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/SmallSet.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/Statistic.h"
25 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/ADT/Triple.h"
27 #include "llvm/Analysis/MemoryBuiltins.h"
28 #include "llvm/Analysis/TargetLibraryInfo.h"
29 #include "llvm/Analysis/ValueTracking.h"
30 #include "llvm/IR/CallSite.h"
31 #include "llvm/IR/DIBuilder.h"
32 #include "llvm/IR/DataLayout.h"
33 #include "llvm/IR/Dominators.h"
34 #include "llvm/IR/Function.h"
35 #include "llvm/IR/IRBuilder.h"
36 #include "llvm/IR/InlineAsm.h"
37 #include "llvm/IR/InstVisitor.h"
38 #include "llvm/IR/IntrinsicInst.h"
39 #include "llvm/IR/LLVMContext.h"
40 #include "llvm/IR/MDBuilder.h"
41 #include "llvm/IR/Module.h"
42 #include "llvm/IR/Type.h"
43 #include "llvm/MC/MCSectionMachO.h"
44 #include "llvm/Support/CommandLine.h"
45 #include "llvm/Support/DataTypes.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/Endian.h"
48 #include "llvm/Support/SwapByteOrder.h"
49 #include "llvm/Support/raw_ostream.h"
50 #include "llvm/Transforms/Scalar.h"
51 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
52 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
53 #include "llvm/Transforms/Utils/Cloning.h"
54 #include "llvm/Transforms/Utils/Local.h"
55 #include "llvm/Transforms/Utils/ModuleUtils.h"
56 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
59 #include <system_error>
63 #define DEBUG_TYPE "asan"
65 static const uint64_t kDefaultShadowScale = 3;
66 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
67 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
68 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
69 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
70 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
71 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
72 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
73 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
74 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
75 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
76 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
78 static const size_t kMinStackMallocSize = 1 << 6; // 64B
79 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
80 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
81 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
83 static const char *const kAsanModuleCtorName = "asan.module_ctor";
84 static const char *const kAsanModuleDtorName = "asan.module_dtor";
85 static const uint64_t kAsanCtorAndDtorPriority = 1;
86 static const char *const kAsanReportErrorTemplate = "__asan_report_";
87 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
88 static const char *const kAsanUnregisterGlobalsName =
89 "__asan_unregister_globals";
90 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
91 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
92 static const char *const kAsanInitName = "__asan_init_v5";
93 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
94 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
95 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
96 static const int kMaxAsanStackMallocSizeClass = 10;
97 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
98 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
99 static const char *const kAsanGenPrefix = "__asan_gen_";
100 static const char *const kSanCovGenPrefix = "__sancov_gen_";
101 static const char *const kAsanPoisonStackMemoryName =
102 "__asan_poison_stack_memory";
103 static const char *const kAsanUnpoisonStackMemoryName =
104 "__asan_unpoison_stack_memory";
106 static const char *const kAsanOptionDetectUAR =
107 "__asan_option_detect_stack_use_after_return";
109 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
110 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
112 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
113 static const size_t kNumberOfAccessSizes = 5;
115 static const unsigned kAllocaRzSize = 32;
117 // Command-line flags.
119 // This flag may need to be replaced with -f[no-]asan-reads.
120 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
121 cl::desc("instrument read instructions"),
122 cl::Hidden, cl::init(true));
123 static cl::opt<bool> ClInstrumentWrites(
124 "asan-instrument-writes", cl::desc("instrument write instructions"),
125 cl::Hidden, cl::init(true));
126 static cl::opt<bool> ClInstrumentAtomics(
127 "asan-instrument-atomics",
128 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
130 static cl::opt<bool> ClAlwaysSlowPath(
131 "asan-always-slow-path",
132 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
134 // This flag limits the number of instructions to be instrumented
135 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
136 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
138 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
139 "asan-max-ins-per-bb", cl::init(10000),
140 cl::desc("maximal number of instructions to instrument in any given BB"),
142 // This flag may need to be replaced with -f[no]asan-stack.
143 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
144 cl::Hidden, cl::init(true));
145 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
146 cl::desc("Check return-after-free"),
147 cl::Hidden, cl::init(true));
148 // This flag may need to be replaced with -f[no]asan-globals.
149 static cl::opt<bool> ClGlobals("asan-globals",
150 cl::desc("Handle global objects"), cl::Hidden,
152 static cl::opt<bool> ClInitializers("asan-initialization-order",
153 cl::desc("Handle C++ initializer order"),
154 cl::Hidden, cl::init(true));
155 static cl::opt<bool> ClInvalidPointerPairs(
156 "asan-detect-invalid-pointer-pair",
157 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
159 static cl::opt<unsigned> ClRealignStack(
160 "asan-realign-stack",
161 cl::desc("Realign stack to the value of this flag (power of two)"),
162 cl::Hidden, cl::init(32));
163 static cl::opt<int> ClInstrumentationWithCallsThreshold(
164 "asan-instrumentation-with-call-threshold",
166 "If the function being instrumented contains more than "
167 "this number of memory accesses, use callbacks instead of "
168 "inline checks (-1 means never use callbacks)."),
169 cl::Hidden, cl::init(7000));
170 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
171 "asan-memory-access-callback-prefix",
172 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
173 cl::init("__asan_"));
174 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
175 cl::desc("instrument dynamic allocas"),
176 cl::Hidden, cl::init(false));
177 static cl::opt<bool> ClSkipPromotableAllocas(
178 "asan-skip-promotable-allocas",
179 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
182 // These flags allow to change the shadow mapping.
183 // The shadow mapping looks like
184 // Shadow = (Mem >> scale) + (1 << offset_log)
185 static cl::opt<int> ClMappingScale("asan-mapping-scale",
186 cl::desc("scale of asan shadow mapping"),
187 cl::Hidden, cl::init(0));
189 // Optimization flags. Not user visible, used mostly for testing
190 // and benchmarking the tool.
191 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
192 cl::Hidden, cl::init(true));
193 static cl::opt<bool> ClOptSameTemp(
194 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
195 cl::Hidden, cl::init(true));
196 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
197 cl::desc("Don't instrument scalar globals"),
198 cl::Hidden, cl::init(true));
199 static cl::opt<bool> ClOptStack(
200 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
201 cl::Hidden, cl::init(false));
203 static cl::opt<bool> ClCheckLifetime(
204 "asan-check-lifetime",
205 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
208 static cl::opt<bool> ClDynamicAllocaStack(
209 "asan-stack-dynamic-alloca",
210 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
213 static cl::opt<uint32_t> ClForceExperiment(
214 "asan-force-experiment",
215 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
219 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
221 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
222 cl::Hidden, cl::init(0));
223 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
224 cl::desc("Debug func"));
225 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
226 cl::Hidden, cl::init(-1));
227 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
228 cl::Hidden, cl::init(-1));
230 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
231 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
232 STATISTIC(NumOptimizedAccessesToGlobalVar,
233 "Number of optimized accesses to global vars");
234 STATISTIC(NumOptimizedAccessesToStackVar,
235 "Number of optimized accesses to stack vars");
238 /// Frontend-provided metadata for source location.
239 struct LocationMetadata {
244 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
246 bool empty() const { return Filename.empty(); }
248 void parse(MDNode *MDN) {
249 assert(MDN->getNumOperands() == 3);
250 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
251 Filename = DIFilename->getString();
253 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
255 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
259 /// Frontend-provided metadata for global variables.
260 class GlobalsMetadata {
263 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
264 LocationMetadata SourceLoc;
270 GlobalsMetadata() : inited_(false) {}
272 void init(Module &M) {
275 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
276 if (!Globals) return;
277 for (auto MDN : Globals->operands()) {
278 // Metadata node contains the global and the fields of "Entry".
279 assert(MDN->getNumOperands() == 5);
280 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
281 // The optimizer may optimize away a global entirely.
283 // We can already have an entry for GV if it was merged with another
285 Entry &E = Entries[GV];
286 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
287 E.SourceLoc.parse(Loc);
288 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
289 E.Name = Name->getString();
290 ConstantInt *IsDynInit =
291 mdconst::extract<ConstantInt>(MDN->getOperand(3));
292 E.IsDynInit |= IsDynInit->isOne();
293 ConstantInt *IsBlacklisted =
294 mdconst::extract<ConstantInt>(MDN->getOperand(4));
295 E.IsBlacklisted |= IsBlacklisted->isOne();
299 /// Returns metadata entry for a given global.
300 Entry get(GlobalVariable *G) const {
301 auto Pos = Entries.find(G);
302 return (Pos != Entries.end()) ? Pos->second : Entry();
307 DenseMap<GlobalVariable *, Entry> Entries;
310 /// This struct defines the shadow mapping using the rule:
311 /// shadow = (mem >> Scale) ADD-or-OR Offset.
312 struct ShadowMapping {
318 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) {
319 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
320 bool IsIOS = TargetTriple.isiOS();
321 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
322 bool IsLinux = TargetTriple.isOSLinux();
323 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
324 TargetTriple.getArch() == llvm::Triple::ppc64le;
325 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
326 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
327 TargetTriple.getArch() == llvm::Triple::mipsel;
328 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
329 TargetTriple.getArch() == llvm::Triple::mips64el;
330 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
331 bool IsWindows = TargetTriple.isOSWindows();
333 ShadowMapping Mapping;
335 if (LongSize == 32) {
339 Mapping.Offset = kMIPS32_ShadowOffset32;
341 Mapping.Offset = kFreeBSD_ShadowOffset32;
343 Mapping.Offset = kIOSShadowOffset32;
345 Mapping.Offset = kWindowsShadowOffset32;
347 Mapping.Offset = kDefaultShadowOffset32;
348 } else { // LongSize == 64
350 Mapping.Offset = kPPC64_ShadowOffset64;
352 Mapping.Offset = kFreeBSD_ShadowOffset64;
353 else if (IsLinux && IsX86_64)
354 Mapping.Offset = kSmallX86_64ShadowOffset;
356 Mapping.Offset = kMIPS64_ShadowOffset64;
358 Mapping.Offset = kAArch64_ShadowOffset64;
360 Mapping.Offset = kDefaultShadowOffset64;
363 Mapping.Scale = kDefaultShadowScale;
364 if (ClMappingScale) {
365 Mapping.Scale = ClMappingScale;
368 // OR-ing shadow offset if more efficient (at least on x86) if the offset
369 // is a power of two, but on ppc64 we have to use add since the shadow
370 // offset is not necessary 1/8-th of the address space.
371 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
376 static size_t RedzoneSizeForScale(int MappingScale) {
377 // Redzone used for stack and globals is at least 32 bytes.
378 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
379 return std::max(32U, 1U << MappingScale);
382 /// AddressSanitizer: instrument the code in module to find memory bugs.
383 struct AddressSanitizer : public FunctionPass {
384 AddressSanitizer() : FunctionPass(ID) {
385 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
387 const char *getPassName() const override {
388 return "AddressSanitizerFunctionPass";
390 void getAnalysisUsage(AnalysisUsage &AU) const override {
391 AU.addRequired<DominatorTreeWrapperPass>();
392 AU.addRequired<TargetLibraryInfoWrapperPass>();
394 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
395 Type *Ty = AI->getAllocatedType();
396 uint64_t SizeInBytes =
397 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
400 /// Check if we want (and can) handle this alloca.
401 bool isInterestingAlloca(AllocaInst &AI);
403 // Check if we have dynamic alloca.
404 bool isDynamicAlloca(AllocaInst &AI) const {
405 return AI.isArrayAllocation() || !AI.isStaticAlloca();
408 /// If it is an interesting memory access, return the PointerOperand
409 /// and set IsWrite/Alignment. Otherwise return nullptr.
410 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
411 uint64_t *TypeSize, unsigned *Alignment);
412 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
413 bool UseCalls, const DataLayout &DL);
414 void instrumentPointerComparisonOrSubtraction(Instruction *I);
415 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
416 Value *Addr, uint32_t TypeSize, bool IsWrite,
417 Value *SizeArgument, bool UseCalls, uint32_t Exp);
418 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
419 uint32_t TypeSize, bool IsWrite,
420 Value *SizeArgument, bool UseCalls,
422 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
423 Value *ShadowValue, uint32_t TypeSize);
424 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
425 bool IsWrite, size_t AccessSizeIndex,
426 Value *SizeArgument, uint32_t Exp);
427 void instrumentMemIntrinsic(MemIntrinsic *MI);
428 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
429 bool runOnFunction(Function &F) override;
430 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
431 bool doInitialization(Module &M) override;
432 static char ID; // Pass identification, replacement for typeid
434 DominatorTree &getDominatorTree() const { return *DT; }
437 void initializeCallbacks(Module &M);
439 bool LooksLikeCodeInBug11395(Instruction *I);
440 bool GlobalIsLinkerInitialized(GlobalVariable *G);
441 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
442 uint64_t TypeSize) const;
448 ShadowMapping Mapping;
450 Function *AsanCtorFunction;
451 Function *AsanInitFunction;
452 Function *AsanHandleNoReturnFunc;
453 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
454 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
455 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
456 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
457 // This array is indexed by AccessIsWrite and Experiment.
458 Function *AsanErrorCallbackSized[2][2];
459 Function *AsanMemoryAccessCallbackSized[2][2];
460 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
462 GlobalsMetadata GlobalsMD;
463 DenseMap<AllocaInst *, bool> ProcessedAllocas;
465 friend struct FunctionStackPoisoner;
468 class AddressSanitizerModule : public ModulePass {
470 AddressSanitizerModule() : ModulePass(ID) {}
471 bool runOnModule(Module &M) override;
472 static char ID; // Pass identification, replacement for typeid
473 const char *getPassName() const override { return "AddressSanitizerModule"; }
476 void initializeCallbacks(Module &M);
478 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
479 bool ShouldInstrumentGlobal(GlobalVariable *G);
480 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
481 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
482 size_t MinRedzoneSizeForGlobal() const {
483 return RedzoneSizeForScale(Mapping.Scale);
486 GlobalsMetadata GlobalsMD;
490 ShadowMapping Mapping;
491 Function *AsanPoisonGlobals;
492 Function *AsanUnpoisonGlobals;
493 Function *AsanRegisterGlobals;
494 Function *AsanUnregisterGlobals;
497 // Stack poisoning does not play well with exception handling.
498 // When an exception is thrown, we essentially bypass the code
499 // that unpoisones the stack. This is why the run-time library has
500 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
501 // stack in the interceptor. This however does not work inside the
502 // actual function which catches the exception. Most likely because the
503 // compiler hoists the load of the shadow value somewhere too high.
504 // This causes asan to report a non-existing bug on 453.povray.
505 // It sounds like an LLVM bug.
506 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
508 AddressSanitizer &ASan;
513 ShadowMapping Mapping;
515 SmallVector<AllocaInst *, 16> AllocaVec;
516 SmallVector<Instruction *, 8> RetVec;
517 unsigned StackAlignment;
519 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
520 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
521 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
522 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
524 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
525 struct AllocaPoisonCall {
526 IntrinsicInst *InsBefore;
531 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
533 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
534 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
535 AllocaInst *DynamicAllocaLayout = nullptr;
537 // Maps Value to an AllocaInst from which the Value is originated.
538 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
539 AllocaForValueMapTy AllocaForValue;
541 bool HasNonEmptyInlineAsm;
542 std::unique_ptr<CallInst> EmptyInlineAsm;
544 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
547 DIB(*F.getParent(), /*AllowUnresolved*/ false),
549 IntptrTy(ASan.IntptrTy),
550 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
551 Mapping(ASan.Mapping),
552 StackAlignment(1 << Mapping.Scale),
553 HasNonEmptyInlineAsm(false),
554 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
556 bool runOnFunction() {
557 if (!ClStack) return false;
558 // Collect alloca, ret, lifetime instructions etc.
559 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
561 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
563 initializeCallbacks(*F.getParent());
573 // Finds all Alloca instructions and puts
574 // poisoned red zones around all of them.
575 // Then unpoison everything back before the function returns.
578 void createDynamicAllocasInitStorage();
580 // ----------------------- Visitors.
581 /// \brief Collect all Ret instructions.
582 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
584 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
586 IRBuilder<> IRB(InstBefore);
587 IRB.CreateCall(AsanAllocasUnpoisonFunc,
588 {IRB.CreateLoad(DynamicAllocaLayout),
589 IRB.CreatePtrToInt(SavedStack, IntptrTy)});
592 // Unpoison dynamic allocas redzones.
593 void unpoisonDynamicAllocas() {
594 for (auto &Ret : RetVec)
595 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
597 for (auto &StackRestoreInst : StackRestoreVec)
598 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
599 StackRestoreInst->getOperand(0));
602 // Deploy and poison redzones around dynamic alloca call. To do this, we
603 // should replace this call with another one with changed parameters and
604 // replace all its uses with new address, so
605 // addr = alloca type, old_size, align
607 // new_size = (old_size + additional_size) * sizeof(type)
608 // tmp = alloca i8, new_size, max(align, 32)
609 // addr = tmp + 32 (first 32 bytes are for the left redzone).
610 // Additional_size is added to make new memory allocation contain not only
611 // requested memory, but also left, partial and right redzones.
612 void handleDynamicAllocaCall(AllocaInst *AI);
614 /// \brief Collect Alloca instructions we want (and can) handle.
615 void visitAllocaInst(AllocaInst &AI) {
616 if (!ASan.isInterestingAlloca(AI)) return;
618 StackAlignment = std::max(StackAlignment, AI.getAlignment());
619 if (ASan.isDynamicAlloca(AI))
620 DynamicAllocaVec.push_back(&AI);
622 AllocaVec.push_back(&AI);
625 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
627 void visitIntrinsicInst(IntrinsicInst &II) {
628 Intrinsic::ID ID = II.getIntrinsicID();
629 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
630 if (!ClCheckLifetime) return;
631 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
633 // Found lifetime intrinsic, add ASan instrumentation if necessary.
634 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
635 // If size argument is undefined, don't do anything.
636 if (Size->isMinusOne()) return;
637 // Check that size doesn't saturate uint64_t and can
638 // be stored in IntptrTy.
639 const uint64_t SizeValue = Size->getValue().getLimitedValue();
640 if (SizeValue == ~0ULL ||
641 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
643 // Find alloca instruction that corresponds to llvm.lifetime argument.
644 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
646 bool DoPoison = (ID == Intrinsic::lifetime_end);
647 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
648 AllocaPoisonCallVec.push_back(APC);
651 void visitCallInst(CallInst &CI) {
652 HasNonEmptyInlineAsm |=
653 CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get());
656 // ---------------------- Helpers.
657 void initializeCallbacks(Module &M);
659 bool doesDominateAllExits(const Instruction *I) const {
660 for (auto Ret : RetVec) {
661 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
666 /// Finds alloca where the value comes from.
667 AllocaInst *findAllocaForValue(Value *V);
668 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
669 Value *ShadowBase, bool DoPoison);
670 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
672 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
674 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
676 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
677 Instruction *ThenTerm, Value *ValueIfFalse);
682 char AddressSanitizer::ID = 0;
683 INITIALIZE_PASS_BEGIN(
684 AddressSanitizer, "asan",
685 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
687 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
689 AddressSanitizer, "asan",
690 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
692 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
693 return new AddressSanitizer();
696 char AddressSanitizerModule::ID = 0;
698 AddressSanitizerModule, "asan-module",
699 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
702 ModulePass *llvm::createAddressSanitizerModulePass() {
703 return new AddressSanitizerModule();
706 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
707 size_t Res = countTrailingZeros(TypeSize / 8);
708 assert(Res < kNumberOfAccessSizes);
712 // \brief Create a constant for Str so that we can pass it to the run-time lib.
713 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
715 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
716 // We use private linkage for module-local strings. If they can be merged
717 // with another one, we set the unnamed_addr attribute.
719 new GlobalVariable(M, StrConst->getType(), true,
720 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
721 if (AllowMerging) GV->setUnnamedAddr(true);
722 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
726 /// \brief Create a global describing a source location.
727 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
728 LocationMetadata MD) {
729 Constant *LocData[] = {
730 createPrivateGlobalForString(M, MD.Filename, true),
731 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
732 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
734 auto LocStruct = ConstantStruct::getAnon(LocData);
735 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
736 GlobalValue::PrivateLinkage, LocStruct,
738 GV->setUnnamedAddr(true);
742 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
743 return G->getName().find(kAsanGenPrefix) == 0 ||
744 G->getName().find(kSanCovGenPrefix) == 0;
747 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
749 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
750 if (Mapping.Offset == 0) return Shadow;
751 // (Shadow >> scale) | offset
752 if (Mapping.OrShadowOffset)
753 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
755 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
758 // Instrument memset/memmove/memcpy
759 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
761 if (isa<MemTransferInst>(MI)) {
763 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
764 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
765 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
766 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
767 } else if (isa<MemSetInst>(MI)) {
770 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
771 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
772 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
774 MI->eraseFromParent();
777 /// Check if we want (and can) handle this alloca.
778 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
779 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
781 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
782 return PreviouslySeenAllocaInfo->getSecond();
785 (AI.getAllocatedType()->isSized() &&
786 // alloca() may be called with 0 size, ignore it.
787 getAllocaSizeInBytes(&AI) > 0 &&
788 // We are only interested in allocas not promotable to registers.
789 // Promotable allocas are common under -O0.
790 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI) ||
791 isDynamicAlloca(AI)));
793 ProcessedAllocas[&AI] = IsInteresting;
794 return IsInteresting;
797 /// If I is an interesting memory access, return the PointerOperand
798 /// and set IsWrite/Alignment. Otherwise return nullptr.
799 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
802 unsigned *Alignment) {
803 // Skip memory accesses inserted by another instrumentation.
804 if (I->getMetadata("nosanitize")) return nullptr;
806 Value *PtrOperand = nullptr;
807 const DataLayout &DL = I->getModule()->getDataLayout();
808 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
809 if (!ClInstrumentReads) return nullptr;
811 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
812 *Alignment = LI->getAlignment();
813 PtrOperand = LI->getPointerOperand();
814 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
815 if (!ClInstrumentWrites) return nullptr;
817 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
818 *Alignment = SI->getAlignment();
819 PtrOperand = SI->getPointerOperand();
820 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
821 if (!ClInstrumentAtomics) return nullptr;
823 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
825 PtrOperand = RMW->getPointerOperand();
826 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
827 if (!ClInstrumentAtomics) return nullptr;
829 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
831 PtrOperand = XCHG->getPointerOperand();
834 // Treat memory accesses to promotable allocas as non-interesting since they
835 // will not cause memory violations. This greatly speeds up the instrumented
836 // executable at -O0.
837 if (ClSkipPromotableAllocas)
838 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
839 return isInterestingAlloca(*AI) ? AI : nullptr;
844 static bool isPointerOperand(Value *V) {
845 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
848 // This is a rough heuristic; it may cause both false positives and
849 // false negatives. The proper implementation requires cooperation with
851 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
852 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
853 if (!Cmp->isRelational()) return false;
854 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
855 if (BO->getOpcode() != Instruction::Sub) return false;
859 if (!isPointerOperand(I->getOperand(0)) ||
860 !isPointerOperand(I->getOperand(1)))
865 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
866 // If a global variable does not have dynamic initialization we don't
867 // have to instrument it. However, if a global does not have initializer
868 // at all, we assume it has dynamic initializer (in other TU).
869 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
872 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
875 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
876 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
877 for (int i = 0; i < 2; i++) {
878 if (Param[i]->getType()->isPointerTy())
879 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
881 IRB.CreateCall(F, Param);
884 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
885 Instruction *I, bool UseCalls,
886 const DataLayout &DL) {
887 bool IsWrite = false;
888 unsigned Alignment = 0;
889 uint64_t TypeSize = 0;
890 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
893 // Optimization experiments.
894 // The experiments can be used to evaluate potential optimizations that remove
895 // instrumentation (assess false negatives). Instead of completely removing
896 // some instrumentation, you set Exp to a non-zero value (mask of optimization
897 // experiments that want to remove instrumentation of this instruction).
898 // If Exp is non-zero, this pass will emit special calls into runtime
899 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
900 // make runtime terminate the program in a special way (with a different
901 // exit status). Then you run the new compiler on a buggy corpus, collect
902 // the special terminations (ideally, you don't see them at all -- no false
903 // negatives) and make the decision on the optimization.
904 uint32_t Exp = ClForceExperiment;
906 if (ClOpt && ClOptGlobals) {
907 // If initialization order checking is disabled, a simple access to a
908 // dynamically initialized global is always valid.
909 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
910 if (G != NULL && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
911 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
912 NumOptimizedAccessesToGlobalVar++;
917 if (ClOpt && ClOptStack) {
918 // A direct inbounds access to a stack variable is always valid.
919 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
920 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
921 NumOptimizedAccessesToStackVar++;
927 NumInstrumentedWrites++;
929 NumInstrumentedReads++;
931 unsigned Granularity = 1 << Mapping.Scale;
932 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
933 // if the data is properly aligned.
934 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
936 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
937 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
939 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
943 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
944 Value *Addr, bool IsWrite,
945 size_t AccessSizeIndex,
948 IRBuilder<> IRB(InsertBefore);
949 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
950 CallInst *Call = nullptr;
953 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
954 {Addr, SizeArgument});
956 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
957 {Addr, SizeArgument, ExpVal});
961 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
963 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
967 // We don't do Call->setDoesNotReturn() because the BB already has
968 // UnreachableInst at the end.
969 // This EmptyAsm is required to avoid callback merge.
970 IRB.CreateCall(EmptyAsm, {});
974 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
977 size_t Granularity = 1 << Mapping.Scale;
978 // Addr & (Granularity - 1)
979 Value *LastAccessedByte =
980 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
981 // (Addr & (Granularity - 1)) + size - 1
982 if (TypeSize / 8 > 1)
983 LastAccessedByte = IRB.CreateAdd(
984 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
985 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
987 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
988 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
989 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
992 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
993 Instruction *InsertBefore, Value *Addr,
994 uint32_t TypeSize, bool IsWrite,
995 Value *SizeArgument, bool UseCalls,
997 IRBuilder<> IRB(InsertBefore);
998 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
999 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1003 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1006 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1007 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1012 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1013 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1014 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1015 Value *CmpVal = Constant::getNullValue(ShadowTy);
1016 Value *ShadowValue =
1017 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1019 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1020 size_t Granularity = 1 << Mapping.Scale;
1021 TerminatorInst *CrashTerm = nullptr;
1023 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1024 // We use branch weights for the slow path check, to indicate that the slow
1025 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1026 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1027 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1028 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1029 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1030 IRB.SetInsertPoint(CheckTerm);
1031 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1032 BasicBlock *CrashBlock =
1033 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1034 CrashTerm = new UnreachableInst(*C, CrashBlock);
1035 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1036 ReplaceInstWithInst(CheckTerm, NewTerm);
1038 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1041 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1042 AccessSizeIndex, SizeArgument, Exp);
1043 Crash->setDebugLoc(OrigIns->getDebugLoc());
1046 // Instrument unusual size or unusual alignment.
1047 // We can not do it with a single check, so we do 1-byte check for the first
1048 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1049 // to report the actual access size.
1050 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1051 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1052 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1054 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1055 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1058 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1061 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1062 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1064 Value *LastByte = IRB.CreateIntToPtr(
1065 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1067 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1068 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1072 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1073 GlobalValue *ModuleName) {
1074 // Set up the arguments to our poison/unpoison functions.
1075 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1077 // Add a call to poison all external globals before the given function starts.
1078 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1079 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1081 // Add calls to unpoison all globals before each return instruction.
1082 for (auto &BB : GlobalInit.getBasicBlockList())
1083 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1084 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1087 void AddressSanitizerModule::createInitializerPoisonCalls(
1088 Module &M, GlobalValue *ModuleName) {
1089 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1091 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1092 for (Use &OP : CA->operands()) {
1093 if (isa<ConstantAggregateZero>(OP)) continue;
1094 ConstantStruct *CS = cast<ConstantStruct>(OP);
1096 // Must have a function or null ptr.
1097 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1098 if (F->getName() == kAsanModuleCtorName) continue;
1099 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1100 // Don't instrument CTORs that will run before asan.module_ctor.
1101 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1102 poisonOneInitializer(*F, ModuleName);
1107 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1108 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1109 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1111 if (GlobalsMD.get(G).IsBlacklisted) return false;
1112 if (!Ty->isSized()) return false;
1113 if (!G->hasInitializer()) return false;
1114 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1115 // Touch only those globals that will not be defined in other modules.
1116 // Don't handle ODR linkage types and COMDATs since other modules may be built
1118 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1119 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1120 G->getLinkage() != GlobalVariable::InternalLinkage)
1122 if (G->hasComdat()) return false;
1123 // Two problems with thread-locals:
1124 // - The address of the main thread's copy can't be computed at link-time.
1125 // - Need to poison all copies, not just the main thread's one.
1126 if (G->isThreadLocal()) return false;
1127 // For now, just ignore this Global if the alignment is large.
1128 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1130 if (G->hasSection()) {
1131 StringRef Section(G->getSection());
1133 // Globals from llvm.metadata aren't emitted, do not instrument them.
1134 if (Section == "llvm.metadata") return false;
1136 // Callbacks put into the CRT initializer/terminator sections
1137 // should not be instrumented.
1138 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1139 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1140 if (Section.startswith(".CRT")) {
1141 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1145 if (TargetTriple.isOSBinFormatMachO()) {
1146 StringRef ParsedSegment, ParsedSection;
1147 unsigned TAA = 0, StubSize = 0;
1149 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1150 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1151 if (!ErrorCode.empty()) {
1152 assert(false && "Invalid section specifier.");
1156 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1157 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1159 if (ParsedSegment == "__OBJC" ||
1160 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1161 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1164 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1165 // Constant CFString instances are compiled in the following way:
1166 // -- the string buffer is emitted into
1167 // __TEXT,__cstring,cstring_literals
1168 // -- the constant NSConstantString structure referencing that buffer
1169 // is placed into __DATA,__cfstring
1170 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1171 // Moreover, it causes the linker to crash on OS X 10.7
1172 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1173 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1176 // The linker merges the contents of cstring_literals and removes the
1178 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1179 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1188 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1189 IRBuilder<> IRB(*C);
1190 // Declare our poisoning and unpoisoning functions.
1191 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1192 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1193 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1194 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1195 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1196 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1197 // Declare functions that register/unregister globals.
1198 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1199 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1200 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1201 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1202 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1203 IntptrTy, IntptrTy, nullptr));
1204 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1207 // This function replaces all global variables with new variables that have
1208 // trailing redzones. It also creates a function that poisons
1209 // redzones and inserts this function into llvm.global_ctors.
1210 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1213 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1215 for (auto &G : M.globals()) {
1216 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1219 size_t n = GlobalsToChange.size();
1220 if (n == 0) return false;
1222 // A global is described by a structure
1225 // size_t size_with_redzone;
1226 // const char *name;
1227 // const char *module_name;
1228 // size_t has_dynamic_init;
1229 // void *source_location;
1230 // We initialize an array of such structures and pass it to a run-time call.
1231 StructType *GlobalStructTy =
1232 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1233 IntptrTy, IntptrTy, nullptr);
1234 SmallVector<Constant *, 16> Initializers(n);
1236 bool HasDynamicallyInitializedGlobals = false;
1238 // We shouldn't merge same module names, as this string serves as unique
1239 // module ID in runtime.
1240 GlobalVariable *ModuleName = createPrivateGlobalForString(
1241 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1243 auto &DL = M.getDataLayout();
1244 for (size_t i = 0; i < n; i++) {
1245 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1246 GlobalVariable *G = GlobalsToChange[i];
1248 auto MD = GlobalsMD.get(G);
1249 // Create string holding the global name (use global name from metadata
1250 // if it's available, otherwise just write the name of global variable).
1251 GlobalVariable *Name = createPrivateGlobalForString(
1252 M, MD.Name.empty() ? G->getName() : MD.Name,
1253 /*AllowMerging*/ true);
1255 PointerType *PtrTy = cast<PointerType>(G->getType());
1256 Type *Ty = PtrTy->getElementType();
1257 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1258 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1259 // MinRZ <= RZ <= kMaxGlobalRedzone
1260 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1261 uint64_t RZ = std::max(
1262 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1263 uint64_t RightRedzoneSize = RZ;
1264 // Round up to MinRZ
1265 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1266 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1267 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1269 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1270 Constant *NewInitializer =
1271 ConstantStruct::get(NewTy, G->getInitializer(),
1272 Constant::getNullValue(RightRedZoneTy), nullptr);
1274 // Create a new global variable with enough space for a redzone.
1275 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1276 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1277 Linkage = GlobalValue::InternalLinkage;
1278 GlobalVariable *NewGlobal =
1279 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1280 "", G, G->getThreadLocalMode());
1281 NewGlobal->copyAttributesFrom(G);
1282 NewGlobal->setAlignment(MinRZ);
1285 Indices2[0] = IRB.getInt32(0);
1286 Indices2[1] = IRB.getInt32(0);
1288 G->replaceAllUsesWith(
1289 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1290 NewGlobal->takeName(G);
1291 G->eraseFromParent();
1293 Constant *SourceLoc;
1294 if (!MD.SourceLoc.empty()) {
1295 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1296 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1298 SourceLoc = ConstantInt::get(IntptrTy, 0);
1301 Initializers[i] = ConstantStruct::get(
1302 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1303 ConstantInt::get(IntptrTy, SizeInBytes),
1304 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1305 ConstantExpr::getPointerCast(Name, IntptrTy),
1306 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1307 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1309 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1311 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1314 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1315 GlobalVariable *AllGlobals = new GlobalVariable(
1316 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1317 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1319 // Create calls for poisoning before initializers run and unpoisoning after.
1320 if (HasDynamicallyInitializedGlobals)
1321 createInitializerPoisonCalls(M, ModuleName);
1322 IRB.CreateCall(AsanRegisterGlobals,
1323 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1324 ConstantInt::get(IntptrTy, n)});
1326 // We also need to unregister globals at the end, e.g. when a shared library
1328 Function *AsanDtorFunction =
1329 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1330 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1331 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1332 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1333 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1334 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1335 ConstantInt::get(IntptrTy, n)});
1336 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1342 bool AddressSanitizerModule::runOnModule(Module &M) {
1343 C = &(M.getContext());
1344 int LongSize = M.getDataLayout().getPointerSizeInBits();
1345 IntptrTy = Type::getIntNTy(*C, LongSize);
1346 TargetTriple = Triple(M.getTargetTriple());
1347 Mapping = getShadowMapping(TargetTriple, LongSize);
1348 initializeCallbacks(M);
1350 bool Changed = false;
1352 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1354 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1356 if (ClGlobals) Changed |= InstrumentGlobals(IRB, M);
1361 void AddressSanitizer::initializeCallbacks(Module &M) {
1362 IRBuilder<> IRB(*C);
1363 // Create __asan_report* callbacks.
1364 // IsWrite, TypeSize and Exp are encoded in the function name.
1365 for (int Exp = 0; Exp < 2; Exp++) {
1366 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1367 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1368 const std::string ExpStr = Exp ? "exp_" : "";
1369 const Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1370 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1371 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1372 kAsanReportErrorTemplate + ExpStr + TypeStr + "_n",
1373 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1374 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1375 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1376 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N",
1377 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1378 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1379 AccessSizeIndex++) {
1380 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1381 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1382 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1383 kAsanReportErrorTemplate + ExpStr + Suffix, IRB.getVoidTy(),
1384 IntptrTy, ExpType, nullptr));
1385 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1386 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1387 ClMemoryAccessCallbackPrefix + ExpStr + Suffix, IRB.getVoidTy(),
1388 IntptrTy, ExpType, nullptr));
1393 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1394 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1395 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1396 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1397 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1398 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1399 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1400 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1401 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1403 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1404 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1406 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1407 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1408 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1409 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1410 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1411 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1412 StringRef(""), StringRef(""),
1413 /*hasSideEffects=*/true);
1417 bool AddressSanitizer::doInitialization(Module &M) {
1418 // Initialize the private fields. No one has accessed them before.
1422 C = &(M.getContext());
1423 LongSize = M.getDataLayout().getPointerSizeInBits();
1424 IntptrTy = Type::getIntNTy(*C, LongSize);
1425 TargetTriple = Triple(M.getTargetTriple());
1427 std::tie(AsanCtorFunction, AsanInitFunction) =
1428 createSanitizerCtorAndInitFunctions(M, kAsanModuleCtorName, kAsanInitName,
1429 /*InitArgTypes=*/{},
1432 Mapping = getShadowMapping(TargetTriple, LongSize);
1434 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1438 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1439 // For each NSObject descendant having a +load method, this method is invoked
1440 // by the ObjC runtime before any of the static constructors is called.
1441 // Therefore we need to instrument such methods with a call to __asan_init
1442 // at the beginning in order to initialize our runtime before any access to
1443 // the shadow memory.
1444 // We cannot just ignore these methods, because they may call other
1445 // instrumented functions.
1446 if (F.getName().find(" load]") != std::string::npos) {
1447 IRBuilder<> IRB(F.begin()->begin());
1448 IRB.CreateCall(AsanInitFunction, {});
1454 bool AddressSanitizer::runOnFunction(Function &F) {
1455 if (&F == AsanCtorFunction) return false;
1456 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1457 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1458 initializeCallbacks(*F.getParent());
1460 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1462 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1463 maybeInsertAsanInitAtFunctionEntry(F);
1465 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1467 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1469 // We want to instrument every address only once per basic block (unless there
1470 // are calls between uses).
1471 SmallSet<Value *, 16> TempsToInstrument;
1472 SmallVector<Instruction *, 16> ToInstrument;
1473 SmallVector<Instruction *, 8> NoReturnCalls;
1474 SmallVector<BasicBlock *, 16> AllBlocks;
1475 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1481 // Fill the set of memory operations to instrument.
1482 for (auto &BB : F) {
1483 AllBlocks.push_back(&BB);
1484 TempsToInstrument.clear();
1485 int NumInsnsPerBB = 0;
1486 for (auto &Inst : BB) {
1487 if (LooksLikeCodeInBug11395(&Inst)) return false;
1488 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1490 if (ClOpt && ClOptSameTemp) {
1491 if (!TempsToInstrument.insert(Addr).second)
1492 continue; // We've seen this temp in the current BB.
1494 } else if (ClInvalidPointerPairs &&
1495 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1496 PointerComparisonsOrSubtracts.push_back(&Inst);
1498 } else if (isa<MemIntrinsic>(Inst)) {
1501 if (isa<AllocaInst>(Inst)) NumAllocas++;
1504 // A call inside BB.
1505 TempsToInstrument.clear();
1506 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1510 ToInstrument.push_back(&Inst);
1512 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1516 bool UseCalls = false;
1517 if (ClInstrumentationWithCallsThreshold >= 0 &&
1518 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1521 const TargetLibraryInfo *TLI =
1522 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1523 const DataLayout &DL = F.getParent()->getDataLayout();
1524 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1525 /*RoundToAlign=*/true);
1528 int NumInstrumented = 0;
1529 for (auto Inst : ToInstrument) {
1530 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1531 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1532 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1533 instrumentMop(ObjSizeVis, Inst, UseCalls,
1534 F.getParent()->getDataLayout());
1536 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1541 FunctionStackPoisoner FSP(F, *this);
1542 bool ChangedStack = FSP.runOnFunction();
1544 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1545 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1546 for (auto CI : NoReturnCalls) {
1547 IRBuilder<> IRB(CI);
1548 IRB.CreateCall(AsanHandleNoReturnFunc, {});
1551 for (auto Inst : PointerComparisonsOrSubtracts) {
1552 instrumentPointerComparisonOrSubtraction(Inst);
1556 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1558 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1563 // Workaround for bug 11395: we don't want to instrument stack in functions
1564 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1565 // FIXME: remove once the bug 11395 is fixed.
1566 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1567 if (LongSize != 32) return false;
1568 CallInst *CI = dyn_cast<CallInst>(I);
1569 if (!CI || !CI->isInlineAsm()) return false;
1570 if (CI->getNumArgOperands() <= 5) return false;
1571 // We have inline assembly with quite a few arguments.
1575 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1576 IRBuilder<> IRB(*C);
1577 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1578 std::string Suffix = itostr(i);
1579 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
1580 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1581 IntptrTy, nullptr));
1582 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
1583 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1584 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1586 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1587 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1588 IntptrTy, IntptrTy, nullptr));
1589 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1590 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1591 IntptrTy, IntptrTy, nullptr));
1592 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1593 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1594 AsanAllocasUnpoisonFunc =
1595 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1596 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1599 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1600 IRBuilder<> &IRB, Value *ShadowBase,
1602 size_t n = ShadowBytes.size();
1604 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1605 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1606 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1607 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1608 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1609 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1611 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1612 if (F.getParent()->getDataLayout().isLittleEndian())
1613 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1615 Val = (Val << 8) | ShadowBytes[i + j];
1618 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1619 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1620 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1621 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1626 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1627 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1628 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1629 assert(LocalStackSize <= kMaxStackMallocSize);
1630 uint64_t MaxSize = kMinStackMallocSize;
1631 for (int i = 0;; i++, MaxSize *= 2)
1632 if (LocalStackSize <= MaxSize) return i;
1633 llvm_unreachable("impossible LocalStackSize");
1636 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1637 // We can not use MemSet intrinsic because it may end up calling the actual
1638 // memset. Size is a multiple of 8.
1639 // Currently this generates 8-byte stores on x86_64; it may be better to
1640 // generate wider stores.
1641 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1642 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1643 assert(!(Size % 8));
1645 // kAsanStackAfterReturnMagic is 0xf5.
1646 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1648 for (int i = 0; i < Size; i += 8) {
1649 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1651 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1652 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1656 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1657 for (const auto &Inst : F.getEntryBlock())
1658 if (!isa<AllocaInst>(Inst)) return Inst.getDebugLoc();
1662 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1664 Instruction *ThenTerm,
1665 Value *ValueIfFalse) {
1666 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1667 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1668 PHI->addIncoming(ValueIfFalse, CondBlock);
1669 BasicBlock *ThenBlock = ThenTerm->getParent();
1670 PHI->addIncoming(ValueIfTrue, ThenBlock);
1674 Value *FunctionStackPoisoner::createAllocaForLayout(
1675 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1678 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1679 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1682 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1683 nullptr, "MyAlloca");
1684 assert(Alloca->isStaticAlloca());
1686 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1687 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1688 Alloca->setAlignment(FrameAlignment);
1689 return IRB.CreatePointerCast(Alloca, IntptrTy);
1692 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
1693 BasicBlock &FirstBB = *F.begin();
1694 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
1695 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
1696 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
1697 DynamicAllocaLayout->setAlignment(32);
1700 void FunctionStackPoisoner::poisonStack() {
1701 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1703 if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
1704 // Handle dynamic allocas.
1705 createDynamicAllocasInitStorage();
1706 for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI);
1708 unpoisonDynamicAllocas();
1711 if (AllocaVec.size() == 0) return;
1713 int StackMallocIdx = -1;
1714 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1716 Instruction *InsBefore = AllocaVec[0];
1717 IRBuilder<> IRB(InsBefore);
1718 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1720 SmallVector<ASanStackVariableDescription, 16> SVD;
1721 SVD.reserve(AllocaVec.size());
1722 for (AllocaInst *AI : AllocaVec) {
1723 ASanStackVariableDescription D = {AI->getName().data(),
1724 ASan.getAllocaSizeInBytes(AI),
1725 AI->getAlignment(), AI, 0};
1728 // Minimal header size (left redzone) is 4 pointers,
1729 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1730 size_t MinHeaderSize = ASan.LongSize / 2;
1731 ASanStackFrameLayout L;
1732 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1733 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1734 uint64_t LocalStackSize = L.FrameSize;
1735 bool DoStackMalloc =
1736 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1737 // Don't do dynamic alloca in presence of inline asm: too often it makes
1738 // assumptions on which registers are available. Don't do stack malloc in the
1739 // presence of inline asm on 32-bit platforms for the same reason.
1740 bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
1741 DoStackMalloc &= !HasNonEmptyInlineAsm || ASan.LongSize != 32;
1743 Value *StaticAlloca =
1744 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1747 Value *LocalStackBase;
1749 if (DoStackMalloc) {
1750 // void *FakeStack = __asan_option_detect_stack_use_after_return
1751 // ? __asan_stack_malloc_N(LocalStackSize)
1753 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1754 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1755 kAsanOptionDetectUAR, IRB.getInt32Ty());
1756 Value *UARIsEnabled =
1757 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1758 Constant::getNullValue(IRB.getInt32Ty()));
1760 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1761 IRBuilder<> IRBIf(Term);
1762 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1763 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1764 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1765 Value *FakeStackValue =
1766 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1767 ConstantInt::get(IntptrTy, LocalStackSize));
1768 IRB.SetInsertPoint(InsBefore);
1769 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1770 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1771 ConstantInt::get(IntptrTy, 0));
1773 Value *NoFakeStack =
1774 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1775 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1776 IRBIf.SetInsertPoint(Term);
1777 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1778 Value *AllocaValue =
1779 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1780 IRB.SetInsertPoint(InsBefore);
1781 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1782 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1784 // void *FakeStack = nullptr;
1785 // void *LocalStackBase = alloca(LocalStackSize);
1786 FakeStack = ConstantInt::get(IntptrTy, 0);
1788 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1791 // Insert poison calls for lifetime intrinsics for alloca.
1792 bool HavePoisonedAllocas = false;
1793 for (const auto &APC : AllocaPoisonCallVec) {
1794 assert(APC.InsBefore);
1796 IRBuilder<> IRB(APC.InsBefore);
1797 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1798 HavePoisonedAllocas |= APC.DoPoison;
1801 // Replace Alloca instructions with base+offset.
1802 for (const auto &Desc : SVD) {
1803 AllocaInst *AI = Desc.AI;
1804 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1805 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1807 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1808 AI->replaceAllUsesWith(NewAllocaPtr);
1811 // The left-most redzone has enough space for at least 4 pointers.
1812 // Write the Magic value to redzone[0].
1813 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1814 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1816 // Write the frame description constant to redzone[1].
1817 Value *BasePlus1 = IRB.CreateIntToPtr(
1818 IRB.CreateAdd(LocalStackBase,
1819 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1821 GlobalVariable *StackDescriptionGlobal =
1822 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1823 /*AllowMerging*/ true);
1824 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1825 IRB.CreateStore(Description, BasePlus1);
1826 // Write the PC to redzone[2].
1827 Value *BasePlus2 = IRB.CreateIntToPtr(
1828 IRB.CreateAdd(LocalStackBase,
1829 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1831 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1833 // Poison the stack redzones at the entry.
1834 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1835 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1837 // (Un)poison the stack before all ret instructions.
1838 for (auto Ret : RetVec) {
1839 IRBuilder<> IRBRet(Ret);
1840 // Mark the current frame as retired.
1841 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1843 if (DoStackMalloc) {
1844 assert(StackMallocIdx >= 0);
1845 // if FakeStack != 0 // LocalStackBase == FakeStack
1846 // // In use-after-return mode, poison the whole stack frame.
1847 // if StackMallocIdx <= 4
1848 // // For small sizes inline the whole thing:
1849 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1850 // **SavedFlagPtr(FakeStack) = 0
1852 // __asan_stack_free_N(FakeStack, LocalStackSize)
1854 // <This is not a fake stack; unpoison the redzones>
1856 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1857 TerminatorInst *ThenTerm, *ElseTerm;
1858 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1860 IRBuilder<> IRBPoison(ThenTerm);
1861 if (StackMallocIdx <= 4) {
1862 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1863 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1864 ClassSize >> Mapping.Scale);
1865 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1867 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1868 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1869 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1870 IRBPoison.CreateStore(
1871 Constant::getNullValue(IRBPoison.getInt8Ty()),
1872 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1874 // For larger frames call __asan_stack_free_*.
1875 IRBPoison.CreateCall(
1876 AsanStackFreeFunc[StackMallocIdx],
1877 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
1880 IRBuilder<> IRBElse(ElseTerm);
1881 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1882 } else if (HavePoisonedAllocas) {
1883 // If we poisoned some allocas in llvm.lifetime analysis,
1884 // unpoison whole stack frame now.
1885 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1887 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1891 // We are done. Remove the old unused alloca instructions.
1892 for (auto AI : AllocaVec) AI->eraseFromParent();
1895 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1896 IRBuilder<> &IRB, bool DoPoison) {
1897 // For now just insert the call to ASan runtime.
1898 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1899 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1901 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
1902 {AddrArg, SizeArg});
1905 // Handling llvm.lifetime intrinsics for a given %alloca:
1906 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1907 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1908 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1909 // could be poisoned by previous llvm.lifetime.end instruction, as the
1910 // variable may go in and out of scope several times, e.g. in loops).
1911 // (3) if we poisoned at least one %alloca in a function,
1912 // unpoison the whole stack frame at function exit.
1914 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1915 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1916 // We're intested only in allocas we can handle.
1917 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
1918 // See if we've already calculated (or started to calculate) alloca for a
1920 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1921 if (I != AllocaForValue.end()) return I->second;
1922 // Store 0 while we're calculating alloca for value V to avoid
1923 // infinite recursion if the value references itself.
1924 AllocaForValue[V] = nullptr;
1925 AllocaInst *Res = nullptr;
1926 if (CastInst *CI = dyn_cast<CastInst>(V))
1927 Res = findAllocaForValue(CI->getOperand(0));
1928 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1929 for (Value *IncValue : PN->incoming_values()) {
1930 // Allow self-referencing phi-nodes.
1931 if (IncValue == PN) continue;
1932 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1933 // AI for incoming values should exist and should all be equal.
1934 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1939 if (Res) AllocaForValue[V] = Res;
1943 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
1944 IRBuilder<> IRB(AI);
1946 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
1947 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
1949 Value *Zero = Constant::getNullValue(IntptrTy);
1950 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
1951 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
1953 // Since we need to extend alloca with additional memory to locate
1954 // redzones, and OldSize is number of allocated blocks with
1955 // ElementSize size, get allocated memory size in bytes by
1956 // OldSize * ElementSize.
1957 const unsigned ElementSize =
1958 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
1960 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
1961 ConstantInt::get(IntptrTy, ElementSize));
1963 // PartialSize = OldSize % 32
1964 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
1966 // Misalign = kAllocaRzSize - PartialSize;
1967 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
1969 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
1970 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
1971 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
1973 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
1974 // Align is added to locate left redzone, PartialPadding for possible
1975 // partial redzone and kAllocaRzSize for right redzone respectively.
1976 Value *AdditionalChunkSize = IRB.CreateAdd(
1977 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
1979 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
1981 // Insert new alloca with new NewSize and Align params.
1982 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
1983 NewAlloca->setAlignment(Align);
1985 // NewAddress = Address + Align
1986 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
1987 ConstantInt::get(IntptrTy, Align));
1989 // Insert __asan_alloca_poison call for new created alloca.
1990 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
1992 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
1993 // for unpoisoning stuff.
1994 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
1996 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
1998 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
1999 AI->replaceAllUsesWith(NewAddressPtr);
2001 // We are done. Erase old alloca from parent.
2002 AI->eraseFromParent();
2005 // isSafeAccess returns true if Addr is always inbounds with respect to its
2006 // base object. For example, it is a field access or an array access with
2007 // constant inbounds index.
2008 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2009 Value *Addr, uint64_t TypeSize) const {
2010 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2011 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2012 uint64_t Size = SizeOffset.first.getZExtValue();
2013 int64_t Offset = SizeOffset.second.getSExtValue();
2014 // Three checks are required to ensure safety:
2015 // . Offset >= 0 (since the offset is given from the base ptr)
2016 // . Size >= Offset (unsigned)
2017 // . Size - Offset >= NeededSize (unsigned)
2018 return Offset >= 0 && Size >= uint64_t(Offset) &&
2019 Size - uint64_t(Offset) >= TypeSize / 8;