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 = false;
572 bool HasReturnsTwiceCall = false;
573 std::unique_ptr<CallInst> EmptyInlineAsm;
575 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
578 DIB(*F.getParent(), /*AllowUnresolved*/ false),
580 IntptrTy(ASan.IntptrTy),
581 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
582 Mapping(ASan.Mapping),
583 StackAlignment(1 << Mapping.Scale),
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 visitCallSite(CallSite CS) {
686 Instruction *I = CS.getInstruction();
687 if (CallInst *CI = dyn_cast<CallInst>(I)) {
688 HasNonEmptyInlineAsm |=
689 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
690 HasReturnsTwiceCall |= CI->canReturnTwice();
694 // ---------------------- Helpers.
695 void initializeCallbacks(Module &M);
697 bool doesDominateAllExits(const Instruction *I) const {
698 for (auto Ret : RetVec) {
699 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
704 /// Finds alloca where the value comes from.
705 AllocaInst *findAllocaForValue(Value *V);
706 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
707 Value *ShadowBase, bool DoPoison);
708 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
710 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
712 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
714 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
715 Instruction *ThenTerm, Value *ValueIfFalse);
720 char AddressSanitizer::ID = 0;
721 INITIALIZE_PASS_BEGIN(
722 AddressSanitizer, "asan",
723 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
725 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
727 AddressSanitizer, "asan",
728 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
730 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel) {
731 return new AddressSanitizer(CompileKernel);
734 char AddressSanitizerModule::ID = 0;
736 AddressSanitizerModule, "asan-module",
737 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
740 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel) {
741 return new AddressSanitizerModule(CompileKernel);
744 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
745 size_t Res = countTrailingZeros(TypeSize / 8);
746 assert(Res < kNumberOfAccessSizes);
750 // \brief Create a constant for Str so that we can pass it to the run-time lib.
751 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
753 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
754 // We use private linkage for module-local strings. If they can be merged
755 // with another one, we set the unnamed_addr attribute.
757 new GlobalVariable(M, StrConst->getType(), true,
758 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
759 if (AllowMerging) GV->setUnnamedAddr(true);
760 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
764 /// \brief Create a global describing a source location.
765 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
766 LocationMetadata MD) {
767 Constant *LocData[] = {
768 createPrivateGlobalForString(M, MD.Filename, true),
769 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
770 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
772 auto LocStruct = ConstantStruct::getAnon(LocData);
773 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
774 GlobalValue::PrivateLinkage, LocStruct,
776 GV->setUnnamedAddr(true);
780 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
781 return G->getName().find(kAsanGenPrefix) == 0 ||
782 G->getName().find(kSanCovGenPrefix) == 0;
785 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
787 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
788 if (Mapping.Offset == 0) return Shadow;
789 // (Shadow >> scale) | offset
790 if (Mapping.OrShadowOffset)
791 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
793 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
796 // Instrument memset/memmove/memcpy
797 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
799 if (isa<MemTransferInst>(MI)) {
801 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
802 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
803 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
804 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
805 } else if (isa<MemSetInst>(MI)) {
808 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
809 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
810 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
812 MI->eraseFromParent();
815 /// Check if we want (and can) handle this alloca.
816 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
817 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
819 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
820 return PreviouslySeenAllocaInfo->getSecond();
823 (AI.getAllocatedType()->isSized() &&
824 // alloca() may be called with 0 size, ignore it.
825 getAllocaSizeInBytes(&AI) > 0 &&
826 // We are only interested in allocas not promotable to registers.
827 // Promotable allocas are common under -O0.
828 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI) ||
829 isDynamicAlloca(AI)));
831 ProcessedAllocas[&AI] = IsInteresting;
832 return IsInteresting;
835 /// If I is an interesting memory access, return the PointerOperand
836 /// and set IsWrite/Alignment. Otherwise return nullptr.
837 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
840 unsigned *Alignment) {
841 // Skip memory accesses inserted by another instrumentation.
842 if (I->getMetadata("nosanitize")) return nullptr;
844 Value *PtrOperand = nullptr;
845 const DataLayout &DL = I->getModule()->getDataLayout();
846 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
847 if (!ClInstrumentReads) return nullptr;
849 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
850 *Alignment = LI->getAlignment();
851 PtrOperand = LI->getPointerOperand();
852 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
853 if (!ClInstrumentWrites) return nullptr;
855 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
856 *Alignment = SI->getAlignment();
857 PtrOperand = SI->getPointerOperand();
858 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
859 if (!ClInstrumentAtomics) return nullptr;
861 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
863 PtrOperand = RMW->getPointerOperand();
864 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
865 if (!ClInstrumentAtomics) return nullptr;
867 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
869 PtrOperand = XCHG->getPointerOperand();
872 // Treat memory accesses to promotable allocas as non-interesting since they
873 // will not cause memory violations. This greatly speeds up the instrumented
874 // executable at -O0.
875 if (ClSkipPromotableAllocas)
876 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
877 return isInterestingAlloca(*AI) ? AI : nullptr;
882 static bool isPointerOperand(Value *V) {
883 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
886 // This is a rough heuristic; it may cause both false positives and
887 // false negatives. The proper implementation requires cooperation with
889 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
890 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
891 if (!Cmp->isRelational()) return false;
892 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
893 if (BO->getOpcode() != Instruction::Sub) return false;
897 if (!isPointerOperand(I->getOperand(0)) ||
898 !isPointerOperand(I->getOperand(1)))
903 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
904 // If a global variable does not have dynamic initialization we don't
905 // have to instrument it. However, if a global does not have initializer
906 // at all, we assume it has dynamic initializer (in other TU).
907 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
910 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
913 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
914 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
915 for (int i = 0; i < 2; i++) {
916 if (Param[i]->getType()->isPointerTy())
917 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
919 IRB.CreateCall(F, Param);
922 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
923 Instruction *I, bool UseCalls,
924 const DataLayout &DL) {
925 bool IsWrite = false;
926 unsigned Alignment = 0;
927 uint64_t TypeSize = 0;
928 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
931 // Optimization experiments.
932 // The experiments can be used to evaluate potential optimizations that remove
933 // instrumentation (assess false negatives). Instead of completely removing
934 // some instrumentation, you set Exp to a non-zero value (mask of optimization
935 // experiments that want to remove instrumentation of this instruction).
936 // If Exp is non-zero, this pass will emit special calls into runtime
937 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
938 // make runtime terminate the program in a special way (with a different
939 // exit status). Then you run the new compiler on a buggy corpus, collect
940 // the special terminations (ideally, you don't see them at all -- no false
941 // negatives) and make the decision on the optimization.
942 uint32_t Exp = ClForceExperiment;
944 if (ClOpt && ClOptGlobals) {
945 // If initialization order checking is disabled, a simple access to a
946 // dynamically initialized global is always valid.
947 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
948 if (G != NULL && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
949 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
950 NumOptimizedAccessesToGlobalVar++;
955 if (ClOpt && ClOptStack) {
956 // A direct inbounds access to a stack variable is always valid.
957 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
958 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
959 NumOptimizedAccessesToStackVar++;
965 NumInstrumentedWrites++;
967 NumInstrumentedReads++;
969 unsigned Granularity = 1 << Mapping.Scale;
970 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
971 // if the data is properly aligned.
972 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
974 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
975 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
977 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
981 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
982 Value *Addr, bool IsWrite,
983 size_t AccessSizeIndex,
986 IRBuilder<> IRB(InsertBefore);
987 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
988 CallInst *Call = nullptr;
991 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
992 {Addr, SizeArgument});
994 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
995 {Addr, SizeArgument, ExpVal});
999 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1001 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1005 // We don't do Call->setDoesNotReturn() because the BB already has
1006 // UnreachableInst at the end.
1007 // This EmptyAsm is required to avoid callback merge.
1008 IRB.CreateCall(EmptyAsm, {});
1012 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1014 uint32_t TypeSize) {
1015 size_t Granularity = 1 << Mapping.Scale;
1016 // Addr & (Granularity - 1)
1017 Value *LastAccessedByte =
1018 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1019 // (Addr & (Granularity - 1)) + size - 1
1020 if (TypeSize / 8 > 1)
1021 LastAccessedByte = IRB.CreateAdd(
1022 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1023 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1025 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1026 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1027 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1030 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1031 Instruction *InsertBefore, Value *Addr,
1032 uint32_t TypeSize, bool IsWrite,
1033 Value *SizeArgument, bool UseCalls,
1035 IRBuilder<> IRB(InsertBefore);
1036 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1037 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1041 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1044 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1045 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1050 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1051 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1052 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1053 Value *CmpVal = Constant::getNullValue(ShadowTy);
1054 Value *ShadowValue =
1055 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1057 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1058 size_t Granularity = 1 << Mapping.Scale;
1059 TerminatorInst *CrashTerm = nullptr;
1061 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1062 // We use branch weights for the slow path check, to indicate that the slow
1063 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1064 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1065 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1066 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1067 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1068 IRB.SetInsertPoint(CheckTerm);
1069 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1070 BasicBlock *CrashBlock =
1071 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1072 CrashTerm = new UnreachableInst(*C, CrashBlock);
1073 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1074 ReplaceInstWithInst(CheckTerm, NewTerm);
1076 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1079 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1080 AccessSizeIndex, SizeArgument, Exp);
1081 Crash->setDebugLoc(OrigIns->getDebugLoc());
1084 // Instrument unusual size or unusual alignment.
1085 // We can not do it with a single check, so we do 1-byte check for the first
1086 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1087 // to report the actual access size.
1088 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1089 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1090 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1092 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1093 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1096 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1099 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1100 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1102 Value *LastByte = IRB.CreateIntToPtr(
1103 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1105 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1106 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1110 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1111 GlobalValue *ModuleName) {
1112 // Set up the arguments to our poison/unpoison functions.
1113 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1115 // Add a call to poison all external globals before the given function starts.
1116 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1117 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1119 // Add calls to unpoison all globals before each return instruction.
1120 for (auto &BB : GlobalInit.getBasicBlockList())
1121 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1122 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1125 void AddressSanitizerModule::createInitializerPoisonCalls(
1126 Module &M, GlobalValue *ModuleName) {
1127 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1129 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1130 for (Use &OP : CA->operands()) {
1131 if (isa<ConstantAggregateZero>(OP)) continue;
1132 ConstantStruct *CS = cast<ConstantStruct>(OP);
1134 // Must have a function or null ptr.
1135 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1136 if (F->getName() == kAsanModuleCtorName) continue;
1137 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1138 // Don't instrument CTORs that will run before asan.module_ctor.
1139 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1140 poisonOneInitializer(*F, ModuleName);
1145 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1146 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1147 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1149 if (GlobalsMD.get(G).IsBlacklisted) return false;
1150 if (!Ty->isSized()) return false;
1151 if (!G->hasInitializer()) return false;
1152 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1153 // Touch only those globals that will not be defined in other modules.
1154 // Don't handle ODR linkage types and COMDATs since other modules may be built
1156 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1157 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1158 G->getLinkage() != GlobalVariable::InternalLinkage)
1160 if (G->hasComdat()) return false;
1161 // Two problems with thread-locals:
1162 // - The address of the main thread's copy can't be computed at link-time.
1163 // - Need to poison all copies, not just the main thread's one.
1164 if (G->isThreadLocal()) return false;
1165 // For now, just ignore this Global if the alignment is large.
1166 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1168 if (G->hasSection()) {
1169 StringRef Section(G->getSection());
1171 // Globals from llvm.metadata aren't emitted, do not instrument them.
1172 if (Section == "llvm.metadata") return false;
1173 // Do not instrument globals from special LLVM sections.
1174 if (Section.find("__llvm") != StringRef::npos) return false;
1176 // Callbacks put into the CRT initializer/terminator sections
1177 // should not be instrumented.
1178 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1179 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1180 if (Section.startswith(".CRT")) {
1181 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1185 if (TargetTriple.isOSBinFormatMachO()) {
1186 StringRef ParsedSegment, ParsedSection;
1187 unsigned TAA = 0, StubSize = 0;
1189 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1190 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1191 if (!ErrorCode.empty()) {
1192 assert(false && "Invalid section specifier.");
1196 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1197 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1199 if (ParsedSegment == "__OBJC" ||
1200 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1201 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1204 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1205 // Constant CFString instances are compiled in the following way:
1206 // -- the string buffer is emitted into
1207 // __TEXT,__cstring,cstring_literals
1208 // -- the constant NSConstantString structure referencing that buffer
1209 // is placed into __DATA,__cfstring
1210 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1211 // Moreover, it causes the linker to crash on OS X 10.7
1212 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1213 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1216 // The linker merges the contents of cstring_literals and removes the
1218 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1219 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1228 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1229 IRBuilder<> IRB(*C);
1230 // Declare our poisoning and unpoisoning functions.
1231 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1232 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1233 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1234 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1235 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1236 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1237 // Declare functions that register/unregister globals.
1238 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1239 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1240 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1241 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1242 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1243 IntptrTy, IntptrTy, nullptr));
1244 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1247 // This function replaces all global variables with new variables that have
1248 // trailing redzones. It also creates a function that poisons
1249 // redzones and inserts this function into llvm.global_ctors.
1250 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1253 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1255 for (auto &G : M.globals()) {
1256 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1259 size_t n = GlobalsToChange.size();
1260 if (n == 0) return false;
1262 // A global is described by a structure
1265 // size_t size_with_redzone;
1266 // const char *name;
1267 // const char *module_name;
1268 // size_t has_dynamic_init;
1269 // void *source_location;
1270 // We initialize an array of such structures and pass it to a run-time call.
1271 StructType *GlobalStructTy =
1272 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1273 IntptrTy, IntptrTy, nullptr);
1274 SmallVector<Constant *, 16> Initializers(n);
1276 bool HasDynamicallyInitializedGlobals = false;
1278 // We shouldn't merge same module names, as this string serves as unique
1279 // module ID in runtime.
1280 GlobalVariable *ModuleName = createPrivateGlobalForString(
1281 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1283 auto &DL = M.getDataLayout();
1284 for (size_t i = 0; i < n; i++) {
1285 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1286 GlobalVariable *G = GlobalsToChange[i];
1288 auto MD = GlobalsMD.get(G);
1289 // Create string holding the global name (use global name from metadata
1290 // if it's available, otherwise just write the name of global variable).
1291 GlobalVariable *Name = createPrivateGlobalForString(
1292 M, MD.Name.empty() ? G->getName() : MD.Name,
1293 /*AllowMerging*/ true);
1295 PointerType *PtrTy = cast<PointerType>(G->getType());
1296 Type *Ty = PtrTy->getElementType();
1297 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1298 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1299 // MinRZ <= RZ <= kMaxGlobalRedzone
1300 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1301 uint64_t RZ = std::max(
1302 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1303 uint64_t RightRedzoneSize = RZ;
1304 // Round up to MinRZ
1305 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1306 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1307 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1309 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1310 Constant *NewInitializer =
1311 ConstantStruct::get(NewTy, G->getInitializer(),
1312 Constant::getNullValue(RightRedZoneTy), nullptr);
1314 // Create a new global variable with enough space for a redzone.
1315 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1316 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1317 Linkage = GlobalValue::InternalLinkage;
1318 GlobalVariable *NewGlobal =
1319 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1320 "", G, G->getThreadLocalMode());
1321 NewGlobal->copyAttributesFrom(G);
1322 NewGlobal->setAlignment(MinRZ);
1325 Indices2[0] = IRB.getInt32(0);
1326 Indices2[1] = IRB.getInt32(0);
1328 G->replaceAllUsesWith(
1329 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1330 NewGlobal->takeName(G);
1331 G->eraseFromParent();
1333 Constant *SourceLoc;
1334 if (!MD.SourceLoc.empty()) {
1335 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1336 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1338 SourceLoc = ConstantInt::get(IntptrTy, 0);
1341 Initializers[i] = ConstantStruct::get(
1342 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1343 ConstantInt::get(IntptrTy, SizeInBytes),
1344 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1345 ConstantExpr::getPointerCast(Name, IntptrTy),
1346 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1347 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1349 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1351 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1354 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1355 GlobalVariable *AllGlobals = new GlobalVariable(
1356 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1357 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1359 // Create calls for poisoning before initializers run and unpoisoning after.
1360 if (HasDynamicallyInitializedGlobals)
1361 createInitializerPoisonCalls(M, ModuleName);
1362 IRB.CreateCall(AsanRegisterGlobals,
1363 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1364 ConstantInt::get(IntptrTy, n)});
1366 // We also need to unregister globals at the end, e.g. when a shared library
1368 Function *AsanDtorFunction =
1369 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1370 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1371 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1372 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1373 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1374 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1375 ConstantInt::get(IntptrTy, n)});
1376 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1382 bool AddressSanitizerModule::runOnModule(Module &M) {
1383 C = &(M.getContext());
1384 int LongSize = M.getDataLayout().getPointerSizeInBits();
1385 IntptrTy = Type::getIntNTy(*C, LongSize);
1386 TargetTriple = Triple(M.getTargetTriple());
1387 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1388 initializeCallbacks(M);
1390 bool Changed = false;
1392 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1393 if (ClGlobals && !CompileKernel) {
1394 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1396 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1397 Changed |= InstrumentGlobals(IRB, M);
1403 void AddressSanitizer::initializeCallbacks(Module &M) {
1404 IRBuilder<> IRB(*C);
1405 // Create __asan_report* callbacks.
1406 // IsWrite, TypeSize and Exp are encoded in the function name.
1407 for (int Exp = 0; Exp < 2; Exp++) {
1408 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1409 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1410 const std::string ExpStr = Exp ? "exp_" : "";
1411 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1412 const std::string EndingStr = CompileKernel ? "_noabort" : "";
1413 Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1414 // TODO(glider): for KASan builds add _noabort to error reporting
1415 // functions and make them actually noabort (remove the UnreachableInst).
1416 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1417 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1418 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr,
1419 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1420 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1421 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1422 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1423 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1424 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1425 AccessSizeIndex++) {
1426 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1427 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1428 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1429 kAsanReportErrorTemplate + ExpStr + Suffix,
1430 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1431 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1432 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1433 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1434 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1439 const std::string MemIntrinCallbackPrefix =
1440 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1441 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1442 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1443 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1444 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1445 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1446 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1447 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1448 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1449 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1451 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1452 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1454 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1455 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1456 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1457 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1458 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1459 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1460 StringRef(""), StringRef(""),
1461 /*hasSideEffects=*/true);
1465 bool AddressSanitizer::doInitialization(Module &M) {
1466 // Initialize the private fields. No one has accessed them before.
1470 C = &(M.getContext());
1471 LongSize = M.getDataLayout().getPointerSizeInBits();
1472 IntptrTy = Type::getIntNTy(*C, LongSize);
1473 TargetTriple = Triple(M.getTargetTriple());
1475 if (!CompileKernel) {
1476 std::tie(AsanCtorFunction, AsanInitFunction) =
1477 createSanitizerCtorAndInitFunctions(
1478 M, kAsanModuleCtorName, kAsanInitName,
1479 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
1480 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1482 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1486 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1487 // For each NSObject descendant having a +load method, this method is invoked
1488 // by the ObjC runtime before any of the static constructors is called.
1489 // Therefore we need to instrument such methods with a call to __asan_init
1490 // at the beginning in order to initialize our runtime before any access to
1491 // the shadow memory.
1492 // We cannot just ignore these methods, because they may call other
1493 // instrumented functions.
1494 if (F.getName().find(" load]") != std::string::npos) {
1495 IRBuilder<> IRB(F.begin()->begin());
1496 IRB.CreateCall(AsanInitFunction, {});
1502 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
1503 // Find the one possible call to llvm.localescape and pre-mark allocas passed
1504 // to it as uninteresting. This assumes we haven't started processing allocas
1505 // yet. This check is done up front because iterating the use list in
1506 // isInterestingAlloca would be algorithmically slower.
1507 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
1509 // Try to get the declaration of llvm.localescape. If it's not in the module,
1510 // we can exit early.
1511 if (!F.getParent()->getFunction("llvm.localescape")) return;
1513 // Look for a call to llvm.localescape call in the entry block. It can't be in
1515 for (Instruction &I : F.getEntryBlock()) {
1516 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
1517 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
1518 // We found a call. Mark all the allocas passed in as uninteresting.
1519 for (Value *Arg : II->arg_operands()) {
1520 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
1521 assert(AI && AI->isStaticAlloca() &&
1522 "non-static alloca arg to localescape");
1523 ProcessedAllocas[AI] = false;
1530 bool AddressSanitizer::runOnFunction(Function &F) {
1531 if (&F == AsanCtorFunction) return false;
1532 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1533 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1534 initializeCallbacks(*F.getParent());
1536 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1538 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1539 maybeInsertAsanInitAtFunctionEntry(F);
1541 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1543 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1545 FunctionStateRAII CleanupObj(this);
1547 // We can't instrument allocas used with llvm.localescape. Only static allocas
1548 // can be passed to that intrinsic.
1549 markEscapedLocalAllocas(F);
1551 // We want to instrument every address only once per basic block (unless there
1552 // are calls between uses).
1553 SmallSet<Value *, 16> TempsToInstrument;
1554 SmallVector<Instruction *, 16> ToInstrument;
1555 SmallVector<Instruction *, 8> NoReturnCalls;
1556 SmallVector<BasicBlock *, 16> AllBlocks;
1557 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1563 // Fill the set of memory operations to instrument.
1564 for (auto &BB : F) {
1565 AllBlocks.push_back(&BB);
1566 TempsToInstrument.clear();
1567 int NumInsnsPerBB = 0;
1568 for (auto &Inst : BB) {
1569 if (LooksLikeCodeInBug11395(&Inst)) return false;
1570 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1572 if (ClOpt && ClOptSameTemp) {
1573 if (!TempsToInstrument.insert(Addr).second)
1574 continue; // We've seen this temp in the current BB.
1576 } else if (ClInvalidPointerPairs &&
1577 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1578 PointerComparisonsOrSubtracts.push_back(&Inst);
1580 } else if (isa<MemIntrinsic>(Inst)) {
1583 if (isa<AllocaInst>(Inst)) NumAllocas++;
1586 // A call inside BB.
1587 TempsToInstrument.clear();
1588 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1592 ToInstrument.push_back(&Inst);
1594 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1600 (ClInstrumentationWithCallsThreshold >= 0 &&
1601 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
1602 const TargetLibraryInfo *TLI =
1603 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1604 const DataLayout &DL = F.getParent()->getDataLayout();
1605 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1606 /*RoundToAlign=*/true);
1609 int NumInstrumented = 0;
1610 for (auto Inst : ToInstrument) {
1611 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1612 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1613 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1614 instrumentMop(ObjSizeVis, Inst, UseCalls,
1615 F.getParent()->getDataLayout());
1617 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1622 FunctionStackPoisoner FSP(F, *this);
1623 bool ChangedStack = FSP.runOnFunction();
1625 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1626 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1627 for (auto CI : NoReturnCalls) {
1628 IRBuilder<> IRB(CI);
1629 IRB.CreateCall(AsanHandleNoReturnFunc, {});
1632 for (auto Inst : PointerComparisonsOrSubtracts) {
1633 instrumentPointerComparisonOrSubtraction(Inst);
1637 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1639 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1644 // Workaround for bug 11395: we don't want to instrument stack in functions
1645 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1646 // FIXME: remove once the bug 11395 is fixed.
1647 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1648 if (LongSize != 32) return false;
1649 CallInst *CI = dyn_cast<CallInst>(I);
1650 if (!CI || !CI->isInlineAsm()) return false;
1651 if (CI->getNumArgOperands() <= 5) return false;
1652 // We have inline assembly with quite a few arguments.
1656 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1657 IRBuilder<> IRB(*C);
1658 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1659 std::string Suffix = itostr(i);
1660 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
1661 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1662 IntptrTy, nullptr));
1663 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
1664 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1665 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1667 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1668 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1669 IntptrTy, IntptrTy, nullptr));
1670 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1671 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1672 IntptrTy, IntptrTy, nullptr));
1673 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1674 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1675 AsanAllocasUnpoisonFunc =
1676 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1677 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1680 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1681 IRBuilder<> &IRB, Value *ShadowBase,
1683 size_t n = ShadowBytes.size();
1685 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1686 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1687 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1688 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1689 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1690 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1692 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1693 if (F.getParent()->getDataLayout().isLittleEndian())
1694 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1696 Val = (Val << 8) | ShadowBytes[i + j];
1699 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1700 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1701 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1702 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1707 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1708 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1709 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1710 assert(LocalStackSize <= kMaxStackMallocSize);
1711 uint64_t MaxSize = kMinStackMallocSize;
1712 for (int i = 0;; i++, MaxSize *= 2)
1713 if (LocalStackSize <= MaxSize) return i;
1714 llvm_unreachable("impossible LocalStackSize");
1717 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1718 // We can not use MemSet intrinsic because it may end up calling the actual
1719 // memset. Size is a multiple of 8.
1720 // Currently this generates 8-byte stores on x86_64; it may be better to
1721 // generate wider stores.
1722 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1723 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1724 assert(!(Size % 8));
1726 // kAsanStackAfterReturnMagic is 0xf5.
1727 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1729 for (int i = 0; i < Size; i += 8) {
1730 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1732 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1733 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1737 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1739 Instruction *ThenTerm,
1740 Value *ValueIfFalse) {
1741 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1742 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1743 PHI->addIncoming(ValueIfFalse, CondBlock);
1744 BasicBlock *ThenBlock = ThenTerm->getParent();
1745 PHI->addIncoming(ValueIfTrue, ThenBlock);
1749 Value *FunctionStackPoisoner::createAllocaForLayout(
1750 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1753 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1754 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1757 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1758 nullptr, "MyAlloca");
1759 assert(Alloca->isStaticAlloca());
1761 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1762 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1763 Alloca->setAlignment(FrameAlignment);
1764 return IRB.CreatePointerCast(Alloca, IntptrTy);
1767 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
1768 BasicBlock &FirstBB = *F.begin();
1769 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
1770 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
1771 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
1772 DynamicAllocaLayout->setAlignment(32);
1775 void FunctionStackPoisoner::poisonStack() {
1776 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1778 if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
1779 // Handle dynamic allocas.
1780 createDynamicAllocasInitStorage();
1781 for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI);
1783 unpoisonDynamicAllocas();
1786 if (AllocaVec.size() == 0) return;
1788 int StackMallocIdx = -1;
1789 DebugLoc EntryDebugLocation;
1790 if (auto SP = getDISubprogram(&F))
1791 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
1793 Instruction *InsBefore = AllocaVec[0];
1794 IRBuilder<> IRB(InsBefore);
1795 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1797 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
1798 // debug info is broken, because only entry-block allocas are treated as
1799 // regular stack slots.
1800 auto InsBeforeB = InsBefore->getParent();
1801 assert(InsBeforeB == &F.getEntryBlock());
1802 for (BasicBlock::iterator I = InsBefore; I != InsBeforeB->end(); ++I)
1803 if (auto *AI = dyn_cast_or_null<AllocaInst>(I))
1804 if (NonInstrumentedStaticAllocaVec.count(AI) > 0)
1805 AI->moveBefore(InsBefore);
1807 // If we have a call to llvm.localescape, keep it in the entry block.
1808 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
1810 SmallVector<ASanStackVariableDescription, 16> SVD;
1811 SVD.reserve(AllocaVec.size());
1812 for (AllocaInst *AI : AllocaVec) {
1813 ASanStackVariableDescription D = {AI->getName().data(),
1814 ASan.getAllocaSizeInBytes(AI),
1815 AI->getAlignment(), AI, 0};
1818 // Minimal header size (left redzone) is 4 pointers,
1819 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1820 size_t MinHeaderSize = ASan.LongSize / 2;
1821 ASanStackFrameLayout L;
1822 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1823 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1824 uint64_t LocalStackSize = L.FrameSize;
1825 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
1826 LocalStackSize <= kMaxStackMallocSize;
1827 bool DoDynamicAlloca = ClDynamicAllocaStack;
1828 // Don't do dynamic alloca or stack malloc if:
1829 // 1) There is inline asm: too often it makes assumptions on which registers
1831 // 2) There is a returns_twice call (typically setjmp), which is
1832 // optimization-hostile, and doesn't play well with introduced indirect
1833 // register-relative calculation of local variable addresses.
1834 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
1835 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
1837 Value *StaticAlloca =
1838 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1841 Value *LocalStackBase;
1843 if (DoStackMalloc) {
1844 // void *FakeStack = __asan_option_detect_stack_use_after_return
1845 // ? __asan_stack_malloc_N(LocalStackSize)
1847 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1848 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1849 kAsanOptionDetectUAR, IRB.getInt32Ty());
1850 Value *UARIsEnabled =
1851 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1852 Constant::getNullValue(IRB.getInt32Ty()));
1854 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1855 IRBuilder<> IRBIf(Term);
1856 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1857 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1858 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1859 Value *FakeStackValue =
1860 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1861 ConstantInt::get(IntptrTy, LocalStackSize));
1862 IRB.SetInsertPoint(InsBefore);
1863 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1864 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1865 ConstantInt::get(IntptrTy, 0));
1867 Value *NoFakeStack =
1868 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1869 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1870 IRBIf.SetInsertPoint(Term);
1871 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1872 Value *AllocaValue =
1873 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1874 IRB.SetInsertPoint(InsBefore);
1875 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1876 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1878 // void *FakeStack = nullptr;
1879 // void *LocalStackBase = alloca(LocalStackSize);
1880 FakeStack = ConstantInt::get(IntptrTy, 0);
1882 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1885 // Insert poison calls for lifetime intrinsics for alloca.
1886 bool HavePoisonedAllocas = false;
1887 for (const auto &APC : AllocaPoisonCallVec) {
1888 assert(APC.InsBefore);
1890 IRBuilder<> IRB(APC.InsBefore);
1891 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1892 HavePoisonedAllocas |= APC.DoPoison;
1895 // Replace Alloca instructions with base+offset.
1896 for (const auto &Desc : SVD) {
1897 AllocaInst *AI = Desc.AI;
1898 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1899 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1901 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1902 AI->replaceAllUsesWith(NewAllocaPtr);
1905 // The left-most redzone has enough space for at least 4 pointers.
1906 // Write the Magic value to redzone[0].
1907 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1908 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1910 // Write the frame description constant to redzone[1].
1911 Value *BasePlus1 = IRB.CreateIntToPtr(
1912 IRB.CreateAdd(LocalStackBase,
1913 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1915 GlobalVariable *StackDescriptionGlobal =
1916 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1917 /*AllowMerging*/ true);
1918 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1919 IRB.CreateStore(Description, BasePlus1);
1920 // Write the PC to redzone[2].
1921 Value *BasePlus2 = IRB.CreateIntToPtr(
1922 IRB.CreateAdd(LocalStackBase,
1923 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1925 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1927 // Poison the stack redzones at the entry.
1928 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1929 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1931 // (Un)poison the stack before all ret instructions.
1932 for (auto Ret : RetVec) {
1933 IRBuilder<> IRBRet(Ret);
1934 // Mark the current frame as retired.
1935 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1937 if (DoStackMalloc) {
1938 assert(StackMallocIdx >= 0);
1939 // if FakeStack != 0 // LocalStackBase == FakeStack
1940 // // In use-after-return mode, poison the whole stack frame.
1941 // if StackMallocIdx <= 4
1942 // // For small sizes inline the whole thing:
1943 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1944 // **SavedFlagPtr(FakeStack) = 0
1946 // __asan_stack_free_N(FakeStack, LocalStackSize)
1948 // <This is not a fake stack; unpoison the redzones>
1950 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1951 TerminatorInst *ThenTerm, *ElseTerm;
1952 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1954 IRBuilder<> IRBPoison(ThenTerm);
1955 if (StackMallocIdx <= 4) {
1956 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1957 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1958 ClassSize >> Mapping.Scale);
1959 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1961 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1962 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1963 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1964 IRBPoison.CreateStore(
1965 Constant::getNullValue(IRBPoison.getInt8Ty()),
1966 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1968 // For larger frames call __asan_stack_free_*.
1969 IRBPoison.CreateCall(
1970 AsanStackFreeFunc[StackMallocIdx],
1971 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
1974 IRBuilder<> IRBElse(ElseTerm);
1975 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1976 } else if (HavePoisonedAllocas) {
1977 // If we poisoned some allocas in llvm.lifetime analysis,
1978 // unpoison whole stack frame now.
1979 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1981 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1985 // We are done. Remove the old unused alloca instructions.
1986 for (auto AI : AllocaVec) AI->eraseFromParent();
1989 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1990 IRBuilder<> &IRB, bool DoPoison) {
1991 // For now just insert the call to ASan runtime.
1992 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1993 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1995 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
1996 {AddrArg, SizeArg});
1999 // Handling llvm.lifetime intrinsics for a given %alloca:
2000 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2001 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2002 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2003 // could be poisoned by previous llvm.lifetime.end instruction, as the
2004 // variable may go in and out of scope several times, e.g. in loops).
2005 // (3) if we poisoned at least one %alloca in a function,
2006 // unpoison the whole stack frame at function exit.
2008 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2009 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2010 // We're intested only in allocas we can handle.
2011 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2012 // See if we've already calculated (or started to calculate) alloca for a
2014 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2015 if (I != AllocaForValue.end()) return I->second;
2016 // Store 0 while we're calculating alloca for value V to avoid
2017 // infinite recursion if the value references itself.
2018 AllocaForValue[V] = nullptr;
2019 AllocaInst *Res = nullptr;
2020 if (CastInst *CI = dyn_cast<CastInst>(V))
2021 Res = findAllocaForValue(CI->getOperand(0));
2022 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2023 for (Value *IncValue : PN->incoming_values()) {
2024 // Allow self-referencing phi-nodes.
2025 if (IncValue == PN) continue;
2026 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2027 // AI for incoming values should exist and should all be equal.
2028 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2033 if (Res) AllocaForValue[V] = Res;
2037 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2038 IRBuilder<> IRB(AI);
2040 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2041 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2043 Value *Zero = Constant::getNullValue(IntptrTy);
2044 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2045 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2047 // Since we need to extend alloca with additional memory to locate
2048 // redzones, and OldSize is number of allocated blocks with
2049 // ElementSize size, get allocated memory size in bytes by
2050 // OldSize * ElementSize.
2051 const unsigned ElementSize =
2052 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2054 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2055 ConstantInt::get(IntptrTy, ElementSize));
2057 // PartialSize = OldSize % 32
2058 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2060 // Misalign = kAllocaRzSize - PartialSize;
2061 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2063 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2064 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2065 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2067 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2068 // Align is added to locate left redzone, PartialPadding for possible
2069 // partial redzone and kAllocaRzSize for right redzone respectively.
2070 Value *AdditionalChunkSize = IRB.CreateAdd(
2071 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2073 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2075 // Insert new alloca with new NewSize and Align params.
2076 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2077 NewAlloca->setAlignment(Align);
2079 // NewAddress = Address + Align
2080 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2081 ConstantInt::get(IntptrTy, Align));
2083 // Insert __asan_alloca_poison call for new created alloca.
2084 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2086 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2087 // for unpoisoning stuff.
2088 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2090 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2092 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2093 AI->replaceAllUsesWith(NewAddressPtr);
2095 // We are done. Erase old alloca from parent.
2096 AI->eraseFromParent();
2099 // isSafeAccess returns true if Addr is always inbounds with respect to its
2100 // base object. For example, it is a field access or an array access with
2101 // constant inbounds index.
2102 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2103 Value *Addr, uint64_t TypeSize) const {
2104 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2105 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2106 uint64_t Size = SizeOffset.first.getZExtValue();
2107 int64_t Offset = SizeOffset.second.getSExtValue();
2108 // Three checks are required to ensure safety:
2109 // . Offset >= 0 (since the offset is given from the base ptr)
2110 // . Size >= Offset (unsigned)
2111 // . Size - Offset >= NeededSize (unsigned)
2112 return Offset >= 0 && Size >= uint64_t(Offset) &&
2113 Size - uint64_t(Offset) >= TypeSize / 8;