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_v5";
95 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
96 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
97 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
98 static const int kMaxAsanStackMallocSizeClass = 10;
99 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
100 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
101 static const char *const kAsanGenPrefix = "__asan_gen_";
102 static const char *const kSanCovGenPrefix = "__sancov_gen_";
103 static const char *const kAsanPoisonStackMemoryName =
104 "__asan_poison_stack_memory";
105 static const char *const kAsanUnpoisonStackMemoryName =
106 "__asan_unpoison_stack_memory";
108 static const char *const kAsanOptionDetectUAR =
109 "__asan_option_detect_stack_use_after_return";
111 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
112 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
114 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
115 static const size_t kNumberOfAccessSizes = 5;
117 static const unsigned kAllocaRzSize = 32;
119 // Command-line flags.
120 static cl::opt<bool> ClEnableKasan(
121 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
122 cl::Hidden, cl::init(false));
124 // This flag may need to be replaced with -f[no-]asan-reads.
125 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
126 cl::desc("instrument read instructions"),
127 cl::Hidden, cl::init(true));
128 static cl::opt<bool> ClInstrumentWrites(
129 "asan-instrument-writes", cl::desc("instrument write instructions"),
130 cl::Hidden, cl::init(true));
131 static cl::opt<bool> ClInstrumentAtomics(
132 "asan-instrument-atomics",
133 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
135 static cl::opt<bool> ClAlwaysSlowPath(
136 "asan-always-slow-path",
137 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
139 // This flag limits the number of instructions to be instrumented
140 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
141 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
143 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
144 "asan-max-ins-per-bb", cl::init(10000),
145 cl::desc("maximal number of instructions to instrument in any given BB"),
147 // This flag may need to be replaced with -f[no]asan-stack.
148 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
149 cl::Hidden, cl::init(true));
150 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
151 cl::desc("Check return-after-free"),
152 cl::Hidden, cl::init(true));
153 // This flag may need to be replaced with -f[no]asan-globals.
154 static cl::opt<bool> ClGlobals("asan-globals",
155 cl::desc("Handle global objects"), cl::Hidden,
157 static cl::opt<bool> ClInitializers("asan-initialization-order",
158 cl::desc("Handle C++ initializer order"),
159 cl::Hidden, cl::init(true));
160 static cl::opt<bool> ClInvalidPointerPairs(
161 "asan-detect-invalid-pointer-pair",
162 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
164 static cl::opt<unsigned> ClRealignStack(
165 "asan-realign-stack",
166 cl::desc("Realign stack to the value of this flag (power of two)"),
167 cl::Hidden, cl::init(32));
168 static cl::opt<int> ClInstrumentationWithCallsThreshold(
169 "asan-instrumentation-with-call-threshold",
171 "If the function being instrumented contains more than "
172 "this number of memory accesses, use callbacks instead of "
173 "inline checks (-1 means never use callbacks)."),
174 cl::Hidden, cl::init(7000));
175 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
176 "asan-memory-access-callback-prefix",
177 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
178 cl::init("__asan_"));
179 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
180 cl::desc("instrument dynamic allocas"),
181 cl::Hidden, cl::init(false));
182 static cl::opt<bool> ClSkipPromotableAllocas(
183 "asan-skip-promotable-allocas",
184 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
187 // These flags allow to change the shadow mapping.
188 // The shadow mapping looks like
189 // Shadow = (Mem >> scale) + (1 << offset_log)
190 static cl::opt<int> ClMappingScale("asan-mapping-scale",
191 cl::desc("scale of asan shadow mapping"),
192 cl::Hidden, cl::init(0));
194 // Optimization flags. Not user visible, used mostly for testing
195 // and benchmarking the tool.
196 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
197 cl::Hidden, cl::init(true));
198 static cl::opt<bool> ClOptSameTemp(
199 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
200 cl::Hidden, cl::init(true));
201 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
202 cl::desc("Don't instrument scalar globals"),
203 cl::Hidden, cl::init(true));
204 static cl::opt<bool> ClOptStack(
205 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
206 cl::Hidden, cl::init(false));
208 static cl::opt<bool> ClCheckLifetime(
209 "asan-check-lifetime",
210 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
213 static cl::opt<bool> ClDynamicAllocaStack(
214 "asan-stack-dynamic-alloca",
215 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
218 static cl::opt<uint32_t> ClForceExperiment(
219 "asan-force-experiment",
220 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
224 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
226 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
227 cl::Hidden, cl::init(0));
228 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
229 cl::desc("Debug func"));
230 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
231 cl::Hidden, cl::init(-1));
232 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
233 cl::Hidden, cl::init(-1));
235 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
236 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
237 STATISTIC(NumOptimizedAccessesToGlobalVar,
238 "Number of optimized accesses to global vars");
239 STATISTIC(NumOptimizedAccessesToStackVar,
240 "Number of optimized accesses to stack vars");
243 /// Frontend-provided metadata for source location.
244 struct LocationMetadata {
249 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
251 bool empty() const { return Filename.empty(); }
253 void parse(MDNode *MDN) {
254 assert(MDN->getNumOperands() == 3);
255 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
256 Filename = DIFilename->getString();
258 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
260 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
264 /// Frontend-provided metadata for global variables.
265 class GlobalsMetadata {
268 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
269 LocationMetadata SourceLoc;
275 GlobalsMetadata() : inited_(false) {}
277 void init(Module &M) {
280 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
281 if (!Globals) return;
282 for (auto MDN : Globals->operands()) {
283 // Metadata node contains the global and the fields of "Entry".
284 assert(MDN->getNumOperands() == 5);
285 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
286 // The optimizer may optimize away a global entirely.
288 // We can already have an entry for GV if it was merged with another
290 Entry &E = Entries[GV];
291 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
292 E.SourceLoc.parse(Loc);
293 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
294 E.Name = Name->getString();
295 ConstantInt *IsDynInit =
296 mdconst::extract<ConstantInt>(MDN->getOperand(3));
297 E.IsDynInit |= IsDynInit->isOne();
298 ConstantInt *IsBlacklisted =
299 mdconst::extract<ConstantInt>(MDN->getOperand(4));
300 E.IsBlacklisted |= IsBlacklisted->isOne();
304 /// Returns metadata entry for a given global.
305 Entry get(GlobalVariable *G) const {
306 auto Pos = Entries.find(G);
307 return (Pos != Entries.end()) ? Pos->second : Entry();
312 DenseMap<GlobalVariable *, Entry> Entries;
315 /// This struct defines the shadow mapping using the rule:
316 /// shadow = (mem >> Scale) ADD-or-OR Offset.
317 struct ShadowMapping {
323 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
325 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
326 bool IsIOS = TargetTriple.isiOS();
327 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
328 bool IsLinux = TargetTriple.isOSLinux();
329 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
330 TargetTriple.getArch() == llvm::Triple::ppc64le;
331 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
332 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
333 TargetTriple.getArch() == llvm::Triple::mipsel;
334 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
335 TargetTriple.getArch() == llvm::Triple::mips64el;
336 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
337 bool IsWindows = TargetTriple.isOSWindows();
339 ShadowMapping Mapping;
342 // Android is always PIE, which means that the beginning of the address
343 // space is always available.
345 } else if (LongSize == 32) {
347 Mapping.Offset = kMIPS32_ShadowOffset32;
349 Mapping.Offset = kFreeBSD_ShadowOffset32;
351 Mapping.Offset = kIOSShadowOffset32;
353 Mapping.Offset = kWindowsShadowOffset32;
355 Mapping.Offset = kDefaultShadowOffset32;
356 } else { // LongSize == 64
358 Mapping.Offset = kPPC64_ShadowOffset64;
360 Mapping.Offset = kFreeBSD_ShadowOffset64;
361 else if (IsLinux && IsX86_64) {
363 Mapping.Offset = kLinuxKasan_ShadowOffset64;
365 Mapping.Offset = kSmallX86_64ShadowOffset;
367 Mapping.Offset = kMIPS64_ShadowOffset64;
369 Mapping.Offset = kAArch64_ShadowOffset64;
371 Mapping.Offset = kDefaultShadowOffset64;
374 Mapping.Scale = kDefaultShadowScale;
375 if (ClMappingScale) {
376 Mapping.Scale = ClMappingScale;
379 // OR-ing shadow offset if more efficient (at least on x86) if the offset
380 // is a power of two, but on ppc64 we have to use add since the shadow
381 // offset is not necessary 1/8-th of the address space.
382 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
387 static size_t RedzoneSizeForScale(int MappingScale) {
388 // Redzone used for stack and globals is at least 32 bytes.
389 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
390 return std::max(32U, 1U << MappingScale);
393 /// AddressSanitizer: instrument the code in module to find memory bugs.
394 struct AddressSanitizer : public FunctionPass {
395 explicit AddressSanitizer(bool CompileKernel = false)
396 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan) {
397 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
399 const char *getPassName() const override {
400 return "AddressSanitizerFunctionPass";
402 void getAnalysisUsage(AnalysisUsage &AU) const override {
403 AU.addRequired<DominatorTreeWrapperPass>();
404 AU.addRequired<TargetLibraryInfoWrapperPass>();
406 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
407 Type *Ty = AI->getAllocatedType();
408 uint64_t SizeInBytes =
409 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
412 /// Check if we want (and can) handle this alloca.
413 bool isInterestingAlloca(AllocaInst &AI);
415 // Check if we have dynamic alloca.
416 bool isDynamicAlloca(AllocaInst &AI) const {
417 return AI.isArrayAllocation() || !AI.isStaticAlloca();
420 /// If it is an interesting memory access, return the PointerOperand
421 /// and set IsWrite/Alignment. Otherwise return nullptr.
422 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
423 uint64_t *TypeSize, unsigned *Alignment);
424 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
425 bool UseCalls, const DataLayout &DL);
426 void instrumentPointerComparisonOrSubtraction(Instruction *I);
427 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
428 Value *Addr, uint32_t TypeSize, bool IsWrite,
429 Value *SizeArgument, bool UseCalls, uint32_t Exp);
430 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
431 uint32_t TypeSize, bool IsWrite,
432 Value *SizeArgument, bool UseCalls,
434 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
435 Value *ShadowValue, uint32_t TypeSize);
436 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
437 bool IsWrite, size_t AccessSizeIndex,
438 Value *SizeArgument, uint32_t Exp);
439 void instrumentMemIntrinsic(MemIntrinsic *MI);
440 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
441 bool runOnFunction(Function &F) override;
442 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
443 void markEscapedLocalAllocas(Function &F);
444 bool doInitialization(Module &M) override;
445 static char ID; // Pass identification, replacement for typeid
447 DominatorTree &getDominatorTree() const { return *DT; }
450 void initializeCallbacks(Module &M);
452 bool LooksLikeCodeInBug11395(Instruction *I);
453 bool GlobalIsLinkerInitialized(GlobalVariable *G);
454 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
455 uint64_t TypeSize) const;
457 /// Helper to cleanup per-function state.
458 struct FunctionStateRAII {
459 AddressSanitizer *Pass;
460 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
461 assert(Pass->ProcessedAllocas.empty() &&
462 "last pass forgot to clear cache");
464 ~FunctionStateRAII() { Pass->ProcessedAllocas.clear(); }
472 ShadowMapping Mapping;
474 Function *AsanCtorFunction = nullptr;
475 Function *AsanInitFunction = nullptr;
476 Function *AsanHandleNoReturnFunc;
477 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
478 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
479 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
480 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
481 // This array is indexed by AccessIsWrite and Experiment.
482 Function *AsanErrorCallbackSized[2][2];
483 Function *AsanMemoryAccessCallbackSized[2][2];
484 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
486 GlobalsMetadata GlobalsMD;
487 DenseMap<AllocaInst *, bool> ProcessedAllocas;
489 friend struct FunctionStackPoisoner;
492 class AddressSanitizerModule : public ModulePass {
494 explicit AddressSanitizerModule(bool CompileKernel = false)
495 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan) {}
496 bool runOnModule(Module &M) override;
497 static char ID; // Pass identification, replacement for typeid
498 const char *getPassName() const override { return "AddressSanitizerModule"; }
501 void initializeCallbacks(Module &M);
503 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
504 bool ShouldInstrumentGlobal(GlobalVariable *G);
505 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
506 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
507 size_t MinRedzoneSizeForGlobal() const {
508 return RedzoneSizeForScale(Mapping.Scale);
511 GlobalsMetadata GlobalsMD;
516 ShadowMapping Mapping;
517 Function *AsanPoisonGlobals;
518 Function *AsanUnpoisonGlobals;
519 Function *AsanRegisterGlobals;
520 Function *AsanUnregisterGlobals;
523 // Stack poisoning does not play well with exception handling.
524 // When an exception is thrown, we essentially bypass the code
525 // that unpoisones the stack. This is why the run-time library has
526 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
527 // stack in the interceptor. This however does not work inside the
528 // actual function which catches the exception. Most likely because the
529 // compiler hoists the load of the shadow value somewhere too high.
530 // This causes asan to report a non-existing bug on 453.povray.
531 // It sounds like an LLVM bug.
532 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
534 AddressSanitizer &ASan;
539 ShadowMapping Mapping;
541 SmallVector<AllocaInst *, 16> AllocaVec;
542 SmallSetVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec;
543 SmallVector<Instruction *, 8> RetVec;
544 unsigned StackAlignment;
546 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
547 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
548 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
549 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
551 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
552 struct AllocaPoisonCall {
553 IntrinsicInst *InsBefore;
558 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
560 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
561 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
562 AllocaInst *DynamicAllocaLayout = nullptr;
563 IntrinsicInst *LocalEscapeCall = nullptr;
565 // Maps Value to an AllocaInst from which the Value is originated.
566 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
567 AllocaForValueMapTy AllocaForValue;
569 bool HasNonEmptyInlineAsm;
570 std::unique_ptr<CallInst> EmptyInlineAsm;
572 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
575 DIB(*F.getParent(), /*AllowUnresolved*/ false),
577 IntptrTy(ASan.IntptrTy),
578 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
579 Mapping(ASan.Mapping),
580 StackAlignment(1 << Mapping.Scale),
581 HasNonEmptyInlineAsm(false),
582 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
584 bool runOnFunction() {
585 if (!ClStack) return false;
586 // Collect alloca, ret, lifetime instructions etc.
587 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
589 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
591 initializeCallbacks(*F.getParent());
601 // Finds all Alloca instructions and puts
602 // poisoned red zones around all of them.
603 // Then unpoison everything back before the function returns.
606 void createDynamicAllocasInitStorage();
608 // ----------------------- Visitors.
609 /// \brief Collect all Ret instructions.
610 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
612 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
614 IRBuilder<> IRB(InstBefore);
615 IRB.CreateCall(AsanAllocasUnpoisonFunc,
616 {IRB.CreateLoad(DynamicAllocaLayout),
617 IRB.CreatePtrToInt(SavedStack, IntptrTy)});
620 // Unpoison dynamic allocas redzones.
621 void unpoisonDynamicAllocas() {
622 for (auto &Ret : RetVec)
623 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
625 for (auto &StackRestoreInst : StackRestoreVec)
626 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
627 StackRestoreInst->getOperand(0));
630 // Deploy and poison redzones around dynamic alloca call. To do this, we
631 // should replace this call with another one with changed parameters and
632 // replace all its uses with new address, so
633 // addr = alloca type, old_size, align
635 // new_size = (old_size + additional_size) * sizeof(type)
636 // tmp = alloca i8, new_size, max(align, 32)
637 // addr = tmp + 32 (first 32 bytes are for the left redzone).
638 // Additional_size is added to make new memory allocation contain not only
639 // requested memory, but also left, partial and right redzones.
640 void handleDynamicAllocaCall(AllocaInst *AI);
642 /// \brief Collect Alloca instructions we want (and can) handle.
643 void visitAllocaInst(AllocaInst &AI) {
644 if (!ASan.isInterestingAlloca(AI)) {
645 if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.insert(&AI);
649 StackAlignment = std::max(StackAlignment, AI.getAlignment());
650 if (ASan.isDynamicAlloca(AI))
651 DynamicAllocaVec.push_back(&AI);
653 AllocaVec.push_back(&AI);
656 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
658 void visitIntrinsicInst(IntrinsicInst &II) {
659 Intrinsic::ID ID = II.getIntrinsicID();
660 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
661 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
662 if (!ClCheckLifetime) return;
663 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
665 // Found lifetime intrinsic, add ASan instrumentation if necessary.
666 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
667 // If size argument is undefined, don't do anything.
668 if (Size->isMinusOne()) return;
669 // Check that size doesn't saturate uint64_t and can
670 // be stored in IntptrTy.
671 const uint64_t SizeValue = Size->getValue().getLimitedValue();
672 if (SizeValue == ~0ULL ||
673 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
675 // Find alloca instruction that corresponds to llvm.lifetime argument.
676 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
678 bool DoPoison = (ID == Intrinsic::lifetime_end);
679 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
680 AllocaPoisonCallVec.push_back(APC);
683 void visitCallInst(CallInst &CI) {
684 HasNonEmptyInlineAsm |=
685 CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get());
688 // ---------------------- Helpers.
689 void initializeCallbacks(Module &M);
691 bool doesDominateAllExits(const Instruction *I) const {
692 for (auto Ret : RetVec) {
693 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
698 /// Finds alloca where the value comes from.
699 AllocaInst *findAllocaForValue(Value *V);
700 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
701 Value *ShadowBase, bool DoPoison);
702 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
704 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
706 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
708 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
709 Instruction *ThenTerm, Value *ValueIfFalse);
714 char AddressSanitizer::ID = 0;
715 INITIALIZE_PASS_BEGIN(
716 AddressSanitizer, "asan",
717 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
719 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
721 AddressSanitizer, "asan",
722 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
724 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel) {
725 return new AddressSanitizer(CompileKernel);
728 char AddressSanitizerModule::ID = 0;
730 AddressSanitizerModule, "asan-module",
731 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
734 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel) {
735 return new AddressSanitizerModule(CompileKernel);
738 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
739 size_t Res = countTrailingZeros(TypeSize / 8);
740 assert(Res < kNumberOfAccessSizes);
744 // \brief Create a constant for Str so that we can pass it to the run-time lib.
745 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
747 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
748 // We use private linkage for module-local strings. If they can be merged
749 // with another one, we set the unnamed_addr attribute.
751 new GlobalVariable(M, StrConst->getType(), true,
752 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
753 if (AllowMerging) GV->setUnnamedAddr(true);
754 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
758 /// \brief Create a global describing a source location.
759 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
760 LocationMetadata MD) {
761 Constant *LocData[] = {
762 createPrivateGlobalForString(M, MD.Filename, true),
763 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
764 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
766 auto LocStruct = ConstantStruct::getAnon(LocData);
767 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
768 GlobalValue::PrivateLinkage, LocStruct,
770 GV->setUnnamedAddr(true);
774 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
775 return G->getName().find(kAsanGenPrefix) == 0 ||
776 G->getName().find(kSanCovGenPrefix) == 0;
779 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
781 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
782 if (Mapping.Offset == 0) return Shadow;
783 // (Shadow >> scale) | offset
784 if (Mapping.OrShadowOffset)
785 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
787 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
790 // Instrument memset/memmove/memcpy
791 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
793 if (isa<MemTransferInst>(MI)) {
795 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
796 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
797 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
798 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
799 } else if (isa<MemSetInst>(MI)) {
802 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
803 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
804 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
806 MI->eraseFromParent();
809 /// Check if we want (and can) handle this alloca.
810 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
811 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
813 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
814 return PreviouslySeenAllocaInfo->getSecond();
817 (AI.getAllocatedType()->isSized() &&
818 // alloca() may be called with 0 size, ignore it.
819 getAllocaSizeInBytes(&AI) > 0 &&
820 // We are only interested in allocas not promotable to registers.
821 // Promotable allocas are common under -O0.
822 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI) ||
823 isDynamicAlloca(AI)));
825 ProcessedAllocas[&AI] = IsInteresting;
826 return IsInteresting;
829 /// If I is an interesting memory access, return the PointerOperand
830 /// and set IsWrite/Alignment. Otherwise return nullptr.
831 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
834 unsigned *Alignment) {
835 // Skip memory accesses inserted by another instrumentation.
836 if (I->getMetadata("nosanitize")) return nullptr;
838 Value *PtrOperand = nullptr;
839 const DataLayout &DL = I->getModule()->getDataLayout();
840 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
841 if (!ClInstrumentReads) return nullptr;
843 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
844 *Alignment = LI->getAlignment();
845 PtrOperand = LI->getPointerOperand();
846 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
847 if (!ClInstrumentWrites) return nullptr;
849 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
850 *Alignment = SI->getAlignment();
851 PtrOperand = SI->getPointerOperand();
852 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
853 if (!ClInstrumentAtomics) return nullptr;
855 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
857 PtrOperand = RMW->getPointerOperand();
858 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
859 if (!ClInstrumentAtomics) return nullptr;
861 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
863 PtrOperand = XCHG->getPointerOperand();
866 // Treat memory accesses to promotable allocas as non-interesting since they
867 // will not cause memory violations. This greatly speeds up the instrumented
868 // executable at -O0.
869 if (ClSkipPromotableAllocas)
870 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
871 return isInterestingAlloca(*AI) ? AI : nullptr;
876 static bool isPointerOperand(Value *V) {
877 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
880 // This is a rough heuristic; it may cause both false positives and
881 // false negatives. The proper implementation requires cooperation with
883 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
884 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
885 if (!Cmp->isRelational()) return false;
886 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
887 if (BO->getOpcode() != Instruction::Sub) return false;
891 if (!isPointerOperand(I->getOperand(0)) ||
892 !isPointerOperand(I->getOperand(1)))
897 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
898 // If a global variable does not have dynamic initialization we don't
899 // have to instrument it. However, if a global does not have initializer
900 // at all, we assume it has dynamic initializer (in other TU).
901 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
904 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
907 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
908 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
909 for (int i = 0; i < 2; i++) {
910 if (Param[i]->getType()->isPointerTy())
911 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
913 IRB.CreateCall(F, Param);
916 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
917 Instruction *I, bool UseCalls,
918 const DataLayout &DL) {
919 bool IsWrite = false;
920 unsigned Alignment = 0;
921 uint64_t TypeSize = 0;
922 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
925 // Optimization experiments.
926 // The experiments can be used to evaluate potential optimizations that remove
927 // instrumentation (assess false negatives). Instead of completely removing
928 // some instrumentation, you set Exp to a non-zero value (mask of optimization
929 // experiments that want to remove instrumentation of this instruction).
930 // If Exp is non-zero, this pass will emit special calls into runtime
931 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
932 // make runtime terminate the program in a special way (with a different
933 // exit status). Then you run the new compiler on a buggy corpus, collect
934 // the special terminations (ideally, you don't see them at all -- no false
935 // negatives) and make the decision on the optimization.
936 uint32_t Exp = ClForceExperiment;
938 if (ClOpt && ClOptGlobals) {
939 // If initialization order checking is disabled, a simple access to a
940 // dynamically initialized global is always valid.
941 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
942 if (G != NULL && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
943 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
944 NumOptimizedAccessesToGlobalVar++;
949 if (ClOpt && ClOptStack) {
950 // A direct inbounds access to a stack variable is always valid.
951 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
952 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
953 NumOptimizedAccessesToStackVar++;
959 NumInstrumentedWrites++;
961 NumInstrumentedReads++;
963 unsigned Granularity = 1 << Mapping.Scale;
964 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
965 // if the data is properly aligned.
966 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
968 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
969 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
971 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
975 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
976 Value *Addr, bool IsWrite,
977 size_t AccessSizeIndex,
980 IRBuilder<> IRB(InsertBefore);
981 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
982 CallInst *Call = nullptr;
985 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
986 {Addr, SizeArgument});
988 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
989 {Addr, SizeArgument, ExpVal});
993 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
995 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
999 // We don't do Call->setDoesNotReturn() because the BB already has
1000 // UnreachableInst at the end.
1001 // This EmptyAsm is required to avoid callback merge.
1002 IRB.CreateCall(EmptyAsm, {});
1006 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1008 uint32_t TypeSize) {
1009 size_t Granularity = 1 << Mapping.Scale;
1010 // Addr & (Granularity - 1)
1011 Value *LastAccessedByte =
1012 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1013 // (Addr & (Granularity - 1)) + size - 1
1014 if (TypeSize / 8 > 1)
1015 LastAccessedByte = IRB.CreateAdd(
1016 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1017 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1019 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1020 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1021 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1024 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1025 Instruction *InsertBefore, Value *Addr,
1026 uint32_t TypeSize, bool IsWrite,
1027 Value *SizeArgument, bool UseCalls,
1029 IRBuilder<> IRB(InsertBefore);
1030 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1031 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1035 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1038 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1039 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1044 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1045 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1046 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1047 Value *CmpVal = Constant::getNullValue(ShadowTy);
1048 Value *ShadowValue =
1049 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1051 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1052 size_t Granularity = 1 << Mapping.Scale;
1053 TerminatorInst *CrashTerm = nullptr;
1055 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1056 // We use branch weights for the slow path check, to indicate that the slow
1057 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1058 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1059 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1060 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1061 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1062 IRB.SetInsertPoint(CheckTerm);
1063 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1064 BasicBlock *CrashBlock =
1065 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1066 CrashTerm = new UnreachableInst(*C, CrashBlock);
1067 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1068 ReplaceInstWithInst(CheckTerm, NewTerm);
1070 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1073 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1074 AccessSizeIndex, SizeArgument, Exp);
1075 Crash->setDebugLoc(OrigIns->getDebugLoc());
1078 // Instrument unusual size or unusual alignment.
1079 // We can not do it with a single check, so we do 1-byte check for the first
1080 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1081 // to report the actual access size.
1082 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1083 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1084 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1086 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1087 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1090 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1093 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1094 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1096 Value *LastByte = IRB.CreateIntToPtr(
1097 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1099 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1100 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1104 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1105 GlobalValue *ModuleName) {
1106 // Set up the arguments to our poison/unpoison functions.
1107 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1109 // Add a call to poison all external globals before the given function starts.
1110 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1111 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1113 // Add calls to unpoison all globals before each return instruction.
1114 for (auto &BB : GlobalInit.getBasicBlockList())
1115 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1116 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1119 void AddressSanitizerModule::createInitializerPoisonCalls(
1120 Module &M, GlobalValue *ModuleName) {
1121 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1123 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1124 for (Use &OP : CA->operands()) {
1125 if (isa<ConstantAggregateZero>(OP)) continue;
1126 ConstantStruct *CS = cast<ConstantStruct>(OP);
1128 // Must have a function or null ptr.
1129 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1130 if (F->getName() == kAsanModuleCtorName) continue;
1131 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1132 // Don't instrument CTORs that will run before asan.module_ctor.
1133 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1134 poisonOneInitializer(*F, ModuleName);
1139 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1140 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1141 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1143 if (GlobalsMD.get(G).IsBlacklisted) return false;
1144 if (!Ty->isSized()) return false;
1145 if (!G->hasInitializer()) return false;
1146 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1147 // Touch only those globals that will not be defined in other modules.
1148 // Don't handle ODR linkage types and COMDATs since other modules may be built
1150 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1151 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1152 G->getLinkage() != GlobalVariable::InternalLinkage)
1154 if (G->hasComdat()) return false;
1155 // Two problems with thread-locals:
1156 // - The address of the main thread's copy can't be computed at link-time.
1157 // - Need to poison all copies, not just the main thread's one.
1158 if (G->isThreadLocal()) return false;
1159 // For now, just ignore this Global if the alignment is large.
1160 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1162 if (G->hasSection()) {
1163 StringRef Section(G->getSection());
1165 // Globals from llvm.metadata aren't emitted, do not instrument them.
1166 if (Section == "llvm.metadata") return false;
1167 // Do not instrument globals from special LLVM sections.
1168 if (Section.find("__llvm") != StringRef::npos) return false;
1170 // Callbacks put into the CRT initializer/terminator sections
1171 // should not be instrumented.
1172 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1173 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1174 if (Section.startswith(".CRT")) {
1175 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1179 if (TargetTriple.isOSBinFormatMachO()) {
1180 StringRef ParsedSegment, ParsedSection;
1181 unsigned TAA = 0, StubSize = 0;
1183 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1184 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1185 if (!ErrorCode.empty()) {
1186 assert(false && "Invalid section specifier.");
1190 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1191 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1193 if (ParsedSegment == "__OBJC" ||
1194 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1195 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1198 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1199 // Constant CFString instances are compiled in the following way:
1200 // -- the string buffer is emitted into
1201 // __TEXT,__cstring,cstring_literals
1202 // -- the constant NSConstantString structure referencing that buffer
1203 // is placed into __DATA,__cfstring
1204 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1205 // Moreover, it causes the linker to crash on OS X 10.7
1206 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1207 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1210 // The linker merges the contents of cstring_literals and removes the
1212 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1213 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1222 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1223 IRBuilder<> IRB(*C);
1224 // Declare our poisoning and unpoisoning functions.
1225 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1226 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1227 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1228 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1229 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1230 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1231 // Declare functions that register/unregister globals.
1232 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1233 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1234 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1235 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1236 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1237 IntptrTy, IntptrTy, nullptr));
1238 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1241 // This function replaces all global variables with new variables that have
1242 // trailing redzones. It also creates a function that poisons
1243 // redzones and inserts this function into llvm.global_ctors.
1244 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1247 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1249 for (auto &G : M.globals()) {
1250 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1253 size_t n = GlobalsToChange.size();
1254 if (n == 0) return false;
1256 // A global is described by a structure
1259 // size_t size_with_redzone;
1260 // const char *name;
1261 // const char *module_name;
1262 // size_t has_dynamic_init;
1263 // void *source_location;
1264 // We initialize an array of such structures and pass it to a run-time call.
1265 StructType *GlobalStructTy =
1266 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1267 IntptrTy, IntptrTy, nullptr);
1268 SmallVector<Constant *, 16> Initializers(n);
1270 bool HasDynamicallyInitializedGlobals = false;
1272 // We shouldn't merge same module names, as this string serves as unique
1273 // module ID in runtime.
1274 GlobalVariable *ModuleName = createPrivateGlobalForString(
1275 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1277 auto &DL = M.getDataLayout();
1278 for (size_t i = 0; i < n; i++) {
1279 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1280 GlobalVariable *G = GlobalsToChange[i];
1282 auto MD = GlobalsMD.get(G);
1283 // Create string holding the global name (use global name from metadata
1284 // if it's available, otherwise just write the name of global variable).
1285 GlobalVariable *Name = createPrivateGlobalForString(
1286 M, MD.Name.empty() ? G->getName() : MD.Name,
1287 /*AllowMerging*/ true);
1289 PointerType *PtrTy = cast<PointerType>(G->getType());
1290 Type *Ty = PtrTy->getElementType();
1291 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1292 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1293 // MinRZ <= RZ <= kMaxGlobalRedzone
1294 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1295 uint64_t RZ = std::max(
1296 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1297 uint64_t RightRedzoneSize = RZ;
1298 // Round up to MinRZ
1299 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1300 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1301 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1303 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1304 Constant *NewInitializer =
1305 ConstantStruct::get(NewTy, G->getInitializer(),
1306 Constant::getNullValue(RightRedZoneTy), nullptr);
1308 // Create a new global variable with enough space for a redzone.
1309 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1310 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1311 Linkage = GlobalValue::InternalLinkage;
1312 GlobalVariable *NewGlobal =
1313 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1314 "", G, G->getThreadLocalMode());
1315 NewGlobal->copyAttributesFrom(G);
1316 NewGlobal->setAlignment(MinRZ);
1319 Indices2[0] = IRB.getInt32(0);
1320 Indices2[1] = IRB.getInt32(0);
1322 G->replaceAllUsesWith(
1323 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1324 NewGlobal->takeName(G);
1325 G->eraseFromParent();
1327 Constant *SourceLoc;
1328 if (!MD.SourceLoc.empty()) {
1329 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1330 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1332 SourceLoc = ConstantInt::get(IntptrTy, 0);
1335 Initializers[i] = ConstantStruct::get(
1336 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1337 ConstantInt::get(IntptrTy, SizeInBytes),
1338 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1339 ConstantExpr::getPointerCast(Name, IntptrTy),
1340 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1341 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1343 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1345 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1348 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1349 GlobalVariable *AllGlobals = new GlobalVariable(
1350 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1351 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1353 // Create calls for poisoning before initializers run and unpoisoning after.
1354 if (HasDynamicallyInitializedGlobals)
1355 createInitializerPoisonCalls(M, ModuleName);
1356 IRB.CreateCall(AsanRegisterGlobals,
1357 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1358 ConstantInt::get(IntptrTy, n)});
1360 // We also need to unregister globals at the end, e.g. when a shared library
1362 Function *AsanDtorFunction =
1363 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1364 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1365 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1366 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1367 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1368 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1369 ConstantInt::get(IntptrTy, n)});
1370 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1376 bool AddressSanitizerModule::runOnModule(Module &M) {
1377 C = &(M.getContext());
1378 int LongSize = M.getDataLayout().getPointerSizeInBits();
1379 IntptrTy = Type::getIntNTy(*C, LongSize);
1380 TargetTriple = Triple(M.getTargetTriple());
1381 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1382 initializeCallbacks(M);
1384 bool Changed = false;
1386 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1387 if (ClGlobals && !CompileKernel) {
1388 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1390 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1391 Changed |= InstrumentGlobals(IRB, M);
1397 void AddressSanitizer::initializeCallbacks(Module &M) {
1398 IRBuilder<> IRB(*C);
1399 // Create __asan_report* callbacks.
1400 // IsWrite, TypeSize and Exp are encoded in the function name.
1401 for (int Exp = 0; Exp < 2; Exp++) {
1402 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1403 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1404 const std::string ExpStr = Exp ? "exp_" : "";
1405 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1406 const std::string EndingStr = CompileKernel ? "_noabort" : "";
1407 const Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1408 // TODO(glider): for KASan builds add _noabort to error reporting
1409 // functions and make them actually noabort (remove the UnreachableInst).
1410 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1411 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1412 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr,
1413 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1414 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1415 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1416 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1417 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1418 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1419 AccessSizeIndex++) {
1420 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1421 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1422 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1423 kAsanReportErrorTemplate + ExpStr + Suffix,
1424 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1425 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1426 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1427 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1428 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1433 const std::string MemIntrinCallbackPrefix =
1434 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1435 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1436 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1437 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1438 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1439 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1440 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1441 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1442 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1443 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1445 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1446 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1448 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1449 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1450 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1451 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1452 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1453 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1454 StringRef(""), StringRef(""),
1455 /*hasSideEffects=*/true);
1459 bool AddressSanitizer::doInitialization(Module &M) {
1460 // Initialize the private fields. No one has accessed them before.
1464 C = &(M.getContext());
1465 LongSize = M.getDataLayout().getPointerSizeInBits();
1466 IntptrTy = Type::getIntNTy(*C, LongSize);
1467 TargetTriple = Triple(M.getTargetTriple());
1469 if (!CompileKernel) {
1470 std::tie(AsanCtorFunction, AsanInitFunction) =
1471 createSanitizerCtorAndInitFunctions(M, kAsanModuleCtorName, kAsanInitName,
1472 /*InitArgTypes=*/{},
1474 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1476 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1480 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1481 // For each NSObject descendant having a +load method, this method is invoked
1482 // by the ObjC runtime before any of the static constructors is called.
1483 // Therefore we need to instrument such methods with a call to __asan_init
1484 // at the beginning in order to initialize our runtime before any access to
1485 // the shadow memory.
1486 // We cannot just ignore these methods, because they may call other
1487 // instrumented functions.
1488 if (F.getName().find(" load]") != std::string::npos) {
1489 IRBuilder<> IRB(F.begin()->begin());
1490 IRB.CreateCall(AsanInitFunction, {});
1496 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
1497 // Find the one possible call to llvm.localescape and pre-mark allocas passed
1498 // to it as uninteresting. This assumes we haven't started processing allocas
1499 // yet. This check is done up front because iterating the use list in
1500 // isInterestingAlloca would be algorithmically slower.
1501 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
1503 // Try to get the declaration of llvm.localescape. If it's not in the module,
1504 // we can exit early.
1505 if (!F.getParent()->getFunction("llvm.localescape")) return;
1507 // Look for a call to llvm.localescape call in the entry block. It can't be in
1509 for (Instruction &I : F.getEntryBlock()) {
1510 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
1511 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
1512 // We found a call. Mark all the allocas passed in as uninteresting.
1513 for (Value *Arg : II->arg_operands()) {
1514 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
1515 assert(AI && AI->isStaticAlloca() &&
1516 "non-static alloca arg to localescape");
1517 ProcessedAllocas[AI] = false;
1524 bool AddressSanitizer::runOnFunction(Function &F) {
1525 if (&F == AsanCtorFunction) return false;
1526 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1527 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1528 initializeCallbacks(*F.getParent());
1530 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1532 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1533 maybeInsertAsanInitAtFunctionEntry(F);
1535 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1537 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1539 FunctionStateRAII CleanupObj(this);
1541 // We can't instrument allocas used with llvm.localescape. Only static allocas
1542 // can be passed to that intrinsic.
1543 markEscapedLocalAllocas(F);
1545 // We want to instrument every address only once per basic block (unless there
1546 // are calls between uses).
1547 SmallSet<Value *, 16> TempsToInstrument;
1548 SmallVector<Instruction *, 16> ToInstrument;
1549 SmallVector<Instruction *, 8> NoReturnCalls;
1550 SmallVector<BasicBlock *, 16> AllBlocks;
1551 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1557 // Fill the set of memory operations to instrument.
1558 for (auto &BB : F) {
1559 AllBlocks.push_back(&BB);
1560 TempsToInstrument.clear();
1561 int NumInsnsPerBB = 0;
1562 for (auto &Inst : BB) {
1563 if (LooksLikeCodeInBug11395(&Inst)) return false;
1564 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1566 if (ClOpt && ClOptSameTemp) {
1567 if (!TempsToInstrument.insert(Addr).second)
1568 continue; // We've seen this temp in the current BB.
1570 } else if (ClInvalidPointerPairs &&
1571 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1572 PointerComparisonsOrSubtracts.push_back(&Inst);
1574 } else if (isa<MemIntrinsic>(Inst)) {
1577 if (isa<AllocaInst>(Inst)) NumAllocas++;
1580 // A call inside BB.
1581 TempsToInstrument.clear();
1582 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1586 ToInstrument.push_back(&Inst);
1588 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1594 (ClInstrumentationWithCallsThreshold >= 0 &&
1595 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
1596 const TargetLibraryInfo *TLI =
1597 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1598 const DataLayout &DL = F.getParent()->getDataLayout();
1599 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1600 /*RoundToAlign=*/true);
1603 int NumInstrumented = 0;
1604 for (auto Inst : ToInstrument) {
1605 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1606 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1607 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1608 instrumentMop(ObjSizeVis, Inst, UseCalls,
1609 F.getParent()->getDataLayout());
1611 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1616 FunctionStackPoisoner FSP(F, *this);
1617 bool ChangedStack = FSP.runOnFunction();
1619 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1620 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1621 for (auto CI : NoReturnCalls) {
1622 IRBuilder<> IRB(CI);
1623 IRB.CreateCall(AsanHandleNoReturnFunc, {});
1626 for (auto Inst : PointerComparisonsOrSubtracts) {
1627 instrumentPointerComparisonOrSubtraction(Inst);
1631 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1633 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1638 // Workaround for bug 11395: we don't want to instrument stack in functions
1639 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1640 // FIXME: remove once the bug 11395 is fixed.
1641 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1642 if (LongSize != 32) return false;
1643 CallInst *CI = dyn_cast<CallInst>(I);
1644 if (!CI || !CI->isInlineAsm()) return false;
1645 if (CI->getNumArgOperands() <= 5) return false;
1646 // We have inline assembly with quite a few arguments.
1650 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1651 IRBuilder<> IRB(*C);
1652 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1653 std::string Suffix = itostr(i);
1654 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
1655 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1656 IntptrTy, nullptr));
1657 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
1658 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1659 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1661 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1662 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1663 IntptrTy, IntptrTy, nullptr));
1664 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1665 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1666 IntptrTy, IntptrTy, nullptr));
1667 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1668 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1669 AsanAllocasUnpoisonFunc =
1670 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1671 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1674 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1675 IRBuilder<> &IRB, Value *ShadowBase,
1677 size_t n = ShadowBytes.size();
1679 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1680 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1681 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1682 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1683 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1684 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1686 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1687 if (F.getParent()->getDataLayout().isLittleEndian())
1688 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1690 Val = (Val << 8) | ShadowBytes[i + j];
1693 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1694 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1695 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1696 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1701 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1702 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1703 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1704 assert(LocalStackSize <= kMaxStackMallocSize);
1705 uint64_t MaxSize = kMinStackMallocSize;
1706 for (int i = 0;; i++, MaxSize *= 2)
1707 if (LocalStackSize <= MaxSize) return i;
1708 llvm_unreachable("impossible LocalStackSize");
1711 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1712 // We can not use MemSet intrinsic because it may end up calling the actual
1713 // memset. Size is a multiple of 8.
1714 // Currently this generates 8-byte stores on x86_64; it may be better to
1715 // generate wider stores.
1716 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1717 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1718 assert(!(Size % 8));
1720 // kAsanStackAfterReturnMagic is 0xf5.
1721 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1723 for (int i = 0; i < Size; i += 8) {
1724 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1726 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1727 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1731 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1733 Instruction *ThenTerm,
1734 Value *ValueIfFalse) {
1735 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1736 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1737 PHI->addIncoming(ValueIfFalse, CondBlock);
1738 BasicBlock *ThenBlock = ThenTerm->getParent();
1739 PHI->addIncoming(ValueIfTrue, ThenBlock);
1743 Value *FunctionStackPoisoner::createAllocaForLayout(
1744 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1747 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1748 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1751 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1752 nullptr, "MyAlloca");
1753 assert(Alloca->isStaticAlloca());
1755 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1756 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1757 Alloca->setAlignment(FrameAlignment);
1758 return IRB.CreatePointerCast(Alloca, IntptrTy);
1761 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
1762 BasicBlock &FirstBB = *F.begin();
1763 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
1764 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
1765 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
1766 DynamicAllocaLayout->setAlignment(32);
1769 void FunctionStackPoisoner::poisonStack() {
1770 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1772 if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
1773 // Handle dynamic allocas.
1774 createDynamicAllocasInitStorage();
1775 for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI);
1777 unpoisonDynamicAllocas();
1780 if (AllocaVec.size() == 0) return;
1782 int StackMallocIdx = -1;
1783 DebugLoc EntryDebugLocation;
1784 if (auto SP = getDISubprogram(&F))
1785 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
1787 Instruction *InsBefore = AllocaVec[0];
1788 IRBuilder<> IRB(InsBefore);
1789 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1791 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
1792 // debug info is broken, because only entry-block allocas are treated as
1793 // regular stack slots.
1794 auto InsBeforeB = InsBefore->getParent();
1795 assert(InsBeforeB == &F.getEntryBlock());
1796 for (BasicBlock::iterator I = InsBefore; I != InsBeforeB->end(); ++I)
1797 if (auto *AI = dyn_cast_or_null<AllocaInst>(I))
1798 if (NonInstrumentedStaticAllocaVec.count(AI) > 0)
1799 AI->moveBefore(InsBefore);
1801 // If we have a call to llvm.localescape, keep it in the entry block.
1802 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
1804 SmallVector<ASanStackVariableDescription, 16> SVD;
1805 SVD.reserve(AllocaVec.size());
1806 for (AllocaInst *AI : AllocaVec) {
1807 ASanStackVariableDescription D = {AI->getName().data(),
1808 ASan.getAllocaSizeInBytes(AI),
1809 AI->getAlignment(), AI, 0};
1812 // Minimal header size (left redzone) is 4 pointers,
1813 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1814 size_t MinHeaderSize = ASan.LongSize / 2;
1815 ASanStackFrameLayout L;
1816 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1817 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1818 uint64_t LocalStackSize = L.FrameSize;
1819 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
1820 LocalStackSize <= kMaxStackMallocSize;
1821 // Don't do dynamic alloca or stack malloc in presence of inline asm:
1822 // too often it makes assumptions on which registers are available.
1823 bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
1824 DoStackMalloc &= !HasNonEmptyInlineAsm;
1826 Value *StaticAlloca =
1827 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1830 Value *LocalStackBase;
1832 if (DoStackMalloc) {
1833 // void *FakeStack = __asan_option_detect_stack_use_after_return
1834 // ? __asan_stack_malloc_N(LocalStackSize)
1836 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1837 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1838 kAsanOptionDetectUAR, IRB.getInt32Ty());
1839 Value *UARIsEnabled =
1840 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1841 Constant::getNullValue(IRB.getInt32Ty()));
1843 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1844 IRBuilder<> IRBIf(Term);
1845 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1846 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1847 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1848 Value *FakeStackValue =
1849 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1850 ConstantInt::get(IntptrTy, LocalStackSize));
1851 IRB.SetInsertPoint(InsBefore);
1852 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1853 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1854 ConstantInt::get(IntptrTy, 0));
1856 Value *NoFakeStack =
1857 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1858 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1859 IRBIf.SetInsertPoint(Term);
1860 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1861 Value *AllocaValue =
1862 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1863 IRB.SetInsertPoint(InsBefore);
1864 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1865 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1867 // void *FakeStack = nullptr;
1868 // void *LocalStackBase = alloca(LocalStackSize);
1869 FakeStack = ConstantInt::get(IntptrTy, 0);
1871 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1874 // Insert poison calls for lifetime intrinsics for alloca.
1875 bool HavePoisonedAllocas = false;
1876 for (const auto &APC : AllocaPoisonCallVec) {
1877 assert(APC.InsBefore);
1879 IRBuilder<> IRB(APC.InsBefore);
1880 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1881 HavePoisonedAllocas |= APC.DoPoison;
1884 // Replace Alloca instructions with base+offset.
1885 for (const auto &Desc : SVD) {
1886 AllocaInst *AI = Desc.AI;
1887 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1888 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1890 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1891 AI->replaceAllUsesWith(NewAllocaPtr);
1894 // The left-most redzone has enough space for at least 4 pointers.
1895 // Write the Magic value to redzone[0].
1896 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1897 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1899 // Write the frame description constant to redzone[1].
1900 Value *BasePlus1 = IRB.CreateIntToPtr(
1901 IRB.CreateAdd(LocalStackBase,
1902 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1904 GlobalVariable *StackDescriptionGlobal =
1905 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1906 /*AllowMerging*/ true);
1907 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1908 IRB.CreateStore(Description, BasePlus1);
1909 // Write the PC to redzone[2].
1910 Value *BasePlus2 = IRB.CreateIntToPtr(
1911 IRB.CreateAdd(LocalStackBase,
1912 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1914 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1916 // Poison the stack redzones at the entry.
1917 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1918 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1920 // (Un)poison the stack before all ret instructions.
1921 for (auto Ret : RetVec) {
1922 IRBuilder<> IRBRet(Ret);
1923 // Mark the current frame as retired.
1924 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1926 if (DoStackMalloc) {
1927 assert(StackMallocIdx >= 0);
1928 // if FakeStack != 0 // LocalStackBase == FakeStack
1929 // // In use-after-return mode, poison the whole stack frame.
1930 // if StackMallocIdx <= 4
1931 // // For small sizes inline the whole thing:
1932 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1933 // **SavedFlagPtr(FakeStack) = 0
1935 // __asan_stack_free_N(FakeStack, LocalStackSize)
1937 // <This is not a fake stack; unpoison the redzones>
1939 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1940 TerminatorInst *ThenTerm, *ElseTerm;
1941 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1943 IRBuilder<> IRBPoison(ThenTerm);
1944 if (StackMallocIdx <= 4) {
1945 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1946 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1947 ClassSize >> Mapping.Scale);
1948 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1950 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1951 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1952 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1953 IRBPoison.CreateStore(
1954 Constant::getNullValue(IRBPoison.getInt8Ty()),
1955 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1957 // For larger frames call __asan_stack_free_*.
1958 IRBPoison.CreateCall(
1959 AsanStackFreeFunc[StackMallocIdx],
1960 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
1963 IRBuilder<> IRBElse(ElseTerm);
1964 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1965 } else if (HavePoisonedAllocas) {
1966 // If we poisoned some allocas in llvm.lifetime analysis,
1967 // unpoison whole stack frame now.
1968 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1970 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1974 // We are done. Remove the old unused alloca instructions.
1975 for (auto AI : AllocaVec) AI->eraseFromParent();
1978 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1979 IRBuilder<> &IRB, bool DoPoison) {
1980 // For now just insert the call to ASan runtime.
1981 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1982 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1984 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
1985 {AddrArg, SizeArg});
1988 // Handling llvm.lifetime intrinsics for a given %alloca:
1989 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1990 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1991 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1992 // could be poisoned by previous llvm.lifetime.end instruction, as the
1993 // variable may go in and out of scope several times, e.g. in loops).
1994 // (3) if we poisoned at least one %alloca in a function,
1995 // unpoison the whole stack frame at function exit.
1997 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1998 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1999 // We're intested only in allocas we can handle.
2000 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2001 // See if we've already calculated (or started to calculate) alloca for a
2003 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2004 if (I != AllocaForValue.end()) return I->second;
2005 // Store 0 while we're calculating alloca for value V to avoid
2006 // infinite recursion if the value references itself.
2007 AllocaForValue[V] = nullptr;
2008 AllocaInst *Res = nullptr;
2009 if (CastInst *CI = dyn_cast<CastInst>(V))
2010 Res = findAllocaForValue(CI->getOperand(0));
2011 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2012 for (Value *IncValue : PN->incoming_values()) {
2013 // Allow self-referencing phi-nodes.
2014 if (IncValue == PN) continue;
2015 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2016 // AI for incoming values should exist and should all be equal.
2017 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2022 if (Res) AllocaForValue[V] = Res;
2026 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2027 IRBuilder<> IRB(AI);
2029 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2030 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2032 Value *Zero = Constant::getNullValue(IntptrTy);
2033 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2034 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2036 // Since we need to extend alloca with additional memory to locate
2037 // redzones, and OldSize is number of allocated blocks with
2038 // ElementSize size, get allocated memory size in bytes by
2039 // OldSize * ElementSize.
2040 const unsigned ElementSize =
2041 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2043 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2044 ConstantInt::get(IntptrTy, ElementSize));
2046 // PartialSize = OldSize % 32
2047 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2049 // Misalign = kAllocaRzSize - PartialSize;
2050 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2052 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2053 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2054 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2056 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2057 // Align is added to locate left redzone, PartialPadding for possible
2058 // partial redzone and kAllocaRzSize for right redzone respectively.
2059 Value *AdditionalChunkSize = IRB.CreateAdd(
2060 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2062 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2064 // Insert new alloca with new NewSize and Align params.
2065 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2066 NewAlloca->setAlignment(Align);
2068 // NewAddress = Address + Align
2069 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2070 ConstantInt::get(IntptrTy, Align));
2072 // Insert __asan_alloca_poison call for new created alloca.
2073 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2075 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2076 // for unpoisoning stuff.
2077 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2079 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2081 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2082 AI->replaceAllUsesWith(NewAddressPtr);
2084 // We are done. Erase old alloca from parent.
2085 AI->eraseFromParent();
2088 // isSafeAccess returns true if Addr is always inbounds with respect to its
2089 // base object. For example, it is a field access or an array access with
2090 // constant inbounds index.
2091 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2092 Value *Addr, uint64_t TypeSize) const {
2093 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2094 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2095 uint64_t Size = SizeOffset.first.getZExtValue();
2096 int64_t Offset = SizeOffset.second.getSExtValue();
2097 // Three checks are required to ensure safety:
2098 // . Offset >= 0 (since the offset is given from the base ptr)
2099 // . Size >= Offset (unsigned)
2100 // . Size - Offset >= NeededSize (unsigned)
2101 return Offset >= 0 && Size >= uint64_t(Offset) &&
2102 Size - uint64_t(Offset) >= TypeSize / 8;