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(true));
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.isAndroid();
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 = !IsAArch64 && !IsPPC64
385 && !(Mapping.Offset & (Mapping.Offset - 1));
390 static size_t RedzoneSizeForScale(int MappingScale) {
391 // Redzone used for stack and globals is at least 32 bytes.
392 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
393 return std::max(32U, 1U << MappingScale);
396 /// AddressSanitizer: instrument the code in module to find memory bugs.
397 struct AddressSanitizer : public FunctionPass {
398 explicit AddressSanitizer(bool CompileKernel = false)
399 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan) {
400 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
402 const char *getPassName() const override {
403 return "AddressSanitizerFunctionPass";
405 void getAnalysisUsage(AnalysisUsage &AU) const override {
406 AU.addRequired<DominatorTreeWrapperPass>();
407 AU.addRequired<TargetLibraryInfoWrapperPass>();
409 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
410 Type *Ty = AI->getAllocatedType();
411 uint64_t SizeInBytes =
412 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
415 /// Check if we want (and can) handle this alloca.
416 bool isInterestingAlloca(AllocaInst &AI);
418 // Check if we have dynamic alloca.
419 bool isDynamicAlloca(AllocaInst &AI) const {
420 return AI.isArrayAllocation() || !AI.isStaticAlloca();
423 /// If it is an interesting memory access, return the PointerOperand
424 /// and set IsWrite/Alignment. Otherwise return nullptr.
425 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
426 uint64_t *TypeSize, unsigned *Alignment);
427 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
428 bool UseCalls, const DataLayout &DL);
429 void instrumentPointerComparisonOrSubtraction(Instruction *I);
430 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
431 Value *Addr, uint32_t TypeSize, bool IsWrite,
432 Value *SizeArgument, bool UseCalls, uint32_t Exp);
433 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
434 uint32_t TypeSize, bool IsWrite,
435 Value *SizeArgument, bool UseCalls,
437 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
438 Value *ShadowValue, uint32_t TypeSize);
439 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
440 bool IsWrite, size_t AccessSizeIndex,
441 Value *SizeArgument, uint32_t Exp);
442 void instrumentMemIntrinsic(MemIntrinsic *MI);
443 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
444 bool runOnFunction(Function &F) override;
445 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
446 void markEscapedLocalAllocas(Function &F);
447 bool doInitialization(Module &M) override;
448 static char ID; // Pass identification, replacement for typeid
450 DominatorTree &getDominatorTree() const { return *DT; }
453 void initializeCallbacks(Module &M);
455 bool LooksLikeCodeInBug11395(Instruction *I);
456 bool GlobalIsLinkerInitialized(GlobalVariable *G);
457 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
458 uint64_t TypeSize) const;
460 /// Helper to cleanup per-function state.
461 struct FunctionStateRAII {
462 AddressSanitizer *Pass;
463 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
464 assert(Pass->ProcessedAllocas.empty() &&
465 "last pass forgot to clear cache");
467 ~FunctionStateRAII() { Pass->ProcessedAllocas.clear(); }
475 ShadowMapping Mapping;
477 Function *AsanCtorFunction = nullptr;
478 Function *AsanInitFunction = nullptr;
479 Function *AsanHandleNoReturnFunc;
480 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
481 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
482 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
483 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
484 // This array is indexed by AccessIsWrite and Experiment.
485 Function *AsanErrorCallbackSized[2][2];
486 Function *AsanMemoryAccessCallbackSized[2][2];
487 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
489 GlobalsMetadata GlobalsMD;
490 DenseMap<AllocaInst *, bool> ProcessedAllocas;
492 friend struct FunctionStackPoisoner;
495 class AddressSanitizerModule : public ModulePass {
497 explicit AddressSanitizerModule(bool CompileKernel = false)
498 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan) {}
499 bool runOnModule(Module &M) override;
500 static char ID; // Pass identification, replacement for typeid
501 const char *getPassName() const override { return "AddressSanitizerModule"; }
504 void initializeCallbacks(Module &M);
506 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
507 bool ShouldInstrumentGlobal(GlobalVariable *G);
508 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
509 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
510 size_t MinRedzoneSizeForGlobal() const {
511 return RedzoneSizeForScale(Mapping.Scale);
514 GlobalsMetadata GlobalsMD;
519 ShadowMapping Mapping;
520 Function *AsanPoisonGlobals;
521 Function *AsanUnpoisonGlobals;
522 Function *AsanRegisterGlobals;
523 Function *AsanUnregisterGlobals;
526 // Stack poisoning does not play well with exception handling.
527 // When an exception is thrown, we essentially bypass the code
528 // that unpoisones the stack. This is why the run-time library has
529 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
530 // stack in the interceptor. This however does not work inside the
531 // actual function which catches the exception. Most likely because the
532 // compiler hoists the load of the shadow value somewhere too high.
533 // This causes asan to report a non-existing bug on 453.povray.
534 // It sounds like an LLVM bug.
535 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
537 AddressSanitizer &ASan;
542 ShadowMapping Mapping;
544 SmallVector<AllocaInst *, 16> AllocaVec;
545 SmallSetVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec;
546 SmallVector<Instruction *, 8> RetVec;
547 unsigned StackAlignment;
549 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
550 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
551 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
552 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
554 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
555 struct AllocaPoisonCall {
556 IntrinsicInst *InsBefore;
561 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
563 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
564 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
565 AllocaInst *DynamicAllocaLayout = nullptr;
566 IntrinsicInst *LocalEscapeCall = nullptr;
568 // Maps Value to an AllocaInst from which the Value is originated.
569 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
570 AllocaForValueMapTy AllocaForValue;
572 bool HasNonEmptyInlineAsm = false;
573 bool HasReturnsTwiceCall = false;
574 std::unique_ptr<CallInst> EmptyInlineAsm;
576 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
579 DIB(*F.getParent(), /*AllowUnresolved*/ false),
581 IntptrTy(ASan.IntptrTy),
582 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
583 Mapping(ASan.Mapping),
584 StackAlignment(1 << Mapping.Scale),
585 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
587 bool runOnFunction() {
588 if (!ClStack) return false;
589 // Collect alloca, ret, lifetime instructions etc.
590 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
592 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
594 initializeCallbacks(*F.getParent());
604 // Finds all Alloca instructions and puts
605 // poisoned red zones around all of them.
606 // Then unpoison everything back before the function returns.
609 void createDynamicAllocasInitStorage();
611 // ----------------------- Visitors.
612 /// \brief Collect all Ret instructions.
613 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
615 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
617 IRBuilder<> IRB(InstBefore);
618 IRB.CreateCall(AsanAllocasUnpoisonFunc,
619 {IRB.CreateLoad(DynamicAllocaLayout),
620 IRB.CreatePtrToInt(SavedStack, IntptrTy)});
623 // Unpoison dynamic allocas redzones.
624 void unpoisonDynamicAllocas() {
625 for (auto &Ret : RetVec)
626 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
628 for (auto &StackRestoreInst : StackRestoreVec)
629 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
630 StackRestoreInst->getOperand(0));
633 // Deploy and poison redzones around dynamic alloca call. To do this, we
634 // should replace this call with another one with changed parameters and
635 // replace all its uses with new address, so
636 // addr = alloca type, old_size, align
638 // new_size = (old_size + additional_size) * sizeof(type)
639 // tmp = alloca i8, new_size, max(align, 32)
640 // addr = tmp + 32 (first 32 bytes are for the left redzone).
641 // Additional_size is added to make new memory allocation contain not only
642 // requested memory, but also left, partial and right redzones.
643 void handleDynamicAllocaCall(AllocaInst *AI);
645 /// \brief Collect Alloca instructions we want (and can) handle.
646 void visitAllocaInst(AllocaInst &AI) {
647 if (!ASan.isInterestingAlloca(AI)) {
648 if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.insert(&AI);
652 StackAlignment = std::max(StackAlignment, AI.getAlignment());
653 if (ASan.isDynamicAlloca(AI))
654 DynamicAllocaVec.push_back(&AI);
656 AllocaVec.push_back(&AI);
659 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
661 void visitIntrinsicInst(IntrinsicInst &II) {
662 Intrinsic::ID ID = II.getIntrinsicID();
663 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
664 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
665 if (!ClCheckLifetime) return;
666 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
668 // Found lifetime intrinsic, add ASan instrumentation if necessary.
669 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
670 // If size argument is undefined, don't do anything.
671 if (Size->isMinusOne()) return;
672 // Check that size doesn't saturate uint64_t and can
673 // be stored in IntptrTy.
674 const uint64_t SizeValue = Size->getValue().getLimitedValue();
675 if (SizeValue == ~0ULL ||
676 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
678 // Find alloca instruction that corresponds to llvm.lifetime argument.
679 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
681 bool DoPoison = (ID == Intrinsic::lifetime_end);
682 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
683 AllocaPoisonCallVec.push_back(APC);
686 void visitCallSite(CallSite CS) {
687 Instruction *I = CS.getInstruction();
688 if (CallInst *CI = dyn_cast<CallInst>(I)) {
689 HasNonEmptyInlineAsm |=
690 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
691 HasReturnsTwiceCall |= CI->canReturnTwice();
695 // ---------------------- Helpers.
696 void initializeCallbacks(Module &M);
698 bool doesDominateAllExits(const Instruction *I) const {
699 for (auto Ret : RetVec) {
700 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
705 /// Finds alloca where the value comes from.
706 AllocaInst *findAllocaForValue(Value *V);
707 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
708 Value *ShadowBase, bool DoPoison);
709 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
711 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
713 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
715 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
716 Instruction *ThenTerm, Value *ValueIfFalse);
719 } // anonymous namespace
721 char AddressSanitizer::ID = 0;
722 INITIALIZE_PASS_BEGIN(
723 AddressSanitizer, "asan",
724 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
726 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
727 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
729 AddressSanitizer, "asan",
730 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
732 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel) {
733 return new AddressSanitizer(CompileKernel);
736 char AddressSanitizerModule::ID = 0;
738 AddressSanitizerModule, "asan-module",
739 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
742 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel) {
743 return new AddressSanitizerModule(CompileKernel);
746 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
747 size_t Res = countTrailingZeros(TypeSize / 8);
748 assert(Res < kNumberOfAccessSizes);
752 // \brief Create a constant for Str so that we can pass it to the run-time lib.
753 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
755 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
756 // We use private linkage for module-local strings. If they can be merged
757 // with another one, we set the unnamed_addr attribute.
759 new GlobalVariable(M, StrConst->getType(), true,
760 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
761 if (AllowMerging) GV->setUnnamedAddr(true);
762 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
766 /// \brief Create a global describing a source location.
767 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
768 LocationMetadata MD) {
769 Constant *LocData[] = {
770 createPrivateGlobalForString(M, MD.Filename, true),
771 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
772 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
774 auto LocStruct = ConstantStruct::getAnon(LocData);
775 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
776 GlobalValue::PrivateLinkage, LocStruct,
778 GV->setUnnamedAddr(true);
782 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
783 return G->getName().find(kAsanGenPrefix) == 0 ||
784 G->getName().find(kSanCovGenPrefix) == 0;
787 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
789 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
790 if (Mapping.Offset == 0) return Shadow;
791 // (Shadow >> scale) | offset
792 if (Mapping.OrShadowOffset)
793 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
795 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
798 // Instrument memset/memmove/memcpy
799 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
801 if (isa<MemTransferInst>(MI)) {
803 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
804 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
805 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
806 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
807 } else if (isa<MemSetInst>(MI)) {
810 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
811 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
812 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
814 MI->eraseFromParent();
817 /// Check if we want (and can) handle this alloca.
818 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
819 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
821 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
822 return PreviouslySeenAllocaInfo->getSecond();
825 (AI.getAllocatedType()->isSized() &&
826 // alloca() may be called with 0 size, ignore it.
827 getAllocaSizeInBytes(&AI) > 0 &&
828 // We are only interested in allocas not promotable to registers.
829 // Promotable allocas are common under -O0.
830 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
831 // inalloca allocas are not treated as static, and we don't want
832 // dynamic alloca instrumentation for them as well.
833 !AI.isUsedWithInAlloca());
835 ProcessedAllocas[&AI] = IsInteresting;
836 return IsInteresting;
839 /// If I is an interesting memory access, return the PointerOperand
840 /// and set IsWrite/Alignment. Otherwise return nullptr.
841 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
844 unsigned *Alignment) {
845 // Skip memory accesses inserted by another instrumentation.
846 if (I->getMetadata("nosanitize")) return nullptr;
848 Value *PtrOperand = nullptr;
849 const DataLayout &DL = I->getModule()->getDataLayout();
850 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
851 if (!ClInstrumentReads) return nullptr;
853 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
854 *Alignment = LI->getAlignment();
855 PtrOperand = LI->getPointerOperand();
856 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
857 if (!ClInstrumentWrites) return nullptr;
859 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
860 *Alignment = SI->getAlignment();
861 PtrOperand = SI->getPointerOperand();
862 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
863 if (!ClInstrumentAtomics) return nullptr;
865 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
867 PtrOperand = RMW->getPointerOperand();
868 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
869 if (!ClInstrumentAtomics) return nullptr;
871 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
873 PtrOperand = XCHG->getPointerOperand();
876 // Treat memory accesses to promotable allocas as non-interesting since they
877 // will not cause memory violations. This greatly speeds up the instrumented
878 // executable at -O0.
879 if (ClSkipPromotableAllocas)
880 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
881 return isInterestingAlloca(*AI) ? AI : nullptr;
886 static bool isPointerOperand(Value *V) {
887 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
890 // This is a rough heuristic; it may cause both false positives and
891 // false negatives. The proper implementation requires cooperation with
893 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
894 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
895 if (!Cmp->isRelational()) return false;
896 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
897 if (BO->getOpcode() != Instruction::Sub) return false;
901 return isPointerOperand(I->getOperand(0)) &&
902 isPointerOperand(I->getOperand(1));
905 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
906 // If a global variable does not have dynamic initialization we don't
907 // have to instrument it. However, if a global does not have initializer
908 // at all, we assume it has dynamic initializer (in other TU).
909 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
912 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
915 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
916 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
917 for (int i = 0; i < 2; i++) {
918 if (Param[i]->getType()->isPointerTy())
919 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
921 IRB.CreateCall(F, Param);
924 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
925 Instruction *I, bool UseCalls,
926 const DataLayout &DL) {
927 bool IsWrite = false;
928 unsigned Alignment = 0;
929 uint64_t TypeSize = 0;
930 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
933 // Optimization experiments.
934 // The experiments can be used to evaluate potential optimizations that remove
935 // instrumentation (assess false negatives). Instead of completely removing
936 // some instrumentation, you set Exp to a non-zero value (mask of optimization
937 // experiments that want to remove instrumentation of this instruction).
938 // If Exp is non-zero, this pass will emit special calls into runtime
939 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
940 // make runtime terminate the program in a special way (with a different
941 // exit status). Then you run the new compiler on a buggy corpus, collect
942 // the special terminations (ideally, you don't see them at all -- no false
943 // negatives) and make the decision on the optimization.
944 uint32_t Exp = ClForceExperiment;
946 if (ClOpt && ClOptGlobals) {
947 // If initialization order checking is disabled, a simple access to a
948 // dynamically initialized global is always valid.
949 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
950 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
951 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
952 NumOptimizedAccessesToGlobalVar++;
957 if (ClOpt && ClOptStack) {
958 // A direct inbounds access to a stack variable is always valid.
959 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
960 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
961 NumOptimizedAccessesToStackVar++;
967 NumInstrumentedWrites++;
969 NumInstrumentedReads++;
971 unsigned Granularity = 1 << Mapping.Scale;
972 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
973 // if the data is properly aligned.
974 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
976 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
977 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
979 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
983 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
984 Value *Addr, bool IsWrite,
985 size_t AccessSizeIndex,
988 IRBuilder<> IRB(InsertBefore);
989 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
990 CallInst *Call = nullptr;
993 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
994 {Addr, SizeArgument});
996 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
997 {Addr, SizeArgument, ExpVal});
1001 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1003 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1007 // We don't do Call->setDoesNotReturn() because the BB already has
1008 // UnreachableInst at the end.
1009 // This EmptyAsm is required to avoid callback merge.
1010 IRB.CreateCall(EmptyAsm, {});
1014 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1016 uint32_t TypeSize) {
1017 size_t Granularity = 1 << Mapping.Scale;
1018 // Addr & (Granularity - 1)
1019 Value *LastAccessedByte =
1020 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1021 // (Addr & (Granularity - 1)) + size - 1
1022 if (TypeSize / 8 > 1)
1023 LastAccessedByte = IRB.CreateAdd(
1024 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1025 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1027 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1028 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1029 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1032 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1033 Instruction *InsertBefore, Value *Addr,
1034 uint32_t TypeSize, bool IsWrite,
1035 Value *SizeArgument, bool UseCalls,
1037 IRBuilder<> IRB(InsertBefore);
1038 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1039 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1043 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1046 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1047 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1052 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1053 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1054 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1055 Value *CmpVal = Constant::getNullValue(ShadowTy);
1056 Value *ShadowValue =
1057 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1059 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1060 size_t Granularity = 1 << Mapping.Scale;
1061 TerminatorInst *CrashTerm = nullptr;
1063 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1064 // We use branch weights for the slow path check, to indicate that the slow
1065 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1066 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1067 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1068 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1069 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1070 IRB.SetInsertPoint(CheckTerm);
1071 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1072 BasicBlock *CrashBlock =
1073 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1074 CrashTerm = new UnreachableInst(*C, CrashBlock);
1075 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1076 ReplaceInstWithInst(CheckTerm, NewTerm);
1078 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1081 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1082 AccessSizeIndex, SizeArgument, Exp);
1083 Crash->setDebugLoc(OrigIns->getDebugLoc());
1086 // Instrument unusual size or unusual alignment.
1087 // We can not do it with a single check, so we do 1-byte check for the first
1088 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1089 // to report the actual access size.
1090 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1091 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1092 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1094 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1095 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1098 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1101 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1102 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1104 Value *LastByte = IRB.CreateIntToPtr(
1105 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1107 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1108 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1112 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1113 GlobalValue *ModuleName) {
1114 // Set up the arguments to our poison/unpoison functions.
1115 IRBuilder<> IRB(&GlobalInit.front(),
1116 GlobalInit.front().getFirstInsertionPt());
1118 // Add a call to poison all external globals before the given function starts.
1119 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1120 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1122 // Add calls to unpoison all globals before each return instruction.
1123 for (auto &BB : GlobalInit.getBasicBlockList())
1124 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1125 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1128 void AddressSanitizerModule::createInitializerPoisonCalls(
1129 Module &M, GlobalValue *ModuleName) {
1130 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1132 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1133 for (Use &OP : CA->operands()) {
1134 if (isa<ConstantAggregateZero>(OP)) continue;
1135 ConstantStruct *CS = cast<ConstantStruct>(OP);
1137 // Must have a function or null ptr.
1138 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1139 if (F->getName() == kAsanModuleCtorName) continue;
1140 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1141 // Don't instrument CTORs that will run before asan.module_ctor.
1142 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1143 poisonOneInitializer(*F, ModuleName);
1148 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1149 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1150 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1152 if (GlobalsMD.get(G).IsBlacklisted) return false;
1153 if (!Ty->isSized()) return false;
1154 if (!G->hasInitializer()) return false;
1155 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1156 // Touch only those globals that will not be defined in other modules.
1157 // Don't handle ODR linkage types and COMDATs since other modules may be built
1159 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1160 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1161 G->getLinkage() != GlobalVariable::InternalLinkage)
1163 if (G->hasComdat()) return false;
1164 // Two problems with thread-locals:
1165 // - The address of the main thread's copy can't be computed at link-time.
1166 // - Need to poison all copies, not just the main thread's one.
1167 if (G->isThreadLocal()) return false;
1168 // For now, just ignore this Global if the alignment is large.
1169 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1171 if (G->hasSection()) {
1172 StringRef Section(G->getSection());
1174 // Globals from llvm.metadata aren't emitted, do not instrument them.
1175 if (Section == "llvm.metadata") return false;
1176 // Do not instrument globals from special LLVM sections.
1177 if (Section.find("__llvm") != StringRef::npos) return false;
1179 // Do not instrument function pointers to initialization and termination
1180 // routines: dynamic linker will not properly handle redzones.
1181 if (Section.startswith(".preinit_array") ||
1182 Section.startswith(".init_array") ||
1183 Section.startswith(".fini_array")) {
1187 // Callbacks put into the CRT initializer/terminator sections
1188 // should not be instrumented.
1189 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1190 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1191 if (Section.startswith(".CRT")) {
1192 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1196 if (TargetTriple.isOSBinFormatMachO()) {
1197 StringRef ParsedSegment, ParsedSection;
1198 unsigned TAA = 0, StubSize = 0;
1200 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1201 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1202 if (!ErrorCode.empty()) {
1203 assert(false && "Invalid section specifier.");
1207 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1208 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1210 if (ParsedSegment == "__OBJC" ||
1211 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1212 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1215 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1216 // Constant CFString instances are compiled in the following way:
1217 // -- the string buffer is emitted into
1218 // __TEXT,__cstring,cstring_literals
1219 // -- the constant NSConstantString structure referencing that buffer
1220 // is placed into __DATA,__cfstring
1221 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1222 // Moreover, it causes the linker to crash on OS X 10.7
1223 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1224 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1227 // The linker merges the contents of cstring_literals and removes the
1229 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1230 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1239 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1240 IRBuilder<> IRB(*C);
1241 // Declare our poisoning and unpoisoning functions.
1242 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1243 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1244 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1245 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1246 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1247 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1248 // Declare functions that register/unregister globals.
1249 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1250 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1251 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1252 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1253 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1254 IntptrTy, IntptrTy, nullptr));
1255 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1258 // This function replaces all global variables with new variables that have
1259 // trailing redzones. It also creates a function that poisons
1260 // redzones and inserts this function into llvm.global_ctors.
1261 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1264 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1266 for (auto &G : M.globals()) {
1267 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1270 size_t n = GlobalsToChange.size();
1271 if (n == 0) return false;
1273 // A global is described by a structure
1276 // size_t size_with_redzone;
1277 // const char *name;
1278 // const char *module_name;
1279 // size_t has_dynamic_init;
1280 // void *source_location;
1281 // We initialize an array of such structures and pass it to a run-time call.
1282 StructType *GlobalStructTy =
1283 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1284 IntptrTy, IntptrTy, nullptr);
1285 SmallVector<Constant *, 16> Initializers(n);
1287 bool HasDynamicallyInitializedGlobals = false;
1289 // We shouldn't merge same module names, as this string serves as unique
1290 // module ID in runtime.
1291 GlobalVariable *ModuleName = createPrivateGlobalForString(
1292 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1294 auto &DL = M.getDataLayout();
1295 for (size_t i = 0; i < n; i++) {
1296 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1297 GlobalVariable *G = GlobalsToChange[i];
1299 auto MD = GlobalsMD.get(G);
1300 // Create string holding the global name (use global name from metadata
1301 // if it's available, otherwise just write the name of global variable).
1302 GlobalVariable *Name = createPrivateGlobalForString(
1303 M, MD.Name.empty() ? G->getName() : MD.Name,
1304 /*AllowMerging*/ true);
1306 PointerType *PtrTy = cast<PointerType>(G->getType());
1307 Type *Ty = PtrTy->getElementType();
1308 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1309 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1310 // MinRZ <= RZ <= kMaxGlobalRedzone
1311 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1312 uint64_t RZ = std::max(
1313 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1314 uint64_t RightRedzoneSize = RZ;
1315 // Round up to MinRZ
1316 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1317 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1318 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1320 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1321 Constant *NewInitializer =
1322 ConstantStruct::get(NewTy, G->getInitializer(),
1323 Constant::getNullValue(RightRedZoneTy), nullptr);
1325 // Create a new global variable with enough space for a redzone.
1326 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1327 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1328 Linkage = GlobalValue::InternalLinkage;
1329 GlobalVariable *NewGlobal =
1330 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1331 "", G, G->getThreadLocalMode());
1332 NewGlobal->copyAttributesFrom(G);
1333 NewGlobal->setAlignment(MinRZ);
1336 Indices2[0] = IRB.getInt32(0);
1337 Indices2[1] = IRB.getInt32(0);
1339 G->replaceAllUsesWith(
1340 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1341 NewGlobal->takeName(G);
1342 G->eraseFromParent();
1344 Constant *SourceLoc;
1345 if (!MD.SourceLoc.empty()) {
1346 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1347 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1349 SourceLoc = ConstantInt::get(IntptrTy, 0);
1352 Initializers[i] = ConstantStruct::get(
1353 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1354 ConstantInt::get(IntptrTy, SizeInBytes),
1355 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1356 ConstantExpr::getPointerCast(Name, IntptrTy),
1357 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1358 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1360 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1362 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1365 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1366 GlobalVariable *AllGlobals = new GlobalVariable(
1367 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1368 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1370 // Create calls for poisoning before initializers run and unpoisoning after.
1371 if (HasDynamicallyInitializedGlobals)
1372 createInitializerPoisonCalls(M, ModuleName);
1373 IRB.CreateCall(AsanRegisterGlobals,
1374 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1375 ConstantInt::get(IntptrTy, n)});
1377 // We also need to unregister globals at the end, e.g. when a shared library
1379 Function *AsanDtorFunction =
1380 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1381 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1382 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1383 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1384 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1385 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1386 ConstantInt::get(IntptrTy, n)});
1387 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1393 bool AddressSanitizerModule::runOnModule(Module &M) {
1394 C = &(M.getContext());
1395 int LongSize = M.getDataLayout().getPointerSizeInBits();
1396 IntptrTy = Type::getIntNTy(*C, LongSize);
1397 TargetTriple = Triple(M.getTargetTriple());
1398 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1399 initializeCallbacks(M);
1401 bool Changed = false;
1403 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1404 if (ClGlobals && !CompileKernel) {
1405 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1407 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1408 Changed |= InstrumentGlobals(IRB, M);
1414 void AddressSanitizer::initializeCallbacks(Module &M) {
1415 IRBuilder<> IRB(*C);
1416 // Create __asan_report* callbacks.
1417 // IsWrite, TypeSize and Exp are encoded in the function name.
1418 for (int Exp = 0; Exp < 2; Exp++) {
1419 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1420 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1421 const std::string ExpStr = Exp ? "exp_" : "";
1422 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1423 const std::string EndingStr = CompileKernel ? "_noabort" : "";
1424 Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1425 // TODO(glider): for KASan builds add _noabort to error reporting
1426 // functions and make them actually noabort (remove the UnreachableInst).
1427 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1428 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1429 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr,
1430 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1431 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1432 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1433 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1434 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1435 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1436 AccessSizeIndex++) {
1437 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1438 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1439 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1440 kAsanReportErrorTemplate + ExpStr + Suffix,
1441 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1442 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1443 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1444 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1445 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1450 const std::string MemIntrinCallbackPrefix =
1451 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1452 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1453 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1454 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1455 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1456 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1457 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1458 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1459 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1460 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1462 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1463 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1465 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1466 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1467 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1468 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1469 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1470 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1471 StringRef(""), StringRef(""),
1472 /*hasSideEffects=*/true);
1476 bool AddressSanitizer::doInitialization(Module &M) {
1477 // Initialize the private fields. No one has accessed them before.
1481 C = &(M.getContext());
1482 LongSize = M.getDataLayout().getPointerSizeInBits();
1483 IntptrTy = Type::getIntNTy(*C, LongSize);
1484 TargetTriple = Triple(M.getTargetTriple());
1486 if (!CompileKernel) {
1487 std::tie(AsanCtorFunction, AsanInitFunction) =
1488 createSanitizerCtorAndInitFunctions(
1489 M, kAsanModuleCtorName, kAsanInitName,
1490 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
1491 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1493 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1497 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1498 // For each NSObject descendant having a +load method, this method is invoked
1499 // by the ObjC runtime before any of the static constructors is called.
1500 // Therefore we need to instrument such methods with a call to __asan_init
1501 // at the beginning in order to initialize our runtime before any access to
1502 // the shadow memory.
1503 // We cannot just ignore these methods, because they may call other
1504 // instrumented functions.
1505 if (F.getName().find(" load]") != std::string::npos) {
1506 IRBuilder<> IRB(&F.front(), F.front().begin());
1507 IRB.CreateCall(AsanInitFunction, {});
1513 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
1514 // Find the one possible call to llvm.localescape and pre-mark allocas passed
1515 // to it as uninteresting. This assumes we haven't started processing allocas
1516 // yet. This check is done up front because iterating the use list in
1517 // isInterestingAlloca would be algorithmically slower.
1518 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
1520 // Try to get the declaration of llvm.localescape. If it's not in the module,
1521 // we can exit early.
1522 if (!F.getParent()->getFunction("llvm.localescape")) return;
1524 // Look for a call to llvm.localescape call in the entry block. It can't be in
1526 for (Instruction &I : F.getEntryBlock()) {
1527 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
1528 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
1529 // We found a call. Mark all the allocas passed in as uninteresting.
1530 for (Value *Arg : II->arg_operands()) {
1531 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
1532 assert(AI && AI->isStaticAlloca() &&
1533 "non-static alloca arg to localescape");
1534 ProcessedAllocas[AI] = false;
1541 bool AddressSanitizer::runOnFunction(Function &F) {
1542 if (&F == AsanCtorFunction) return false;
1543 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1544 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1545 initializeCallbacks(*F.getParent());
1547 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1549 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1550 maybeInsertAsanInitAtFunctionEntry(F);
1552 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1554 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1556 FunctionStateRAII CleanupObj(this);
1558 // We can't instrument allocas used with llvm.localescape. Only static allocas
1559 // can be passed to that intrinsic.
1560 markEscapedLocalAllocas(F);
1562 // We want to instrument every address only once per basic block (unless there
1563 // are calls between uses).
1564 SmallSet<Value *, 16> TempsToInstrument;
1565 SmallVector<Instruction *, 16> ToInstrument;
1566 SmallVector<Instruction *, 8> NoReturnCalls;
1567 SmallVector<BasicBlock *, 16> AllBlocks;
1568 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1574 // Fill the set of memory operations to instrument.
1575 for (auto &BB : F) {
1576 AllBlocks.push_back(&BB);
1577 TempsToInstrument.clear();
1578 int NumInsnsPerBB = 0;
1579 for (auto &Inst : BB) {
1580 if (LooksLikeCodeInBug11395(&Inst)) return false;
1581 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1583 if (ClOpt && ClOptSameTemp) {
1584 if (!TempsToInstrument.insert(Addr).second)
1585 continue; // We've seen this temp in the current BB.
1587 } else if (ClInvalidPointerPairs &&
1588 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1589 PointerComparisonsOrSubtracts.push_back(&Inst);
1591 } else if (isa<MemIntrinsic>(Inst)) {
1594 if (isa<AllocaInst>(Inst)) NumAllocas++;
1597 // A call inside BB.
1598 TempsToInstrument.clear();
1599 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1603 ToInstrument.push_back(&Inst);
1605 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1611 (ClInstrumentationWithCallsThreshold >= 0 &&
1612 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
1613 const TargetLibraryInfo *TLI =
1614 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1615 const DataLayout &DL = F.getParent()->getDataLayout();
1616 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1617 /*RoundToAlign=*/true);
1620 int NumInstrumented = 0;
1621 for (auto Inst : ToInstrument) {
1622 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1623 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1624 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1625 instrumentMop(ObjSizeVis, Inst, UseCalls,
1626 F.getParent()->getDataLayout());
1628 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1633 FunctionStackPoisoner FSP(F, *this);
1634 bool ChangedStack = FSP.runOnFunction();
1636 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1637 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1638 for (auto CI : NoReturnCalls) {
1639 IRBuilder<> IRB(CI);
1640 IRB.CreateCall(AsanHandleNoReturnFunc, {});
1643 for (auto Inst : PointerComparisonsOrSubtracts) {
1644 instrumentPointerComparisonOrSubtraction(Inst);
1648 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1650 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1655 // Workaround for bug 11395: we don't want to instrument stack in functions
1656 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1657 // FIXME: remove once the bug 11395 is fixed.
1658 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1659 if (LongSize != 32) return false;
1660 CallInst *CI = dyn_cast<CallInst>(I);
1661 if (!CI || !CI->isInlineAsm()) return false;
1662 if (CI->getNumArgOperands() <= 5) return false;
1663 // We have inline assembly with quite a few arguments.
1667 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1668 IRBuilder<> IRB(*C);
1669 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1670 std::string Suffix = itostr(i);
1671 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
1672 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1673 IntptrTy, nullptr));
1674 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
1675 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1676 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1678 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1679 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1680 IntptrTy, IntptrTy, nullptr));
1681 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1682 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1683 IntptrTy, IntptrTy, nullptr));
1684 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1685 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1686 AsanAllocasUnpoisonFunc =
1687 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1688 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1691 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1692 IRBuilder<> &IRB, Value *ShadowBase,
1694 size_t n = ShadowBytes.size();
1696 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1697 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1698 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1699 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1700 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1701 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1703 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1704 if (F.getParent()->getDataLayout().isLittleEndian())
1705 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1707 Val = (Val << 8) | ShadowBytes[i + j];
1710 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1711 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1712 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1713 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1718 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1719 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1720 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1721 assert(LocalStackSize <= kMaxStackMallocSize);
1722 uint64_t MaxSize = kMinStackMallocSize;
1723 for (int i = 0;; i++, MaxSize *= 2)
1724 if (LocalStackSize <= MaxSize) return i;
1725 llvm_unreachable("impossible LocalStackSize");
1728 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1729 // We can not use MemSet intrinsic because it may end up calling the actual
1730 // memset. Size is a multiple of 8.
1731 // Currently this generates 8-byte stores on x86_64; it may be better to
1732 // generate wider stores.
1733 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1734 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1735 assert(!(Size % 8));
1737 // kAsanStackAfterReturnMagic is 0xf5.
1738 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1740 for (int i = 0; i < Size; i += 8) {
1741 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1743 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1744 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1748 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1750 Instruction *ThenTerm,
1751 Value *ValueIfFalse) {
1752 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1753 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1754 PHI->addIncoming(ValueIfFalse, CondBlock);
1755 BasicBlock *ThenBlock = ThenTerm->getParent();
1756 PHI->addIncoming(ValueIfTrue, ThenBlock);
1760 Value *FunctionStackPoisoner::createAllocaForLayout(
1761 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1764 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1765 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1768 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1769 nullptr, "MyAlloca");
1770 assert(Alloca->isStaticAlloca());
1772 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1773 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1774 Alloca->setAlignment(FrameAlignment);
1775 return IRB.CreatePointerCast(Alloca, IntptrTy);
1778 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
1779 BasicBlock &FirstBB = *F.begin();
1780 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
1781 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
1782 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
1783 DynamicAllocaLayout->setAlignment(32);
1786 void FunctionStackPoisoner::poisonStack() {
1787 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1789 // Insert poison calls for lifetime intrinsics for alloca.
1790 bool HavePoisonedAllocas = false;
1791 for (const auto &APC : AllocaPoisonCallVec) {
1792 assert(APC.InsBefore);
1794 IRBuilder<> IRB(APC.InsBefore);
1795 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1796 HavePoisonedAllocas |= APC.DoPoison;
1799 if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
1800 // Handle dynamic allocas.
1801 createDynamicAllocasInitStorage();
1802 for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI);
1804 unpoisonDynamicAllocas();
1807 if (AllocaVec.empty()) return;
1809 int StackMallocIdx = -1;
1810 DebugLoc EntryDebugLocation;
1811 if (auto SP = getDISubprogram(&F))
1812 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
1814 Instruction *InsBefore = AllocaVec[0];
1815 IRBuilder<> IRB(InsBefore);
1816 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1818 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
1819 // debug info is broken, because only entry-block allocas are treated as
1820 // regular stack slots.
1821 auto InsBeforeB = InsBefore->getParent();
1822 assert(InsBeforeB == &F.getEntryBlock());
1823 for (BasicBlock::iterator I(InsBefore); I != InsBeforeB->end(); ++I)
1824 if (auto *AI = dyn_cast<AllocaInst>(I))
1825 if (NonInstrumentedStaticAllocaVec.count(AI) > 0)
1826 AI->moveBefore(InsBefore);
1828 // If we have a call to llvm.localescape, keep it in the entry block.
1829 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
1831 SmallVector<ASanStackVariableDescription, 16> SVD;
1832 SVD.reserve(AllocaVec.size());
1833 for (AllocaInst *AI : AllocaVec) {
1834 ASanStackVariableDescription D = {AI->getName().data(),
1835 ASan.getAllocaSizeInBytes(AI),
1836 AI->getAlignment(), AI, 0};
1839 // Minimal header size (left redzone) is 4 pointers,
1840 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1841 size_t MinHeaderSize = ASan.LongSize / 2;
1842 ASanStackFrameLayout L;
1843 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1844 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1845 uint64_t LocalStackSize = L.FrameSize;
1846 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
1847 LocalStackSize <= kMaxStackMallocSize;
1848 bool DoDynamicAlloca = ClDynamicAllocaStack;
1849 // Don't do dynamic alloca or stack malloc if:
1850 // 1) There is inline asm: too often it makes assumptions on which registers
1852 // 2) There is a returns_twice call (typically setjmp), which is
1853 // optimization-hostile, and doesn't play well with introduced indirect
1854 // register-relative calculation of local variable addresses.
1855 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
1856 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
1858 Value *StaticAlloca =
1859 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1862 Value *LocalStackBase;
1864 if (DoStackMalloc) {
1865 // void *FakeStack = __asan_option_detect_stack_use_after_return
1866 // ? __asan_stack_malloc_N(LocalStackSize)
1868 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1869 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1870 kAsanOptionDetectUAR, IRB.getInt32Ty());
1871 Value *UARIsEnabled =
1872 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1873 Constant::getNullValue(IRB.getInt32Ty()));
1875 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1876 IRBuilder<> IRBIf(Term);
1877 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1878 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1879 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1880 Value *FakeStackValue =
1881 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1882 ConstantInt::get(IntptrTy, LocalStackSize));
1883 IRB.SetInsertPoint(InsBefore);
1884 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1885 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1886 ConstantInt::get(IntptrTy, 0));
1888 Value *NoFakeStack =
1889 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1890 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1891 IRBIf.SetInsertPoint(Term);
1892 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1893 Value *AllocaValue =
1894 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1895 IRB.SetInsertPoint(InsBefore);
1896 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1897 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1899 // void *FakeStack = nullptr;
1900 // void *LocalStackBase = alloca(LocalStackSize);
1901 FakeStack = ConstantInt::get(IntptrTy, 0);
1903 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1906 // Replace Alloca instructions with base+offset.
1907 for (const auto &Desc : SVD) {
1908 AllocaInst *AI = Desc.AI;
1909 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1910 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1912 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1913 AI->replaceAllUsesWith(NewAllocaPtr);
1916 // The left-most redzone has enough space for at least 4 pointers.
1917 // Write the Magic value to redzone[0].
1918 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1919 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1921 // Write the frame description constant to redzone[1].
1922 Value *BasePlus1 = IRB.CreateIntToPtr(
1923 IRB.CreateAdd(LocalStackBase,
1924 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1926 GlobalVariable *StackDescriptionGlobal =
1927 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1928 /*AllowMerging*/ true);
1929 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1930 IRB.CreateStore(Description, BasePlus1);
1931 // Write the PC to redzone[2].
1932 Value *BasePlus2 = IRB.CreateIntToPtr(
1933 IRB.CreateAdd(LocalStackBase,
1934 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1936 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1938 // Poison the stack redzones at the entry.
1939 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1940 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1942 // (Un)poison the stack before all ret instructions.
1943 for (auto Ret : RetVec) {
1944 IRBuilder<> IRBRet(Ret);
1945 // Mark the current frame as retired.
1946 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1948 if (DoStackMalloc) {
1949 assert(StackMallocIdx >= 0);
1950 // if FakeStack != 0 // LocalStackBase == FakeStack
1951 // // In use-after-return mode, poison the whole stack frame.
1952 // if StackMallocIdx <= 4
1953 // // For small sizes inline the whole thing:
1954 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1955 // **SavedFlagPtr(FakeStack) = 0
1957 // __asan_stack_free_N(FakeStack, LocalStackSize)
1959 // <This is not a fake stack; unpoison the redzones>
1961 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1962 TerminatorInst *ThenTerm, *ElseTerm;
1963 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1965 IRBuilder<> IRBPoison(ThenTerm);
1966 if (StackMallocIdx <= 4) {
1967 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1968 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1969 ClassSize >> Mapping.Scale);
1970 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1972 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1973 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1974 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1975 IRBPoison.CreateStore(
1976 Constant::getNullValue(IRBPoison.getInt8Ty()),
1977 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1979 // For larger frames call __asan_stack_free_*.
1980 IRBPoison.CreateCall(
1981 AsanStackFreeFunc[StackMallocIdx],
1982 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
1985 IRBuilder<> IRBElse(ElseTerm);
1986 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1987 } else if (HavePoisonedAllocas) {
1988 // If we poisoned some allocas in llvm.lifetime analysis,
1989 // unpoison whole stack frame now.
1990 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1992 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1996 // We are done. Remove the old unused alloca instructions.
1997 for (auto AI : AllocaVec) AI->eraseFromParent();
2000 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2001 IRBuilder<> &IRB, bool DoPoison) {
2002 // For now just insert the call to ASan runtime.
2003 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2004 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2006 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2007 {AddrArg, SizeArg});
2010 // Handling llvm.lifetime intrinsics for a given %alloca:
2011 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2012 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2013 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2014 // could be poisoned by previous llvm.lifetime.end instruction, as the
2015 // variable may go in and out of scope several times, e.g. in loops).
2016 // (3) if we poisoned at least one %alloca in a function,
2017 // unpoison the whole stack frame at function exit.
2019 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2020 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2021 // We're intested only in allocas we can handle.
2022 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2023 // See if we've already calculated (or started to calculate) alloca for a
2025 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2026 if (I != AllocaForValue.end()) return I->second;
2027 // Store 0 while we're calculating alloca for value V to avoid
2028 // infinite recursion if the value references itself.
2029 AllocaForValue[V] = nullptr;
2030 AllocaInst *Res = nullptr;
2031 if (CastInst *CI = dyn_cast<CastInst>(V))
2032 Res = findAllocaForValue(CI->getOperand(0));
2033 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2034 for (Value *IncValue : PN->incoming_values()) {
2035 // Allow self-referencing phi-nodes.
2036 if (IncValue == PN) continue;
2037 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2038 // AI for incoming values should exist and should all be equal.
2039 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2044 if (Res) AllocaForValue[V] = Res;
2048 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2049 IRBuilder<> IRB(AI);
2051 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2052 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2054 Value *Zero = Constant::getNullValue(IntptrTy);
2055 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2056 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2058 // Since we need to extend alloca with additional memory to locate
2059 // redzones, and OldSize is number of allocated blocks with
2060 // ElementSize size, get allocated memory size in bytes by
2061 // OldSize * ElementSize.
2062 const unsigned ElementSize =
2063 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2065 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2066 ConstantInt::get(IntptrTy, ElementSize));
2068 // PartialSize = OldSize % 32
2069 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2071 // Misalign = kAllocaRzSize - PartialSize;
2072 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2074 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2075 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2076 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2078 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2079 // Align is added to locate left redzone, PartialPadding for possible
2080 // partial redzone and kAllocaRzSize for right redzone respectively.
2081 Value *AdditionalChunkSize = IRB.CreateAdd(
2082 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2084 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2086 // Insert new alloca with new NewSize and Align params.
2087 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2088 NewAlloca->setAlignment(Align);
2090 // NewAddress = Address + Align
2091 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2092 ConstantInt::get(IntptrTy, Align));
2094 // Insert __asan_alloca_poison call for new created alloca.
2095 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2097 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2098 // for unpoisoning stuff.
2099 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2101 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2103 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2104 AI->replaceAllUsesWith(NewAddressPtr);
2106 // We are done. Erase old alloca from parent.
2107 AI->eraseFromParent();
2110 // isSafeAccess returns true if Addr is always inbounds with respect to its
2111 // base object. For example, it is a field access or an array access with
2112 // constant inbounds index.
2113 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2114 Value *Addr, uint64_t TypeSize) const {
2115 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2116 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2117 uint64_t Size = SizeOffset.first.getZExtValue();
2118 int64_t Offset = SizeOffset.second.getSExtValue();
2119 // Three checks are required to ensure safety:
2120 // . Offset >= 0 (since the offset is given from the base ptr)
2121 // . Size >= Offset (unsigned)
2122 // . Size - Offset >= NeededSize (unsigned)
2123 return Offset >= 0 && Size >= uint64_t(Offset) &&
2124 Size - uint64_t(Offset) >= TypeSize / 8;