1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 // Details of the algorithm:
12 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Transforms/Instrumentation.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/DenseSet.h"
20 #include "llvm/ADT/DepthFirstIterator.h"
21 #include "llvm/ADT/SetVector.h"
22 #include "llvm/ADT/SmallSet.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/Statistic.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/Analysis/MemoryBuiltins.h"
29 #include "llvm/Analysis/TargetLibraryInfo.h"
30 #include "llvm/Analysis/ValueTracking.h"
31 #include "llvm/IR/CallSite.h"
32 #include "llvm/IR/DIBuilder.h"
33 #include "llvm/IR/DataLayout.h"
34 #include "llvm/IR/Dominators.h"
35 #include "llvm/IR/Function.h"
36 #include "llvm/IR/IRBuilder.h"
37 #include "llvm/IR/InlineAsm.h"
38 #include "llvm/IR/InstVisitor.h"
39 #include "llvm/IR/IntrinsicInst.h"
40 #include "llvm/IR/LLVMContext.h"
41 #include "llvm/IR/MDBuilder.h"
42 #include "llvm/IR/Module.h"
43 #include "llvm/IR/Type.h"
44 #include "llvm/MC/MCSectionMachO.h"
45 #include "llvm/Support/CommandLine.h"
46 #include "llvm/Support/DataTypes.h"
47 #include "llvm/Support/Debug.h"
48 #include "llvm/Support/Endian.h"
49 #include "llvm/Support/SwapByteOrder.h"
50 #include "llvm/Support/raw_ostream.h"
51 #include "llvm/Transforms/Scalar.h"
52 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
53 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
54 #include "llvm/Transforms/Utils/Cloning.h"
55 #include "llvm/Transforms/Utils/Local.h"
56 #include "llvm/Transforms/Utils/ModuleUtils.h"
57 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
60 #include <system_error>
64 #define DEBUG_TYPE "asan"
66 static const uint64_t kDefaultShadowScale = 3;
67 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
68 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
69 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
70 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
71 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
72 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
73 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
74 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
75 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
76 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
77 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
78 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
80 static const size_t kMinStackMallocSize = 1 << 6; // 64B
81 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
82 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
83 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
85 static const char *const kAsanModuleCtorName = "asan.module_ctor";
86 static const char *const kAsanModuleDtorName = "asan.module_dtor";
87 static const uint64_t kAsanCtorAndDtorPriority = 1;
88 static const char *const kAsanReportErrorTemplate = "__asan_report_";
89 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
90 static const char *const kAsanUnregisterGlobalsName =
91 "__asan_unregister_globals";
92 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
93 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
94 static const char *const kAsanInitName = "__asan_init";
95 static const char *const kAsanVersionCheckName =
96 "__asan_version_mismatch_check_v6";
97 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
98 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
99 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
100 static const int kMaxAsanStackMallocSizeClass = 10;
101 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
102 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
103 static const char *const kAsanGenPrefix = "__asan_gen_";
104 static const char *const kSanCovGenPrefix = "__sancov_gen_";
105 static const char *const kAsanPoisonStackMemoryName =
106 "__asan_poison_stack_memory";
107 static const char *const kAsanUnpoisonStackMemoryName =
108 "__asan_unpoison_stack_memory";
110 static const char *const kAsanOptionDetectUAR =
111 "__asan_option_detect_stack_use_after_return";
113 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
114 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
116 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
117 static const size_t kNumberOfAccessSizes = 5;
119 static const unsigned kAllocaRzSize = 32;
121 // Command-line flags.
122 static cl::opt<bool> ClEnableKasan(
123 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
124 cl::Hidden, cl::init(false));
126 // This flag may need to be replaced with -f[no-]asan-reads.
127 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
128 cl::desc("instrument read instructions"),
129 cl::Hidden, cl::init(true));
130 static cl::opt<bool> ClInstrumentWrites(
131 "asan-instrument-writes", cl::desc("instrument write instructions"),
132 cl::Hidden, cl::init(true));
133 static cl::opt<bool> ClInstrumentAtomics(
134 "asan-instrument-atomics",
135 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
137 static cl::opt<bool> ClAlwaysSlowPath(
138 "asan-always-slow-path",
139 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
141 // This flag limits the number of instructions to be instrumented
142 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
143 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
145 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
146 "asan-max-ins-per-bb", cl::init(10000),
147 cl::desc("maximal number of instructions to instrument in any given BB"),
149 // This flag may need to be replaced with -f[no]asan-stack.
150 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
151 cl::Hidden, cl::init(true));
152 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
153 cl::desc("Check return-after-free"),
154 cl::Hidden, cl::init(true));
155 // This flag may need to be replaced with -f[no]asan-globals.
156 static cl::opt<bool> ClGlobals("asan-globals",
157 cl::desc("Handle global objects"), cl::Hidden,
159 static cl::opt<bool> ClInitializers("asan-initialization-order",
160 cl::desc("Handle C++ initializer order"),
161 cl::Hidden, cl::init(true));
162 static cl::opt<bool> ClInvalidPointerPairs(
163 "asan-detect-invalid-pointer-pair",
164 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
166 static cl::opt<unsigned> ClRealignStack(
167 "asan-realign-stack",
168 cl::desc("Realign stack to the value of this flag (power of two)"),
169 cl::Hidden, cl::init(32));
170 static cl::opt<int> ClInstrumentationWithCallsThreshold(
171 "asan-instrumentation-with-call-threshold",
173 "If the function being instrumented contains more than "
174 "this number of memory accesses, use callbacks instead of "
175 "inline checks (-1 means never use callbacks)."),
176 cl::Hidden, cl::init(7000));
177 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
178 "asan-memory-access-callback-prefix",
179 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
180 cl::init("__asan_"));
181 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
182 cl::desc("instrument dynamic allocas"),
183 cl::Hidden, cl::init(false));
184 static cl::opt<bool> ClSkipPromotableAllocas(
185 "asan-skip-promotable-allocas",
186 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
189 // These flags allow to change the shadow mapping.
190 // The shadow mapping looks like
191 // Shadow = (Mem >> scale) + (1 << offset_log)
192 static cl::opt<int> ClMappingScale("asan-mapping-scale",
193 cl::desc("scale of asan shadow mapping"),
194 cl::Hidden, cl::init(0));
196 // Optimization flags. Not user visible, used mostly for testing
197 // and benchmarking the tool.
198 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
199 cl::Hidden, cl::init(true));
200 static cl::opt<bool> ClOptSameTemp(
201 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
202 cl::Hidden, cl::init(true));
203 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
204 cl::desc("Don't instrument scalar globals"),
205 cl::Hidden, cl::init(true));
206 static cl::opt<bool> ClOptStack(
207 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
208 cl::Hidden, cl::init(false));
210 static cl::opt<bool> ClCheckLifetime(
211 "asan-check-lifetime",
212 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
215 static cl::opt<bool> ClDynamicAllocaStack(
216 "asan-stack-dynamic-alloca",
217 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
220 static cl::opt<uint32_t> ClForceExperiment(
221 "asan-force-experiment",
222 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
226 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
228 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
229 cl::Hidden, cl::init(0));
230 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
231 cl::desc("Debug func"));
232 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
233 cl::Hidden, cl::init(-1));
234 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
235 cl::Hidden, cl::init(-1));
237 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
238 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
239 STATISTIC(NumOptimizedAccessesToGlobalVar,
240 "Number of optimized accesses to global vars");
241 STATISTIC(NumOptimizedAccessesToStackVar,
242 "Number of optimized accesses to stack vars");
245 /// Frontend-provided metadata for source location.
246 struct LocationMetadata {
251 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
253 bool empty() const { return Filename.empty(); }
255 void parse(MDNode *MDN) {
256 assert(MDN->getNumOperands() == 3);
257 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
258 Filename = DIFilename->getString();
260 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
262 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
266 /// Frontend-provided metadata for global variables.
267 class GlobalsMetadata {
270 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
271 LocationMetadata SourceLoc;
277 GlobalsMetadata() : inited_(false) {}
279 void init(Module &M) {
282 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
283 if (!Globals) return;
284 for (auto MDN : Globals->operands()) {
285 // Metadata node contains the global and the fields of "Entry".
286 assert(MDN->getNumOperands() == 5);
287 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
288 // The optimizer may optimize away a global entirely.
290 // We can already have an entry for GV if it was merged with another
292 Entry &E = Entries[GV];
293 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
294 E.SourceLoc.parse(Loc);
295 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
296 E.Name = Name->getString();
297 ConstantInt *IsDynInit =
298 mdconst::extract<ConstantInt>(MDN->getOperand(3));
299 E.IsDynInit |= IsDynInit->isOne();
300 ConstantInt *IsBlacklisted =
301 mdconst::extract<ConstantInt>(MDN->getOperand(4));
302 E.IsBlacklisted |= IsBlacklisted->isOne();
306 /// Returns metadata entry for a given global.
307 Entry get(GlobalVariable *G) const {
308 auto Pos = Entries.find(G);
309 return (Pos != Entries.end()) ? Pos->second : Entry();
314 DenseMap<GlobalVariable *, Entry> Entries;
317 /// This struct defines the shadow mapping using the rule:
318 /// shadow = (mem >> Scale) ADD-or-OR Offset.
319 struct ShadowMapping {
325 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
327 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
328 bool IsIOS = TargetTriple.isiOS();
329 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
330 bool IsLinux = TargetTriple.isOSLinux();
331 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
332 TargetTriple.getArch() == llvm::Triple::ppc64le;
333 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
334 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
335 TargetTriple.getArch() == llvm::Triple::mipsel;
336 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
337 TargetTriple.getArch() == llvm::Triple::mips64el;
338 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
339 bool IsWindows = TargetTriple.isOSWindows();
341 ShadowMapping Mapping;
343 if (LongSize == 32) {
344 // Android is always PIE, which means that the beginning of the address
345 // space is always available.
349 Mapping.Offset = kMIPS32_ShadowOffset32;
351 Mapping.Offset = kFreeBSD_ShadowOffset32;
353 Mapping.Offset = kIOSShadowOffset32;
355 Mapping.Offset = kWindowsShadowOffset32;
357 Mapping.Offset = kDefaultShadowOffset32;
358 } else { // LongSize == 64
360 Mapping.Offset = kPPC64_ShadowOffset64;
362 Mapping.Offset = kFreeBSD_ShadowOffset64;
363 else if (IsLinux && IsX86_64) {
365 Mapping.Offset = kLinuxKasan_ShadowOffset64;
367 Mapping.Offset = kSmallX86_64ShadowOffset;
369 Mapping.Offset = kMIPS64_ShadowOffset64;
371 Mapping.Offset = kAArch64_ShadowOffset64;
373 Mapping.Offset = kDefaultShadowOffset64;
376 Mapping.Scale = kDefaultShadowScale;
377 if (ClMappingScale) {
378 Mapping.Scale = ClMappingScale;
381 // OR-ing shadow offset if more efficient (at least on x86) if the offset
382 // is a power of two, but on ppc64 we have to use add since the shadow
383 // offset is not necessary 1/8-th of the address space.
384 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
389 static size_t RedzoneSizeForScale(int MappingScale) {
390 // Redzone used for stack and globals is at least 32 bytes.
391 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
392 return std::max(32U, 1U << MappingScale);
395 /// AddressSanitizer: instrument the code in module to find memory bugs.
396 struct AddressSanitizer : public FunctionPass {
397 explicit AddressSanitizer(bool CompileKernel = false)
398 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan) {
399 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
401 const char *getPassName() const override {
402 return "AddressSanitizerFunctionPass";
404 void getAnalysisUsage(AnalysisUsage &AU) const override {
405 AU.addRequired<DominatorTreeWrapperPass>();
406 AU.addRequired<TargetLibraryInfoWrapperPass>();
408 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
409 Type *Ty = AI->getAllocatedType();
410 uint64_t SizeInBytes =
411 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
414 /// Check if we want (and can) handle this alloca.
415 bool isInterestingAlloca(AllocaInst &AI);
417 // Check if we have dynamic alloca.
418 bool isDynamicAlloca(AllocaInst &AI) const {
419 return AI.isArrayAllocation() || !AI.isStaticAlloca();
422 /// If it is an interesting memory access, return the PointerOperand
423 /// and set IsWrite/Alignment. Otherwise return nullptr.
424 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
425 uint64_t *TypeSize, unsigned *Alignment);
426 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
427 bool UseCalls, const DataLayout &DL);
428 void instrumentPointerComparisonOrSubtraction(Instruction *I);
429 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
430 Value *Addr, uint32_t TypeSize, bool IsWrite,
431 Value *SizeArgument, bool UseCalls, uint32_t Exp);
432 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
433 uint32_t TypeSize, bool IsWrite,
434 Value *SizeArgument, bool UseCalls,
436 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
437 Value *ShadowValue, uint32_t TypeSize);
438 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
439 bool IsWrite, size_t AccessSizeIndex,
440 Value *SizeArgument, uint32_t Exp);
441 void instrumentMemIntrinsic(MemIntrinsic *MI);
442 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
443 bool runOnFunction(Function &F) override;
444 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
445 void markEscapedLocalAllocas(Function &F);
446 bool doInitialization(Module &M) override;
447 static char ID; // Pass identification, replacement for typeid
449 DominatorTree &getDominatorTree() const { return *DT; }
452 void initializeCallbacks(Module &M);
454 bool LooksLikeCodeInBug11395(Instruction *I);
455 bool GlobalIsLinkerInitialized(GlobalVariable *G);
456 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
457 uint64_t TypeSize) const;
459 /// Helper to cleanup per-function state.
460 struct FunctionStateRAII {
461 AddressSanitizer *Pass;
462 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
463 assert(Pass->ProcessedAllocas.empty() &&
464 "last pass forgot to clear cache");
466 ~FunctionStateRAII() { Pass->ProcessedAllocas.clear(); }
474 ShadowMapping Mapping;
476 Function *AsanCtorFunction = nullptr;
477 Function *AsanInitFunction = nullptr;
478 Function *AsanHandleNoReturnFunc;
479 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
480 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
481 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
482 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
483 // This array is indexed by AccessIsWrite and Experiment.
484 Function *AsanErrorCallbackSized[2][2];
485 Function *AsanMemoryAccessCallbackSized[2][2];
486 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
488 GlobalsMetadata GlobalsMD;
489 DenseMap<AllocaInst *, bool> ProcessedAllocas;
491 friend struct FunctionStackPoisoner;
494 class AddressSanitizerModule : public ModulePass {
496 explicit AddressSanitizerModule(bool CompileKernel = false)
497 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan) {}
498 bool runOnModule(Module &M) override;
499 static char ID; // Pass identification, replacement for typeid
500 const char *getPassName() const override { return "AddressSanitizerModule"; }
503 void initializeCallbacks(Module &M);
505 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
506 bool ShouldInstrumentGlobal(GlobalVariable *G);
507 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
508 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
509 size_t MinRedzoneSizeForGlobal() const {
510 return RedzoneSizeForScale(Mapping.Scale);
513 GlobalsMetadata GlobalsMD;
518 ShadowMapping Mapping;
519 Function *AsanPoisonGlobals;
520 Function *AsanUnpoisonGlobals;
521 Function *AsanRegisterGlobals;
522 Function *AsanUnregisterGlobals;
525 // Stack poisoning does not play well with exception handling.
526 // When an exception is thrown, we essentially bypass the code
527 // that unpoisones the stack. This is why the run-time library has
528 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
529 // stack in the interceptor. This however does not work inside the
530 // actual function which catches the exception. Most likely because the
531 // compiler hoists the load of the shadow value somewhere too high.
532 // This causes asan to report a non-existing bug on 453.povray.
533 // It sounds like an LLVM bug.
534 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
536 AddressSanitizer &ASan;
541 ShadowMapping Mapping;
543 SmallVector<AllocaInst *, 16> AllocaVec;
544 SmallSetVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec;
545 SmallVector<Instruction *, 8> RetVec;
546 unsigned StackAlignment;
548 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
549 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
550 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
551 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
553 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
554 struct AllocaPoisonCall {
555 IntrinsicInst *InsBefore;
560 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
562 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
563 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
564 AllocaInst *DynamicAllocaLayout = nullptr;
565 IntrinsicInst *LocalEscapeCall = nullptr;
567 // Maps Value to an AllocaInst from which the Value is originated.
568 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
569 AllocaForValueMapTy AllocaForValue;
571 bool HasNonEmptyInlineAsm;
572 std::unique_ptr<CallInst> EmptyInlineAsm;
574 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
577 DIB(*F.getParent(), /*AllowUnresolved*/ false),
579 IntptrTy(ASan.IntptrTy),
580 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
581 Mapping(ASan.Mapping),
582 StackAlignment(1 << Mapping.Scale),
583 HasNonEmptyInlineAsm(false),
584 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
586 bool runOnFunction() {
587 if (!ClStack) return false;
588 // Collect alloca, ret, lifetime instructions etc.
589 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
591 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
593 initializeCallbacks(*F.getParent());
603 // Finds all Alloca instructions and puts
604 // poisoned red zones around all of them.
605 // Then unpoison everything back before the function returns.
608 void createDynamicAllocasInitStorage();
610 // ----------------------- Visitors.
611 /// \brief Collect all Ret instructions.
612 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
614 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
616 IRBuilder<> IRB(InstBefore);
617 IRB.CreateCall(AsanAllocasUnpoisonFunc,
618 {IRB.CreateLoad(DynamicAllocaLayout),
619 IRB.CreatePtrToInt(SavedStack, IntptrTy)});
622 // Unpoison dynamic allocas redzones.
623 void unpoisonDynamicAllocas() {
624 for (auto &Ret : RetVec)
625 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
627 for (auto &StackRestoreInst : StackRestoreVec)
628 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
629 StackRestoreInst->getOperand(0));
632 // Deploy and poison redzones around dynamic alloca call. To do this, we
633 // should replace this call with another one with changed parameters and
634 // replace all its uses with new address, so
635 // addr = alloca type, old_size, align
637 // new_size = (old_size + additional_size) * sizeof(type)
638 // tmp = alloca i8, new_size, max(align, 32)
639 // addr = tmp + 32 (first 32 bytes are for the left redzone).
640 // Additional_size is added to make new memory allocation contain not only
641 // requested memory, but also left, partial and right redzones.
642 void handleDynamicAllocaCall(AllocaInst *AI);
644 /// \brief Collect Alloca instructions we want (and can) handle.
645 void visitAllocaInst(AllocaInst &AI) {
646 if (!ASan.isInterestingAlloca(AI)) {
647 if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.insert(&AI);
651 StackAlignment = std::max(StackAlignment, AI.getAlignment());
652 if (ASan.isDynamicAlloca(AI))
653 DynamicAllocaVec.push_back(&AI);
655 AllocaVec.push_back(&AI);
658 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
660 void visitIntrinsicInst(IntrinsicInst &II) {
661 Intrinsic::ID ID = II.getIntrinsicID();
662 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
663 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
664 if (!ClCheckLifetime) return;
665 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
667 // Found lifetime intrinsic, add ASan instrumentation if necessary.
668 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
669 // If size argument is undefined, don't do anything.
670 if (Size->isMinusOne()) return;
671 // Check that size doesn't saturate uint64_t and can
672 // be stored in IntptrTy.
673 const uint64_t SizeValue = Size->getValue().getLimitedValue();
674 if (SizeValue == ~0ULL ||
675 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
677 // Find alloca instruction that corresponds to llvm.lifetime argument.
678 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
680 bool DoPoison = (ID == Intrinsic::lifetime_end);
681 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
682 AllocaPoisonCallVec.push_back(APC);
685 void visitCallInst(CallInst &CI) {
686 HasNonEmptyInlineAsm |=
687 CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get());
690 // ---------------------- Helpers.
691 void initializeCallbacks(Module &M);
693 bool doesDominateAllExits(const Instruction *I) const {
694 for (auto Ret : RetVec) {
695 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
700 /// Finds alloca where the value comes from.
701 AllocaInst *findAllocaForValue(Value *V);
702 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
703 Value *ShadowBase, bool DoPoison);
704 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
706 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
708 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
710 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
711 Instruction *ThenTerm, Value *ValueIfFalse);
716 char AddressSanitizer::ID = 0;
717 INITIALIZE_PASS_BEGIN(
718 AddressSanitizer, "asan",
719 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
721 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
723 AddressSanitizer, "asan",
724 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
726 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel) {
727 return new AddressSanitizer(CompileKernel);
730 char AddressSanitizerModule::ID = 0;
732 AddressSanitizerModule, "asan-module",
733 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
736 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel) {
737 return new AddressSanitizerModule(CompileKernel);
740 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
741 size_t Res = countTrailingZeros(TypeSize / 8);
742 assert(Res < kNumberOfAccessSizes);
746 // \brief Create a constant for Str so that we can pass it to the run-time lib.
747 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
749 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
750 // We use private linkage for module-local strings. If they can be merged
751 // with another one, we set the unnamed_addr attribute.
753 new GlobalVariable(M, StrConst->getType(), true,
754 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
755 if (AllowMerging) GV->setUnnamedAddr(true);
756 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
760 /// \brief Create a global describing a source location.
761 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
762 LocationMetadata MD) {
763 Constant *LocData[] = {
764 createPrivateGlobalForString(M, MD.Filename, true),
765 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
766 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
768 auto LocStruct = ConstantStruct::getAnon(LocData);
769 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
770 GlobalValue::PrivateLinkage, LocStruct,
772 GV->setUnnamedAddr(true);
776 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
777 return G->getName().find(kAsanGenPrefix) == 0 ||
778 G->getName().find(kSanCovGenPrefix) == 0;
781 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
783 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
784 if (Mapping.Offset == 0) return Shadow;
785 // (Shadow >> scale) | offset
786 if (Mapping.OrShadowOffset)
787 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
789 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
792 // Instrument memset/memmove/memcpy
793 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
795 if (isa<MemTransferInst>(MI)) {
797 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
798 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
799 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
800 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
801 } else if (isa<MemSetInst>(MI)) {
804 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
805 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
806 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
808 MI->eraseFromParent();
811 /// Check if we want (and can) handle this alloca.
812 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
813 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
815 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
816 return PreviouslySeenAllocaInfo->getSecond();
819 (AI.getAllocatedType()->isSized() &&
820 // alloca() may be called with 0 size, ignore it.
821 getAllocaSizeInBytes(&AI) > 0 &&
822 // We are only interested in allocas not promotable to registers.
823 // Promotable allocas are common under -O0.
824 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI) ||
825 isDynamicAlloca(AI)));
827 ProcessedAllocas[&AI] = IsInteresting;
828 return IsInteresting;
831 /// If I is an interesting memory access, return the PointerOperand
832 /// and set IsWrite/Alignment. Otherwise return nullptr.
833 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
836 unsigned *Alignment) {
837 // Skip memory accesses inserted by another instrumentation.
838 if (I->getMetadata("nosanitize")) return nullptr;
840 Value *PtrOperand = nullptr;
841 const DataLayout &DL = I->getModule()->getDataLayout();
842 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
843 if (!ClInstrumentReads) return nullptr;
845 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
846 *Alignment = LI->getAlignment();
847 PtrOperand = LI->getPointerOperand();
848 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
849 if (!ClInstrumentWrites) return nullptr;
851 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
852 *Alignment = SI->getAlignment();
853 PtrOperand = SI->getPointerOperand();
854 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
855 if (!ClInstrumentAtomics) return nullptr;
857 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
859 PtrOperand = RMW->getPointerOperand();
860 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
861 if (!ClInstrumentAtomics) return nullptr;
863 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
865 PtrOperand = XCHG->getPointerOperand();
868 // Treat memory accesses to promotable allocas as non-interesting since they
869 // will not cause memory violations. This greatly speeds up the instrumented
870 // executable at -O0.
871 if (ClSkipPromotableAllocas)
872 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
873 return isInterestingAlloca(*AI) ? AI : nullptr;
878 static bool isPointerOperand(Value *V) {
879 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
882 // This is a rough heuristic; it may cause both false positives and
883 // false negatives. The proper implementation requires cooperation with
885 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
886 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
887 if (!Cmp->isRelational()) return false;
888 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
889 if (BO->getOpcode() != Instruction::Sub) return false;
893 if (!isPointerOperand(I->getOperand(0)) ||
894 !isPointerOperand(I->getOperand(1)))
899 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
900 // If a global variable does not have dynamic initialization we don't
901 // have to instrument it. However, if a global does not have initializer
902 // at all, we assume it has dynamic initializer (in other TU).
903 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
906 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
909 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
910 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
911 for (int i = 0; i < 2; i++) {
912 if (Param[i]->getType()->isPointerTy())
913 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
915 IRB.CreateCall(F, Param);
918 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
919 Instruction *I, bool UseCalls,
920 const DataLayout &DL) {
921 bool IsWrite = false;
922 unsigned Alignment = 0;
923 uint64_t TypeSize = 0;
924 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
927 // Optimization experiments.
928 // The experiments can be used to evaluate potential optimizations that remove
929 // instrumentation (assess false negatives). Instead of completely removing
930 // some instrumentation, you set Exp to a non-zero value (mask of optimization
931 // experiments that want to remove instrumentation of this instruction).
932 // If Exp is non-zero, this pass will emit special calls into runtime
933 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
934 // make runtime terminate the program in a special way (with a different
935 // exit status). Then you run the new compiler on a buggy corpus, collect
936 // the special terminations (ideally, you don't see them at all -- no false
937 // negatives) and make the decision on the optimization.
938 uint32_t Exp = ClForceExperiment;
940 if (ClOpt && ClOptGlobals) {
941 // If initialization order checking is disabled, a simple access to a
942 // dynamically initialized global is always valid.
943 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
944 if (G != NULL && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
945 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
946 NumOptimizedAccessesToGlobalVar++;
951 if (ClOpt && ClOptStack) {
952 // A direct inbounds access to a stack variable is always valid.
953 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
954 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
955 NumOptimizedAccessesToStackVar++;
961 NumInstrumentedWrites++;
963 NumInstrumentedReads++;
965 unsigned Granularity = 1 << Mapping.Scale;
966 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
967 // if the data is properly aligned.
968 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
970 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
971 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
973 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
977 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
978 Value *Addr, bool IsWrite,
979 size_t AccessSizeIndex,
982 IRBuilder<> IRB(InsertBefore);
983 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
984 CallInst *Call = nullptr;
987 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
988 {Addr, SizeArgument});
990 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
991 {Addr, SizeArgument, ExpVal});
995 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
997 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1001 // We don't do Call->setDoesNotReturn() because the BB already has
1002 // UnreachableInst at the end.
1003 // This EmptyAsm is required to avoid callback merge.
1004 IRB.CreateCall(EmptyAsm, {});
1008 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1010 uint32_t TypeSize) {
1011 size_t Granularity = 1 << Mapping.Scale;
1012 // Addr & (Granularity - 1)
1013 Value *LastAccessedByte =
1014 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1015 // (Addr & (Granularity - 1)) + size - 1
1016 if (TypeSize / 8 > 1)
1017 LastAccessedByte = IRB.CreateAdd(
1018 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1019 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1021 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1022 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1023 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1026 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1027 Instruction *InsertBefore, Value *Addr,
1028 uint32_t TypeSize, bool IsWrite,
1029 Value *SizeArgument, bool UseCalls,
1031 IRBuilder<> IRB(InsertBefore);
1032 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1033 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1037 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1040 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1041 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1046 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1047 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1048 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1049 Value *CmpVal = Constant::getNullValue(ShadowTy);
1050 Value *ShadowValue =
1051 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1053 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1054 size_t Granularity = 1 << Mapping.Scale;
1055 TerminatorInst *CrashTerm = nullptr;
1057 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1058 // We use branch weights for the slow path check, to indicate that the slow
1059 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1060 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1061 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1062 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1063 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1064 IRB.SetInsertPoint(CheckTerm);
1065 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1066 BasicBlock *CrashBlock =
1067 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1068 CrashTerm = new UnreachableInst(*C, CrashBlock);
1069 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1070 ReplaceInstWithInst(CheckTerm, NewTerm);
1072 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1075 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1076 AccessSizeIndex, SizeArgument, Exp);
1077 Crash->setDebugLoc(OrigIns->getDebugLoc());
1080 // Instrument unusual size or unusual alignment.
1081 // We can not do it with a single check, so we do 1-byte check for the first
1082 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1083 // to report the actual access size.
1084 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1085 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1086 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1088 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1089 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1092 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1095 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1096 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1098 Value *LastByte = IRB.CreateIntToPtr(
1099 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1101 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1102 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1106 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1107 GlobalValue *ModuleName) {
1108 // Set up the arguments to our poison/unpoison functions.
1109 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1111 // Add a call to poison all external globals before the given function starts.
1112 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1113 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1115 // Add calls to unpoison all globals before each return instruction.
1116 for (auto &BB : GlobalInit.getBasicBlockList())
1117 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1118 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1121 void AddressSanitizerModule::createInitializerPoisonCalls(
1122 Module &M, GlobalValue *ModuleName) {
1123 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1125 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1126 for (Use &OP : CA->operands()) {
1127 if (isa<ConstantAggregateZero>(OP)) continue;
1128 ConstantStruct *CS = cast<ConstantStruct>(OP);
1130 // Must have a function or null ptr.
1131 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1132 if (F->getName() == kAsanModuleCtorName) continue;
1133 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1134 // Don't instrument CTORs that will run before asan.module_ctor.
1135 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1136 poisonOneInitializer(*F, ModuleName);
1141 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1142 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1143 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1145 if (GlobalsMD.get(G).IsBlacklisted) return false;
1146 if (!Ty->isSized()) return false;
1147 if (!G->hasInitializer()) return false;
1148 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1149 // Touch only those globals that will not be defined in other modules.
1150 // Don't handle ODR linkage types and COMDATs since other modules may be built
1152 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1153 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1154 G->getLinkage() != GlobalVariable::InternalLinkage)
1156 if (G->hasComdat()) return false;
1157 // Two problems with thread-locals:
1158 // - The address of the main thread's copy can't be computed at link-time.
1159 // - Need to poison all copies, not just the main thread's one.
1160 if (G->isThreadLocal()) return false;
1161 // For now, just ignore this Global if the alignment is large.
1162 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1164 if (G->hasSection()) {
1165 StringRef Section(G->getSection());
1167 // Globals from llvm.metadata aren't emitted, do not instrument them.
1168 if (Section == "llvm.metadata") return false;
1169 // Do not instrument globals from special LLVM sections.
1170 if (Section.find("__llvm") != StringRef::npos) return false;
1172 // Callbacks put into the CRT initializer/terminator sections
1173 // should not be instrumented.
1174 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1175 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1176 if (Section.startswith(".CRT")) {
1177 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1181 if (TargetTriple.isOSBinFormatMachO()) {
1182 StringRef ParsedSegment, ParsedSection;
1183 unsigned TAA = 0, StubSize = 0;
1185 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1186 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1187 if (!ErrorCode.empty()) {
1188 assert(false && "Invalid section specifier.");
1192 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1193 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1195 if (ParsedSegment == "__OBJC" ||
1196 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1197 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1200 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1201 // Constant CFString instances are compiled in the following way:
1202 // -- the string buffer is emitted into
1203 // __TEXT,__cstring,cstring_literals
1204 // -- the constant NSConstantString structure referencing that buffer
1205 // is placed into __DATA,__cfstring
1206 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1207 // Moreover, it causes the linker to crash on OS X 10.7
1208 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1209 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1212 // The linker merges the contents of cstring_literals and removes the
1214 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1215 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1224 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1225 IRBuilder<> IRB(*C);
1226 // Declare our poisoning and unpoisoning functions.
1227 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1228 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1229 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1230 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1231 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1232 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1233 // Declare functions that register/unregister globals.
1234 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1235 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1236 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1237 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1238 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1239 IntptrTy, IntptrTy, nullptr));
1240 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1243 // This function replaces all global variables with new variables that have
1244 // trailing redzones. It also creates a function that poisons
1245 // redzones and inserts this function into llvm.global_ctors.
1246 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1249 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1251 for (auto &G : M.globals()) {
1252 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1255 size_t n = GlobalsToChange.size();
1256 if (n == 0) return false;
1258 // A global is described by a structure
1261 // size_t size_with_redzone;
1262 // const char *name;
1263 // const char *module_name;
1264 // size_t has_dynamic_init;
1265 // void *source_location;
1266 // We initialize an array of such structures and pass it to a run-time call.
1267 StructType *GlobalStructTy =
1268 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1269 IntptrTy, IntptrTy, nullptr);
1270 SmallVector<Constant *, 16> Initializers(n);
1272 bool HasDynamicallyInitializedGlobals = false;
1274 // We shouldn't merge same module names, as this string serves as unique
1275 // module ID in runtime.
1276 GlobalVariable *ModuleName = createPrivateGlobalForString(
1277 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1279 auto &DL = M.getDataLayout();
1280 for (size_t i = 0; i < n; i++) {
1281 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1282 GlobalVariable *G = GlobalsToChange[i];
1284 auto MD = GlobalsMD.get(G);
1285 // Create string holding the global name (use global name from metadata
1286 // if it's available, otherwise just write the name of global variable).
1287 GlobalVariable *Name = createPrivateGlobalForString(
1288 M, MD.Name.empty() ? G->getName() : MD.Name,
1289 /*AllowMerging*/ true);
1291 PointerType *PtrTy = cast<PointerType>(G->getType());
1292 Type *Ty = PtrTy->getElementType();
1293 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1294 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1295 // MinRZ <= RZ <= kMaxGlobalRedzone
1296 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1297 uint64_t RZ = std::max(
1298 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1299 uint64_t RightRedzoneSize = RZ;
1300 // Round up to MinRZ
1301 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1302 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1303 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1305 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1306 Constant *NewInitializer =
1307 ConstantStruct::get(NewTy, G->getInitializer(),
1308 Constant::getNullValue(RightRedZoneTy), nullptr);
1310 // Create a new global variable with enough space for a redzone.
1311 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1312 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1313 Linkage = GlobalValue::InternalLinkage;
1314 GlobalVariable *NewGlobal =
1315 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1316 "", G, G->getThreadLocalMode());
1317 NewGlobal->copyAttributesFrom(G);
1318 NewGlobal->setAlignment(MinRZ);
1321 Indices2[0] = IRB.getInt32(0);
1322 Indices2[1] = IRB.getInt32(0);
1324 G->replaceAllUsesWith(
1325 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1326 NewGlobal->takeName(G);
1327 G->eraseFromParent();
1329 Constant *SourceLoc;
1330 if (!MD.SourceLoc.empty()) {
1331 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1332 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1334 SourceLoc = ConstantInt::get(IntptrTy, 0);
1337 Initializers[i] = ConstantStruct::get(
1338 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1339 ConstantInt::get(IntptrTy, SizeInBytes),
1340 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1341 ConstantExpr::getPointerCast(Name, IntptrTy),
1342 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1343 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1345 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1347 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1350 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1351 GlobalVariable *AllGlobals = new GlobalVariable(
1352 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1353 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1355 // Create calls for poisoning before initializers run and unpoisoning after.
1356 if (HasDynamicallyInitializedGlobals)
1357 createInitializerPoisonCalls(M, ModuleName);
1358 IRB.CreateCall(AsanRegisterGlobals,
1359 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1360 ConstantInt::get(IntptrTy, n)});
1362 // We also need to unregister globals at the end, e.g. when a shared library
1364 Function *AsanDtorFunction =
1365 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1366 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1367 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1368 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1369 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1370 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1371 ConstantInt::get(IntptrTy, n)});
1372 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1378 bool AddressSanitizerModule::runOnModule(Module &M) {
1379 C = &(M.getContext());
1380 int LongSize = M.getDataLayout().getPointerSizeInBits();
1381 IntptrTy = Type::getIntNTy(*C, LongSize);
1382 TargetTriple = Triple(M.getTargetTriple());
1383 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1384 initializeCallbacks(M);
1386 bool Changed = false;
1388 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1389 if (ClGlobals && !CompileKernel) {
1390 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1392 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1393 Changed |= InstrumentGlobals(IRB, M);
1399 void AddressSanitizer::initializeCallbacks(Module &M) {
1400 IRBuilder<> IRB(*C);
1401 // Create __asan_report* callbacks.
1402 // IsWrite, TypeSize and Exp are encoded in the function name.
1403 for (int Exp = 0; Exp < 2; Exp++) {
1404 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1405 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1406 const std::string ExpStr = Exp ? "exp_" : "";
1407 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1408 const std::string EndingStr = CompileKernel ? "_noabort" : "";
1409 const Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1410 // TODO(glider): for KASan builds add _noabort to error reporting
1411 // functions and make them actually noabort (remove the UnreachableInst).
1412 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1413 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1414 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr,
1415 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1416 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1417 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1418 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1419 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1420 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1421 AccessSizeIndex++) {
1422 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1423 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1424 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1425 kAsanReportErrorTemplate + ExpStr + Suffix,
1426 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1427 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1428 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1429 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1430 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1435 const std::string MemIntrinCallbackPrefix =
1436 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1437 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1438 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1439 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1440 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1441 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1442 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1443 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1444 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1445 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1447 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1448 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1450 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1451 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1452 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1453 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1454 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1455 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1456 StringRef(""), StringRef(""),
1457 /*hasSideEffects=*/true);
1461 bool AddressSanitizer::doInitialization(Module &M) {
1462 // Initialize the private fields. No one has accessed them before.
1466 C = &(M.getContext());
1467 LongSize = M.getDataLayout().getPointerSizeInBits();
1468 IntptrTy = Type::getIntNTy(*C, LongSize);
1469 TargetTriple = Triple(M.getTargetTriple());
1471 if (!CompileKernel) {
1472 std::tie(AsanCtorFunction, AsanInitFunction) =
1473 createSanitizerCtorAndInitFunctions(
1474 M, kAsanModuleCtorName, kAsanInitName,
1475 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
1476 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1478 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1482 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1483 // For each NSObject descendant having a +load method, this method is invoked
1484 // by the ObjC runtime before any of the static constructors is called.
1485 // Therefore we need to instrument such methods with a call to __asan_init
1486 // at the beginning in order to initialize our runtime before any access to
1487 // the shadow memory.
1488 // We cannot just ignore these methods, because they may call other
1489 // instrumented functions.
1490 if (F.getName().find(" load]") != std::string::npos) {
1491 IRBuilder<> IRB(F.begin()->begin());
1492 IRB.CreateCall(AsanInitFunction, {});
1498 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
1499 // Find the one possible call to llvm.localescape and pre-mark allocas passed
1500 // to it as uninteresting. This assumes we haven't started processing allocas
1501 // yet. This check is done up front because iterating the use list in
1502 // isInterestingAlloca would be algorithmically slower.
1503 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
1505 // Try to get the declaration of llvm.localescape. If it's not in the module,
1506 // we can exit early.
1507 if (!F.getParent()->getFunction("llvm.localescape")) return;
1509 // Look for a call to llvm.localescape call in the entry block. It can't be in
1511 for (Instruction &I : F.getEntryBlock()) {
1512 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
1513 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
1514 // We found a call. Mark all the allocas passed in as uninteresting.
1515 for (Value *Arg : II->arg_operands()) {
1516 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
1517 assert(AI && AI->isStaticAlloca() &&
1518 "non-static alloca arg to localescape");
1519 ProcessedAllocas[AI] = false;
1526 bool AddressSanitizer::runOnFunction(Function &F) {
1527 if (&F == AsanCtorFunction) return false;
1528 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1529 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1530 initializeCallbacks(*F.getParent());
1532 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1534 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1535 maybeInsertAsanInitAtFunctionEntry(F);
1537 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1539 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1541 FunctionStateRAII CleanupObj(this);
1543 // We can't instrument allocas used with llvm.localescape. Only static allocas
1544 // can be passed to that intrinsic.
1545 markEscapedLocalAllocas(F);
1547 // We want to instrument every address only once per basic block (unless there
1548 // are calls between uses).
1549 SmallSet<Value *, 16> TempsToInstrument;
1550 SmallVector<Instruction *, 16> ToInstrument;
1551 SmallVector<Instruction *, 8> NoReturnCalls;
1552 SmallVector<BasicBlock *, 16> AllBlocks;
1553 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1559 // Fill the set of memory operations to instrument.
1560 for (auto &BB : F) {
1561 AllBlocks.push_back(&BB);
1562 TempsToInstrument.clear();
1563 int NumInsnsPerBB = 0;
1564 for (auto &Inst : BB) {
1565 if (LooksLikeCodeInBug11395(&Inst)) return false;
1566 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1568 if (ClOpt && ClOptSameTemp) {
1569 if (!TempsToInstrument.insert(Addr).second)
1570 continue; // We've seen this temp in the current BB.
1572 } else if (ClInvalidPointerPairs &&
1573 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1574 PointerComparisonsOrSubtracts.push_back(&Inst);
1576 } else if (isa<MemIntrinsic>(Inst)) {
1579 if (isa<AllocaInst>(Inst)) NumAllocas++;
1582 // A call inside BB.
1583 TempsToInstrument.clear();
1584 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1588 ToInstrument.push_back(&Inst);
1590 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1596 (ClInstrumentationWithCallsThreshold >= 0 &&
1597 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
1598 const TargetLibraryInfo *TLI =
1599 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1600 const DataLayout &DL = F.getParent()->getDataLayout();
1601 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1602 /*RoundToAlign=*/true);
1605 int NumInstrumented = 0;
1606 for (auto Inst : ToInstrument) {
1607 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1608 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1609 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1610 instrumentMop(ObjSizeVis, Inst, UseCalls,
1611 F.getParent()->getDataLayout());
1613 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1618 FunctionStackPoisoner FSP(F, *this);
1619 bool ChangedStack = FSP.runOnFunction();
1621 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1622 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1623 for (auto CI : NoReturnCalls) {
1624 IRBuilder<> IRB(CI);
1625 IRB.CreateCall(AsanHandleNoReturnFunc, {});
1628 for (auto Inst : PointerComparisonsOrSubtracts) {
1629 instrumentPointerComparisonOrSubtraction(Inst);
1633 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1635 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1640 // Workaround for bug 11395: we don't want to instrument stack in functions
1641 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1642 // FIXME: remove once the bug 11395 is fixed.
1643 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1644 if (LongSize != 32) return false;
1645 CallInst *CI = dyn_cast<CallInst>(I);
1646 if (!CI || !CI->isInlineAsm()) return false;
1647 if (CI->getNumArgOperands() <= 5) return false;
1648 // We have inline assembly with quite a few arguments.
1652 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1653 IRBuilder<> IRB(*C);
1654 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1655 std::string Suffix = itostr(i);
1656 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
1657 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1658 IntptrTy, nullptr));
1659 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
1660 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1661 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1663 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1664 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1665 IntptrTy, IntptrTy, nullptr));
1666 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1667 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1668 IntptrTy, IntptrTy, nullptr));
1669 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1670 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1671 AsanAllocasUnpoisonFunc =
1672 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1673 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1676 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1677 IRBuilder<> &IRB, Value *ShadowBase,
1679 size_t n = ShadowBytes.size();
1681 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1682 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1683 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1684 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1685 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1686 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1688 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1689 if (F.getParent()->getDataLayout().isLittleEndian())
1690 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1692 Val = (Val << 8) | ShadowBytes[i + j];
1695 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1696 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1697 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1698 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1703 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1704 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1705 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1706 assert(LocalStackSize <= kMaxStackMallocSize);
1707 uint64_t MaxSize = kMinStackMallocSize;
1708 for (int i = 0;; i++, MaxSize *= 2)
1709 if (LocalStackSize <= MaxSize) return i;
1710 llvm_unreachable("impossible LocalStackSize");
1713 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1714 // We can not use MemSet intrinsic because it may end up calling the actual
1715 // memset. Size is a multiple of 8.
1716 // Currently this generates 8-byte stores on x86_64; it may be better to
1717 // generate wider stores.
1718 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1719 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1720 assert(!(Size % 8));
1722 // kAsanStackAfterReturnMagic is 0xf5.
1723 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1725 for (int i = 0; i < Size; i += 8) {
1726 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1728 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1729 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1733 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1735 Instruction *ThenTerm,
1736 Value *ValueIfFalse) {
1737 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1738 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1739 PHI->addIncoming(ValueIfFalse, CondBlock);
1740 BasicBlock *ThenBlock = ThenTerm->getParent();
1741 PHI->addIncoming(ValueIfTrue, ThenBlock);
1745 Value *FunctionStackPoisoner::createAllocaForLayout(
1746 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1749 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1750 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1753 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1754 nullptr, "MyAlloca");
1755 assert(Alloca->isStaticAlloca());
1757 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1758 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1759 Alloca->setAlignment(FrameAlignment);
1760 return IRB.CreatePointerCast(Alloca, IntptrTy);
1763 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
1764 BasicBlock &FirstBB = *F.begin();
1765 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
1766 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
1767 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
1768 DynamicAllocaLayout->setAlignment(32);
1771 void FunctionStackPoisoner::poisonStack() {
1772 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1774 if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
1775 // Handle dynamic allocas.
1776 createDynamicAllocasInitStorage();
1777 for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI);
1779 unpoisonDynamicAllocas();
1782 if (AllocaVec.size() == 0) return;
1784 int StackMallocIdx = -1;
1785 DebugLoc EntryDebugLocation;
1786 if (auto SP = getDISubprogram(&F))
1787 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
1789 Instruction *InsBefore = AllocaVec[0];
1790 IRBuilder<> IRB(InsBefore);
1791 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1793 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
1794 // debug info is broken, because only entry-block allocas are treated as
1795 // regular stack slots.
1796 auto InsBeforeB = InsBefore->getParent();
1797 assert(InsBeforeB == &F.getEntryBlock());
1798 for (BasicBlock::iterator I = InsBefore; I != InsBeforeB->end(); ++I)
1799 if (auto *AI = dyn_cast_or_null<AllocaInst>(I))
1800 if (NonInstrumentedStaticAllocaVec.count(AI) > 0)
1801 AI->moveBefore(InsBefore);
1803 // If we have a call to llvm.localescape, keep it in the entry block.
1804 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
1806 SmallVector<ASanStackVariableDescription, 16> SVD;
1807 SVD.reserve(AllocaVec.size());
1808 for (AllocaInst *AI : AllocaVec) {
1809 ASanStackVariableDescription D = {AI->getName().data(),
1810 ASan.getAllocaSizeInBytes(AI),
1811 AI->getAlignment(), AI, 0};
1814 // Minimal header size (left redzone) is 4 pointers,
1815 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1816 size_t MinHeaderSize = ASan.LongSize / 2;
1817 ASanStackFrameLayout L;
1818 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1819 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1820 uint64_t LocalStackSize = L.FrameSize;
1821 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
1822 LocalStackSize <= kMaxStackMallocSize;
1823 // Don't do dynamic alloca or stack malloc in presence of inline asm:
1824 // too often it makes assumptions on which registers are available.
1825 bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
1826 DoStackMalloc &= !HasNonEmptyInlineAsm;
1828 Value *StaticAlloca =
1829 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1832 Value *LocalStackBase;
1834 if (DoStackMalloc) {
1835 // void *FakeStack = __asan_option_detect_stack_use_after_return
1836 // ? __asan_stack_malloc_N(LocalStackSize)
1838 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1839 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1840 kAsanOptionDetectUAR, IRB.getInt32Ty());
1841 Value *UARIsEnabled =
1842 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1843 Constant::getNullValue(IRB.getInt32Ty()));
1845 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1846 IRBuilder<> IRBIf(Term);
1847 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1848 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1849 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1850 Value *FakeStackValue =
1851 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1852 ConstantInt::get(IntptrTy, LocalStackSize));
1853 IRB.SetInsertPoint(InsBefore);
1854 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1855 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1856 ConstantInt::get(IntptrTy, 0));
1858 Value *NoFakeStack =
1859 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1860 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1861 IRBIf.SetInsertPoint(Term);
1862 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1863 Value *AllocaValue =
1864 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1865 IRB.SetInsertPoint(InsBefore);
1866 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1867 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1869 // void *FakeStack = nullptr;
1870 // void *LocalStackBase = alloca(LocalStackSize);
1871 FakeStack = ConstantInt::get(IntptrTy, 0);
1873 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1876 // Insert poison calls for lifetime intrinsics for alloca.
1877 bool HavePoisonedAllocas = false;
1878 for (const auto &APC : AllocaPoisonCallVec) {
1879 assert(APC.InsBefore);
1881 IRBuilder<> IRB(APC.InsBefore);
1882 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1883 HavePoisonedAllocas |= APC.DoPoison;
1886 // Replace Alloca instructions with base+offset.
1887 for (const auto &Desc : SVD) {
1888 AllocaInst *AI = Desc.AI;
1889 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1890 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1892 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1893 AI->replaceAllUsesWith(NewAllocaPtr);
1896 // The left-most redzone has enough space for at least 4 pointers.
1897 // Write the Magic value to redzone[0].
1898 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1899 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1901 // Write the frame description constant to redzone[1].
1902 Value *BasePlus1 = IRB.CreateIntToPtr(
1903 IRB.CreateAdd(LocalStackBase,
1904 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1906 GlobalVariable *StackDescriptionGlobal =
1907 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1908 /*AllowMerging*/ true);
1909 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1910 IRB.CreateStore(Description, BasePlus1);
1911 // Write the PC to redzone[2].
1912 Value *BasePlus2 = IRB.CreateIntToPtr(
1913 IRB.CreateAdd(LocalStackBase,
1914 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1916 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1918 // Poison the stack redzones at the entry.
1919 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1920 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1922 // (Un)poison the stack before all ret instructions.
1923 for (auto Ret : RetVec) {
1924 IRBuilder<> IRBRet(Ret);
1925 // Mark the current frame as retired.
1926 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1928 if (DoStackMalloc) {
1929 assert(StackMallocIdx >= 0);
1930 // if FakeStack != 0 // LocalStackBase == FakeStack
1931 // // In use-after-return mode, poison the whole stack frame.
1932 // if StackMallocIdx <= 4
1933 // // For small sizes inline the whole thing:
1934 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1935 // **SavedFlagPtr(FakeStack) = 0
1937 // __asan_stack_free_N(FakeStack, LocalStackSize)
1939 // <This is not a fake stack; unpoison the redzones>
1941 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1942 TerminatorInst *ThenTerm, *ElseTerm;
1943 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1945 IRBuilder<> IRBPoison(ThenTerm);
1946 if (StackMallocIdx <= 4) {
1947 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1948 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1949 ClassSize >> Mapping.Scale);
1950 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1952 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1953 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1954 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1955 IRBPoison.CreateStore(
1956 Constant::getNullValue(IRBPoison.getInt8Ty()),
1957 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1959 // For larger frames call __asan_stack_free_*.
1960 IRBPoison.CreateCall(
1961 AsanStackFreeFunc[StackMallocIdx],
1962 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
1965 IRBuilder<> IRBElse(ElseTerm);
1966 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1967 } else if (HavePoisonedAllocas) {
1968 // If we poisoned some allocas in llvm.lifetime analysis,
1969 // unpoison whole stack frame now.
1970 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1972 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1976 // We are done. Remove the old unused alloca instructions.
1977 for (auto AI : AllocaVec) AI->eraseFromParent();
1980 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1981 IRBuilder<> &IRB, bool DoPoison) {
1982 // For now just insert the call to ASan runtime.
1983 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1984 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1986 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
1987 {AddrArg, SizeArg});
1990 // Handling llvm.lifetime intrinsics for a given %alloca:
1991 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1992 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1993 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1994 // could be poisoned by previous llvm.lifetime.end instruction, as the
1995 // variable may go in and out of scope several times, e.g. in loops).
1996 // (3) if we poisoned at least one %alloca in a function,
1997 // unpoison the whole stack frame at function exit.
1999 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2000 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2001 // We're intested only in allocas we can handle.
2002 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2003 // See if we've already calculated (or started to calculate) alloca for a
2005 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2006 if (I != AllocaForValue.end()) return I->second;
2007 // Store 0 while we're calculating alloca for value V to avoid
2008 // infinite recursion if the value references itself.
2009 AllocaForValue[V] = nullptr;
2010 AllocaInst *Res = nullptr;
2011 if (CastInst *CI = dyn_cast<CastInst>(V))
2012 Res = findAllocaForValue(CI->getOperand(0));
2013 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2014 for (Value *IncValue : PN->incoming_values()) {
2015 // Allow self-referencing phi-nodes.
2016 if (IncValue == PN) continue;
2017 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2018 // AI for incoming values should exist and should all be equal.
2019 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2024 if (Res) AllocaForValue[V] = Res;
2028 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2029 IRBuilder<> IRB(AI);
2031 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2032 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2034 Value *Zero = Constant::getNullValue(IntptrTy);
2035 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2036 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2038 // Since we need to extend alloca with additional memory to locate
2039 // redzones, and OldSize is number of allocated blocks with
2040 // ElementSize size, get allocated memory size in bytes by
2041 // OldSize * ElementSize.
2042 const unsigned ElementSize =
2043 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2045 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2046 ConstantInt::get(IntptrTy, ElementSize));
2048 // PartialSize = OldSize % 32
2049 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2051 // Misalign = kAllocaRzSize - PartialSize;
2052 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2054 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2055 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2056 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2058 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2059 // Align is added to locate left redzone, PartialPadding for possible
2060 // partial redzone and kAllocaRzSize for right redzone respectively.
2061 Value *AdditionalChunkSize = IRB.CreateAdd(
2062 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2064 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2066 // Insert new alloca with new NewSize and Align params.
2067 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2068 NewAlloca->setAlignment(Align);
2070 // NewAddress = Address + Align
2071 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2072 ConstantInt::get(IntptrTy, Align));
2074 // Insert __asan_alloca_poison call for new created alloca.
2075 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2077 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2078 // for unpoisoning stuff.
2079 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2081 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2083 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2084 AI->replaceAllUsesWith(NewAddressPtr);
2086 // We are done. Erase old alloca from parent.
2087 AI->eraseFromParent();
2090 // isSafeAccess returns true if Addr is always inbounds with respect to its
2091 // base object. For example, it is a field access or an array access with
2092 // constant inbounds index.
2093 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2094 Value *Addr, uint64_t TypeSize) const {
2095 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2096 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2097 uint64_t Size = SizeOffset.first.getZExtValue();
2098 int64_t Offset = SizeOffset.second.getSExtValue();
2099 // Three checks are required to ensure safety:
2100 // . Offset >= 0 (since the offset is given from the base ptr)
2101 // . Size >= Offset (unsigned)
2102 // . Size - Offset >= NeededSize (unsigned)
2103 return Offset >= 0 && Size >= uint64_t(Offset) &&
2104 Size - uint64_t(Offset) >= TypeSize / 8;