the number of instructions to be instrumented
239// in any given BB. Normally, this should be set to unlimited (INT_MAX),
240// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
241// set it to 10000.
242static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
243 "asan-max-ins-per-bb", cl::init(10000),
244 cl::desc("maximal number of instructions to instrument in any given BB"),
245 cl::Hidden);
246
247// This flag may need to be replaced with -f[no]asan-stack.
248static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
249 cl::Hidden, cl::init(true));
250static cl::opt<uint32_t> ClMaxInlinePoisoningSize(
251 "asan-max-inline-poisoning-size",
252 cl::desc(
253 "Inline shadow poisoning for blocks up to the given size in bytes."),
254 cl::Hidden, cl::init(64));
255
256static cl::opt<AsanDetectStackUseAfterReturnMode> ClUseAfterReturn(
257 "asan-use-after-return",
258 cl::desc("Sets the mode of detection for stack-use-after-return."),
259 cl::values(
260 clEnumValN(AsanDetectStackUseAfterReturnMode::Never, "never",llvm::cl::OptionEnumValue { "never", int(AsanDetectStackUseAfterReturnMode
::Never), "Never detect stack use after return." }
261 "Never detect stack use after return.")llvm::cl::OptionEnumValue { "never", int(AsanDetectStackUseAfterReturnMode
::Never), "Never detect stack use after return." }
,
262 clEnumValN(llvm::cl::OptionEnumValue { "runtime", int(AsanDetectStackUseAfterReturnMode
::Runtime), "Detect stack use after return if " "binary flag 'ASAN_OPTIONS=detect_stack_use_after_return' is set."
}
263 AsanDetectStackUseAfterReturnMode::Runtime, "runtime",llvm::cl::OptionEnumValue { "runtime", int(AsanDetectStackUseAfterReturnMode
::Runtime), "Detect stack use after return if " "binary flag 'ASAN_OPTIONS=detect_stack_use_after_return' is set."
}
264 "Detect stack use after return if "llvm::cl::OptionEnumValue { "runtime", int(AsanDetectStackUseAfterReturnMode
::Runtime), "Detect stack use after return if " "binary flag 'ASAN_OPTIONS=detect_stack_use_after_return' is set."
}
265 "binary flag 'ASAN_OPTIONS=detect_stack_use_after_return' is set.")llvm::cl::OptionEnumValue { "runtime", int(AsanDetectStackUseAfterReturnMode
::Runtime), "Detect stack use after return if " "binary flag 'ASAN_OPTIONS=detect_stack_use_after_return' is set."
}
,
266 clEnumValN(AsanDetectStackUseAfterReturnMode::Always, "always",llvm::cl::OptionEnumValue { "always", int(AsanDetectStackUseAfterReturnMode
::Always), "Always detect stack use after return." }
267 "Always detect stack use after return.")llvm::cl::OptionEnumValue { "always", int(AsanDetectStackUseAfterReturnMode
::Always), "Always detect stack use after return." }
),
268 cl::Hidden, cl::init(AsanDetectStackUseAfterReturnMode::Runtime));
269
270static cl::opt<bool> ClRedzoneByvalArgs("asan-redzone-byval-args",
271 cl::desc("Create redzones for byval "
272 "arguments (extra copy "
273 "required)"), cl::Hidden,
274 cl::init(true));
275
276static cl::opt<bool> ClUseAfterScope("asan-use-after-scope",
277 cl::desc("Check stack-use-after-scope"),
278 cl::Hidden, cl::init(false));
279
280// This flag may need to be replaced with -f[no]asan-globals.
281static cl::opt<bool> ClGlobals("asan-globals",
282 cl::desc("Handle global objects"), cl::Hidden,
283 cl::init(true));
284
285static cl::opt<bool> ClInitializers("asan-initialization-order",
286 cl::desc("Handle C++ initializer order"),
287 cl::Hidden, cl::init(true));
288
289static cl::opt<bool> ClInvalidPointerPairs(
290 "asan-detect-invalid-pointer-pair",
291 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
292 cl::init(false));
293
294static cl::opt<bool> ClInvalidPointerCmp(
295 "asan-detect-invalid-pointer-cmp",
296 cl::desc("Instrument <, <=, >, >= with pointer operands"), cl::Hidden,
297 cl::init(false));
298
299static cl::opt<bool> ClInvalidPointerSub(
300 "asan-detect-invalid-pointer-sub",
301 cl::desc("Instrument - operations with pointer operands"), cl::Hidden,
302 cl::init(false));
303
304static cl::opt<unsigned> ClRealignStack(
305 "asan-realign-stack",
306 cl::desc("Realign stack to the value of this flag (power of two)"),
307 cl::Hidden, cl::init(32));
308
309static cl::opt<int> ClInstrumentationWithCallsThreshold(
310 "asan-instrumentation-with-call-threshold",
311 cl::desc(
312 "If the function being instrumented contains more than "
313 "this number of memory accesses, use callbacks instead of "
314 "inline checks (-1 means never use callbacks)."),
315 cl::Hidden, cl::init(7000));
316
317static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
318 "asan-memory-access-callback-prefix",
319 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
320 cl::init("__asan_"));
321
322static cl::opt<bool>
323 ClInstrumentDynamicAllocas("asan-instrument-dynamic-allocas",
324 cl::desc("instrument dynamic allocas"),
325 cl::Hidden, cl::init(true));
326
327static cl::opt<bool> ClSkipPromotableAllocas(
328 "asan-skip-promotable-allocas",
329 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
330 cl::init(true));
331
332// These flags allow to change the shadow mapping.
333// The shadow mapping looks like
334// Shadow = (Mem >> scale) + offset
335
336static cl::opt<int> ClMappingScale("asan-mapping-scale",
337 cl::desc("scale of asan shadow mapping"),
338 cl::Hidden, cl::init(0));
339
340static cl::opt<uint64_t>
341 ClMappingOffset("asan-mapping-offset",
342 cl::desc("offset of asan shadow mapping [EXPERIMENTAL]"),
343 cl::Hidden, cl::init(0));
344
345// Optimization flags. Not user visible, used mostly for testing
346// and benchmarking the tool.
347
348static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
349 cl::Hidden, cl::init(true));
350
351static cl::opt<bool> ClOptSameTemp(
352 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
353 cl::Hidden, cl::init(true));
354
355static cl::opt<bool> ClOptGlobals("asan-opt-globals",
356 cl::desc("Don't instrument scalar globals"),
357 cl::Hidden, cl::init(true));
358
359static cl::opt<bool> ClOptStack(
360 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
361 cl::Hidden, cl::init(false));
362
363static cl::opt<bool> ClDynamicAllocaStack(
364 "asan-stack-dynamic-alloca",
365 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
366 cl::init(true));
367
368static cl::opt<uint32_t> ClForceExperiment(
369 "asan-force-experiment",
370 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
371 cl::init(0));
372
373static cl::opt<bool>
374 ClUsePrivateAlias("asan-use-private-alias",
375 cl::desc("Use private aliases for global variables"),
376 cl::Hidden, cl::init(false));
377
378static cl::opt<bool>
379 ClUseOdrIndicator("asan-use-odr-indicator",
380 cl::desc("Use odr indicators to improve ODR reporting"),
381 cl::Hidden, cl::init(false));
382
383static cl::opt<bool>
384 ClUseGlobalsGC("asan-globals-live-support",
385 cl::desc("Use linker features to support dead "
386 "code stripping of globals"),
387 cl::Hidden, cl::init(true));
388
389// This is on by default even though there is a bug in gold:
390// https://sourceware.org/bugzilla/show_bug.cgi?id=19002
391static cl::opt<bool>
392 ClWithComdat("asan-with-comdat",
393 cl::desc("Place ASan constructors in comdat sections"),
394 cl::Hidden, cl::init(true));
395
396static cl::opt<AsanDtorKind> ClOverrideDestructorKind(
397 "asan-destructor-kind",
398 cl::desc("Sets the ASan destructor kind. The default is to use the value "
399 "provided to the pass constructor"),
400 cl::values(clEnumValN(AsanDtorKind::None, "none", "No destructors")llvm::cl::OptionEnumValue { "none", int(AsanDtorKind::None), "No destructors"
}
,
401 clEnumValN(AsanDtorKind::Global, "global",llvm::cl::OptionEnumValue { "global", int(AsanDtorKind::Global
), "Use global destructors" }
402 "Use global destructors")llvm::cl::OptionEnumValue { "global", int(AsanDtorKind::Global
), "Use global destructors" }
),
403 cl::init(AsanDtorKind::Invalid), cl::Hidden);
404
405// Debug flags.
406
407static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
408 cl::init(0));
409
410static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
411 cl::Hidden, cl::init(0));
412
413static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
414 cl::desc("Debug func"));
415
416static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
417 cl::Hidden, cl::init(-1));
418
419static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug max inst"),
420 cl::Hidden, cl::init(-1));
421
422STATISTIC(NumInstrumentedReads, "Number of instrumented reads")static llvm::Statistic NumInstrumentedReads = {"asan", "NumInstrumentedReads"
, "Number of instrumented reads"}
;
423STATISTIC(NumInstrumentedWrites, "Number of instrumented writes")static llvm::Statistic NumInstrumentedWrites = {"asan", "NumInstrumentedWrites"
, "Number of instrumented writes"}
;
424STATISTIC(NumOptimizedAccessesToGlobalVar,static llvm::Statistic NumOptimizedAccessesToGlobalVar = {"asan"
, "NumOptimizedAccessesToGlobalVar", "Number of optimized accesses to global vars"
}
425 "Number of optimized accesses to global vars")static llvm::Statistic NumOptimizedAccessesToGlobalVar = {"asan"
, "NumOptimizedAccessesToGlobalVar", "Number of optimized accesses to global vars"
}
;
426STATISTIC(NumOptimizedAccessesToStackVar,static llvm::Statistic NumOptimizedAccessesToStackVar = {"asan"
, "NumOptimizedAccessesToStackVar", "Number of optimized accesses to stack vars"
}
427 "Number of optimized accesses to stack vars")static llvm::Statistic NumOptimizedAccessesToStackVar = {"asan"
, "NumOptimizedAccessesToStackVar", "Number of optimized accesses to stack vars"
}
;
428
429namespace {
430
431/// This struct defines the shadow mapping using the rule:
432/// shadow = (mem >> Scale) ADD-or-OR Offset.
433/// If InGlobal is true, then
434/// extern char __asan_shadow[];
435/// shadow = (mem >> Scale) + &__asan_shadow
436struct ShadowMapping {
437 int Scale;
438 uint64_t Offset;
439 bool OrShadowOffset;
440 bool InGlobal;
441};
442
443} // end anonymous namespace
444
445static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
446 bool IsKasan) {
447 bool IsAndroid = TargetTriple.isAndroid();
448 bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
449 bool IsMacOS = TargetTriple.isMacOSX();
450 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
451 bool IsNetBSD = TargetTriple.isOSNetBSD();
452 bool IsPS4CPU = TargetTriple.isPS4CPU();
453 bool IsLinux = TargetTriple.isOSLinux();
454 bool IsPPC64 = TargetTriple.getArch() == Triple::ppc64 ||
455 TargetTriple.getArch() == Triple::ppc64le;
456 bool IsSystemZ = TargetTriple.getArch() == Triple::systemz;
457 bool IsX86_64 = TargetTriple.getArch() == Triple::x86_64;
458 bool IsMIPS32 = TargetTriple.isMIPS32();
459 bool IsMIPS64 = TargetTriple.isMIPS64();
460 bool IsArmOrThumb = TargetTriple.isARM() || TargetTriple.isThumb();
461 bool IsAArch64 = TargetTriple.getArch() == Triple::aarch64;
462 bool IsRISCV64 = TargetTriple.getArch() == Triple::riscv64;
463 bool IsWindows = TargetTriple.isOSWindows();
464 bool IsFuchsia = TargetTriple.isOSFuchsia();
465 bool IsEmscripten = TargetTriple.isOSEmscripten();
466 bool IsAMDGPU = TargetTriple.isAMDGPU();
467
468 ShadowMapping Mapping;
469
470 Mapping.Scale = kDefaultShadowScale;
471 if (ClMappingScale.getNumOccurrences() > 0) {
472 Mapping.Scale = ClMappingScale;
473 }
474
475 if (LongSize == 32) {
476 if (IsAndroid)
477 Mapping.Offset = kDynamicShadowSentinel;
478 else if (IsMIPS32)
479 Mapping.Offset = kMIPS32_ShadowOffset32;
480 else if (IsFreeBSD)
481 Mapping.Offset = kFreeBSD_ShadowOffset32;
482 else if (IsNetBSD)
483 Mapping.Offset = kNetBSD_ShadowOffset32;
484 else if (IsIOS)
485 Mapping.Offset = kDynamicShadowSentinel;
486 else if (IsWindows)
487 Mapping.Offset = kWindowsShadowOffset32;
488 else if (IsEmscripten)
489 Mapping.Offset = kEmscriptenShadowOffset;
490 else
491 Mapping.Offset = kDefaultShadowOffset32;
492 } else { // LongSize == 64
493 // Fuchsia is always PIE, which means that the beginning of the address
494 // space is always available.
495 if (IsFuchsia)
496 Mapping.Offset = 0;
497 else if (IsPPC64)
498 Mapping.Offset = kPPC64_ShadowOffset64;
499 else if (IsSystemZ)
500 Mapping.Offset = kSystemZ_ShadowOffset64;
501 else if (IsFreeBSD && !IsMIPS64) {
502 if (IsKasan)
503 Mapping.Offset = kFreeBSDKasan_ShadowOffset64;
504 else
505 Mapping.Offset = kFreeBSD_ShadowOffset64;
506 } else if (IsNetBSD) {
507 if (IsKasan)
508 Mapping.Offset = kNetBSDKasan_ShadowOffset64;
509 else
510 Mapping.Offset = kNetBSD_ShadowOffset64;
511 } else if (IsPS4CPU)
512 Mapping.Offset = kPS4CPU_ShadowOffset64;
513 else if (IsLinux && IsX86_64) {
514 if (IsKasan)
515 Mapping.Offset = kLinuxKasan_ShadowOffset64;
516 else
517 Mapping.Offset = (kSmallX86_64ShadowOffsetBase &
518 (kSmallX86_64ShadowOffsetAlignMask << Mapping.Scale));
519 } else if (IsWindows && IsX86_64) {
520 Mapping.Offset = kWindowsShadowOffset64;
521 } else if (IsMIPS64)
522 Mapping.Offset = kMIPS64_ShadowOffset64;
523 else if (IsIOS)
524 Mapping.Offset = kDynamicShadowSentinel;
525 else if (IsMacOS && IsAArch64)
526 Mapping.Offset = kDynamicShadowSentinel;
527 else if (IsAArch64)
528 Mapping.Offset = kAArch64_ShadowOffset64;
529 else if (IsRISCV64)
530 Mapping.Offset = kRISCV64_ShadowOffset64;
531 else if (IsAMDGPU)
532 Mapping.Offset = (kSmallX86_64ShadowOffsetBase &
533 (kSmallX86_64ShadowOffsetAlignMask << Mapping.Scale));
534 else
535 Mapping.Offset = kDefaultShadowOffset64;
536 }
537
538 if (ClForceDynamicShadow) {
539 Mapping.Offset = kDynamicShadowSentinel;
540 }
541
542 if (ClMappingOffset.getNumOccurrences() > 0) {
543 Mapping.Offset = ClMappingOffset;
544 }
545
546 // OR-ing shadow offset if more efficient (at least on x86) if the offset
547 // is a power of two, but on ppc64 we have to use add since the shadow
548 // offset is not necessary 1/8-th of the address space. On SystemZ,
549 // we could OR the constant in a single instruction, but it's more
550 // efficient to load it once and use indexed addressing.
551 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ && !IsPS4CPU &&
552 !IsRISCV64 &&
553 !(Mapping.Offset & (Mapping.Offset - 1)) &&
554 Mapping.Offset != kDynamicShadowSentinel;
555 bool IsAndroidWithIfuncSupport =
556 IsAndroid && !TargetTriple.isAndroidVersionLT(21);
557 Mapping.InGlobal = ClWithIfunc && IsAndroidWithIfuncSupport && IsArmOrThumb;
558
559 return Mapping;
560}
561
562static uint64_t getRedzoneSizeForScale(int MappingScale) {
563 // Redzone used for stack and globals is at least 32 bytes.
564 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
565 return std::max(32U, 1U << MappingScale);
566}
567
568static uint64_t GetCtorAndDtorPriority(Triple &TargetTriple) {
569 if (TargetTriple.isOSEmscripten()) {
570 return kAsanEmscriptenCtorAndDtorPriority;
571 } else {
572 return kAsanCtorAndDtorPriority;
573 }
574}
575
576namespace {
577
578/// Module analysis for getting various metadata about the module.
579class ASanGlobalsMetadataWrapperPass : public ModulePass {
580public:
581 static char ID;
582
583 ASanGlobalsMetadataWrapperPass() : ModulePass(ID) {
584 initializeASanGlobalsMetadataWrapperPassPass(
585 *PassRegistry::getPassRegistry());
586 }
587
588 bool runOnModule(Module &M) override {
589 GlobalsMD = GlobalsMetadata(M);
590 return false;
591 }
592
593 StringRef getPassName() const override {
594 return "ASanGlobalsMetadataWrapperPass";
595 }
596
597 void getAnalysisUsage(AnalysisUsage &AU) const override {
598 AU.setPreservesAll();
599 }
600
601 GlobalsMetadata &getGlobalsMD() { return GlobalsMD; }
602
603private:
604 GlobalsMetadata GlobalsMD;
605};
606
607char ASanGlobalsMetadataWrapperPass::ID = 0;
608
609/// AddressSanitizer: instrument the code in module to find memory bugs.
610struct AddressSanitizer {
611 AddressSanitizer(Module &M, const GlobalsMetadata *GlobalsMD,
612 bool CompileKernel = false, bool Recover = false,
613 bool UseAfterScope = false,
614 AsanDetectStackUseAfterReturnMode UseAfterReturn =
615 AsanDetectStackUseAfterReturnMode::Runtime)
616 : CompileKernel(ClEnableKasan.getNumOccurrences() > 0 ? ClEnableKasan
617 : CompileKernel),
618 Recover(ClRecover.getNumOccurrences() > 0 ? ClRecover : Recover),
619 UseAfterScope(UseAfterScope || ClUseAfterScope),
620 UseAfterReturn(ClUseAfterReturn.getNumOccurrences() ? ClUseAfterReturn
621 : UseAfterReturn),
622 GlobalsMD(*GlobalsMD) {
623 C = &(M.getContext());
624 LongSize = M.getDataLayout().getPointerSizeInBits();
625 IntptrTy = Type::getIntNTy(*C, LongSize);
626 TargetTriple = Triple(M.getTargetTriple());
627
628 Mapping = getShadowMapping(TargetTriple, LongSize, this->CompileKernel);
629
630 assert(this->UseAfterReturn != AsanDetectStackUseAfterReturnMode::Invalid)((void)0);
631 }
632
633 uint64_t getAllocaSizeInBytes(const AllocaInst &AI) const {
634 uint64_t ArraySize = 1;
635 if (AI.isArrayAllocation()) {
19
Assuming the condition is true
20
Taking true branch
636 const ConstantInt *CI = dyn_cast<ConstantInt>(AI.getArraySize());
21
Assuming the object is not a 'ConstantInt'
22
'CI' initialized to a null pointer value
637 assert(CI && "non-constant array size")((void)0);
638 ArraySize = CI->getZExtValue();
23
Called C++ object pointer is null
639 }
640 Type *Ty = AI.getAllocatedType();
641 uint64_t SizeInBytes =
642 AI.getModule()->getDataLayout().getTypeAllocSize(Ty);
643 return SizeInBytes * ArraySize;
644 }
645
646 /// Check if we want (and can) handle this alloca.
647 bool isInterestingAlloca(const AllocaInst &AI);
648
649 bool ignoreAccess(Value *Ptr);
650 void getInterestingMemoryOperands(
651 Instruction *I, SmallVectorImpl<InterestingMemoryOperand> &Interesting);
652
653 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
654 InterestingMemoryOperand &O, bool UseCalls,
655 const DataLayout &DL);
656 void instrumentPointerComparisonOrSubtraction(Instruction *I);
657 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
658 Value *Addr, uint32_t TypeSize, bool IsWrite,
659 Value *SizeArgument, bool UseCalls, uint32_t Exp);
660 Instruction *instrumentAMDGPUAddress(Instruction *OrigIns,
661 Instruction *InsertBefore, Value *Addr,
662 uint32_t TypeSize, bool IsWrite,
663 Value *SizeArgument);
664 void instrumentUnusualSizeOrAlignment(Instruction *I,
665 Instruction *InsertBefore, Value *Addr,
666 uint32_t TypeSize, bool IsWrite,
667 Value *SizeArgument, bool UseCalls,
668 uint32_t Exp);
669 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
670 Value *ShadowValue, uint32_t TypeSize);
671 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
672 bool IsWrite, size_t AccessSizeIndex,
673 Value *SizeArgument, uint32_t Exp);
674 void instrumentMemIntrinsic(MemIntrinsic *MI);
675 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
676 bool suppressInstrumentationSiteForDebug(int &Instrumented);
677 bool instrumentFunction(Function &F, const TargetLibraryInfo *TLI);
678 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
679 bool maybeInsertDynamicShadowAtFunctionEntry(Function &F);
680 void markEscapedLocalAllocas(Function &F);
681
682private:
683 friend struct FunctionStackPoisoner;
684
685 void initializeCallbacks(Module &M);
686
687 bool LooksLikeCodeInBug11395(Instruction *I);
688 bool GlobalIsLinkerInitialized(GlobalVariable *G);
689 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
690 uint64_t TypeSize) const;
691
692 /// Helper to cleanup per-function state.
693 struct FunctionStateRAII {
694 AddressSanitizer *Pass;
695
696 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
697 assert(Pass->ProcessedAllocas.empty() &&((void)0)
698 "last pass forgot to clear cache")((void)0);
699 assert(!Pass->LocalDynamicShadow)((void)0);
700 }
701
702 ~FunctionStateRAII() {
703 Pass->LocalDynamicShadow = nullptr;
704 Pass->ProcessedAllocas.clear();
705 }
706 };
707
708 LLVMContext *C;
709 Triple TargetTriple;
710 int LongSize;
711 bool CompileKernel;
712 bool Recover;
713 bool UseAfterScope;
714 AsanDetectStackUseAfterReturnMode UseAfterReturn;
715 Type *IntptrTy;
716 ShadowMapping Mapping;
717 FunctionCallee AsanHandleNoReturnFunc;
718 FunctionCallee AsanPtrCmpFunction, AsanPtrSubFunction;
719 Constant *AsanShadowGlobal;
720
721 // These arrays is indexed by AccessIsWrite, Experiment and log2(AccessSize).
722 FunctionCallee AsanErrorCallback[2][2][kNumberOfAccessSizes];
723 FunctionCallee AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
724
725 // These arrays is indexed by AccessIsWrite and Experiment.
726 FunctionCallee AsanErrorCallbackSized[2][2];
727 FunctionCallee AsanMemoryAccessCallbackSized[2][2];
728
729 FunctionCallee AsanMemmove, AsanMemcpy, AsanMemset;
730 Value *LocalDynamicShadow = nullptr;
731 const GlobalsMetadata &GlobalsMD;
732 DenseMap<const AllocaInst *, bool> ProcessedAllocas;
733
734 FunctionCallee AMDGPUAddressShared;
735 FunctionCallee AMDGPUAddressPrivate;
736};
737
738class AddressSanitizerLegacyPass : public FunctionPass {
739public:
740 static char ID;
741
742 explicit AddressSanitizerLegacyPass(
743 bool CompileKernel = false, bool Recover = false,
744 bool UseAfterScope = false,
745 AsanDetectStackUseAfterReturnMode UseAfterReturn =
746 AsanDetectStackUseAfterReturnMode::Runtime)
747 : FunctionPass(ID), CompileKernel(CompileKernel), Recover(Recover),
748 UseAfterScope(UseAfterScope), UseAfterReturn(UseAfterReturn) {
749 initializeAddressSanitizerLegacyPassPass(*PassRegistry::getPassRegistry());
750 }
751
752 StringRef getPassName() const override {
753 return "AddressSanitizerFunctionPass";
754 }
755
756 void getAnalysisUsage(AnalysisUsage &AU) const override {
757 AU.addRequired<ASanGlobalsMetadataWrapperPass>();
758 AU.addRequired<TargetLibraryInfoWrapperPass>();
759 }
760
761 bool runOnFunction(Function &F) override {
762 GlobalsMetadata &GlobalsMD =
763 getAnalysis<ASanGlobalsMetadataWrapperPass>().getGlobalsMD();
764 const TargetLibraryInfo *TLI =
765 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
766 AddressSanitizer ASan(*F.getParent(), &GlobalsMD, CompileKernel, Recover,
767 UseAfterScope, UseAfterReturn);
768 return ASan.instrumentFunction(F, TLI);
769 }
770
771private:
772 bool CompileKernel;
773 bool Recover;
774 bool UseAfterScope;
775 AsanDetectStackUseAfterReturnMode UseAfterReturn;
776};
777
778class ModuleAddressSanitizer {
779public:
780 ModuleAddressSanitizer(Module &M, const GlobalsMetadata *GlobalsMD,
781 bool CompileKernel = false, bool Recover = false,
782 bool UseGlobalsGC = true, bool UseOdrIndicator = false,
783 AsanDtorKind DestructorKind = AsanDtorKind::Global)
784 : GlobalsMD(*GlobalsMD),
785 CompileKernel(ClEnableKasan.getNumOccurrences() > 0 ? ClEnableKasan
786 : CompileKernel),
787 Recover(ClRecover.getNumOccurrences() > 0 ? ClRecover : Recover),
788 UseGlobalsGC(UseGlobalsGC && ClUseGlobalsGC && !this->CompileKernel),
789 // Enable aliases as they should have no downside with ODR indicators.
790 UsePrivateAlias(UseOdrIndicator || ClUsePrivateAlias),
791 UseOdrIndicator(UseOdrIndicator || ClUseOdrIndicator),
792 // Not a typo: ClWithComdat is almost completely pointless without
793 // ClUseGlobalsGC (because then it only works on modules without
794 // globals, which are rare); it is a prerequisite for ClUseGlobalsGC;
795 // and both suffer from gold PR19002 for which UseGlobalsGC constructor
796 // argument is designed as workaround. Therefore, disable both
797 // ClWithComdat and ClUseGlobalsGC unless the frontend says it's ok to
798 // do globals-gc.
799 UseCtorComdat(UseGlobalsGC && ClWithComdat && !this->CompileKernel),
800 DestructorKind(DestructorKind) {
801 C = &(M.getContext());
802 int LongSize = M.getDataLayout().getPointerSizeInBits();
803 IntptrTy = Type::getIntNTy(*C, LongSize);
804 TargetTriple = Triple(M.getTargetTriple());
805 Mapping = getShadowMapping(TargetTriple, LongSize, this->CompileKernel);
806
807 if (ClOverrideDestructorKind != AsanDtorKind::Invalid)
808 this->DestructorKind = ClOverrideDestructorKind;
809 assert(this->DestructorKind != AsanDtorKind::Invalid)((void)0);
810 }
811
812 bool instrumentModule(Module &);
813
814private:
815 void initializeCallbacks(Module &M);
816
817 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat);
818 void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
819 ArrayRef<GlobalVariable *> ExtendedGlobals,
820 ArrayRef<Constant *> MetadataInitializers);
821 void InstrumentGlobalsELF(IRBuilder<> &IRB, Module &M,
822 ArrayRef<GlobalVariable *> ExtendedGlobals,
823 ArrayRef<Constant *> MetadataInitializers,
824 const std::string &UniqueModuleId);
825 void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
826 ArrayRef<GlobalVariable *> ExtendedGlobals,
827 ArrayRef<Constant *> MetadataInitializers);
828 void
829 InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M,
830 ArrayRef<GlobalVariable *> ExtendedGlobals,
831 ArrayRef<Constant *> MetadataInitializers);
832
833 GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
834 StringRef OriginalName);
835 void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata,
836 StringRef InternalSuffix);
837 Instruction *CreateAsanModuleDtor(Module &M);
838
839 const GlobalVariable *getExcludedAliasedGlobal(const GlobalAlias &GA) const;
840 bool shouldInstrumentGlobal(GlobalVariable *G) const;
841 bool ShouldUseMachOGlobalsSection() const;
842 StringRef getGlobalMetadataSection() const;
843 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
844 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
845 uint64_t getMinRedzoneSizeForGlobal() const {
846 return getRedzoneSizeForScale(Mapping.Scale);
847 }
848 uint64_t getRedzoneSizeForGlobal(uint64_t SizeInBytes) const;
849 int GetAsanVersion(const Module &M) const;
850
851 const GlobalsMetadata &GlobalsMD;
852 bool CompileKernel;
853 bool Recover;
854 bool UseGlobalsGC;
855 bool UsePrivateAlias;
856 bool UseOdrIndicator;
857 bool UseCtorComdat;
858 AsanDtorKind DestructorKind;
859 Type *IntptrTy;
860 LLVMContext *C;
861 Triple TargetTriple;
862 ShadowMapping Mapping;
863 FunctionCallee AsanPoisonGlobals;
864 FunctionCallee AsanUnpoisonGlobals;
865 FunctionCallee AsanRegisterGlobals;
866 FunctionCallee AsanUnregisterGlobals;
867 FunctionCallee AsanRegisterImageGlobals;
868 FunctionCallee AsanUnregisterImageGlobals;
869 FunctionCallee AsanRegisterElfGlobals;
870 FunctionCallee AsanUnregisterElfGlobals;
871
872 Function *AsanCtorFunction = nullptr;
873 Function *AsanDtorFunction = nullptr;
874};
875
876class ModuleAddressSanitizerLegacyPass : public ModulePass {
877public:
878 static char ID;
879
880 explicit ModuleAddressSanitizerLegacyPass(
881 bool CompileKernel = false, bool Recover = false, bool UseGlobalGC = true,
882 bool UseOdrIndicator = false,
883 AsanDtorKind DestructorKind = AsanDtorKind::Global)
884 : ModulePass(ID), CompileKernel(CompileKernel), Recover(Recover),
885 UseGlobalGC(UseGlobalGC), UseOdrIndicator(UseOdrIndicator),
886 DestructorKind(DestructorKind) {
887 initializeModuleAddressSanitizerLegacyPassPass(
888 *PassRegistry::getPassRegistry());
889 }
890
891 StringRef getPassName() const override { return "ModuleAddressSanitizer"; }
892
893 void getAnalysisUsage(AnalysisUsage &AU) const override {
894 AU.addRequired<ASanGlobalsMetadataWrapperPass>();
895 }
896
897 bool runOnModule(Module &M) override {
898 GlobalsMetadata &GlobalsMD =
899 getAnalysis<ASanGlobalsMetadataWrapperPass>().getGlobalsMD();
900 ModuleAddressSanitizer ASanModule(M, &GlobalsMD, CompileKernel, Recover,
901 UseGlobalGC, UseOdrIndicator,
902 DestructorKind);
903 return ASanModule.instrumentModule(M);
904 }
905
906private:
907 bool CompileKernel;
908 bool Recover;
909 bool UseGlobalGC;
910 bool UseOdrIndicator;
911 AsanDtorKind DestructorKind;
912};
913
914// Stack poisoning does not play well with exception handling.
915// When an exception is thrown, we essentially bypass the code
916// that unpoisones the stack. This is why the run-time library has
917// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
918// stack in the interceptor. This however does not work inside the
919// actual function which catches the exception. Most likely because the
920// compiler hoists the load of the shadow value somewhere too high.
921// This causes asan to report a non-existing bug on 453.povray.
922// It sounds like an LLVM bug.
923struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
924 Function &F;
925 AddressSanitizer &ASan;
926 DIBuilder DIB;
927 LLVMContext *C;
928 Type *IntptrTy;
929 Type *IntptrPtrTy;
930 ShadowMapping Mapping;
931
932 SmallVector<AllocaInst *, 16> AllocaVec;
933 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
934 SmallVector<Instruction *, 8> RetVec;
935
936 FunctionCallee AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
937 AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
938 FunctionCallee AsanSetShadowFunc[0x100] = {};
939 FunctionCallee AsanPoisonStackMemoryFunc, AsanUnpoisonStackMemoryFunc;
940 FunctionCallee AsanAllocaPoisonFunc, AsanAllocasUnpoisonFunc;
941
942 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
943 struct AllocaPoisonCall {
944 IntrinsicInst *InsBefore;
945 AllocaInst *AI;
946 uint64_t Size;
947 bool DoPoison;
948 };
949 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
950 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
951 bool HasUntracedLifetimeIntrinsic = false;
952
953 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
954 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
955 AllocaInst *DynamicAllocaLayout = nullptr;
956 IntrinsicInst *LocalEscapeCall = nullptr;
957
958 bool HasInlineAsm = false;
959 bool HasReturnsTwiceCall = false;
960 bool PoisonStack;
961
962 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
963 : F(F), ASan(ASan), DIB(*F.getParent(), /*AllowUnresolved*/ false),
964 C(ASan.C), IntptrTy(ASan.IntptrTy),
965 IntptrPtrTy(PointerType::get(IntptrTy, 0)), Mapping(ASan.Mapping),
966 PoisonStack(ClStack &&
967 !Triple(F.getParent()->getTargetTriple()).isAMDGPU()) {}
968
969 bool runOnFunction() {
970 if (!PoisonStack)
971 return false;
972
973 if (ClRedzoneByvalArgs)
974 copyArgsPassedByValToAllocas();
975
976 // Collect alloca, ret, lifetime instructions etc.
977 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
978
979 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
980
981 initializeCallbacks(*F.getParent());
982
983 if (HasUntracedLifetimeIntrinsic) {
984 // If there are lifetime intrinsics which couldn't be traced back to an
985 // alloca, we may not know exactly when a variable enters scope, and
986 // therefore should "fail safe" by not poisoning them.
987 StaticAllocaPoisonCallVec.clear();
988 DynamicAllocaPoisonCallVec.clear();
989 }
990
991 processDynamicAllocas();
992 processStaticAllocas();
993
994 if (ClDebugStack) {
995 LLVM_DEBUG(dbgs() << F)do { } while (false);
996 }
997 return true;
998 }
999
1000 // Arguments marked with the "byval" attribute are implicitly copied without
1001 // using an alloca instruction. To produce redzones for those arguments, we
1002 // copy them a second time into memory allocated with an alloca instruction.
1003 void copyArgsPassedByValToAllocas();
1004
1005 // Finds all Alloca instructions and puts
1006 // poisoned red zones around all of them.
1007 // Then unpoison everything back before the function returns.
1008 void processStaticAllocas();
1009 void processDynamicAllocas();
1010
1011 void createDynamicAllocasInitStorage();
1012
1013 // ----------------------- Visitors.
1014 /// Collect all Ret instructions, or the musttail call instruction if it
1015 /// precedes the return instruction.
1016 void visitReturnInst(ReturnInst &RI) {
1017 if (CallInst *CI = RI.getParent()->getTerminatingMustTailCall())
1018 RetVec.push_back(CI);
1019 else
1020 RetVec.push_back(&RI);
1021 }
1022
1023 /// Collect all Resume instructions.
1024 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
1025
1026 /// Collect all CatchReturnInst instructions.
1027 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
1028
1029 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
1030 Value *SavedStack) {
1031 IRBuilder<> IRB(InstBefore);
1032 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
1033 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
1034 // need to adjust extracted SP to compute the address of the most recent
1035 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
1036 // this purpose.
1037 if (!isa<ReturnInst>(InstBefore)) {
1038 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
1039 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
1040 {IntptrTy});
1041
1042 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
1043
1044 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
1045 DynamicAreaOffset);
1046 }
1047
1048 IRB.CreateCall(
1049 AsanAllocasUnpoisonFunc,
1050 {IRB.CreateLoad(IntptrTy, DynamicAllocaLayout), DynamicAreaPtr});
1051 }
1052
1053 // Unpoison dynamic allocas redzones.
1054 void unpoisonDynamicAllocas() {
1055 for (Instruction *Ret : RetVec)
1056 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
1057
1058 for (Instruction *StackRestoreInst : StackRestoreVec)
1059 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
1060 StackRestoreInst->getOperand(0));
1061 }
1062
1063 // Deploy and poison redzones around dynamic alloca call. To do this, we
1064 // should replace this call with another one with changed parameters and
1065 // replace all its uses with new address, so
1066 // addr = alloca type, old_size, align
1067 // is replaced by
1068 // new_size = (old_size + additional_size) * sizeof(type)
1069 // tmp = alloca i8, new_size, max(align, 32)
1070 // addr = tmp + 32 (first 32 bytes are for the left redzone).
1071 // Additional_size is added to make new memory allocation contain not only
1072 // requested memory, but also left, partial and right redzones.
1073 void handleDynamicAllocaCall(AllocaInst *AI);
1074
1075 /// Collect Alloca instructions we want (and can) handle.
1076 void visitAllocaInst(AllocaInst &AI) {
1077 if (!ASan.isInterestingAlloca(AI)) {
1078 if (AI.isStaticAlloca()) {
1079 // Skip over allocas that are present *before* the first instrumented
1080 // alloca, we don't want to move those around.
1081 if (AllocaVec.empty())
1082 return;
1083
1084 StaticAllocasToMoveUp.push_back(&AI);
1085 }
1086 return;
1087 }
1088
1089 if (!AI.isStaticAlloca())
1090 DynamicAllocaVec.push_back(&AI);
1091 else
1092 AllocaVec.push_back(&AI);
1093 }
1094
1095 /// Collect lifetime intrinsic calls to check for use-after-scope
1096 /// errors.
1097 void visitIntrinsicInst(IntrinsicInst &II) {
1098 Intrinsic::ID ID = II.getIntrinsicID();
1099 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
1
Assuming 'ID' is not equal to stackrestore
2
Taking false branch
1100 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
3
Assuming 'ID' is not equal to localescape
4
Taking false branch
1101 if (!ASan.UseAfterScope)
5
Assuming field 'UseAfterScope' is true
6
Taking false branch
1102 return;
1103 if (!II.isLifetimeStartOrEnd())
7
Assuming the condition is false
8
Taking false branch
1104 return;
1105 // Found lifetime intrinsic, add ASan instrumentation if necessary.
1106 auto *Size = cast<ConstantInt>(II.getArgOperand(0));
1107 // If size argument is undefined, don't do anything.
1108 if (Size->isMinusOne()) return;
9
Taking false branch
1109 // Check that size doesn't saturate uint64_t and can
1110 // be stored in IntptrTy.
1111 const uint64_t SizeValue = Size->getValue().getLimitedValue();
1112 if (SizeValue == ~0ULL ||
10
Assuming the condition is false
12
Taking false branch
1113 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
11
Assuming the condition is false
1114 return;
1115 // Find alloca instruction that corresponds to llvm.lifetime argument.
1116 // Currently we can only handle lifetime markers pointing to the
1117 // beginning of the alloca.
1118 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1), true);
1119 if (!AI) {
13
Assuming 'AI' is non-null
14
Taking false branch
1120 HasUntracedLifetimeIntrinsic = true;
1121 return;
1122 }
1123 // We're interested only in allocas we can handle.
1124 if (!ASan.isInterestingAlloca(*AI))
15
Calling 'AddressSanitizer::isInterestingAlloca'
1125 return;
1126 bool DoPoison = (ID == Intrinsic::lifetime_end);
1127 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
1128 if (AI->isStaticAlloca())
1129 StaticAllocaPoisonCallVec.push_back(APC);
1130 else if (ClInstrumentDynamicAllocas)
1131 DynamicAllocaPoisonCallVec.push_back(APC);
1132 }
1133
1134 void visitCallBase(CallBase &CB) {
1135 if (CallInst *CI = dyn_cast<CallInst>(&CB)) {
1136 HasInlineAsm |= CI->isInlineAsm() && &CB != ASan.LocalDynamicShadow;
1137 HasReturnsTwiceCall |= CI->canReturnTwice();
1138 }
1139 }
1140
1141 // ---------------------- Helpers.
1142 void initializeCallbacks(Module &M);
1143
1144 // Copies bytes from ShadowBytes into shadow memory for indexes where
1145 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
1146 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
1147 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
1148 IRBuilder<> &IRB, Value *ShadowBase);
1149 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
1150 size_t Begin, size_t End, IRBuilder<> &IRB,
1151 Value *ShadowBase);
1152 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
1153 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
1154 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
1155
1156 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
1157
1158 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
1159 bool Dynamic);
1160 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
1161 Instruction *ThenTerm, Value *ValueIfFalse);
1162};
1163
1164} // end anonymous namespace
1165
1166void LocationMetadata::parse(MDNode *MDN) {
1167 assert(MDN->getNumOperands() == 3)((void)0);
1168 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
1169 Filename = DIFilename->getString();
1170 LineNo = mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
1171 ColumnNo =
1172 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
1173}
1174
1175// FIXME: It would be cleaner to instead attach relevant metadata to the globals
1176// we want to sanitize instead and reading this metadata on each pass over a
1177// function instead of reading module level metadata at first.
1178GlobalsMetadata::GlobalsMetadata(Module &M) {
1179 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
1180 if (!Globals)
1181 return;
1182 for (auto MDN : Globals->operands()) {
1183 // Metadata node contains the global and the fields of "Entry".
1184 assert(MDN->getNumOperands() == 5)((void)0);
1185 auto *V = mdconst::extract_or_null<Constant>(MDN->getOperand(0));
1186 // The optimizer may optimize away a global entirely.
1187 if (!V)
1188 continue;
1189 auto *StrippedV = V->stripPointerCasts();
1190 auto *GV = dyn_cast<GlobalVariable>(StrippedV);
1191 if (!GV)
1192 continue;
1193 // We can already have an entry for GV if it was merged with another
1194 // global.
1195 Entry &E = Entries[GV];
1196 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
1197 E.SourceLoc.parse(Loc);
1198 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
1199 E.Name = Name->getString();
1200 ConstantInt *IsDynInit = mdconst::extract<ConstantInt>(MDN->getOperand(3));
1201 E.IsDynInit |= IsDynInit->isOne();
1202 ConstantInt *IsExcluded =
1203 mdconst::extract<ConstantInt>(MDN->getOperand(4));
1204 E.IsExcluded |= IsExcluded->isOne();
1205 }
1206}
1207
1208AnalysisKey ASanGlobalsMetadataAnalysis::Key;
1209
1210GlobalsMetadata ASanGlobalsMetadataAnalysis::run(Module &M,
1211 ModuleAnalysisManager &AM) {
1212 return GlobalsMetadata(M);
1213}
1214
1215AddressSanitizerPass::AddressSanitizerPass(
1216 bool CompileKernel, bool Recover, bool UseAfterScope,
1217 AsanDetectStackUseAfterReturnMode UseAfterReturn)
1218 : CompileKernel(CompileKernel), Recover(Recover),
1219 UseAfterScope(UseAfterScope), UseAfterReturn(UseAfterReturn) {}
1220
1221PreservedAnalyses AddressSanitizerPass::run(Function &F,
1222 AnalysisManager<Function> &AM) {
1223 auto &MAMProxy = AM.getResult<ModuleAnalysisManagerFunctionProxy>(F);
1224 Module &M = *F.getParent();
1225 if (auto *R = MAMProxy.getCachedResult<ASanGlobalsMetadataAnalysis>(M)) {
1226 const TargetLibraryInfo *TLI = &AM.getResult<TargetLibraryAnalysis>(F);
1227 AddressSanitizer Sanitizer(M, R, CompileKernel, Recover, UseAfterScope,
1228 UseAfterReturn);
1229 if (Sanitizer.instrumentFunction(F, TLI))
1230 return PreservedAnalyses::none();
1231 return PreservedAnalyses::all();
1232 }
1233
1234 report_fatal_error(
1235 "The ASanGlobalsMetadataAnalysis is required to run before "
1236 "AddressSanitizer can run");
1237 return PreservedAnalyses::all();
1238}
1239
1240ModuleAddressSanitizerPass::ModuleAddressSanitizerPass(
1241 bool CompileKernel, bool Recover, bool UseGlobalGC, bool UseOdrIndicator,
1242 AsanDtorKind DestructorKind)
1243 : CompileKernel(CompileKernel), Recover(Recover), UseGlobalGC(UseGlobalGC),
1244 UseOdrIndicator(UseOdrIndicator), DestructorKind(DestructorKind) {}
1245
1246PreservedAnalyses ModuleAddressSanitizerPass::run(Module &M,
1247 AnalysisManager<Module> &AM) {
1248 GlobalsMetadata &GlobalsMD = AM.getResult<ASanGlobalsMetadataAnalysis>(M);
1249 ModuleAddressSanitizer Sanitizer(M, &GlobalsMD, CompileKernel, Recover,
1250 UseGlobalGC, UseOdrIndicator,
1251 DestructorKind);
1252 if (Sanitizer.instrumentModule(M))
1253 return PreservedAnalyses::none();
1254 return PreservedAnalyses::all();
1255}
1256
1257INITIALIZE_PASS(ASanGlobalsMetadataWrapperPass, "asan-globals-md",static void *initializeASanGlobalsMetadataWrapperPassPassOnce
(PassRegistry &Registry) { PassInfo *PI = new PassInfo( "Read metadata to mark which globals should be instrumented "
"when running ASan.", "asan-globals-md", &ASanGlobalsMetadataWrapperPass
::ID, PassInfo::NormalCtor_t(callDefaultCtor<ASanGlobalsMetadataWrapperPass
>), false, true); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeASanGlobalsMetadataWrapperPassPassFlag
; void llvm::initializeASanGlobalsMetadataWrapperPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeASanGlobalsMetadataWrapperPassPassFlag
, initializeASanGlobalsMetadataWrapperPassPassOnce, std::ref(
Registry)); }
1258 "Read metadata to mark which globals should be instrumented "static void *initializeASanGlobalsMetadataWrapperPassPassOnce
(PassRegistry &Registry) { PassInfo *PI = new PassInfo( "Read metadata to mark which globals should be instrumented "
"when running ASan.", "asan-globals-md", &ASanGlobalsMetadataWrapperPass
::ID, PassInfo::NormalCtor_t(callDefaultCtor<ASanGlobalsMetadataWrapperPass
>), false, true); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeASanGlobalsMetadataWrapperPassPassFlag
; void llvm::initializeASanGlobalsMetadataWrapperPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeASanGlobalsMetadataWrapperPassPassFlag
, initializeASanGlobalsMetadataWrapperPassPassOnce, std::ref(
Registry)); }
1259 "when running ASan.",static void *initializeASanGlobalsMetadataWrapperPassPassOnce
(PassRegistry &Registry) { PassInfo *PI = new PassInfo( "Read metadata to mark which globals should be instrumented "
"when running ASan.", "asan-globals-md", &ASanGlobalsMetadataWrapperPass
::ID, PassInfo::NormalCtor_t(callDefaultCtor<ASanGlobalsMetadataWrapperPass
>), false, true); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeASanGlobalsMetadataWrapperPassPassFlag
; void llvm::initializeASanGlobalsMetadataWrapperPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeASanGlobalsMetadataWrapperPassPassFlag
, initializeASanGlobalsMetadataWrapperPassPassOnce, std::ref(
Registry)); }
1260 false, true)static void *initializeASanGlobalsMetadataWrapperPassPassOnce
(PassRegistry &Registry) { PassInfo *PI = new PassInfo( "Read metadata to mark which globals should be instrumented "
"when running ASan.", "asan-globals-md", &ASanGlobalsMetadataWrapperPass
::ID, PassInfo::NormalCtor_t(callDefaultCtor<ASanGlobalsMetadataWrapperPass
>), false, true); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeASanGlobalsMetadataWrapperPassPassFlag
; void llvm::initializeASanGlobalsMetadataWrapperPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeASanGlobalsMetadataWrapperPassPassFlag
, initializeASanGlobalsMetadataWrapperPassPassOnce, std::ref(
Registry)); }
1261
1262char AddressSanitizerLegacyPass::ID = 0;
1263
1264INITIALIZE_PASS_BEGIN(static void *initializeAddressSanitizerLegacyPassPassOnce(PassRegistry
&Registry) {
1265 AddressSanitizerLegacyPass, "asan",static void *initializeAddressSanitizerLegacyPassPassOnce(PassRegistry
&Registry) {
1266 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,static void *initializeAddressSanitizerLegacyPassPassOnce(PassRegistry
&Registry) {
1267 false)static void *initializeAddressSanitizerLegacyPassPassOnce(PassRegistry
&Registry) {
1268INITIALIZE_PASS_DEPENDENCY(ASanGlobalsMetadataWrapperPass)initializeASanGlobalsMetadataWrapperPassPass(Registry);
1269INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)initializeTargetLibraryInfoWrapperPassPass(Registry);
1270INITIALIZE_PASS_END(PassInfo *PI = new PassInfo( "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
, "asan", &AddressSanitizerLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<AddressSanitizerLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeAddressSanitizerLegacyPassPassFlag; void
llvm::initializeAddressSanitizerLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeAddressSanitizerLegacyPassPassFlag
, initializeAddressSanitizerLegacyPassPassOnce, std::ref(Registry
)); }
1271 AddressSanitizerLegacyPass, "asan",PassInfo *PI = new PassInfo( "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
, "asan", &AddressSanitizerLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<AddressSanitizerLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeAddressSanitizerLegacyPassPassFlag; void
llvm::initializeAddressSanitizerLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeAddressSanitizerLegacyPassPassFlag
, initializeAddressSanitizerLegacyPassPassOnce, std::ref(Registry
)); }
1272 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,PassInfo *PI = new PassInfo( "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
, "asan", &AddressSanitizerLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<AddressSanitizerLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeAddressSanitizerLegacyPassPassFlag; void
llvm::initializeAddressSanitizerLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeAddressSanitizerLegacyPassPassFlag
, initializeAddressSanitizerLegacyPassPassOnce, std::ref(Registry
)); }
1273 false)PassInfo *PI = new PassInfo( "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
, "asan", &AddressSanitizerLegacyPass::ID, PassInfo::NormalCtor_t
(callDefaultCtor<AddressSanitizerLegacyPass>), false, false
); Registry.registerPass(*PI, true); return PI; } static llvm
::once_flag InitializeAddressSanitizerLegacyPassPassFlag; void
llvm::initializeAddressSanitizerLegacyPassPass(PassRegistry &
Registry) { llvm::call_once(InitializeAddressSanitizerLegacyPassPassFlag
, initializeAddressSanitizerLegacyPassPassOnce, std::ref(Registry
)); }
1274
1275FunctionPass *llvm::createAddressSanitizerFunctionPass(
1276 bool CompileKernel, bool Recover, bool UseAfterScope,
1277 AsanDetectStackUseAfterReturnMode UseAfterReturn) {
1278 assert(!CompileKernel || Recover)((void)0);
1279 return new AddressSanitizerLegacyPass(CompileKernel, Recover, UseAfterScope,
1280 UseAfterReturn);
1281}
1282
1283char ModuleAddressSanitizerLegacyPass::ID = 0;
1284
1285INITIALIZE_PASS(static void *initializeModuleAddressSanitizerLegacyPassPassOnce
(PassRegistry &Registry) { PassInfo *PI = new PassInfo( "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
"ModulePass", "asan-module", &ModuleAddressSanitizerLegacyPass
::ID, PassInfo::NormalCtor_t(callDefaultCtor<ModuleAddressSanitizerLegacyPass
>), false, false); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeModuleAddressSanitizerLegacyPassPassFlag
; void llvm::initializeModuleAddressSanitizerLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeModuleAddressSanitizerLegacyPassPassFlag
, initializeModuleAddressSanitizerLegacyPassPassOnce, std::ref
(Registry)); }
1286 ModuleAddressSanitizerLegacyPass, "asan-module",static void *initializeModuleAddressSanitizerLegacyPassPassOnce
(PassRegistry &Registry) { PassInfo *PI = new PassInfo( "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
"ModulePass", "asan-module", &ModuleAddressSanitizerLegacyPass
::ID, PassInfo::NormalCtor_t(callDefaultCtor<ModuleAddressSanitizerLegacyPass
>), false, false); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeModuleAddressSanitizerLegacyPassPassFlag
; void llvm::initializeModuleAddressSanitizerLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeModuleAddressSanitizerLegacyPassPassFlag
, initializeModuleAddressSanitizerLegacyPassPassOnce, std::ref
(Registry)); }
1287 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."static void *initializeModuleAddressSanitizerLegacyPassPassOnce
(PassRegistry &Registry) { PassInfo *PI = new PassInfo( "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
"ModulePass", "asan-module", &ModuleAddressSanitizerLegacyPass
::ID, PassInfo::NormalCtor_t(callDefaultCtor<ModuleAddressSanitizerLegacyPass
>), false, false); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeModuleAddressSanitizerLegacyPassPassFlag
; void llvm::initializeModuleAddressSanitizerLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeModuleAddressSanitizerLegacyPassPassFlag
, initializeModuleAddressSanitizerLegacyPassPassOnce, std::ref
(Registry)); }
1288 "ModulePass",static void *initializeModuleAddressSanitizerLegacyPassPassOnce
(PassRegistry &Registry) { PassInfo *PI = new PassInfo( "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
"ModulePass", "asan-module", &ModuleAddressSanitizerLegacyPass
::ID, PassInfo::NormalCtor_t(callDefaultCtor<ModuleAddressSanitizerLegacyPass
>), false, false); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeModuleAddressSanitizerLegacyPassPassFlag
; void llvm::initializeModuleAddressSanitizerLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeModuleAddressSanitizerLegacyPassPassFlag
, initializeModuleAddressSanitizerLegacyPassPassOnce, std::ref
(Registry)); }
1289 false, false)static void *initializeModuleAddressSanitizerLegacyPassPassOnce
(PassRegistry &Registry) { PassInfo *PI = new PassInfo( "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
"ModulePass", "asan-module", &ModuleAddressSanitizerLegacyPass
::ID, PassInfo::NormalCtor_t(callDefaultCtor<ModuleAddressSanitizerLegacyPass
>), false, false); Registry.registerPass(*PI, true); return
PI; } static llvm::once_flag InitializeModuleAddressSanitizerLegacyPassPassFlag
; void llvm::initializeModuleAddressSanitizerLegacyPassPass(PassRegistry
&Registry) { llvm::call_once(InitializeModuleAddressSanitizerLegacyPassPassFlag
, initializeModuleAddressSanitizerLegacyPassPassOnce, std::ref
(Registry)); }
1290
1291ModulePass *llvm::createModuleAddressSanitizerLegacyPassPass(
1292 bool CompileKernel, bool Recover, bool UseGlobalsGC, bool UseOdrIndicator,
1293 AsanDtorKind Destructor) {
1294 assert(!CompileKernel || Recover)((void)0);
1295 return new ModuleAddressSanitizerLegacyPass(
1296 CompileKernel, Recover, UseGlobalsGC, UseOdrIndicator, Destructor);
1297}
1298
1299static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
1300 size_t Res = countTrailingZeros(TypeSize / 8);
1301 assert(Res < kNumberOfAccessSizes)((void)0);
1302 return Res;
1303}
1304
1305/// Create a global describing a source location.
1306static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
1307 LocationMetadata MD) {
1308 Constant *LocData[] = {
1309 createPrivateGlobalForString(M, MD.Filename, true, kAsanGenPrefix),
1310 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
1311 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
1312 };
1313 auto LocStruct = ConstantStruct::getAnon(LocData);
1314 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
1315 GlobalValue::PrivateLinkage, LocStruct,
1316 kAsanGenPrefix);
1317 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
1318 return GV;
1319}
1320
1321/// Check if \p G has been created by a trusted compiler pass.
1322static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
1323 // Do not instrument @llvm.global_ctors, @llvm.used, etc.
1324 if (G->getName().startswith("llvm."))
1325 return true;
1326
1327 // Do not instrument asan globals.
1328 if (G->getName().startswith(kAsanGenPrefix) ||
1329 G->getName().startswith(kSanCovGenPrefix) ||
1330 G->getName().startswith(kODRGenPrefix))
1331 return true;
1332
1333 // Do not instrument gcov counter arrays.
1334 if (G->getName() == "__llvm_gcov_ctr")
1335 return true;
1336
1337 return false;
1338}
1339
1340static bool isUnsupportedAMDGPUAddrspace(Value *Addr) {
1341 Type *PtrTy = cast<PointerType>(Addr->getType()->getScalarType());
1342 unsigned int AddrSpace = PtrTy->getPointerAddressSpace();
1343 if (AddrSpace == 3 || AddrSpace == 5)
1344 return true;
1345 return false;
1346}
1347
1348Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
1349 // Shadow >> scale
1350 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
1351 if (Mapping.Offset == 0) return Shadow;
1352 // (Shadow >> scale) | offset
1353 Value *ShadowBase;
1354 if (LocalDynamicShadow)
1355 ShadowBase = LocalDynamicShadow;
1356 else
1357 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
1358 if (Mapping.OrShadowOffset)
1359 return IRB.CreateOr(Shadow, ShadowBase);
1360 else
1361 return IRB.CreateAdd(Shadow, ShadowBase);
1362}
1363
1364// Instrument memset/memmove/memcpy
1365void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
1366 IRBuilder<> IRB(MI);
1367 if (isa<MemTransferInst>(MI)) {
1368 IRB.CreateCall(
1369 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
1370 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1371 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
1372 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1373 } else if (isa<MemSetInst>(MI)) {
1374 IRB.CreateCall(
1375 AsanMemset,
1376 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1377 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
1378 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1379 }
1380 MI->eraseFromParent();
1381}
1382
1383/// Check if we want (and can) handle this alloca.
1384bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
1385 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
1386
1387 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
16
Taking false branch
1388 return PreviouslySeenAllocaInfo->getSecond();
1389
1390 bool IsInteresting =
1391 (AI.getAllocatedType()->isSized() &&
1392 // alloca() may be called with 0 size, ignore it.
1393 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
17
Assuming the condition is false
18
Calling 'AddressSanitizer::getAllocaSizeInBytes'
1394 // We are only interested in allocas not promotable to registers.
1395 // Promotable allocas are common under -O0.
1396 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
1397 // inalloca allocas are not treated as static, and we don't want
1398 // dynamic alloca instrumentation for them as well.
1399 !AI.isUsedWithInAlloca() &&
1400 // swifterror allocas are register promoted by ISel
1401 !AI.isSwiftError());
1402
1403 ProcessedAllocas[&AI] = IsInteresting;
1404 return IsInteresting;
1405}
1406
1407bool AddressSanitizer::ignoreAccess(Value *Ptr) {
1408 // Instrument acesses from different address spaces only for AMDGPU.
1409 Type *PtrTy = cast<PointerType>(Ptr->getType()->getScalarType());
1410 if (PtrTy->getPointerAddressSpace() != 0 &&
1411 !(TargetTriple.isAMDGPU() && !isUnsupportedAMDGPUAddrspace(Ptr)))
1412 return true;
1413
1414 // Ignore swifterror addresses.
1415 // swifterror memory addresses are mem2reg promoted by instruction
1416 // selection. As such they cannot have regular uses like an instrumentation
1417 // function and it makes no sense to track them as memory.
1418 if (Ptr->isSwiftError())
1419 return true;
1420
1421 // Treat memory accesses to promotable allocas as non-interesting since they
1422 // will not cause memory violations. This greatly speeds up the instrumented
1423 // executable at -O0.
1424 if (auto AI = dyn_cast_or_null<AllocaInst>(Ptr))
1425 if (ClSkipPromotableAllocas && !isInterestingAlloca(*AI))
1426 return true;
1427
1428 return false;
1429}
1430
1431void AddressSanitizer::getInterestingMemoryOperands(
1432 Instruction *I, SmallVectorImpl<InterestingMemoryOperand> &Interesting) {
1433 // Skip memory accesses inserted by another instrumentation.
1434 if (I->hasMetadata("nosanitize"))
1435 return;
1436
1437 // Do not instrument the load fetching the dynamic shadow address.
1438 if (LocalDynamicShadow == I)
1439 return;
1440
1441 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1442 if (!ClInstrumentReads || ignoreAccess(LI->getPointerOperand()))
1443 return;
1444 Interesting.emplace_back(I, LI->getPointerOperandIndex(), false,
1445 LI->getType(), LI->getAlign());
1446 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1447 if (!ClInstrumentWrites || ignoreAccess(SI->getPointerOperand()))
1448 return;
1449 Interesting.emplace_back(I, SI->getPointerOperandIndex(), true,
1450 SI->getValueOperand()->getType(), SI->getAlign());
1451 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1452 if (!ClInstrumentAtomics || ignoreAccess(RMW->getPointerOperand()))
1453 return;
1454 Interesting.emplace_back(I, RMW->getPointerOperandIndex(), true,
1455 RMW->getValOperand()->getType(), None);
1456 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1457 if (!ClInstrumentAtomics || ignoreAccess(XCHG->getPointerOperand()))
1458 return;
1459 Interesting.emplace_back(I, XCHG->getPointerOperandIndex(), true,
1460 XCHG->getCompareOperand()->getType(), None);
1461 } else if (auto CI = dyn_cast<CallInst>(I)) {
1462 auto *F = CI->getCalledFunction();
1463 if (F && (F->getName().startswith("llvm.masked.load.") ||
1464 F->getName().startswith("llvm.masked.store."))) {
1465 bool IsWrite = F->getName().startswith("llvm.masked.store.");
1466 // Masked store has an initial operand for the value.
1467 unsigned OpOffset = IsWrite ? 1 : 0;
1468 if (IsWrite ? !ClInstrumentWrites : !ClInstrumentReads)
1469 return;
1470
1471 auto BasePtr = CI->getOperand(OpOffset);
1472 if (ignoreAccess(BasePtr))
1473 return;
1474 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1475 MaybeAlign Alignment = Align(1);
1476 // Otherwise no alignment guarantees. We probably got Undef.
1477 if (auto *Op = dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1478 Alignment = Op->getMaybeAlignValue();
1479 Value *Mask = CI->getOperand(2 + OpOffset);
1480 Interesting.emplace_back(I, OpOffset, IsWrite, Ty, Alignment, Mask);
1481 } else {
1482 for (unsigned ArgNo = 0; ArgNo < CI->getNumArgOperands(); ArgNo++) {
1483 if (!ClInstrumentByval || !CI->isByValArgument(ArgNo) ||
1484 ignoreAccess(CI->getArgOperand(ArgNo)))
1485 continue;
1486 Type *Ty = CI->getParamByValType(ArgNo);
1487 Interesting.emplace_back(I, ArgNo, false, Ty, Align(1));
1488 }
1489 }
1490 }
1491}
1492
1493static bool isPointerOperand(Value *V) {
1494 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1495}
1496
1497// This is a rough heuristic; it may cause both false positives and
1498// false negatives. The proper implementation requires cooperation with
1499// the frontend.
1500static bool isInterestingPointerComparison(Instruction *I) {
1501 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1502 if (!Cmp->isRelational())
1503 return false;
1504 } else {
1505 return false;
1506 }
1507 return isPointerOperand(I->getOperand(0)) &&
1508 isPointerOperand(I->getOperand(1));
1509}
1510
1511// This is a rough heuristic; it may cause both false positives and
1512// false negatives. The proper implementation requires cooperation with
1513// the frontend.
1514static bool isInterestingPointerSubtraction(Instruction *I) {
1515 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1516 if (BO->getOpcode() != Instruction::Sub)
1517 return false;
1518 } else {
1519 return false;
1520 }
1521 return isPointerOperand(I->getOperand(0)) &&
1522 isPointerOperand(I->getOperand(1));
1523}
1524
1525bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1526 // If a global variable does not have dynamic initialization we don't
1527 // have to instrument it. However, if a global does not have initializer
1528 // at all, we assume it has dynamic initializer (in other TU).
1529 //
1530 // FIXME: Metadata should be attched directly to the global directly instead
1531 // of being added to llvm.asan.globals.
1532 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1533}
1534
1535void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1536 Instruction *I) {
1537 IRBuilder<> IRB(I);
1538 FunctionCallee F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1539 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1540 for (Value *&i : Param) {
1541 if (i->getType()->isPointerTy())
1542 i = IRB.CreatePointerCast(i, IntptrTy);
1543 }
1544 IRB.CreateCall(F, Param);
1545}
1546
1547static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1548 Instruction *InsertBefore, Value *Addr,
1549 MaybeAlign Alignment, unsigned Granularity,
1550 uint32_t TypeSize, bool IsWrite,
1551 Value *SizeArgument, bool UseCalls,
1552 uint32_t Exp) {
1553 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1554 // if the data is properly aligned.
1555 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1556 TypeSize == 128) &&
1557 (!Alignment || *Alignment >= Granularity || *Alignment >= TypeSize / 8))
1558 return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
1559 nullptr, UseCalls, Exp);
1560 Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
1561 IsWrite, nullptr, UseCalls, Exp);
1562}
1563
1564static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1565 const DataLayout &DL, Type *IntptrTy,
1566 Value *Mask, Instruction *I,
1567 Value *Addr, MaybeAlign Alignment,
1568 unsigned Granularity, uint32_t TypeSize,
1569 bool IsWrite, Value *SizeArgument,
1570 bool UseCalls, uint32_t Exp) {
1571 auto *VTy = cast<FixedVectorType>(
1572 cast<PointerType>(Addr->getType())->getElementType());
1573 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1574 unsigned Num = VTy->getNumElements();
1575 auto Zero = ConstantInt::get(IntptrTy, 0);
1576 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1577 Value *InstrumentedAddress = nullptr;
1578 Instruction *InsertBefore = I;
1579 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
1580 // dyn_cast as we might get UndefValue
1581 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
1582 if (Masked->isZero())
1583 // Mask is constant false, so no instrumentation needed.
1584 continue;
1585 // If we have a true or undef value, fall through to doInstrumentAddress
1586 // with InsertBefore == I
1587 }
1588 } else {
1589 IRBuilder<> IRB(I);
1590 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
1591 Instruction *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
1592 InsertBefore = ThenTerm;
1593 }
1594
1595 IRBuilder<> IRB(InsertBefore);
1596 InstrumentedAddress =
1597 IRB.CreateGEP(VTy, Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1598 doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
1599 Granularity, ElemTypeSize, IsWrite, SizeArgument,
1600 UseCalls, Exp);
1601 }
1602}
1603
1604void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1605 InterestingMemoryOperand &O, bool UseCalls,
1606 const DataLayout &DL) {
1607 Value *Addr = O.getPtr();
1608
1609 // Optimization experiments.
1610 // The experiments can be used to evaluate potential optimizations that remove
1611 // instrumentation (assess false negatives). Instead of completely removing
1612 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1613 // experiments that want to remove instrumentation of this instruction).
1614 // If Exp is non-zero, this pass will emit special calls into runtime
1615 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1616 // make runtime terminate the program in a special way (with a different
1617 // exit status). Then you run the new compiler on a buggy corpus, collect
1618 // the special terminations (ideally, you don't see them at all -- no false
1619 // negatives) and make the decision on the optimization.
1620 uint32_t Exp = ClForceExperiment;
1621
1622 if (ClOpt && ClOptGlobals) {
1623 // If initialization order checking is disabled, a simple access to a
1624 // dynamically initialized global is always valid.
1625 GlobalVariable *G = dyn_cast<GlobalVariable>(getUnderlyingObject(Addr));
1626 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1627 isSafeAccess(ObjSizeVis, Addr, O.TypeSize)) {
1628 NumOptimizedAccessesToGlobalVar++;
1629 return;
1630 }
1631 }
1632
1633 if (ClOpt && ClOptStack) {
1634 // A direct inbounds access to a stack variable is always valid.
1635 if (isa<AllocaInst>(getUnderlyingObject(Addr)) &&
1636 isSafeAccess(ObjSizeVis, Addr, O.TypeSize)) {
1637 NumOptimizedAccessesToStackVar++;
1638 return;
1639 }
1640 }
1641
1642 if (O.IsWrite)
1643 NumInstrumentedWrites++;
1644 else
1645 NumInstrumentedReads++;
1646
1647 unsigned Granularity = 1 << Mapping.Scale;
1648 if (O.MaybeMask) {
1649 instrumentMaskedLoadOrStore(this, DL, IntptrTy, O.MaybeMask, O.getInsn(),
1650 Addr, O.Alignment, Granularity, O.TypeSize,
1651 O.IsWrite, nullptr, UseCalls, Exp);
1652 } else {
1653 doInstrumentAddress(this, O.getInsn(), O.getInsn(), Addr, O.Alignment,
1654 Granularity, O.TypeSize, O.IsWrite, nullptr, UseCalls,
1655 Exp);
1656 }
1657}
1658
1659Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1660 Value *Addr, bool IsWrite,
1661 size_t AccessSizeIndex,
1662 Value *SizeArgument,
1663 uint32_t Exp) {
1664 IRBuilder<> IRB(InsertBefore);
1665 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1666 CallInst *Call = nullptr;
1667 if (SizeArgument) {
1668 if (Exp == 0)
1669 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1670 {Addr, SizeArgument});
1671 else
1672 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1673 {Addr, SizeArgument, ExpVal});
1674 } else {
1675 if (Exp == 0)
1676 Call =
1677 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1678 else
1679 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1680 {Addr, ExpVal});
1681 }
1682
1683 Call->setCannotMerge();
1684 return Call;
1685}
1686
1687Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1688 Value *ShadowValue,
1689 uint32_t TypeSize) {
1690 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1691 // Addr & (Granularity - 1)
1692 Value *LastAccessedByte =
1693 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1694 // (Addr & (Granularity - 1)) + size - 1
1695 if (TypeSize / 8 > 1)
1696 LastAccessedByte = IRB.CreateAdd(
1697 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1698 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1699 LastAccessedByte =
1700 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1701 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1702 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1703}
1704
1705Instruction *AddressSanitizer::instrumentAMDGPUAddress(
1706 Instruction *OrigIns, Instruction *InsertBefore, Value *Addr,
1707 uint32_t TypeSize, bool IsWrite, Value *SizeArgument) {
1708 // Do not instrument unsupported addrspaces.
1709 if (isUnsupportedAMDGPUAddrspace(Addr))
1710 return nullptr;
1711 Type *PtrTy = cast<PointerType>(Addr->getType()->getScalarType());
1712 // Follow host instrumentation for global and constant addresses.
1713 if (PtrTy->getPointerAddressSpace() != 0)
1714 return InsertBefore;
1715 // Instrument generic addresses in supported addressspaces.
1716 IRBuilder<> IRB(InsertBefore);
1717 Value *AddrLong = IRB.CreatePointerCast(Addr, IRB.getInt8PtrTy());
1718 Value *IsShared = IRB.CreateCall(AMDGPUAddressShared, {AddrLong});
1719 Value *IsPrivate = IRB.CreateCall(AMDGPUAddressPrivate, {AddrLong});
1720 Value *IsSharedOrPrivate = IRB.CreateOr(IsShared, IsPrivate);
1721 Value *Cmp = IRB.CreateICmpNE(IRB.getTrue(), IsSharedOrPrivate);
1722 Value *AddrSpaceZeroLanding =
1723 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
1724 InsertBefore = cast<Instruction>(AddrSpaceZeroLanding);
1725 return InsertBefore;
1726}
1727
1728void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1729 Instruction *InsertBefore, Value *Addr,
1730 uint32_t TypeSize, bool IsWrite,
1731 Value *SizeArgument, bool UseCalls,
1732 uint32_t Exp) {
1733 if (TargetTriple.isAMDGPU()) {
1734 InsertBefore = instrumentAMDGPUAddress(OrigIns, InsertBefore, Addr,
1735 TypeSize, IsWrite, SizeArgument);
1736 if (!InsertBefore)
1737 return;
1738 }
1739
1740 IRBuilder<> IRB(InsertBefore);
1741 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1742 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1743
1744 if (UseCalls) {
1745 if (Exp == 0)
1746 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1747 AddrLong);
1748 else
1749 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1750 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1751 return;
1752 }
1753
1754 Type *ShadowTy =
1755 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1756 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1757 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1758 Value *CmpVal = Constant::getNullValue(ShadowTy);
1759 Value *ShadowValue =
1760 IRB.CreateLoad(ShadowTy, IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1761
1762 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1763 size_t Granularity = 1ULL << Mapping.Scale;
1764 Instruction *CrashTerm = nullptr;
1765
1766 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1767 // We use branch weights for the slow path check, to indicate that the slow
1768 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1769 Instruction *CheckTerm = SplitBlockAndInsertIfThen(
1770 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1771 assert(cast<BranchInst>(CheckTerm)->isUnconditional())((void)0);
1772 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1773 IRB.SetInsertPoint(CheckTerm);
1774 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1775 if (Recover) {
1776 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1777 } else {
1778 BasicBlock *CrashBlock =
1779 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1780 CrashTerm = new UnreachableInst(*C, CrashBlock);
1781 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1782 ReplaceInstWithInst(CheckTerm, NewTerm);
1783 }
1784 } else {
1785 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1786 }
1787
1788 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1789 AccessSizeIndex, SizeArgument, Exp);
1790 Crash->setDebugLoc(OrigIns->getDebugLoc());
1791}
1792
1793// Instrument unusual size or unusual alignment.
1794// We can not do it with a single check, so we do 1-byte check for the first
1795// and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1796// to report the actual access size.
1797void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1798 Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
1799 bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1800 IRBuilder<> IRB(InsertBefore);
1801 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1802 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1803 if (UseCalls) {
1804 if (Exp == 0)
1805 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1806 {AddrLong, Size});
1807 else
1808 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1809 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1810 } else {
1811 Value *LastByte = IRB.CreateIntToPtr(
1812 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1813 Addr->getType());
1814 instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
1815 instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
1816 }
1817}
1818
1819void ModuleAddressSanitizer::poisonOneInitializer(Function &GlobalInit,
1820 GlobalValue *ModuleName) {
1821 // Set up the arguments to our poison/unpoison functions.
1822 IRBuilder<> IRB(&GlobalInit.front(),
1823 GlobalInit.front().getFirstInsertionPt());
1824
1825 // Add a call to poison all external globals before the given function starts.
1826 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1827 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1828
1829 // Add calls to unpoison all globals before each return instruction.
1830 for (auto &BB : GlobalInit.getBasicBlockList())
1831 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1832 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1833}
1834
1835void ModuleAddressSanitizer::createInitializerPoisonCalls(
1836 Module &M, GlobalValue *ModuleName) {
1837 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1838 if (!GV)
1839 return;
1840
1841 ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
1842 if (!CA)
1843 return;
1844
1845 for (Use &OP : CA->operands()) {
1846 if (isa<ConstantAggregateZero>(OP)) continue;
1847 ConstantStruct *CS = cast<ConstantStruct>(OP);
1848
1849 // Must have a function or null ptr.
1850 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1851 if (F->getName() == kAsanModuleCtorName) continue;
1852 auto *Priority = cast<ConstantInt>(CS->getOperand(0));
1853 // Don't instrument CTORs that will run before asan.module_ctor.
1854 if (Priority->getLimitedValue() <= GetCtorAndDtorPriority(TargetTriple))
1855 continue;
1856 poisonOneInitializer(*F, ModuleName);
1857 }
1858 }
1859}
1860
1861const GlobalVariable *
1862ModuleAddressSanitizer::getExcludedAliasedGlobal(const GlobalAlias &GA) const {
1863 // In case this function should be expanded to include rules that do not just
1864 // apply when CompileKernel is true, either guard all existing rules with an
1865 // 'if (CompileKernel) { ... }' or be absolutely sure that all these rules
1866 // should also apply to user space.
1867 assert(CompileKernel && "Only expecting to be called when compiling kernel")((void)0);
1868
1869 const Constant *C = GA.getAliasee();
1870
1871 // When compiling the kernel, globals that are aliased by symbols prefixed
1872 // by "__" are special and cannot be padded with a redzone.
1873 if (GA.getName().startswith("__"))
1874 return dyn_cast<GlobalVariable>(C->stripPointerCastsAndAliases());
1875
1876 return nullptr;
1877}
1878
1879bool ModuleAddressSanitizer::shouldInstrumentGlobal(GlobalVariable *G) const {
1880 Type *Ty = G->getValueType();
1881 LLVM_DEBUG(dbgs() << "GLOBAL: " << *G << "\n")do { } while (false);
1882
1883 // FIXME: Metadata should be attched directly to the global directly instead
1884 // of being added to llvm.asan.globals.
1885 if (GlobalsMD.get(G).IsExcluded) return false;
1886 if (!Ty->isSized()) return false;
1887 if (!G->hasInitializer()) return false;
1888 // Globals in address space 1 and 4 are supported for AMDGPU.
1889 if (G->getAddressSpace() &&
1890 !(TargetTriple.isAMDGPU() && !isUnsupportedAMDGPUAddrspace(G)))
1891 return false;
1892 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1893 // Two problems with thread-locals:
1894 // - The address of the main thread's copy can't be computed at link-time.
1895 // - Need to poison all copies, not just the main thread's one.
1896 if (G->isThreadLocal()) return false;
1897 // For now, just ignore this Global if the alignment is large.
1898 if (G->getAlignment() > getMinRedzoneSizeForGlobal()) return false;
1899
1900 // For non-COFF targets, only instrument globals known to be defined by this
1901 // TU.
1902 // FIXME: We can instrument comdat globals on ELF if we are using the
1903 // GC-friendly metadata scheme.
1904 if (!TargetTriple.isOSBinFormatCOFF()) {
1905 if (!G->hasExactDefinition() || G->hasComdat())
1906 return false;
1907 } else {
1908 // On COFF, don't instrument non-ODR linkages.
1909 if (G->isInterposable())
1910 return false;
1911 }
1912
1913 // If a comdat is present, it must have a selection kind that implies ODR
1914 // semantics: no duplicates, any, or exact match.
1915 if (Comdat *C = G->getComdat()) {
1916 switch (C->getSelectionKind()) {
1917 case Comdat::Any:
1918 case Comdat::ExactMatch:
1919 case Comdat::NoDeduplicate:
1920 break;
1921 case Comdat::Largest:
1922 case Comdat::SameSize:
1923 return false;
1924 }
1925 }
1926
1927 if (G->hasSection()) {
1928 // The kernel uses explicit sections for mostly special global variables
1929 // that we should not instrument. E.g. the kernel may rely on their layout
1930 // without redzones, or remove them at link time ("discard.*"), etc.
1931 if (CompileKernel)
1932 return false;
1933
1934 StringRef Section = G->getSection();
1935
1936 // Globals from llvm.metadata aren't emitted, do not instrument them.
1937 if (Section == "llvm.metadata") return false;
1938 // Do not instrument globals from special LLVM sections.
1939 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1940
1941 // Do not instrument function pointers to initialization and termination
1942 // routines: dynamic linker will not properly handle redzones.
1943 if (Section.startswith(".preinit_array") ||
1944 Section.startswith(".init_array") ||
1945 Section.startswith(".fini_array")) {
1946 return false;
1947 }
1948
1949 // Do not instrument user-defined sections (with names resembling
1950 // valid C identifiers)
1951 if (TargetTriple.isOSBinFormatELF()) {
1952 if (llvm::all_of(Section,
1953 [](char c) { return llvm::isAlnum(c) || c == '_'; }))
1954 return false;
1955 }
1956
1957 // On COFF, if the section name contains '$', it is highly likely that the
1958 // user is using section sorting to create an array of globals similar to
1959 // the way initialization callbacks are registered in .init_array and
1960 // .CRT$XCU. The ATL also registers things in .ATL$__[azm]. Adding redzones
1961 // to such globals is counterproductive, because the intent is that they
1962 // will form an array, and out-of-bounds accesses are expected.
1963 // See https://github.com/google/sanitizers/issues/305
1964 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1965 if (TargetTriple.isOSBinFormatCOFF() && Section.contains('$')) {
1966 LLVM_DEBUG(dbgs() << "Ignoring global in sorted section (contains '$'): "do { } while (false)
1967 << *G << "\n")do { } while (false);
1968 return false;
1969 }
1970
1971 if (TargetTriple.isOSBinFormatMachO()) {
1972 StringRef ParsedSegment, ParsedSection;
1973 unsigned TAA = 0, StubSize = 0;
1974 bool TAAParsed;
1975 cantFail(MCSectionMachO::ParseSectionSpecifier(
1976 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize));
1977
1978 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1979 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1980 // them.
1981 if (ParsedSegment == "__OBJC" ||
1982 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1983 LLVM_DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n")do { } while (false);
1984 return false;
1985 }
1986 // See https://github.com/google/sanitizers/issues/32
1987 // Constant CFString instances are compiled in the following way:
1988 // -- the string buffer is emitted into
1989 // __TEXT,__cstring,cstring_literals
1990 // -- the constant NSConstantString structure referencing that buffer
1991 // is placed into __DATA,__cfstring
1992 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1993 // Moreover, it causes the linker to crash on OS X 10.7
1994 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1995 LLVM_DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n")do { } while (false);
1996 return false;
1997 }
1998 // The linker merges the contents of cstring_literals and removes the
1999 // trailing zeroes.
2000 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
2001 LLVM_DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n")do { } while (false);
2002 return false;
2003 }
2004 }
2005 }
2006
2007 if (CompileKernel) {
2008 // Globals that prefixed by "__" are special and cannot be padded with a
2009 // redzone.
2010 if (G->getName().startswith("__"))
2011 return false;
2012 }
2013
2014 return true;
2015}
2016
2017// On Mach-O platforms, we emit global metadata in a separate section of the
2018// binary in order to allow the linker to properly dead strip. This is only
2019// supported on recent versions of ld64.
2020bool ModuleAddressSanitizer::ShouldUseMachOGlobalsSection() const {
2021 if (!TargetTriple.isOSBinFormatMachO())
2022 return false;
2023
2024 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
2025 return true;
2026 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
2027 return true;
2028 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
2029 return true;
2030
2031 return false;
2032}
2033
2034StringRef ModuleAddressSanitizer::getGlobalMetadataSection() const {
2035 switch (TargetTriple.getObjectFormat()) {
2036 case Triple::COFF: return ".ASAN$GL";
2037 case Triple::ELF: return "asan_globals";
2038 case Triple::MachO: return "__DATA,__asan_globals,regular";
2039 case Triple::Wasm:
2040 case Triple::GOFF:
2041 case Triple::XCOFF:
2042 report_fatal_error(
2043 "ModuleAddressSanitizer not implemented for object file format");
2044 case Triple::UnknownObjectFormat:
2045 break;
2046 }
2047 llvm_unreachable("unsupported object format")__builtin_unreachable();
2048}
2049
2050void ModuleAddressSanitizer::initializeCallbacks(Module &M) {
2051 IRBuilder<> IRB(*C);
2052
2053 // Declare our poisoning and unpoisoning functions.
2054 AsanPoisonGlobals =
2055 M.getOrInsertFunction(kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy);
2056 AsanUnpoisonGlobals =
2057 M.getOrInsertFunction(kAsanUnpoisonGlobalsName, IRB.getVoidTy());
2058
2059 // Declare functions that register/unregister globals.
2060 AsanRegisterGlobals = M.getOrInsertFunction(
2061 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy);
2062 AsanUnregisterGlobals = M.getOrInsertFunction(
2063 kAsanUnregisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy);
2064
2065 // Declare the functions that find globals in a shared object and then invoke
2066 // the (un)register function on them.
2067 AsanRegisterImageGlobals = M.getOrInsertFunction(
2068 kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy);
2069 AsanUnregisterImageGlobals = M.getOrInsertFunction(
2070 kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy);
2071
2072 AsanRegisterElfGlobals =
2073 M.getOrInsertFunction(kAsanRegisterElfGlobalsName, IRB.getVoidTy(),
2074 IntptrTy, IntptrTy, IntptrTy);
2075 AsanUnregisterElfGlobals =
2076 M.getOrInsertFunction(kAsanUnregisterElfGlobalsName, IRB.getVoidTy(),
2077 IntptrTy, IntptrTy, IntptrTy);
2078}
2079
2080// Put the metadata and the instrumented global in the same group. This ensures
2081// that the metadata is discarded if the instrumented global is discarded.
2082void ModuleAddressSanitizer::SetComdatForGlobalMetadata(
2083 GlobalVariable *G, GlobalVariable *Metadata, StringRef InternalSuffix) {
2084 Module &M = *G->getParent();
2085 Comdat *C = G->getComdat();
2086 if (!C) {
2087 if (!G->hasName()) {
2088 // If G is unnamed, it must be internal. Give it an artificial name
2089 // so we can put it in a comdat.
2090 assert(G->hasLocalLinkage())((void)0);
2091 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
2092 }
2093
2094 if (!InternalSuffix.empty() && G->hasLocalLinkage()) {
2095 std::string Name = std::string(G->getName());
2096 Name += InternalSuffix;
2097 C = M.getOrInsertComdat(Name);
2098 } else {
2099 C = M.getOrInsertComdat(G->getName());
2100 }
2101
2102 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF. Also upgrade private
2103 // linkage to internal linkage so that a symbol table entry is emitted. This
2104 // is necessary in order to create the comdat group.
2105 if (TargetTriple.isOSBinFormatCOFF()) {
2106 C->setSelectionKind(Comdat::NoDeduplicate);
2107 if (G->hasPrivateLinkage())
2108 G->setLinkage(GlobalValue::InternalLinkage);
2109 }
2110 G->setComdat(C);
2111 }
2112
2113 assert(G->hasComdat())((void)0);
2114 Metadata->setComdat(G->getComdat());
2115}
2116
2117// Create a separate metadata global and put it in the appropriate ASan
2118// global registration section.
2119GlobalVariable *
2120ModuleAddressSanitizer::CreateMetadataGlobal(Module &M, Constant *Initializer,
2121 StringRef OriginalName) {
2122 auto Linkage = TargetTriple.isOSBinFormatMachO()
2123 ? GlobalVariable::InternalLinkage
2124 : GlobalVariable::PrivateLinkage;
2125 GlobalVariable *Metadata = new GlobalVariable(
2126 M, Initializer->getType(), false, Linkage, Initializer,
2127 Twine("__asan_global_") + GlobalValue::dropLLVMManglingEscape(OriginalName));
2128 Metadata->setSection(getGlobalMetadataSection());
2129 return Metadata;
2130}
2131
2132Instruction *ModuleAddressSanitizer::CreateAsanModuleDtor(Module &M) {
2133 AsanDtorFunction = Function::createWithDefaultAttr(
2134 FunctionType::get(Type::getVoidTy(*C), false),
2135 GlobalValue::InternalLinkage, 0, kAsanModuleDtorName, &M);
2136 AsanDtorFunction->addAttribute(AttributeList::FunctionIndex,
2137 Attribute::NoUnwind);
2138 // Ensure Dtor cannot be discarded, even if in a comdat.
2139 appendToUsed(M, {AsanDtorFunction});
2140 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
2141
2142 return ReturnInst::Create(*C, AsanDtorBB);
2143}
2144
2145void ModuleAddressSanitizer::InstrumentGlobalsCOFF(
2146 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2147 ArrayRef<Constant *> MetadataInitializers) {
2148 assert(ExtendedGlobals.size() == MetadataInitializers.size())((void)0);
2149 auto &DL = M.getDataLayout();
2150
2151 SmallVector<GlobalValue *, 16> MetadataGlobals(ExtendedGlobals.size());
2152 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
2153 Constant *Initializer = MetadataInitializers[i];
2154 GlobalVariable *G = ExtendedGlobals[i];
2155 GlobalVariable *Metadata =
2156 CreateMetadataGlobal(M, Initializer, G->getName());
2157 MDNode *MD = MDNode::get(M.getContext(), ValueAsMetadata::get(G));
2158 Metadata->setMetadata(LLVMContext::MD_associated, MD);
2159 MetadataGlobals[i] = Metadata;
2160
2161 // The MSVC linker always inserts padding when linking incrementally. We
2162 // cope with that by aligning each struct to its size, which must be a power
2163 // of two.
2164 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
2165 assert(isPowerOf2_32(SizeOfGlobalStruct) &&((void)0)
2166 "global metadata will not be padded appropriately")((void)0);
2167 Metadata->setAlignment(assumeAligned(SizeOfGlobalStruct));
2168
2169 SetComdatForGlobalMetadata(G, Metadata, "");
2170 }
2171
2172 // Update llvm.compiler.used, adding the new metadata globals. This is
2173 // needed so that during LTO these variables stay alive.
2174 if (!MetadataGlobals.empty())
2175 appendToCompilerUsed(M, MetadataGlobals);
2176}
2177
2178void ModuleAddressSanitizer::InstrumentGlobalsELF(
2179 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2180 ArrayRef<Constant *> MetadataInitializers,
2181 const std::string &UniqueModuleId) {
2182 assert(ExtendedGlobals.size() == MetadataInitializers.size())((void)0);
2183
2184 // Putting globals in a comdat changes the semantic and potentially cause
2185 // false negative odr violations at link time. If odr indicators are used, we
2186 // keep the comdat sections, as link time odr violations will be dectected on
2187 // the odr indicator symbols.
2188 bool UseComdatForGlobalsGC = UseOdrIndicator;
2189
2190 SmallVector<GlobalValue *, 16> MetadataGlobals(ExtendedGlobals.size());
2191 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
2192 GlobalVariable *G = ExtendedGlobals[i];
2193 GlobalVariable *Metadata =
2194 CreateMetadataGlobal(M, MetadataInitializers[i], G->getName());
2195 MDNode *MD = MDNode::get(M.getContext(), ValueAsMetadata::get(G));
2196 Metadata->setMetadata(LLVMContext::MD_associated, MD);
2197 MetadataGlobals[i] = Metadata;
2198
2199 if (UseComdatForGlobalsGC)
2200 SetComdatForGlobalMetadata(G, Metadata, UniqueModuleId);
2201 }
2202
2203 // Update llvm.compiler.used, adding the new metadata globals. This is
2204 // needed so that during LTO these variables stay alive.
2205 if (!MetadataGlobals.empty())
2206 appendToCompilerUsed(M, MetadataGlobals);
2207
2208 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
2209 // to look up the loaded image that contains it. Second, we can store in it
2210 // whether registration has already occurred, to prevent duplicate
2211 // registration.
2212 //
2213 // Common linkage ensures that there is only one global per shared library.
2214 GlobalVariable *RegisteredFlag = new GlobalVariable(
2215 M, IntptrTy, false, GlobalVariable::CommonLinkage,
2216 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
2217 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
2218
2219 // Create start and stop symbols.
2220 GlobalVariable *StartELFMetadata = new GlobalVariable(
2221 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
2222 "__start_" + getGlobalMetadataSection());
2223 StartELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
2224 GlobalVariable *StopELFMetadata = new GlobalVariable(
2225 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
2226 "__stop_" + getGlobalMetadataSection());
2227 StopELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
2228
2229 // Create a call to register the globals with the runtime.
2230 IRB.CreateCall(AsanRegisterElfGlobals,
2231 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
2232 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
2233 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
2234
2235 // We also need to unregister globals at the end, e.g., when a shared library
2236 // gets closed.
2237 if (DestructorKind != AsanDtorKind::None) {
2238 IRBuilder<> IrbDtor(CreateAsanModuleDtor(M));
2239 IrbDtor.CreateCall(AsanUnregisterElfGlobals,
2240 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
2241 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
2242 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
2243 }
2244}
2245
2246void ModuleAddressSanitizer::InstrumentGlobalsMachO(
2247 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2248 ArrayRef<Constant *> MetadataInitializers) {
2249 assert(ExtendedGlobals.size() == MetadataInitializers.size())((void)0);
2250
2251 // On recent Mach-O platforms, use a structure which binds the liveness of
2252 // the global variable to the metadata struct. Keep the list of "Liveness" GV
2253 // created to be added to llvm.compiler.used
2254 StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy);
2255 SmallVector<GlobalValue *, 16> LivenessGlobals(ExtendedGlobals.size());
2256
2257 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
2258 Constant *Initializer = MetadataInitializers[i];
2259 GlobalVariable *G = ExtendedGlobals[i];
2260 GlobalVariable *Metadata =
2261 CreateMetadataGlobal(M, Initializer, G->getName());
2262
2263 // On recent Mach-O platforms, we emit the global metadata in a way that
2264 // allows the linker to properly strip dead globals.
2265 auto LivenessBinder =
2266 ConstantStruct::get(LivenessTy, Initializer->getAggregateElement(0u),
2267 ConstantExpr::getPointerCast(Metadata, IntptrTy));
2268 GlobalVariable *Liveness = new GlobalVariable(
2269 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
2270 Twine("__asan_binder_") + G->getName());
2271 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
2272 LivenessGlobals[i] = Liveness;
2273 }
2274
2275 // Update llvm.compiler.used, adding the new liveness globals. This is
2276 // needed so that during LTO these variables stay alive. The alternative
2277 // would be to have the linker handling the LTO symbols, but libLTO
2278 // current API does not expose access to the section for each symbol.
2279 if (!LivenessGlobals.empty())
2280 appendToCompilerUsed(M, LivenessGlobals);
2281
2282 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
2283 // to look up the loaded image that contains it. Second, we can store in it
2284 // whether registration has already occurred, to prevent duplicate
2285 // registration.
2286 //
2287 // common linkage ensures that there is only one global per shared library.
2288 GlobalVariable *RegisteredFlag = new GlobalVariable(
2289 M, IntptrTy, false, GlobalVariable::CommonLinkage,
2290 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
2291 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
2292
2293 IRB.CreateCall(AsanRegisterImageGlobals,
2294 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
2295
2296 // We also need to unregister globals at the end, e.g., when a shared library
2297 // gets closed.
2298 if (DestructorKind != AsanDtorKind::None) {
2299 IRBuilder<> IrbDtor(CreateAsanModuleDtor(M));
2300 IrbDtor.CreateCall(AsanUnregisterImageGlobals,
2301 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
2302 }
2303}
2304
2305void ModuleAddressSanitizer::InstrumentGlobalsWithMetadataArray(
2306 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2307 ArrayRef<Constant *> MetadataInitializers) {
2308 assert(ExtendedGlobals.size() == MetadataInitializers.size())((void)0);
2309 unsigned N = ExtendedGlobals.size();
2310 assert(N > 0)((void)0);
2311
2312 // On platforms that don't have a custom metadata section, we emit an array
2313 // of global metadata structures.
2314 ArrayType *ArrayOfGlobalStructTy =
2315 ArrayType::get(MetadataInitializers[0]->getType(), N);
2316 auto AllGlobals = new GlobalVariable(
2317 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
2318 ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
2319 if (Mapping.Scale > 3)
2320 AllGlobals->setAlignment(Align(1ULL << Mapping.Scale));
2321
2322 IRB.CreateCall(AsanRegisterGlobals,
2323 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
2324 ConstantInt::get(IntptrTy, N)});
2325
2326 // We also need to unregister globals at the end, e.g., when a shared library
2327 // gets closed.
2328 if (DestructorKind != AsanDtorKind::None) {
2329 IRBuilder<> IrbDtor(CreateAsanModuleDtor(M));
2330 IrbDtor.CreateCall(AsanUnregisterGlobals,
2331 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
2332 ConstantInt::get(IntptrTy, N)});
2333 }
2334}
2335
2336// This function replaces all global variables with new variables that have
2337// trailing redzones. It also creates a function that poisons
2338// redzones and inserts this function into llvm.global_ctors.
2339// Sets *CtorComdat to true if the global registration code emitted into the
2340// asan constructor is comdat-compatible.
2341bool ModuleAddressSanitizer::InstrumentGlobals(IRBuilder<> &IRB, Module &M,
2342 bool *CtorComdat) {
2343 *CtorComdat = false;
2344
2345 // Build set of globals that are aliased by some GA, where
2346 // getExcludedAliasedGlobal(GA) returns the relevant GlobalVariable.
2347 SmallPtrSet<const GlobalVariable *, 16> AliasedGlobalExclusions;
2348 if (CompileKernel) {
2349 for (auto &GA : M.aliases()) {
2350 if (const GlobalVariable *GV = getExcludedAliasedGlobal(GA))
2351 AliasedGlobalExclusions.insert(GV);
2352 }
2353 }
2354
2355 SmallVector<GlobalVariable *, 16> GlobalsToChange;
2356 for (auto &G : M.globals()) {
2357 if (!AliasedGlobalExclusions.count(&G) && shouldInstrumentGlobal(&G))
2358 GlobalsToChange.push_back(&G);
2359 }
2360
2361 size_t n = GlobalsToChange.size();
2362 if (n == 0) {
2363 *CtorComdat = true;
2364 return false;
2365 }
2366
2367 auto &DL = M.getDataLayout();
2368
2369 // A global is described by a structure
2370 // size_t beg;
2371 // size_t size;
2372 // size_t size_with_redzone;
2373 // const char *name;
2374 // const char *module_name;
2375 // size_t has_dynamic_init;
2376 // void *source_location;
2377 // size_t odr_indicator;
2378 // We initialize an array of such structures and pass it to a run-time call.
2379 StructType *GlobalStructTy =
2380 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
2381 IntptrTy, IntptrTy, IntptrTy);
2382 SmallVector<GlobalVariable *, 16> NewGlobals(n);
2383 SmallVector<Constant *, 16> Initializers(n);
2384
2385 bool HasDynamicallyInitializedGlobals = false;
2386
2387 // We shouldn't merge same module names, as this string serves as unique
2388 // module ID in runtime.
2389 GlobalVariable *ModuleName = createPrivateGlobalForString(
2390 M, M.getModuleIdentifier(), /*AllowMerging*/ false, kAsanGenPrefix);
2391
2392 for (size_t i = 0; i < n; i++) {
2393 GlobalVariable *G = GlobalsToChange[i];
2394
2395 // FIXME: Metadata should be attched directly to the global directly instead
2396 // of being added to llvm.asan.globals.
2397 auto MD = GlobalsMD.get(G);
2398 StringRef NameForGlobal = G->getName();
2399 // Create string holding the global name (use global name from metadata
2400 // if it's available, otherwise just write the name of global variable).
2401 GlobalVariable *Name = createPrivateGlobalForString(
2402 M, MD.Name.empty() ? NameForGlobal : MD.Name,
2403 /*AllowMerging*/ true, kAsanGenPrefix);
2404
2405 Type *Ty = G->getValueType();
2406 const uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
2407 const uint64_t RightRedzoneSize = getRedzoneSizeForGlobal(SizeInBytes);
2408 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
2409
2410 StructType *NewTy = StructType::get(Ty, RightRedZoneTy);
2411 Constant *NewInitializer = ConstantStruct::get(
2412 NewTy, G->getInitializer(), Constant::getNullValue(RightRedZoneTy));
2413
2414 // Create a new global variable with enough space for a redzone.
2415 GlobalValue::LinkageTypes Linkage = G->getLinkage();
2416 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
2417 Linkage = GlobalValue::InternalLinkage;
2418 GlobalVariable *NewGlobal = new GlobalVariable(
2419 M, NewTy, G->isConstant(), Linkage, NewInitializer, "", G,
2420 G->getThreadLocalMode(), G->getAddressSpace());
2421 NewGlobal->copyAttributesFrom(G);
2422 NewGlobal->setComdat(G->getComdat());
2423 NewGlobal->setAlignment(MaybeAlign(getMinRedzoneSizeForGlobal()));
2424 // Don't fold globals with redzones. ODR violation detector and redzone
2425 // poisoning implicitly creates a dependence on the global's address, so it
2426 // is no longer valid for it to be marked unnamed_addr.
2427 NewGlobal->setUnnamedAddr(GlobalValue::UnnamedAddr::None);
2428
2429 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
2430 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
2431 G->isConstant()) {
2432 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
2433 if (Seq && Seq->isCString())
2434 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
2435 }
2436
2437 // Transfer the debug info and type metadata. The payload starts at offset
2438 // zero so we can copy the metadata over as is.
2439 NewGlobal->copyMetadata(G, 0);
2440
2441 Value *Indices2[2];
2442 Indices2[0] = IRB.getInt32(0);
2443 Indices2[1] = IRB.getInt32(0);
2444
2445 G->replaceAllUsesWith(
2446 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
2447 NewGlobal->takeName(G);
2448 G->eraseFromParent();
2449 NewGlobals[i] = NewGlobal;
2450
2451 Constant *SourceLoc;
2452 if (!MD.SourceLoc.empty()) {
2453 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
2454 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
2455 } else {
2456 SourceLoc = ConstantInt::get(IntptrTy, 0);
2457 }
2458
2459 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
2460 GlobalValue *InstrumentedGlobal = NewGlobal;
2461
2462 bool CanUsePrivateAliases =
2463 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO() ||
2464 TargetTriple.isOSBinFormatWasm();
2465 if (CanUsePrivateAliases && UsePrivateAlias) {
2466 // Create local alias for NewGlobal to avoid crash on ODR between
2467 // instrumented and non-instrumented libraries.
2468 InstrumentedGlobal =
2469 GlobalAlias::create(GlobalValue::PrivateLinkage, "", NewGlobal);
2470 }
2471
2472 // ODR should not happen for local linkage.
2473 if (NewGlobal->hasLocalLinkage()) {
2474 ODRIndicator = ConstantExpr::getIntToPtr(ConstantInt::get(IntptrTy, -1),
2475 IRB.getInt8PtrTy());
2476 } else if (UseOdrIndicator) {
2477 // With local aliases, we need to provide another externally visible
2478 // symbol __odr_asan_XXX to detect ODR violation.
2479 auto *ODRIndicatorSym =
2480 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
2481 Constant::getNullValue(IRB.getInt8Ty()),
2482 kODRGenPrefix + NameForGlobal, nullptr,
2483 NewGlobal->getThreadLocalMode());
2484
2485 // Set meaningful attributes for indicator symbol.
2486 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
2487 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
2488 ODRIndicatorSym->setAlignment(Align(1));
2489 ODRIndicator = ODRIndicatorSym;
2490 }
2491
2492 Constant *Initializer = ConstantStruct::get(
2493 GlobalStructTy,
2494 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
2495 ConstantInt::get(IntptrTy, SizeInBytes),
2496 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
2497 ConstantExpr::getPointerCast(Name, IntptrTy),
2498 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
2499 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
2500 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy));
2501
2502 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
2503
2504 LLVM_DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n")do { } while (false);
2505
2506 Initializers[i] = Initializer;
2507 }
2508
2509 // Add instrumented globals to llvm.compiler.used list to avoid LTO from
2510 // ConstantMerge'ing them.
2511 SmallVector<GlobalValue *, 16> GlobalsToAddToUsedList;
2512 for (size_t i = 0; i < n; i++) {
2513 GlobalVariable *G = NewGlobals[i];
2514 if (G->getName().empty()) continue;
2515 GlobalsToAddToUsedList.push_back(G);
2516 }
2517 appendToCompilerUsed(M, ArrayRef<GlobalValue *>(GlobalsToAddToUsedList));
2518
2519 std::string ELFUniqueModuleId =
2520 (UseGlobalsGC && TargetTriple.isOSBinFormatELF()) ? getUniqueModuleId(&M)
2521 : "";
2522
2523 if (!ELFUniqueModuleId.empty()) {
2524 InstrumentGlobalsELF(IRB, M, NewGlobals, Initializers, ELFUniqueModuleId);
2525 *CtorComdat = true;
2526 } else if (UseGlobalsGC && TargetTriple.isOSBinFormatCOFF()) {
2527 InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
2528 } else if (UseGlobalsGC && ShouldUseMachOGlobalsSection()) {
2529 InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
2530 } else {
2531 InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
2532 }
2533
2534 // Create calls for poisoning before initializers run and unpoisoning after.
2535 if (HasDynamicallyInitializedGlobals)
2536 createInitializerPoisonCalls(M, ModuleName);
2537
2538 LLVM_DEBUG(dbgs() << M)do { } while (false);
2539 return true;
2540}
2541
2542uint64_t
2543ModuleAddressSanitizer::getRedzoneSizeForGlobal(uint64_t SizeInBytes) const {
2544 constexpr uint64_t kMaxRZ = 1 << 18;
2545 const uint64_t MinRZ = getMinRedzoneSizeForGlobal();
2546
2547 uint64_t RZ = 0;
2548 if (SizeInBytes <= MinRZ / 2) {
2549 // Reduce redzone size for small size objects, e.g. int, char[1]. MinRZ is
2550 // at least 32 bytes, optimize when SizeInBytes is less than or equal to
2551 // half of MinRZ.
2552 RZ = MinRZ - SizeInBytes;
2553 } else {
2554 // Calculate RZ, where MinRZ <= RZ <= MaxRZ, and RZ ~ 1/4 * SizeInBytes.
2555 RZ = std::max(MinRZ, std::min(kMaxRZ, (SizeInBytes / MinRZ / 4) * MinRZ));
2556
2557 // Round up to multiple of MinRZ.
2558 if (SizeInBytes % MinRZ)
2559 RZ += MinRZ - (SizeInBytes % MinRZ);
2560 }
2561
2562 assert((RZ + SizeInBytes) % MinRZ == 0)((void)0);
2563
2564 return RZ;
2565}
2566
2567int ModuleAddressSanitizer::GetAsanVersion(const Module &M) const {
2568 int LongSize = M.getDataLayout().getPointerSizeInBits();
2569 bool isAndroid = Triple(M.getTargetTriple()).isAndroid();
2570 int Version = 8;
2571 // 32-bit Android is one version ahead because of the switch to dynamic
2572 // shadow.
2573 Version += (LongSize == 32 && isAndroid);
2574 return Version;
2575}
2576
2577bool ModuleAddressSanitizer::instrumentModule(Module &M) {
2578 initializeCallbacks(M);
2579
2580 // Create a module constructor. A destructor is created lazily because not all
2581 // platforms, and not all modules need it.
2582 if (CompileKernel) {
2583 // The kernel always builds with its own runtime, and therefore does not
2584 // need the init and version check calls.
2585 AsanCtorFunction = createSanitizerCtor(M, kAsanModuleCtorName);
2586 } else {
2587 std::string AsanVersion = std::to_string(GetAsanVersion(M));
2588 std::string VersionCheckName =
2589 ClInsertVersionCheck ? (kAsanVersionCheckNamePrefix + AsanVersion) : "";
2590 std::tie(AsanCtorFunction, std::ignore) =
2591 createSanitizerCtorAndInitFunctions(M, kAsanModuleCtorName,
2592 kAsanInitName, /*InitArgTypes=*/{},
2593 /*InitArgs=*/{}, VersionCheckName);
2594 }
2595
2596 bool CtorComdat = true;
2597 if (ClGlobals) {
2598 IRBuilder<> IRB(AsanCtorFunction->getEntryBlock().getTerminator());
2599 InstrumentGlobals(IRB, M, &CtorComdat);
2600 }
2601
2602 const uint64_t Priority = GetCtorAndDtorPriority(TargetTriple);
2603
2604 // Put the constructor and destructor in comdat if both
2605 // (1) global instrumentation is not TU-specific
2606 // (2) target is ELF.
2607 if (UseCtorComdat && TargetTriple.isOSBinFormatELF() && CtorComdat) {
2608 AsanCtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleCtorName));
2609 appendToGlobalCtors(M, AsanCtorFunction, Priority, AsanCtorFunction);
2610 if (AsanDtorFunction) {
2611 AsanDtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleDtorName));
2612 appendToGlobalDtors(M, AsanDtorFunction, Priority, AsanDtorFunction);
2613 }
2614 } else {
2615 appendToGlobalCtors(M, AsanCtorFunction, Priority);
2616 if (AsanDtorFunction)
2617 appendToGlobalDtors(M, AsanDtorFunction, Priority);
2618 }
2619
2620 return true;
2621}
2622
2623void AddressSanitizer::initializeCallbacks(Module &M) {
2624 IRBuilder<> IRB(*C);
2625 // Create __asan_report* callbacks.
2626 // IsWrite, TypeSize and Exp are encoded in the function name.
2627 for (int Exp = 0; Exp < 2; Exp++) {
2628 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
2629 const std::string TypeStr = AccessIsWrite ? "store" : "load";
2630 const std::string ExpStr = Exp ? "exp_" : "";
2631 const std::string EndingStr = Recover ? "_noabort" : "";
2632
2633 SmallVector<Type *, 3> Args2 = {IntptrTy, IntptrTy};
2634 SmallVector<Type *, 2> Args1{1, IntptrTy};
2635 if (Exp) {
2636 Type *ExpType = Type::getInt32Ty(*C);
2637 Args2.push_back(ExpType);
2638 Args1.push_back(ExpType);
2639 }
2640 AsanErrorCallbackSized[AccessIsWrite][Exp] = M.getOrInsertFunction(
2641 kAsanReportErrorTemplate + ExpStr + TypeStr + "_n" + EndingStr,
2642 FunctionType::get(IRB.getVoidTy(), Args2, false));
2643
2644 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] = M.getOrInsertFunction(
2645 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
2646 FunctionType::get(IRB.getVoidTy(), Args2, false));
2647
2648 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
2649 AccessSizeIndex++) {
2650 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
2651 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2652 M.getOrInsertFunction(
2653 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
2654 FunctionType::get(IRB.getVoidTy(), Args1, false));
2655
2656 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2657 M.getOrInsertFunction(
2658 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
2659 FunctionType::get(IRB.getVoidTy(), Args1, false));
2660 }
2661 }
2662 }
2663
2664 const std::string MemIntrinCallbackPrefix =
2665 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
2666 AsanMemmove = M.getOrInsertFunction(MemIntrinCallbackPrefix + "memmove",
2667 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
2668 IRB.getInt8PtrTy(), IntptrTy);
2669 AsanMemcpy = M.getOrInsertFunction(MemIntrinCallbackPrefix + "memcpy",
2670 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
2671 IRB.getInt8PtrTy(), IntptrTy);
2672 AsanMemset = M.getOrInsertFunction(MemIntrinCallbackPrefix + "memset",
2673 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
2674 IRB.getInt32Ty(), IntptrTy);
2675
2676 AsanHandleNoReturnFunc =
2677 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy());
2678
2679 AsanPtrCmpFunction =
2680 M.getOrInsertFunction(kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy);
2681 AsanPtrSubFunction =
2682 M.getOrInsertFunction(kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy);
2683 if (Mapping.InGlobal)
2684 AsanShadowGlobal = M.getOrInsertGlobal("__asan_shadow",
2685 ArrayType::get(IRB.getInt8Ty(), 0));
2686
2687 AMDGPUAddressShared = M.getOrInsertFunction(
2688 kAMDGPUAddressSharedName, IRB.getInt1Ty(), IRB.getInt8PtrTy());
2689 AMDGPUAddressPrivate = M.getOrInsertFunction(
2690 kAMDGPUAddressPrivateName, IRB.getInt1Ty(), IRB.getInt8PtrTy());
2691}
2692
2693bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
2694 // For each NSObject descendant having a +load method, this method is invoked
2695 // by the ObjC runtime before any of the static constructors is called.
2696 // Therefore we need to instrument such methods with a call to __asan_init
2697 // at the beginning in order to initialize our runtime before any access to
2698 // the shadow memory.
2699 // We cannot just ignore these methods, because they may call other
2700 // instrumented functions.
2701 if (F.getName().find(" load]") != std::string::npos) {
2702 FunctionCallee AsanInitFunction =
2703 declareSanitizerInitFunction(*F.getParent(), kAsanInitName, {});
2704 IRBuilder<> IRB(&F.front(), F.front().begin());
2705 IRB.CreateCall(AsanInitFunction, {});
2706 return true;
2707 }
2708 return false;
2709}
2710
2711bool AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
2712 // Generate code only when dynamic addressing is needed.
2713 if (Mapping.Offset != kDynamicShadowSentinel)
2714 return false;
2715
2716 IRBuilder<> IRB(&F.front().front());
2717 if (Mapping.InGlobal) {
2718 if (ClWithIfuncSuppressRemat) {
2719 // An empty inline asm with input reg == output reg.
2720 // An opaque pointer-to-int cast, basically.
2721 InlineAsm *Asm = InlineAsm::get(
2722 FunctionType::get(IntptrTy, {AsanShadowGlobal->getType()}, false),
2723 StringRef(""), StringRef("=r,0"),
2724 /*hasSideEffects=*/false);
2725 LocalDynamicShadow =
2726 IRB.CreateCall(Asm, {AsanShadowGlobal}, ".asan.shadow");
2727 } else {
2728 LocalDynamicShadow =
2729 IRB.CreatePointerCast(AsanShadowGlobal, IntptrTy, ".asan.shadow");
2730 }
2731 } else {
2732 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
2733 kAsanShadowMemoryDynamicAddress, IntptrTy);
2734 LocalDynamicShadow = IRB.CreateLoad(IntptrTy, GlobalDynamicAddress);
2735 }
2736 return true;
2737}
2738
2739void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
2740 // Find the one possible call to llvm.localescape and pre-mark allocas passed
2741 // to it as uninteresting. This assumes we haven't started processing allocas
2742 // yet. This check is done up front because iterating the use list in
2743 // isInterestingAlloca would be algorithmically slower.
2744 assert(ProcessedAllocas.empty() && "must process localescape before allocas")((void)0);
2745
2746 // Try to get the declaration of llvm.localescape. If it's not in the module,
2747 // we can exit early.
2748 if (!F.getParent()->getFunction("llvm.localescape")) return;
2749
2750 // Look for a call to llvm.localescape call in the entry block. It can't be in
2751 // any other block.
2752 for (Instruction &I : F.getEntryBlock()) {
2753 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2754 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2755 // We found a call. Mark all the allocas passed in as uninteresting.
2756 for (Value *Arg : II->arg_operands()) {
2757 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2758 assert(AI && AI->isStaticAlloca() &&((void)0)
2759 "non-static alloca arg to localescape")((void)0);
2760 ProcessedAllocas[AI] = false;
2761 }
2762 break;
2763 }
2764 }
2765}
2766
2767bool AddressSanitizer::suppressInstrumentationSiteForDebug(int &Instrumented) {
2768 bool ShouldInstrument =
2769 ClDebugMin < 0 || ClDebugMax < 0 ||
2770 (Instrumented >= ClDebugMin && Instrumented <= ClDebugMax);
2771 Instrumented++;
2772 return !ShouldInstrument;
2773}
2774
2775bool AddressSanitizer::instrumentFunction(Function &F,
2776 const TargetLibraryInfo *TLI) {
2777 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2778 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2779 if (F.getName().startswith("__asan_")) return false;
2780
2781 bool FunctionModified = false;
2782
2783 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2784 // This function needs to be called even if the function body is not
2785 // instrumented.
2786 if (maybeInsertAsanInitAtFunctionEntry(F))
2787 FunctionModified = true;
2788
2789 // Leave if the function doesn't need instrumentation.
2790 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2791
2792 LLVM_DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n")do { } while (false);
2793
2794 initializeCallbacks(*F.getParent());
2795
2796 FunctionStateRAII CleanupObj(this);
2797
2798 FunctionModified |= maybeInsertDynamicShadowAtFunctionEntry(F);
2799
2800 // We can't instrument allocas used with llvm.localescape. Only static allocas
2801 // can be passed to that intrinsic.
2802 markEscapedLocalAllocas(F);
2803
2804 // We want to instrument every address only once per basic block (unless there
2805 // are calls between uses).
2806 SmallPtrSet<Value *, 16> TempsToInstrument;
2807 SmallVector<InterestingMemoryOperand, 16> OperandsToInstrument;
2808 SmallVector<MemIntrinsic *, 16> IntrinToInstrument;
2809 SmallVector<Instruction *, 8> NoReturnCalls;
2810 SmallVector<BasicBlock *, 16> AllBlocks;
2811 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2812 int NumAllocas = 0;
2813
2814 // Fill the set of memory operations to instrument.
2815 for (auto &BB : F) {
2816 AllBlocks.push_back(&BB);
2817 TempsToInstrument.clear();
2818 int NumInsnsPerBB = 0;
2819 for (auto &Inst : BB) {
2820 if (LooksLikeCodeInBug11395(&Inst)) return false;
2821 SmallVector<InterestingMemoryOperand, 1> InterestingOperands;
2822 getInterestingMemoryOperands(&Inst, InterestingOperands);
2823
2824 if (!InterestingOperands.empty()) {
2825 for (auto &Operand : InterestingOperands) {
2826 if (ClOpt && ClOptSameTemp) {
2827 Value *Ptr = Operand.getPtr();
2828 // If we have a mask, skip instrumentation if we've already
2829 // instrumented the full object. But don't add to TempsToInstrument
2830 // because we might get another load/store with a different mask.
2831 if (Operand.MaybeMask) {
2832 if (TempsToInstrument.count(Ptr))
2833 continue; // We've seen this (whole) temp in the current BB.
2834 } else {
2835 if (!TempsToInstrument.insert(Ptr).second)
2836 continue; // We've seen this temp in the current BB.
2837 }
2838 }
2839 OperandsToInstrument.push_back(Operand);
2840 NumInsnsPerBB++;
2841 }
2842 } else if (((ClInvalidPointerPairs || ClInvalidPointerCmp) &&
2843 isInterestingPointerComparison(&Inst)) ||
2844 ((ClInvalidPointerPairs || ClInvalidPointerSub) &&
2845 isInterestingPointerSubtraction(&Inst))) {
2846 PointerComparisonsOrSubtracts.push_back(&Inst);
2847 } else if (MemIntrinsic *MI = dyn_cast<MemIntrinsic>(&Inst)) {
2848 // ok, take it.
2849 IntrinToInstrument.push_back(MI);
2850 NumInsnsPerBB++;
2851 } else {
2852 if (isa<AllocaInst>(Inst)) NumAllocas++;
2853 if (auto *CB = dyn_cast<CallBase>(&Inst)) {
2854 // A call inside BB.
2855 TempsToInstrument.clear();
2856 if (CB->doesNotReturn() && !CB->hasMetadata("nosanitize"))
2857 NoReturnCalls.push_back(CB);
2858 }
2859 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2860 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2861 }
2862 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2863 }
2864 }
2865
2866 bool UseCalls = (ClInstrumentationWithCallsThreshold >= 0 &&
2867 OperandsToInstrument.size() + IntrinToInstrument.size() >
2868 (unsigned)ClInstrumentationWithCallsThreshold);
2869 const DataLayout &DL = F.getParent()->getDataLayout();
2870 ObjectSizeOpts ObjSizeOpts;
2871 ObjSizeOpts.RoundToAlign = true;
2872 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(), ObjSizeOpts);
2873
2874 // Instrument.
2875 int NumInstrumented = 0;
2876 for (auto &Operand : OperandsToInstrument) {
2877 if (!suppressInstrumentationSiteForDebug(NumInstrumented))
2878 instrumentMop(ObjSizeVis, Operand, UseCalls,
2879 F.getParent()->getDataLayout());
2880 FunctionModified = true;
2881 }
2882 for (auto Inst : IntrinToInstrument) {
2883 if (!suppressInstrumentationSiteForDebug(NumInstrumented))
2884 instrumentMemIntrinsic(Inst);
2885 FunctionModified = true;
2886 }
2887
2888 FunctionStackPoisoner FSP(F, *this);
2889 bool ChangedStack = FSP.runOnFunction();
2890
2891 // We must unpoison the stack before NoReturn calls (throw, _exit, etc).
2892 // See e.g. https://github.com/google/sanitizers/issues/37
2893 for (auto CI : NoReturnCalls) {
2894 IRBuilder<> IRB(CI);
2895 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2896 }
2897
2898 for (auto Inst : PointerComparisonsOrSubtracts) {
2899 instrumentPointerComparisonOrSubtraction(Inst);
2900 FunctionModified = true;
2901 }
2902
2903 if (ChangedStack || !NoReturnCalls.empty())
2904 FunctionModified = true;
2905
2906 LLVM_DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "do { } while (false)
2907 << F << "\n")do { } while (false);
2908
2909 return FunctionModified;
2910}
2911
2912// Workaround for bug 11395: we don't want to instrument stack in functions
2913// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2914// FIXME: remove once the bug 11395 is fixed.
2915bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2916 if (LongSize != 32) return false;
2917 CallInst *CI = dyn_cast<CallInst>(I);
2918 if (!CI || !CI->isInlineAsm()) return false;
2919 if (CI->getNumArgOperands() <= 5) return false;
2920 // We have inline assembly with quite a few arguments.
2921 return true;
2922}
2923
2924void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2925 IRBuilder<> IRB(*C);
2926 if (ASan.UseAfterReturn == AsanDetectStackUseAfterReturnMode::Always ||
2927 ASan.UseAfterReturn == AsanDetectStackUseAfterReturnMode::Runtime) {
2928 const char *MallocNameTemplate =
2929 ASan.UseAfterReturn == AsanDetectStackUseAfterReturnMode::Always
2930 ? kAsanStackMallocAlwaysNameTemplate
2931 : kAsanStackMallocNameTemplate;
2932 for (int Index = 0; Index <= kMaxAsanStackMallocSizeClass; Index++) {
2933 std::string Suffix = itostr(Index);
2934 AsanStackMallocFunc[Index] = M.getOrInsertFunction(
2935 MallocNameTemplate + Suffix, IntptrTy, IntptrTy);
2936 AsanStackFreeFunc[Index] =
2937 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2938 IRB.getVoidTy(), IntptrTy, IntptrTy);
2939 }
2940 }
2941 if (ASan.UseAfterScope) {
2942 AsanPoisonStackMemoryFunc = M.getOrInsertFunction(
2943 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy);
2944 AsanUnpoisonStackMemoryFunc = M.getOrInsertFunction(
2945 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy);
2946 }
2947
2948 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2949 std::ostringstream Name;
2950 Name << kAsanSetShadowPrefix;
2951 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2952 AsanSetShadowFunc[Val] =
2953 M.getOrInsertFunction(Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy);
2954 }
2955
2956 AsanAllocaPoisonFunc = M.getOrInsertFunction(
2957 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy);
2958 AsanAllocasUnpoisonFunc = M.getOrInsertFunction(
2959 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy);
2960}
2961
2962void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2963 ArrayRef<uint8_t> ShadowBytes,
2964 size_t Begin, size_t End,
2965 IRBuilder<> &IRB,
2966 Value *ShadowBase) {
2967 if (Begin >= End)
2968 return;
2969
2970 const size_t LargestStoreSizeInBytes =
2971 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2972
2973 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2974
2975 // Poison given range in shadow using larges store size with out leading and
2976 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2977 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2978 // middle of a store.
2979 for (size_t i = Begin; i < End;) {
2980 if (!ShadowMask[i]) {
2981 assert(!ShadowBytes[i])((void)0);
2982 ++i;
2983 continue;
2984 }
2985
2986 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2987 // Fit store size into the range.
2988 while (StoreSizeInBytes > End - i)
2989 StoreSizeInBytes /= 2;
2990
2991 // Minimize store size by trimming trailing zeros.
2992 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2993 while (j <= StoreSizeInBytes / 2)
2994 StoreSizeInBytes /= 2;
2995 }
2996
2997 uint64_t Val = 0;
2998 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2999 if (IsLittleEndian)
3000 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
3001 else
3002 Val = (Val << 8) | ShadowBytes[i + j];
3003 }
3004
3005 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
3006 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
3007 IRB.CreateAlignedStore(
3008 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()),
3009 Align(1));
3010
3011 i += StoreSizeInBytes;
3012 }
3013}
3014
3015void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
3016 ArrayRef<uint8_t> ShadowBytes,
3017 IRBuilder<> &IRB, Value *ShadowBase) {
3018 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
3019}
3020
3021void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
3022 ArrayRef<uint8_t> ShadowBytes,
3023 size_t Begin, size_t End,
3024 IRBuilder<> &IRB, Value *ShadowBase) {
3025 assert(ShadowMask.size() == ShadowBytes.size())((void)0);
3026 size_t Done = Begin;
3027 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
3028 if (!ShadowMask[i]) {
3029 assert(!ShadowBytes[i])((void)0);
3030 continue;
3031 }
3032 uint8_t Val = ShadowBytes[i];
3033 if (!AsanSetShadowFunc[Val])
3034 continue;
3035
3036 // Skip same values.
3037 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
3038 }
3039
3040 if (j - i >= ClMaxInlinePoisoningSize) {
3041 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
3042 IRB.CreateCall(AsanSetShadowFunc[Val],
3043 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
3044 ConstantInt::get(IntptrTy, j - i)});
3045 Done = j;
3046 }
3047 }
3048
3049 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
3050}
3051
3052// Fake stack allocator (asan_fake_stack.h) has 11 size classes
3053// for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
3054static int StackMallocSizeClass(uint64_t LocalStackSize) {
3055 assert(LocalStackSize <= kMaxStackMallocSize)((void)0);
3056 uint64_t MaxSize = kMinStackMallocSize;
3057 for (int i = 0;; i++, MaxSize *= 2)
3058 if (LocalStackSize <= MaxSize) return i;
3059 llvm_unreachable("impossible LocalStackSize")__builtin_unreachable();
3060}
3061
3062void FunctionStackPoisoner::copyArgsPassedByValToAllocas() {
3063 Instruction *CopyInsertPoint = &F.front().front();
3064 if (CopyInsertPoint == ASan.LocalDynamicShadow) {
3065 // Insert after the dynamic shadow location is determined
3066 CopyInsertPoint = CopyInsertPoint->getNextNode();
3067 assert(CopyInsertPoint)((void)0);
3068 }
3069 IRBuilder<> IRB(CopyInsertPoint);
3070 const DataLayout &DL = F.getParent()->getDataLayout();
3071 for (Argument &Arg : F.args()) {
3072 if (Arg.hasByValAttr()) {
3073 Type *Ty = Arg.getParamByValType();
3074 const Align Alignment =
3075 DL.getValueOrABITypeAlignment(Arg.getParamAlign(), Ty);
3076
3077 AllocaInst *AI = IRB.CreateAlloca(
3078 Ty, nullptr,
3079 (Arg.hasName() ? Arg.getName() : "Arg" + Twine(Arg.getArgNo())) +
3080 ".byval");
3081 AI->setAlignment(Alignment);
3082 Arg.replaceAllUsesWith(AI);
3083
3084 uint64_t AllocSize = DL.getTypeAllocSize(Ty);
3085 IRB.CreateMemCpy(AI, Alignment, &Arg, Alignment, AllocSize);
3086 }
3087 }
3088}
3089
3090PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
3091 Value *ValueIfTrue,
3092 Instruction *ThenTerm,
3093 Value *ValueIfFalse) {
3094 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
3095 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
3096 PHI->addIncoming(ValueIfFalse, CondBlock);
3097 BasicBlock *ThenBlock = ThenTerm->getParent();
3098 PHI->addIncoming(ValueIfTrue, ThenBlock);
3099 return PHI;
3100}
3101
3102Value *FunctionStackPoisoner::createAllocaForLayout(
3103 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
3104 AllocaInst *Alloca;
3105 if (Dynamic) {
3106 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
3107 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
3108 "MyAlloca");
3109 } else {
3110 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
3111 nullptr, "MyAlloca");
3112 assert(Alloca->isStaticAlloca())((void)0);
3113 }
3114 assert((ClRealignStack & (ClRealignStack - 1)) == 0)((void)0);
3115 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
3116 Alloca->setAlignment(Align(FrameAlignment));
3117 return IRB.CreatePointerCast(Alloca, IntptrTy);
3118}
3119
3120void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
3121 BasicBlock &FirstBB = *F.begin();
3122 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
3123 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
3124 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
3125 DynamicAllocaLayout->setAlignment(Align(32));
3126}
3127
3128void FunctionStackPoisoner::processDynamicAllocas() {
3129 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
3130 assert(DynamicAllocaPoisonCallVec.empty())((void)0);
3131 return;
3132 }
3133
3134 // Insert poison calls for lifetime intrinsics for dynamic allocas.
3135 for (const auto &APC : DynamicAllocaPoisonCallVec) {
3136 assert(APC.InsBefore)((void)0);
3137 assert(APC.AI)((void)0);
3138 assert(ASan.isInterestingAlloca(*APC.AI))((void)0);
3139 assert(!APC.AI->isStaticAlloca())((void)0);
3140
3141 IRBuilder<> IRB(APC.InsBefore);
3142 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
3143 // Dynamic allocas will be unpoisoned unconditionally below in
3144 // unpoisonDynamicAllocas.
3145 // Flag that we need unpoison static allocas.
3146 }
3147
3148 // Handle dynamic allocas.
3149 createDynamicAllocasInitStorage();
3150 for (auto &AI : DynamicAllocaVec)
3151 handleDynamicAllocaCall(AI);
3152 unpoisonDynamicAllocas();
3153}
3154
3155/// Collect instructions in the entry block after \p InsBefore which initialize
3156/// permanent storage for a function argument. These instructions must remain in
3157/// the entry block so that uninitialized values do not appear in backtraces. An
3158/// added benefit is that this conserves spill slots. This does not move stores
3159/// before instrumented / "interesting" allocas.
3160static void findStoresToUninstrumentedArgAllocas(
3161 AddressSanitizer &ASan, Instruction &InsBefore,
3162 SmallVectorImpl<Instruction *> &InitInsts) {
3163 Instruction *Start = InsBefore.getNextNonDebugInstruction();
3164 for (Instruction *It = Start; It; It = It->getNextNonDebugInstruction()) {
3165 // Argument initialization looks like:
3166 // 1) store <Argument>, <Alloca> OR
3167 // 2) <CastArgument> = cast <Argument> to ...
3168 // store <CastArgument> to <Alloca>
3169 // Do not consider any other kind of instruction.
3170 //
3171 // Note: This covers all known cases, but may not be exhaustive. An
3172 // alternative to pattern-matching stores is to DFS over all Argument uses:
3173 // this might be more general, but is probably much more complicated.
3174 if (isa<AllocaInst>(It) || isa<CastInst>(It))
3175 continue;
3176 if (auto *Store = dyn_cast<StoreInst>(It)) {
3177 // The store destination must be an alloca that isn't interesting for
3178 // ASan to instrument. These are moved up before InsBefore, and they're
3179 // not interesting because allocas for arguments can be mem2reg'd.
3180 auto *Alloca = dyn_cast<AllocaInst>(Store->getPointerOperand());
3181 if (!Alloca || ASan.isInterestingAlloca(*Alloca))
3182 continue;
3183
3184 Value *Val = Store->getValueOperand();
3185 bool IsDirectArgInit = isa<Argument>(Val);
3186 bool IsArgInitViaCast =
3187 isa<CastInst>(Val) &&
3188 isa<Argument>(cast<CastInst>(Val)->getOperand(0)) &&
3189 // Check that the cast appears directly before the store. Otherwise
3190 // moving the cast before InsBefore may break the IR.
3191 Val == It->getPrevNonDebugInstruction();
3192 bool IsArgInit = IsDirectArgInit || IsArgInitViaCast;
3193 if (!IsArgInit)
3194 continue;
3195
3196 if (IsArgInitViaCast)
3197 InitInsts.push_back(cast<Instruction>(Val));
3198 InitInsts.push_back(Store);
3199 continue;
3200 }
3201
3202 // Do not reorder past unknown instructions: argument initialization should
3203 // only involve casts and stores.
3204 return;
3205 }
3206}
3207
3208void FunctionStackPoisoner::processStaticAllocas() {
3209 if (AllocaVec.empty()) {
3210 assert(StaticAllocaPoisonCallVec.empty())((void)0);
3211 return;
3212 }
3213
3214 int StackMallocIdx = -1;
3215 DebugLoc EntryDebugLocation;
3216 if (auto SP = F.getSubprogram())
3217 EntryDebugLocation =
3218 DILocation::get(SP->getContext(), SP->getScopeLine(), 0, SP);
3219
3220 Instruction *InsBefore = AllocaVec[0];
3221 IRBuilder<> IRB(InsBefore);
3222
3223 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
3224 // debug info is broken, because only entry-block allocas are treated as
3225 // regular stack slots.
3226 auto InsBeforeB = InsBefore->getParent();
3227 assert(InsBeforeB == &F.getEntryBlock())((void)0);
3228 for (auto *AI : StaticAllocasToMoveUp)
3229 if (AI->getParent() == InsBeforeB)
3230 AI->moveBefore(InsBefore);
3231
3232 // Move stores of arguments into entry-block allocas as well. This prevents
3233 // extra stack slots from being generated (to house the argument values until
3234 // they can be stored into the allocas). This also prevents uninitialized
3235 // values from being shown in backtraces.
3236 SmallVector<Instruction *, 8> ArgInitInsts;
3237 findStoresToUninstrumentedArgAllocas(ASan, *InsBefore, ArgInitInsts);
3238 for (Instruction *ArgInitInst : ArgInitInsts)
3239 ArgInitInst->moveBefore(InsBefore);
3240
3241 // If we have a call to llvm.localescape, keep it in the entry block.
3242 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
3243
3244 SmallVector<ASanStackVariableDescription, 16> SVD;
3245 SVD.reserve(AllocaVec.size());
3246 for (AllocaInst *AI : AllocaVec) {
3247 ASanStackVariableDescription D = {AI->getName().data(),
3248 ASan.getAllocaSizeInBytes(*AI),
3249 0,
3250 AI->getAlignment(),
3251 AI,
3252 0,
3253 0};
3254 SVD.push_back(D);
3255 }
3256
3257 // Minimal header size (left redzone) is 4 pointers,
3258 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
3259 size_t Granularity = 1ULL << Mapping.Scale;
3260 size_t MinHeaderSize = std::max((size_t)ASan.LongSize / 2, Granularity);
3261 const ASanStackFrameLayout &L =
3262 ComputeASanStackFrameLayout(SVD, Granularity, MinHeaderSize);
3263
3264 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
3265 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
3266 for (auto &Desc : SVD)
3267 AllocaToSVDMap[Desc.AI] = &Desc;
3268
3269 // Update SVD with information from lifetime intrinsics.
3270 for (const auto &APC : StaticAllocaPoisonCallVec) {
3271 assert(APC.InsBefore)((void)0);
3272 assert(APC.AI)((void)0);
3273 assert(ASan.isInterestingAlloca(*APC.AI))((void)0);
3274 assert(APC.AI->isStaticAlloca())((void)0);
3275
3276 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
3277 Desc.LifetimeSize = Desc.Size;
3278 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
3279 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
3280 if (LifetimeLoc->getFile() == FnLoc->getFile())
3281 if (unsigned Line = LifetimeLoc->getLine())
3282 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
3283 }
3284 }
3285 }
3286
3287 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
3288 LLVM_DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n")do { } while (false);
3289 uint64_t LocalStackSize = L.FrameSize;
3290 bool DoStackMalloc =
3291 ASan.UseAfterReturn != AsanDetectStackUseAfterReturnMode::Never &&
3292 !ASan.CompileKernel && LocalStackSize <= kMaxStackMallocSize;
3293 bool DoDynamicAlloca = ClDynamicAllocaStack;
3294 // Don't do dynamic alloca or stack malloc if:
3295 // 1) There is inline asm: too often it makes assumptions on which registers
3296 // are available.
3297 // 2) There is a returns_twice call (typically setjmp), which is
3298 // optimization-hostile, and doesn't play well with introduced indirect
3299 // register-relative calculation of local variable addresses.
3300 DoDynamicAlloca &= !HasInlineAsm && !HasReturnsTwiceCall;
3301 DoStackMalloc &= !HasInlineAsm && !HasReturnsTwiceCall;
3302
3303 Value *StaticAlloca =
3304 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
3305
3306 Value *FakeStack;
3307 Value *LocalStackBase;
3308 Value *LocalStackBaseAlloca;
3309 uint8_t DIExprFlags = DIExpression::ApplyOffset;
3310
3311 if (DoStackMalloc) {
3312 LocalStackBaseAlloca =
3313 IRB.CreateAlloca(IntptrTy, nullptr, "asan_local_stack_base");
3314 if (ASan.UseAfterReturn == AsanDetectStackUseAfterReturnMode::Runtime) {
3315 // void *FakeStack = __asan_option_detect_stack_use_after_return
3316 // ? __asan_stack_malloc_N(LocalStackSize)
3317 // : nullptr;
3318 // void *LocalStackBase = (FakeStack) ? FakeStack :
3319 // alloca(LocalStackSize);
3320 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
3321 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
3322 Value *UseAfterReturnIsEnabled = IRB.CreateICmpNE(
3323 IRB.CreateLoad(IRB.getInt32Ty(), OptionDetectUseAfterReturn),
3324 Constant::getNullValue(IRB.getInt32Ty()));
3325 Instruction *Term =
3326 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
3327 IRBuilder<> IRBIf(Term);
3328 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
3329 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass)((void)0);
3330 Value *FakeStackValue =
3331 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
3332 ConstantInt::get(IntptrTy, LocalStackSize));
3333 IRB.SetInsertPoint(InsBefore);
3334 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
3335 ConstantInt::get(IntptrTy, 0));
3336 } else {
3337 // assert(ASan.UseAfterReturn == AsanDetectStackUseAfterReturnMode:Always)
3338 // void *FakeStack = __asan_stack_malloc_N(LocalStackSize);
3339 // void *LocalStackBase = (FakeStack) ? FakeStack :
3340 // alloca(LocalStackSize);
3341 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
3342 FakeStack = IRB.CreateCall(AsanStackMallocFunc[StackMallocIdx],
3343 ConstantInt::get(IntptrTy, LocalStackSize));
3344 }
3345 Value *NoFakeStack =
3346 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
3347 Instruction *Term =
3348 SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
3349 IRBuilder<> IRBIf(Term);
3350 Value *AllocaValue =
3351 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
3352
3353 IRB.SetInsertPoint(InsBefore);
3354 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
3355 IRB.CreateStore(LocalStackBase, LocalStackBaseAlloca);
3356 DIExprFlags |= DIExpression::DerefBefore;
3357 } else {
3358 // void *FakeStack = nullptr;
3359 // void *LocalStackBase = alloca(LocalStackSize);
3360 FakeStack = ConstantInt::get(IntptrTy, 0);
3361 LocalStackBase =
3362 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
3363 LocalStackBaseAlloca = LocalStackBase;
3364 }
3365
3366 // It shouldn't matter whether we pass an `alloca` or a `ptrtoint` as the
3367 // dbg.declare address opereand, but passing a `ptrtoint` seems to confuse
3368 // later passes and can result in dropped variable coverage in debug info.
3369 Value *LocalStackBaseAllocaPtr =
3370 isa<PtrToIntInst>(LocalStackBaseAlloca)
3371 ? cast<PtrToIntInst>(LocalStackBaseAlloca)->getPointerOperand()
3372 : LocalStackBaseAlloca;
3373 assert(isa<AllocaInst>(LocalStackBaseAllocaPtr) &&((void)0)
3374 "Variable descriptions relative to ASan stack base will be dropped")((void)0);
3375
3376 // Replace Alloca instructions with base+offset.
3377 for (const auto &Desc : SVD) {
3378 AllocaInst *AI = Desc.AI;
3379 replaceDbgDeclare(AI, LocalStackBaseAllocaPtr, DIB, DIExprFlags,
3380 Desc.Offset);
3381 Value *NewAllocaPtr = IRB.CreateIntToPtr(
3382 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
3383 AI->getType());
3384 AI->replaceAllUsesWith(NewAllocaPtr);
3385 }
3386
3387 // The left-most redzone has enough space for at least 4 pointers.
3388 // Write the Magic value to redzone[0].
3389 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
3390 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
3391 BasePlus0);
3392 // Write the frame description constant to redzone[1].
3393 Value *BasePlus1 = IRB.CreateIntToPtr(
3394 IRB.CreateAdd(LocalStackBase,
3395 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
3396 IntptrPtrTy);
3397 GlobalVariable *StackDescriptionGlobal =
3398 createPrivateGlobalForString(*F.getParent(), DescriptionString,
3399 /*AllowMerging*/ true, kAsanGenPrefix);
3400 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
3401 IRB.CreateStore(Description, BasePlus1);
3402 // Write the PC to redzone[2].
3403 Value *BasePlus2 = IRB.CreateIntToPtr(
3404 IRB.CreateAdd(LocalStackBase,
3405 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
3406 IntptrPtrTy);
3407 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
3408
3409 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
3410
3411 // Poison the stack red zones at the entry.
3412 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
3413 // As mask we must use most poisoned case: red zones and after scope.
3414 // As bytes we can use either the same or just red zones only.
3415 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
3416
3417 if (!StaticAllocaPoisonCallVec.empty()) {
3418 const auto &ShadowInScope = GetShadowBytes(SVD, L);
3419
3420 // Poison static allocas near lifetime intrinsics.
3421 for (const auto &APC : StaticAllocaPoisonCallVec) {
3422 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
3423 assert(Desc.Offset % L.Granularity == 0)((void)0);
3424 size_t Begin = Desc.Offset / L.Granularity;
3425 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
3426
3427 IRBuilder<> IRB(APC.InsBefore);
3428 copyToShadow(ShadowAfterScope,
3429 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
3430 IRB, ShadowBase);
3431 }
3432 }
3433
3434 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
3435 SmallVector<uint8_t, 64> ShadowAfterReturn;
3436
3437 // (Un)poison the stack before all ret instructions.
3438 for (Instruction *Ret : RetVec) {
3439 IRBuilder<> IRBRet(Ret);
3440 // Mark the current frame as retired.
3441 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
3442 BasePlus0);
3443 if (DoStackMalloc) {
3444 assert(StackMallocIdx >= 0)((void)0);
3445 // if FakeStack != 0 // LocalStackBase == FakeStack
3446 // // In use-after-return mode, poison the whole stack frame.
3447 // if StackMallocIdx <= 4
3448 // // For small sizes inline the whole thing:
3449 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
3450 // **SavedFlagPtr(FakeStack) = 0
3451 // else
3452 // __asan_stack_free_N(FakeStack, LocalStackSize)
3453 // else
3454 // <This is not a fake stack; unpoison the redzones>
3455 Value *Cmp =
3456 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
3457 Instruction *ThenTerm, *ElseTerm;
3458 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
3459
3460 IRBuilder<> IRBPoison(ThenTerm);
3461 if (StackMallocIdx <= 4) {
3462 int ClassSize = kMinStackMallocSize << StackMallocIdx;
3463 ShadowAfterReturn.resize(ClassSize / L.Granularity,
3464 kAsanStackUseAfterReturnMagic);
3465 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
3466 ShadowBase);
3467 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
3468 FakeStack,
3469 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
3470 Value *SavedFlagPtr = IRBPoison.CreateLoad(
3471 IntptrTy, IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
3472 IRBPoison.CreateStore(
3473 Constant::getNullValue(IRBPoison.getInt8Ty()),
3474 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
3475 } else {
3476 // For larger frames call __asan_stack_free_*.
3477 IRBPoison.CreateCall(
3478 AsanStackFreeFunc[StackMallocIdx],
3479 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
3480 }
3481
3482 IRBuilder<> IRBElse(ElseTerm);
3483 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
3484 } else {
3485 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
3486 }
3487 }
3488
3489 // We are done. Remove the old unused alloca instructions.
3490 for (auto AI : AllocaVec) AI->eraseFromParent();
3491}
3492
3493void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
3494 IRBuilder<> &IRB, bool DoPoison) {
3495 // For now just insert the call to ASan runtime.
3496 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
3497 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
3498 IRB.CreateCall(
3499 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
3500 {AddrArg, SizeArg});
3501}
3502
3503// Handling llvm.lifetime intrinsics for a given %alloca:
3504// (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
3505// (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
3506// invalid accesses) and unpoison it for llvm.lifetime.start (the memory
3507// could be poisoned by previous llvm.lifetime.end instruction, as the
3508// variable may go in and out of scope several times, e.g. in loops).
3509// (3) if we poisoned at least one %alloca in a function,
3510// unpoison the whole stack frame at function exit.
3511void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
3512 IRBuilder<> IRB(AI);
3513
3514 const unsigned Alignment = std::max(kAllocaRzSize, AI->getAlignment());
3515 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
3516
3517 Value *Zero = Constant::getNullValue(IntptrTy);
3518 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
3519 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
3520
3521 // Since we need to extend alloca with additional memory to locate
3522 // redzones, and OldSize is number of allocated blocks with
3523 // ElementSize size, get allocated memory size in bytes by
3524 // OldSize * ElementSize.
3525 const unsigned ElementSize =
3526 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
3527 Value *OldSize =
3528 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
3529 ConstantInt::get(IntptrTy, ElementSize));
3530
3531 // PartialSize = OldSize % 32
3532 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
3533
3534 // Misalign = kAllocaRzSize - PartialSize;
3535 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
3536
3537 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
3538 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
3539 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
3540
3541 // AdditionalChunkSize = Alignment + PartialPadding + kAllocaRzSize
3542 // Alignment is added to locate left redzone, PartialPadding for possible
3543 // partial redzone and kAllocaRzSize for right redzone respectively.
3544 Value *AdditionalChunkSize = IRB.CreateAdd(
3545 ConstantInt::get(IntptrTy, Alignment + kAllocaRzSize), PartialPadding);
3546
3547 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
3548
3549 // Insert new alloca with new NewSize and Alignment params.
3550 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
3551 NewAlloca->setAlignment(Align(Alignment));
3552
3553 // NewAddress = Address + Alignment
3554 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
3555 ConstantInt::get(IntptrTy, Alignment));
3556
3557 // Insert __asan_alloca_poison call for new created alloca.
3558 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
3559
3560 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
3561 // for unpoisoning stuff.
3562 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
3563
3564 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
3565
3566 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
3567 AI->replaceAllUsesWith(NewAddressPtr);
3568
3569 // We are done. Erase old alloca from parent.
3570 AI->eraseFromParent();
3571}
3572
3573// isSafeAccess returns true if Addr is always inbounds with respect to its
3574// base object. For example, it is a field access or an array access with
3575// constant inbounds index.
3576bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
3577 Value *Addr, uint64_t TypeSize) const {
3578 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
3579 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
3580 uint64_t Size = SizeOffset.first.getZExtValue();
3581 int64_t Offset = SizeOffset.second.getSExtValue();
3582 // Three checks are required to ensure safety:
3583 // . Offset >= 0 (since the offset is given from the base ptr)
3584 // . Size >= Offset (unsigned)
3585 // . Size - Offset >= NeededSize (unsigned)
3586 return Offset >= 0 && Size >= uint64_t(Offset) &&
3587 Size - uint64_t(Offset) >= TypeSize / 8;
3588}