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 #define DEBUG_TYPE "asan"
18 #include "llvm/Transforms/Instrumentation.h"
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/DepthFirstIterator.h"
22 #include "llvm/ADT/OwningPtr.h"
23 #include "llvm/ADT/SmallSet.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/Statistic.h"
27 #include "llvm/ADT/StringExtras.h"
28 #include "llvm/ADT/Triple.h"
29 #include "llvm/DIBuilder.h"
30 #include "llvm/IR/CallSite.h"
31 #include "llvm/IR/DataLayout.h"
32 #include "llvm/IR/Function.h"
33 #include "llvm/IR/IRBuilder.h"
34 #include "llvm/IR/InlineAsm.h"
35 #include "llvm/IR/IntrinsicInst.h"
36 #include "llvm/IR/LLVMContext.h"
37 #include "llvm/IR/MDBuilder.h"
38 #include "llvm/IR/Module.h"
39 #include "llvm/IR/Type.h"
40 #include "llvm/InstVisitor.h"
41 #include "llvm/Support/CommandLine.h"
42 #include "llvm/Support/DataTypes.h"
43 #include "llvm/Support/Debug.h"
44 #include "llvm/Support/Endian.h"
45 #include "llvm/Support/system_error.h"
46 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
47 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
48 #include "llvm/Transforms/Utils/Cloning.h"
49 #include "llvm/Transforms/Utils/Local.h"
50 #include "llvm/Transforms/Utils/ModuleUtils.h"
51 #include "llvm/Transforms/Utils/SpecialCaseList.h"
57 static const uint64_t kDefaultShadowScale = 3;
58 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
59 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
60 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
61 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
62 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
63 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
64 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
66 static const size_t kMinStackMallocSize = 1 << 6; // 64B
67 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
68 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
69 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
71 static const char *const kAsanModuleCtorName = "asan.module_ctor";
72 static const char *const kAsanModuleDtorName = "asan.module_dtor";
73 static const int kAsanCtorAndCtorPriority = 1;
74 static const char *const kAsanReportErrorTemplate = "__asan_report_";
75 static const char *const kAsanReportLoadN = "__asan_report_load_n";
76 static const char *const kAsanReportStoreN = "__asan_report_store_n";
77 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
78 static const char *const kAsanUnregisterGlobalsName =
79 "__asan_unregister_globals";
80 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
81 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
82 static const char *const kAsanInitName = "__asan_init_v3";
83 static const char *const kAsanCovName = "__sanitizer_cov";
84 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
85 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
86 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
87 static const int kMaxAsanStackMallocSizeClass = 10;
88 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
89 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
90 static const char *const kAsanGenPrefix = "__asan_gen_";
91 static const char *const kAsanPoisonStackMemoryName =
92 "__asan_poison_stack_memory";
93 static const char *const kAsanUnpoisonStackMemoryName =
94 "__asan_unpoison_stack_memory";
96 static const char *const kAsanOptionDetectUAR =
97 "__asan_option_detect_stack_use_after_return";
100 static const int kAsanStackAfterReturnMagic = 0xf5;
103 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
104 static const size_t kNumberOfAccessSizes = 5;
106 // Command-line flags.
108 // This flag may need to be replaced with -f[no-]asan-reads.
109 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
110 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
111 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
112 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
113 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
114 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
115 cl::Hidden, cl::init(true));
116 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
117 cl::desc("use instrumentation with slow path for all accesses"),
118 cl::Hidden, cl::init(false));
119 // This flag limits the number of instructions to be instrumented
120 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
121 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
123 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
125 cl::desc("maximal number of instructions to instrument in any given BB"),
127 // This flag may need to be replaced with -f[no]asan-stack.
128 static cl::opt<bool> ClStack("asan-stack",
129 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
130 // This flag may need to be replaced with -f[no]asan-use-after-return.
131 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
132 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
133 // This flag may need to be replaced with -f[no]asan-globals.
134 static cl::opt<bool> ClGlobals("asan-globals",
135 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
136 static cl::opt<int> ClCoverage("asan-coverage",
137 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"),
138 cl::Hidden, cl::init(false));
139 static cl::opt<bool> ClInitializers("asan-initialization-order",
140 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
141 static cl::opt<bool> ClMemIntrin("asan-memintrin",
142 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
143 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
144 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
145 cl::Hidden, cl::init(false));
146 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
147 cl::desc("Realign stack to the value of this flag (power of two)"),
148 cl::Hidden, cl::init(32));
149 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
150 cl::desc("File containing the list of objects to ignore "
151 "during instrumentation"), cl::Hidden);
153 // This is an experimental feature that will allow to choose between
154 // instrumented and non-instrumented code at link-time.
155 // If this option is on, just before instrumenting a function we create its
156 // clone; if the function is not changed by asan the clone is deleted.
157 // If we end up with a clone, we put the instrumented function into a section
158 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
160 // This is still a prototype, we need to figure out a way to keep two copies of
161 // a function so that the linker can easily choose one of them.
162 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
163 cl::desc("Keep uninstrumented copies of functions"),
164 cl::Hidden, cl::init(false));
166 // These flags allow to change the shadow mapping.
167 // The shadow mapping looks like
168 // Shadow = (Mem >> scale) + (1 << offset_log)
169 static cl::opt<int> ClMappingScale("asan-mapping-scale",
170 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
172 // Optimization flags. Not user visible, used mostly for testing
173 // and benchmarking the tool.
174 static cl::opt<bool> ClOpt("asan-opt",
175 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
176 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
177 cl::desc("Instrument the same temp just once"), cl::Hidden,
179 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
180 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
182 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
183 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
184 cl::Hidden, cl::init(false));
187 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
189 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
190 cl::Hidden, cl::init(0));
191 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
192 cl::Hidden, cl::desc("Debug func"));
193 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
194 cl::Hidden, cl::init(-1));
195 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
196 cl::Hidden, cl::init(-1));
198 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
199 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
200 STATISTIC(NumOptimizedAccessesToGlobalArray,
201 "Number of optimized accesses to global arrays");
202 STATISTIC(NumOptimizedAccessesToGlobalVar,
203 "Number of optimized accesses to global vars");
206 /// A set of dynamically initialized globals extracted from metadata.
207 class SetOfDynamicallyInitializedGlobals {
209 void Init(Module& M) {
210 // Clang generates metadata identifying all dynamically initialized globals.
211 NamedMDNode *DynamicGlobals =
212 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
215 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
216 MDNode *MDN = DynamicGlobals->getOperand(i);
217 assert(MDN->getNumOperands() == 1);
218 Value *VG = MDN->getOperand(0);
219 // The optimizer may optimize away a global entirely, in which case we
220 // cannot instrument access to it.
223 DynInitGlobals.insert(cast<GlobalVariable>(VG));
226 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
228 SmallSet<GlobalValue*, 32> DynInitGlobals;
231 /// This struct defines the shadow mapping using the rule:
232 /// shadow = (mem >> Scale) ADD-or-OR Offset.
233 struct ShadowMapping {
239 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
240 llvm::Triple TargetTriple(M.getTargetTriple());
241 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
242 // bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
243 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
244 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
245 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
246 TargetTriple.getArch() == llvm::Triple::ppc64le;
247 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
248 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
249 TargetTriple.getArch() == llvm::Triple::mipsel;
251 ShadowMapping Mapping;
253 if (LongSize == 32) {
257 Mapping.Offset = kMIPS32_ShadowOffset32;
259 Mapping.Offset = kFreeBSD_ShadowOffset32;
261 Mapping.Offset = kDefaultShadowOffset32;
262 } else { // LongSize == 64
264 Mapping.Offset = kPPC64_ShadowOffset64;
266 Mapping.Offset = kFreeBSD_ShadowOffset64;
267 else if (IsLinux && IsX86_64)
268 Mapping.Offset = kSmallX86_64ShadowOffset;
270 Mapping.Offset = kDefaultShadowOffset64;
273 Mapping.Scale = kDefaultShadowScale;
274 if (ClMappingScale) {
275 Mapping.Scale = ClMappingScale;
278 // OR-ing shadow offset if more efficient (at least on x86) if the offset
279 // is a power of two, but on ppc64 we have to use add since the shadow
280 // offset is not necessary 1/8-th of the address space.
281 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
286 static size_t RedzoneSizeForScale(int MappingScale) {
287 // Redzone used for stack and globals is at least 32 bytes.
288 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
289 return std::max(32U, 1U << MappingScale);
292 /// AddressSanitizer: instrument the code in module to find memory bugs.
293 struct AddressSanitizer : public FunctionPass {
294 AddressSanitizer(bool CheckInitOrder = true,
295 bool CheckUseAfterReturn = false,
296 bool CheckLifetime = false,
297 StringRef BlacklistFile = StringRef())
299 CheckInitOrder(CheckInitOrder || ClInitializers),
300 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
301 CheckLifetime(CheckLifetime || ClCheckLifetime),
302 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
304 const char *getPassName() const override {
305 return "AddressSanitizerFunctionPass";
307 void instrumentMop(Instruction *I);
308 void instrumentPointerComparisonOrSubtraction(Instruction *I);
309 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
310 Value *Addr, uint32_t TypeSize, bool IsWrite,
311 Value *SizeArgument);
312 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
313 Value *ShadowValue, uint32_t TypeSize);
314 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
315 bool IsWrite, size_t AccessSizeIndex,
316 Value *SizeArgument);
317 bool instrumentMemIntrinsic(MemIntrinsic *MI);
318 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
320 Instruction *InsertBefore, bool IsWrite);
321 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
322 bool runOnFunction(Function &F) override;
323 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
324 bool doInitialization(Module &M) override;
325 static char ID; // Pass identification, replacement for typeid
328 void initializeCallbacks(Module &M);
330 bool ShouldInstrumentGlobal(GlobalVariable *G);
331 bool LooksLikeCodeInBug11395(Instruction *I);
332 void FindDynamicInitializers(Module &M);
333 bool GlobalIsLinkerInitialized(GlobalVariable *G);
334 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks);
335 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
338 bool CheckUseAfterReturn;
340 SmallString<64> BlacklistFile;
343 const DataLayout *DL;
346 ShadowMapping Mapping;
347 Function *AsanCtorFunction;
348 Function *AsanInitFunction;
349 Function *AsanHandleNoReturnFunc;
350 Function *AsanCovFunction;
351 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
352 OwningPtr<SpecialCaseList> BL;
353 // This array is indexed by AccessIsWrite and log2(AccessSize).
354 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
355 // This array is indexed by AccessIsWrite.
356 Function *AsanErrorCallbackSized[2];
358 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
360 friend struct FunctionStackPoisoner;
363 class AddressSanitizerModule : public ModulePass {
365 AddressSanitizerModule(bool CheckInitOrder = true,
366 StringRef BlacklistFile = StringRef())
368 CheckInitOrder(CheckInitOrder || ClInitializers),
369 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
371 bool runOnModule(Module &M) override;
372 static char ID; // Pass identification, replacement for typeid
373 const char *getPassName() const override {
374 return "AddressSanitizerModule";
378 void initializeCallbacks(Module &M);
380 bool ShouldInstrumentGlobal(GlobalVariable *G);
381 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
382 size_t MinRedzoneSizeForGlobal() const {
383 return RedzoneSizeForScale(Mapping.Scale);
387 SmallString<64> BlacklistFile;
389 OwningPtr<SpecialCaseList> BL;
390 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
393 const DataLayout *DL;
394 ShadowMapping Mapping;
395 Function *AsanPoisonGlobals;
396 Function *AsanUnpoisonGlobals;
397 Function *AsanRegisterGlobals;
398 Function *AsanUnregisterGlobals;
401 // Stack poisoning does not play well with exception handling.
402 // When an exception is thrown, we essentially bypass the code
403 // that unpoisones the stack. This is why the run-time library has
404 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
405 // stack in the interceptor. This however does not work inside the
406 // actual function which catches the exception. Most likely because the
407 // compiler hoists the load of the shadow value somewhere too high.
408 // This causes asan to report a non-existing bug on 453.povray.
409 // It sounds like an LLVM bug.
410 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
412 AddressSanitizer &ASan;
417 ShadowMapping Mapping;
419 SmallVector<AllocaInst*, 16> AllocaVec;
420 SmallVector<Instruction*, 8> RetVec;
421 unsigned StackAlignment;
423 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
424 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
425 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
427 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
428 struct AllocaPoisonCall {
429 IntrinsicInst *InsBefore;
434 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
436 // Maps Value to an AllocaInst from which the Value is originated.
437 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
438 AllocaForValueMapTy AllocaForValue;
440 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
441 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
442 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
443 Mapping(ASan.Mapping),
444 StackAlignment(1 << Mapping.Scale) {}
446 bool runOnFunction() {
447 if (!ClStack) return false;
448 // Collect alloca, ret, lifetime instructions etc.
449 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
450 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
451 BasicBlock *BB = *DI;
454 if (AllocaVec.empty()) return false;
456 initializeCallbacks(*F.getParent());
466 // Finds all static Alloca instructions and puts
467 // poisoned red zones around all of them.
468 // Then unpoison everything back before the function returns.
471 // ----------------------- Visitors.
472 /// \brief Collect all Ret instructions.
473 void visitReturnInst(ReturnInst &RI) {
474 RetVec.push_back(&RI);
477 /// \brief Collect Alloca instructions we want (and can) handle.
478 void visitAllocaInst(AllocaInst &AI) {
479 if (!isInterestingAlloca(AI)) return;
481 StackAlignment = std::max(StackAlignment, AI.getAlignment());
482 AllocaVec.push_back(&AI);
485 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
487 void visitIntrinsicInst(IntrinsicInst &II) {
488 if (!ASan.CheckLifetime) return;
489 Intrinsic::ID ID = II.getIntrinsicID();
490 if (ID != Intrinsic::lifetime_start &&
491 ID != Intrinsic::lifetime_end)
493 // Found lifetime intrinsic, add ASan instrumentation if necessary.
494 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
495 // If size argument is undefined, don't do anything.
496 if (Size->isMinusOne()) return;
497 // Check that size doesn't saturate uint64_t and can
498 // be stored in IntptrTy.
499 const uint64_t SizeValue = Size->getValue().getLimitedValue();
500 if (SizeValue == ~0ULL ||
501 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
503 // Find alloca instruction that corresponds to llvm.lifetime argument.
504 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
506 bool DoPoison = (ID == Intrinsic::lifetime_end);
507 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
508 AllocaPoisonCallVec.push_back(APC);
511 // ---------------------- Helpers.
512 void initializeCallbacks(Module &M);
514 // Check if we want (and can) handle this alloca.
515 bool isInterestingAlloca(AllocaInst &AI) const {
516 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
517 AI.getAllocatedType()->isSized() &&
518 // alloca() may be called with 0 size, ignore it.
519 getAllocaSizeInBytes(&AI) > 0);
522 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
523 Type *Ty = AI->getAllocatedType();
524 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
527 /// Finds alloca where the value comes from.
528 AllocaInst *findAllocaForValue(Value *V);
529 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
530 Value *ShadowBase, bool DoPoison);
531 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
533 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
539 char AddressSanitizer::ID = 0;
540 INITIALIZE_PASS(AddressSanitizer, "asan",
541 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
543 FunctionPass *llvm::createAddressSanitizerFunctionPass(
544 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
545 StringRef BlacklistFile) {
546 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
547 CheckLifetime, BlacklistFile);
550 char AddressSanitizerModule::ID = 0;
551 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
552 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
553 "ModulePass", false, false)
554 ModulePass *llvm::createAddressSanitizerModulePass(
555 bool CheckInitOrder, StringRef BlacklistFile) {
556 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
559 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
560 size_t Res = countTrailingZeros(TypeSize / 8);
561 assert(Res < kNumberOfAccessSizes);
565 // \brief Create a constant for Str so that we can pass it to the run-time lib.
566 static GlobalVariable *createPrivateGlobalForString(
567 Module &M, StringRef Str, bool AllowMerging) {
568 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
569 // We use private linkage for module-local strings. If they can be merged
570 // with another one, we set the unnamed_addr attribute.
572 new GlobalVariable(M, StrConst->getType(), true,
573 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
575 GV->setUnnamedAddr(true);
576 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
580 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
581 return G->getName().find(kAsanGenPrefix) == 0;
584 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
586 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
587 if (Mapping.Offset == 0)
589 // (Shadow >> scale) | offset
590 if (Mapping.OrShadowOffset)
591 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
593 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
596 void AddressSanitizer::instrumentMemIntrinsicParam(
597 Instruction *OrigIns,
598 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
599 IRBuilder<> IRB(InsertBefore);
600 if (Size->getType() != IntptrTy)
601 Size = IRB.CreateIntCast(Size, IntptrTy, false);
602 // Check the first byte.
603 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
604 // Check the last byte.
605 IRB.SetInsertPoint(InsertBefore);
606 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
607 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
608 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
609 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
612 // Instrument memset/memmove/memcpy
613 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
614 Value *Dst = MI->getDest();
615 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
616 Value *Src = MemTran ? MemTran->getSource() : 0;
617 Value *Length = MI->getLength();
619 Constant *ConstLength = dyn_cast<Constant>(Length);
620 Instruction *InsertBefore = MI;
622 if (ConstLength->isNullValue()) return false;
624 // The size is not a constant so it could be zero -- check at run-time.
625 IRBuilder<> IRB(InsertBefore);
627 Value *Cmp = IRB.CreateICmpNE(Length,
628 Constant::getNullValue(Length->getType()));
629 InsertBefore = SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
632 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
634 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
638 // If I is an interesting memory access, return the PointerOperand
639 // and set IsWrite. Otherwise return NULL.
640 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
641 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
642 if (!ClInstrumentReads) return NULL;
644 return LI->getPointerOperand();
646 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
647 if (!ClInstrumentWrites) return NULL;
649 return SI->getPointerOperand();
651 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
652 if (!ClInstrumentAtomics) return NULL;
654 return RMW->getPointerOperand();
656 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
657 if (!ClInstrumentAtomics) return NULL;
659 return XCHG->getPointerOperand();
664 static bool isPointerOperand(Value *V) {
665 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
668 // This is a rough heuristic; it may cause both false positives and
669 // false negatives. The proper implementation requires cooperation with
671 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
672 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
673 if (!Cmp->isRelational())
675 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
676 if (BO->getOpcode() != Instruction::Sub)
681 if (!isPointerOperand(I->getOperand(0)) ||
682 !isPointerOperand(I->getOperand(1)))
687 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
688 // If a global variable does not have dynamic initialization we don't
689 // have to instrument it. However, if a global does not have initializer
690 // at all, we assume it has dynamic initializer (in other TU).
691 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
695 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
697 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
698 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
699 for (int i = 0; i < 2; i++) {
700 if (Param[i]->getType()->isPointerTy())
701 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
703 IRB.CreateCall2(F, Param[0], Param[1]);
706 void AddressSanitizer::instrumentMop(Instruction *I) {
707 bool IsWrite = false;
708 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
710 if (ClOpt && ClOptGlobals) {
711 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
712 // If initialization order checking is disabled, a simple access to a
713 // dynamically initialized global is always valid.
714 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
715 NumOptimizedAccessesToGlobalVar++;
719 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
720 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
721 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
722 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
723 NumOptimizedAccessesToGlobalArray++;
730 Type *OrigPtrTy = Addr->getType();
731 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
733 assert(OrigTy->isSized());
734 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
736 assert((TypeSize % 8) == 0);
739 NumInstrumentedWrites++;
741 NumInstrumentedReads++;
743 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
744 if (TypeSize == 8 || TypeSize == 16 ||
745 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
746 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
747 // Instrument unusual size (but still multiple of 8).
748 // We can not do it with a single check, so we do 1-byte check for the first
749 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
750 // to report the actual access size.
752 Value *LastByte = IRB.CreateIntToPtr(
753 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
754 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
756 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
757 instrumentAddress(I, I, Addr, 8, IsWrite, Size);
758 instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
761 // Validate the result of Module::getOrInsertFunction called for an interface
762 // function of AddressSanitizer. If the instrumented module defines a function
763 // with the same name, their prototypes must match, otherwise
764 // getOrInsertFunction returns a bitcast.
765 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
766 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
767 FuncOrBitcast->dump();
768 report_fatal_error("trying to redefine an AddressSanitizer "
769 "interface function");
772 Instruction *AddressSanitizer::generateCrashCode(
773 Instruction *InsertBefore, Value *Addr,
774 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
775 IRBuilder<> IRB(InsertBefore);
776 CallInst *Call = SizeArgument
777 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
778 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
780 // We don't do Call->setDoesNotReturn() because the BB already has
781 // UnreachableInst at the end.
782 // This EmptyAsm is required to avoid callback merge.
783 IRB.CreateCall(EmptyAsm);
787 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
790 size_t Granularity = 1 << Mapping.Scale;
791 // Addr & (Granularity - 1)
792 Value *LastAccessedByte = IRB.CreateAnd(
793 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
794 // (Addr & (Granularity - 1)) + size - 1
795 if (TypeSize / 8 > 1)
796 LastAccessedByte = IRB.CreateAdd(
797 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
798 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
799 LastAccessedByte = IRB.CreateIntCast(
800 LastAccessedByte, ShadowValue->getType(), false);
801 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
802 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
805 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
806 Instruction *InsertBefore,
807 Value *Addr, uint32_t TypeSize,
808 bool IsWrite, Value *SizeArgument) {
809 IRBuilder<> IRB(InsertBefore);
810 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
812 Type *ShadowTy = IntegerType::get(
813 *C, std::max(8U, TypeSize >> Mapping.Scale));
814 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
815 Value *ShadowPtr = memToShadow(AddrLong, IRB);
816 Value *CmpVal = Constant::getNullValue(ShadowTy);
817 Value *ShadowValue = IRB.CreateLoad(
818 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
820 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
821 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
822 size_t Granularity = 1 << Mapping.Scale;
823 TerminatorInst *CrashTerm = 0;
825 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
826 TerminatorInst *CheckTerm =
827 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
828 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
829 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
830 IRB.SetInsertPoint(CheckTerm);
831 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
832 BasicBlock *CrashBlock =
833 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
834 CrashTerm = new UnreachableInst(*C, CrashBlock);
835 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
836 ReplaceInstWithInst(CheckTerm, NewTerm);
838 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
841 Instruction *Crash = generateCrashCode(
842 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
843 Crash->setDebugLoc(OrigIns->getDebugLoc());
846 void AddressSanitizerModule::createInitializerPoisonCalls(
847 Module &M, GlobalValue *ModuleName) {
848 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
849 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
850 // If that function is not present, this TU contains no globals, or they have
851 // all been optimized away
855 // Set up the arguments to our poison/unpoison functions.
856 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
858 // Add a call to poison all external globals before the given function starts.
859 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
860 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
862 // Add calls to unpoison all globals before each return instruction.
863 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
865 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
866 CallInst::Create(AsanUnpoisonGlobals, "", RI);
871 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
872 Type *Ty = cast<PointerType>(G->getType())->getElementType();
873 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
875 if (BL->isIn(*G)) return false;
876 if (!Ty->isSized()) return false;
877 if (!G->hasInitializer()) return false;
878 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
879 // Touch only those globals that will not be defined in other modules.
880 // Don't handle ODR type linkages since other modules may be built w/o asan.
881 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
882 G->getLinkage() != GlobalVariable::PrivateLinkage &&
883 G->getLinkage() != GlobalVariable::InternalLinkage)
885 // Two problems with thread-locals:
886 // - The address of the main thread's copy can't be computed at link-time.
887 // - Need to poison all copies, not just the main thread's one.
888 if (G->isThreadLocal())
890 // For now, just ignore this Global if the alignment is large.
891 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
893 // Ignore all the globals with the names starting with "\01L_OBJC_".
894 // Many of those are put into the .cstring section. The linker compresses
895 // that section by removing the spare \0s after the string terminator, so
896 // our redzones get broken.
897 if ((G->getName().find("\01L_OBJC_") == 0) ||
898 (G->getName().find("\01l_OBJC_") == 0)) {
899 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
903 if (G->hasSection()) {
904 StringRef Section(G->getSection());
905 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
906 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
908 if ((Section.find("__OBJC,") == 0) ||
909 (Section.find("__DATA, __objc_") == 0)) {
910 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
913 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
914 // Constant CFString instances are compiled in the following way:
915 // -- the string buffer is emitted into
916 // __TEXT,__cstring,cstring_literals
917 // -- the constant NSConstantString structure referencing that buffer
918 // is placed into __DATA,__cfstring
919 // Therefore there's no point in placing redzones into __DATA,__cfstring.
920 // Moreover, it causes the linker to crash on OS X 10.7
921 if (Section.find("__DATA,__cfstring") == 0) {
922 DEBUG(dbgs() << "Ignoring CFString: " << *G);
930 void AddressSanitizerModule::initializeCallbacks(Module &M) {
932 // Declare our poisoning and unpoisoning functions.
933 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
934 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
935 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
936 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
937 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
938 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
939 // Declare functions that register/unregister globals.
940 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
941 kAsanRegisterGlobalsName, IRB.getVoidTy(),
942 IntptrTy, IntptrTy, NULL));
943 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
944 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
945 kAsanUnregisterGlobalsName,
946 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
947 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
950 // This function replaces all global variables with new variables that have
951 // trailing redzones. It also creates a function that poisons
952 // redzones and inserts this function into llvm.global_ctors.
953 bool AddressSanitizerModule::runOnModule(Module &M) {
954 if (!ClGlobals) return false;
956 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
959 DL = &DLP->getDataLayout();
961 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
962 if (BL->isIn(M)) return false;
963 C = &(M.getContext());
964 int LongSize = DL->getPointerSizeInBits();
965 IntptrTy = Type::getIntNTy(*C, LongSize);
966 Mapping = getShadowMapping(M, LongSize);
967 initializeCallbacks(M);
968 DynamicallyInitializedGlobals.Init(M);
970 SmallVector<GlobalVariable *, 16> GlobalsToChange;
972 for (Module::GlobalListType::iterator G = M.global_begin(),
973 E = M.global_end(); G != E; ++G) {
974 if (ShouldInstrumentGlobal(G))
975 GlobalsToChange.push_back(G);
978 size_t n = GlobalsToChange.size();
979 if (n == 0) return false;
981 // A global is described by a structure
984 // size_t size_with_redzone;
986 // const char *module_name;
987 // size_t has_dynamic_init;
988 // We initialize an array of such structures and pass it to a run-time call.
989 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
991 IntptrTy, IntptrTy, NULL);
992 SmallVector<Constant *, 16> Initializers(n);
994 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
996 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
998 bool HasDynamicallyInitializedGlobals = false;
1000 // We shouldn't merge same module names, as this string serves as unique
1001 // module ID in runtime.
1002 GlobalVariable *ModuleName = createPrivateGlobalForString(
1003 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1005 for (size_t i = 0; i < n; i++) {
1006 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1007 GlobalVariable *G = GlobalsToChange[i];
1008 PointerType *PtrTy = cast<PointerType>(G->getType());
1009 Type *Ty = PtrTy->getElementType();
1010 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1011 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1012 // MinRZ <= RZ <= kMaxGlobalRedzone
1013 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1014 uint64_t RZ = std::max(MinRZ,
1015 std::min(kMaxGlobalRedzone,
1016 (SizeInBytes / MinRZ / 4) * MinRZ));
1017 uint64_t RightRedzoneSize = RZ;
1018 // Round up to MinRZ
1019 if (SizeInBytes % MinRZ)
1020 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1021 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1022 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1023 // Determine whether this global should be poisoned in initialization.
1024 bool GlobalHasDynamicInitializer =
1025 DynamicallyInitializedGlobals.Contains(G);
1026 // Don't check initialization order if this global is blacklisted.
1027 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
1029 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1030 Constant *NewInitializer = ConstantStruct::get(
1031 NewTy, G->getInitializer(),
1032 Constant::getNullValue(RightRedZoneTy), NULL);
1034 GlobalVariable *Name =
1035 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
1037 // Create a new global variable with enough space for a redzone.
1038 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1039 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1040 Linkage = GlobalValue::InternalLinkage;
1041 GlobalVariable *NewGlobal = new GlobalVariable(
1042 M, NewTy, G->isConstant(), Linkage,
1043 NewInitializer, "", G, G->getThreadLocalMode());
1044 NewGlobal->copyAttributesFrom(G);
1045 NewGlobal->setAlignment(MinRZ);
1048 Indices2[0] = IRB.getInt32(0);
1049 Indices2[1] = IRB.getInt32(0);
1051 G->replaceAllUsesWith(
1052 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1053 NewGlobal->takeName(G);
1054 G->eraseFromParent();
1056 Initializers[i] = ConstantStruct::get(
1058 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1059 ConstantInt::get(IntptrTy, SizeInBytes),
1060 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1061 ConstantExpr::getPointerCast(Name, IntptrTy),
1062 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1063 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1066 // Populate the first and last globals declared in this TU.
1067 if (CheckInitOrder && GlobalHasDynamicInitializer)
1068 HasDynamicallyInitializedGlobals = true;
1070 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1073 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1074 GlobalVariable *AllGlobals = new GlobalVariable(
1075 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1076 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1078 // Create calls for poisoning before initializers run and unpoisoning after.
1079 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1080 createInitializerPoisonCalls(M, ModuleName);
1081 IRB.CreateCall2(AsanRegisterGlobals,
1082 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1083 ConstantInt::get(IntptrTy, n));
1085 // We also need to unregister globals at the end, e.g. when a shared library
1087 Function *AsanDtorFunction = Function::Create(
1088 FunctionType::get(Type::getVoidTy(*C), false),
1089 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1090 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1091 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1092 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1093 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1094 ConstantInt::get(IntptrTy, n));
1095 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1101 void AddressSanitizer::initializeCallbacks(Module &M) {
1102 IRBuilder<> IRB(*C);
1103 // Create __asan_report* callbacks.
1104 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1105 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1106 AccessSizeIndex++) {
1107 // IsWrite and TypeSize are encoded in the function name.
1108 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1109 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1110 // If we are merging crash callbacks, they have two parameters.
1111 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1112 checkInterfaceFunction(M.getOrInsertFunction(
1113 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1116 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1117 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1118 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1119 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1121 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1122 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1123 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1124 kAsanCovName, IRB.getVoidTy(), NULL));
1125 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1126 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1127 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1128 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1129 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1130 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1131 StringRef(""), StringRef(""),
1132 /*hasSideEffects=*/true);
1136 bool AddressSanitizer::doInitialization(Module &M) {
1137 // Initialize the private fields. No one has accessed them before.
1138 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1141 DL = &DLP->getDataLayout();
1143 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1144 DynamicallyInitializedGlobals.Init(M);
1146 C = &(M.getContext());
1147 LongSize = DL->getPointerSizeInBits();
1148 IntptrTy = Type::getIntNTy(*C, LongSize);
1150 AsanCtorFunction = Function::Create(
1151 FunctionType::get(Type::getVoidTy(*C), false),
1152 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1153 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1154 // call __asan_init in the module ctor.
1155 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1156 AsanInitFunction = checkInterfaceFunction(
1157 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1158 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1159 IRB.CreateCall(AsanInitFunction);
1161 Mapping = getShadowMapping(M, LongSize);
1163 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1167 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1168 // For each NSObject descendant having a +load method, this method is invoked
1169 // by the ObjC runtime before any of the static constructors is called.
1170 // Therefore we need to instrument such methods with a call to __asan_init
1171 // at the beginning in order to initialize our runtime before any access to
1172 // the shadow memory.
1173 // We cannot just ignore these methods, because they may call other
1174 // instrumented functions.
1175 if (F.getName().find(" load]") != std::string::npos) {
1176 IRBuilder<> IRB(F.begin()->begin());
1177 IRB.CreateCall(AsanInitFunction);
1183 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1184 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1185 // Skip static allocas at the top of the entry block so they don't become
1186 // dynamic when we split the block. If we used our optimized stack layout,
1187 // then there will only be one alloca and it will come first.
1188 for (; IP != BE; ++IP) {
1189 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1190 if (!AI || !AI->isStaticAlloca())
1194 IRBuilder<> IRB(IP);
1195 Type *Int8Ty = IRB.getInt8Ty();
1196 GlobalVariable *Guard = new GlobalVariable(
1197 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1198 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1199 LoadInst *Load = IRB.CreateLoad(Guard);
1200 Load->setAtomic(Monotonic);
1201 Load->setAlignment(1);
1202 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1203 Instruction *Ins = SplitBlockAndInsertIfThen(
1204 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1205 IRB.SetInsertPoint(Ins);
1206 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1207 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1208 Instruction *Call = IRB.CreateCall(AsanCovFunction);
1209 Call->setDebugLoc(IP->getDebugLoc());
1210 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1211 Store->setAtomic(Monotonic);
1212 Store->setAlignment(1);
1215 // Poor man's coverage that works with ASan.
1216 // We create a Guard boolean variable with the same linkage
1217 // as the function and inject this code into the entry block (-asan-coverage=1)
1218 // or all blocks (-asan-coverage=2):
1220 // __sanitizer_cov(&F);
1223 // The accesses to Guard are atomic. The rest of the logic is
1224 // in __sanitizer_cov (it's fine to call it more than once).
1226 // This coverage implementation provides very limited data:
1227 // it only tells if a given function (block) was ever executed.
1228 // No counters, no per-edge data.
1229 // But for many use cases this is what we need and the added slowdown
1230 // is negligible. This simple implementation will probably be obsoleted
1231 // by the upcoming Clang-based coverage implementation.
1232 // By having it here and now we hope to
1233 // a) get the functionality to users earlier and
1234 // b) collect usage statistics to help improve Clang coverage design.
1235 bool AddressSanitizer::InjectCoverage(Function &F,
1236 const ArrayRef<BasicBlock *> AllBlocks) {
1237 if (!ClCoverage) return false;
1239 if (ClCoverage == 1) {
1240 InjectCoverageAtBlock(F, F.getEntryBlock());
1242 for (size_t i = 0, n = AllBlocks.size(); i < n; i++)
1243 InjectCoverageAtBlock(F, *AllBlocks[i]);
1248 bool AddressSanitizer::runOnFunction(Function &F) {
1249 if (BL->isIn(F)) return false;
1250 if (&F == AsanCtorFunction) return false;
1251 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1252 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1253 initializeCallbacks(*F.getParent());
1255 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1256 maybeInsertAsanInitAtFunctionEntry(F);
1258 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1261 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1264 // We want to instrument every address only once per basic block (unless there
1265 // are calls between uses).
1266 SmallSet<Value*, 16> TempsToInstrument;
1267 SmallVector<Instruction*, 16> ToInstrument;
1268 SmallVector<Instruction*, 8> NoReturnCalls;
1269 SmallVector<BasicBlock*, 16> AllBlocks;
1270 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1274 // Fill the set of memory operations to instrument.
1275 for (Function::iterator FI = F.begin(), FE = F.end();
1277 AllBlocks.push_back(FI);
1278 TempsToInstrument.clear();
1279 int NumInsnsPerBB = 0;
1280 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1282 if (LooksLikeCodeInBug11395(BI)) return false;
1283 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1284 if (ClOpt && ClOptSameTemp) {
1285 if (!TempsToInstrument.insert(Addr))
1286 continue; // We've seen this temp in the current BB.
1288 } else if (ClInvalidPointerPairs &&
1289 isInterestingPointerComparisonOrSubtraction(BI)) {
1290 PointerComparisonsOrSubtracts.push_back(BI);
1292 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1295 if (isa<AllocaInst>(BI))
1299 // A call inside BB.
1300 TempsToInstrument.clear();
1301 if (CS.doesNotReturn())
1302 NoReturnCalls.push_back(CS.getInstruction());
1306 ToInstrument.push_back(BI);
1308 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1313 Function *UninstrumentedDuplicate = 0;
1314 bool LikelyToInstrument =
1315 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1316 if (ClKeepUninstrumented && LikelyToInstrument) {
1317 ValueToValueMapTy VMap;
1318 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1319 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1320 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1321 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1325 int NumInstrumented = 0;
1326 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1327 Instruction *Inst = ToInstrument[i];
1328 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1329 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1330 if (isInterestingMemoryAccess(Inst, &IsWrite))
1331 instrumentMop(Inst);
1333 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1338 FunctionStackPoisoner FSP(F, *this);
1339 bool ChangedStack = FSP.runOnFunction();
1341 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1342 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1343 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1344 Instruction *CI = NoReturnCalls[i];
1345 IRBuilder<> IRB(CI);
1346 IRB.CreateCall(AsanHandleNoReturnFunc);
1349 for (size_t i = 0, n = PointerComparisonsOrSubtracts.size(); i != n; i++) {
1350 instrumentPointerComparisonOrSubtraction(PointerComparisonsOrSubtracts[i]);
1354 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1356 if (InjectCoverage(F, AllBlocks))
1359 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1361 if (ClKeepUninstrumented) {
1363 // No instrumentation is done, no need for the duplicate.
1364 if (UninstrumentedDuplicate)
1365 UninstrumentedDuplicate->eraseFromParent();
1367 // The function was instrumented. We must have the duplicate.
1368 assert(UninstrumentedDuplicate);
1369 UninstrumentedDuplicate->setSection("NOASAN");
1370 assert(!F.hasSection());
1371 F.setSection("ASAN");
1378 // Workaround for bug 11395: we don't want to instrument stack in functions
1379 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1380 // FIXME: remove once the bug 11395 is fixed.
1381 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1382 if (LongSize != 32) return false;
1383 CallInst *CI = dyn_cast<CallInst>(I);
1384 if (!CI || !CI->isInlineAsm()) return false;
1385 if (CI->getNumArgOperands() <= 5) return false;
1386 // We have inline assembly with quite a few arguments.
1390 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1391 IRBuilder<> IRB(*C);
1392 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1393 std::string Suffix = itostr(i);
1394 AsanStackMallocFunc[i] = checkInterfaceFunction(
1395 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1396 IntptrTy, IntptrTy, NULL));
1397 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1398 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1399 IntptrTy, IntptrTy, NULL));
1401 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1402 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1403 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1404 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1408 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1409 IRBuilder<> &IRB, Value *ShadowBase,
1411 size_t n = ShadowBytes.size();
1413 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1414 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1415 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1416 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1417 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1418 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1420 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1421 if (ASan.DL->isLittleEndian())
1422 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1424 Val = (Val << 8) | ShadowBytes[i + j];
1427 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1428 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1429 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1430 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1435 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1436 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1437 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1438 assert(LocalStackSize <= kMaxStackMallocSize);
1439 uint64_t MaxSize = kMinStackMallocSize;
1440 for (int i = 0; ; i++, MaxSize *= 2)
1441 if (LocalStackSize <= MaxSize)
1443 llvm_unreachable("impossible LocalStackSize");
1446 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1447 // We can not use MemSet intrinsic because it may end up calling the actual
1448 // memset. Size is a multiple of 8.
1449 // Currently this generates 8-byte stores on x86_64; it may be better to
1450 // generate wider stores.
1451 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1452 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1453 assert(!(Size % 8));
1454 assert(kAsanStackAfterReturnMagic == 0xf5);
1455 for (int i = 0; i < Size; i += 8) {
1456 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1457 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1458 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1462 void FunctionStackPoisoner::poisonStack() {
1463 int StackMallocIdx = -1;
1465 assert(AllocaVec.size() > 0);
1466 Instruction *InsBefore = AllocaVec[0];
1467 IRBuilder<> IRB(InsBefore);
1469 SmallVector<ASanStackVariableDescription, 16> SVD;
1470 SVD.reserve(AllocaVec.size());
1471 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1472 AllocaInst *AI = AllocaVec[i];
1473 ASanStackVariableDescription D = { AI->getName().data(),
1474 getAllocaSizeInBytes(AI),
1475 AI->getAlignment(), AI, 0};
1478 // Minimal header size (left redzone) is 4 pointers,
1479 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1480 size_t MinHeaderSize = ASan.LongSize / 2;
1481 ASanStackFrameLayout L;
1482 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1483 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1484 uint64_t LocalStackSize = L.FrameSize;
1485 bool DoStackMalloc =
1486 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1488 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1489 AllocaInst *MyAlloca =
1490 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1491 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1492 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1493 MyAlloca->setAlignment(FrameAlignment);
1494 assert(MyAlloca->isStaticAlloca());
1495 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1496 Value *LocalStackBase = OrigStackBase;
1498 if (DoStackMalloc) {
1499 // LocalStackBase = OrigStackBase
1500 // if (__asan_option_detect_stack_use_after_return)
1501 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1502 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1503 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1504 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1505 kAsanOptionDetectUAR, IRB.getInt32Ty());
1506 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1507 Constant::getNullValue(IRB.getInt32Ty()));
1508 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1509 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1510 IRBuilder<> IRBIf(Term);
1511 LocalStackBase = IRBIf.CreateCall2(
1512 AsanStackMallocFunc[StackMallocIdx],
1513 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1514 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1515 IRB.SetInsertPoint(InsBefore);
1516 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1517 Phi->addIncoming(OrigStackBase, CmpBlock);
1518 Phi->addIncoming(LocalStackBase, SetBlock);
1519 LocalStackBase = Phi;
1522 // Insert poison calls for lifetime intrinsics for alloca.
1523 bool HavePoisonedAllocas = false;
1524 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1525 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1526 assert(APC.InsBefore);
1528 IRBuilder<> IRB(APC.InsBefore);
1529 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1530 HavePoisonedAllocas |= APC.DoPoison;
1533 // Replace Alloca instructions with base+offset.
1534 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1535 AllocaInst *AI = SVD[i].AI;
1536 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1537 IRB.CreateAdd(LocalStackBase,
1538 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1540 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1541 AI->replaceAllUsesWith(NewAllocaPtr);
1544 // The left-most redzone has enough space for at least 4 pointers.
1545 // Write the Magic value to redzone[0].
1546 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1547 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1549 // Write the frame description constant to redzone[1].
1550 Value *BasePlus1 = IRB.CreateIntToPtr(
1551 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1553 GlobalVariable *StackDescriptionGlobal =
1554 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1555 /*AllowMerging*/true);
1556 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1558 IRB.CreateStore(Description, BasePlus1);
1559 // Write the PC to redzone[2].
1560 Value *BasePlus2 = IRB.CreateIntToPtr(
1561 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1562 2 * ASan.LongSize/8)),
1564 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1566 // Poison the stack redzones at the entry.
1567 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1568 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1570 // (Un)poison the stack before all ret instructions.
1571 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1572 Instruction *Ret = RetVec[i];
1573 IRBuilder<> IRBRet(Ret);
1574 // Mark the current frame as retired.
1575 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1577 if (DoStackMalloc) {
1578 assert(StackMallocIdx >= 0);
1579 // if LocalStackBase != OrigStackBase:
1580 // // In use-after-return mode, poison the whole stack frame.
1581 // if StackMallocIdx <= 4
1582 // // For small sizes inline the whole thing:
1583 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1584 // **SavedFlagPtr(LocalStackBase) = 0
1586 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1588 // <This is not a fake stack; unpoison the redzones>
1589 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1590 TerminatorInst *ThenTerm, *ElseTerm;
1591 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1593 IRBuilder<> IRBPoison(ThenTerm);
1594 if (StackMallocIdx <= 4) {
1595 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1596 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1597 ClassSize >> Mapping.Scale);
1598 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1600 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1601 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1602 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1603 IRBPoison.CreateStore(
1604 Constant::getNullValue(IRBPoison.getInt8Ty()),
1605 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1607 // For larger frames call __asan_stack_free_*.
1608 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1609 ConstantInt::get(IntptrTy, LocalStackSize),
1613 IRBuilder<> IRBElse(ElseTerm);
1614 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1615 } else if (HavePoisonedAllocas) {
1616 // If we poisoned some allocas in llvm.lifetime analysis,
1617 // unpoison whole stack frame now.
1618 assert(LocalStackBase == OrigStackBase);
1619 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1621 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1625 // We are done. Remove the old unused alloca instructions.
1626 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1627 AllocaVec[i]->eraseFromParent();
1630 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1631 IRBuilder<> &IRB, bool DoPoison) {
1632 // For now just insert the call to ASan runtime.
1633 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1634 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1635 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1636 : AsanUnpoisonStackMemoryFunc,
1640 // Handling llvm.lifetime intrinsics for a given %alloca:
1641 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1642 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1643 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1644 // could be poisoned by previous llvm.lifetime.end instruction, as the
1645 // variable may go in and out of scope several times, e.g. in loops).
1646 // (3) if we poisoned at least one %alloca in a function,
1647 // unpoison the whole stack frame at function exit.
1649 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1650 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1651 // We're intested only in allocas we can handle.
1652 return isInterestingAlloca(*AI) ? AI : 0;
1653 // See if we've already calculated (or started to calculate) alloca for a
1655 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1656 if (I != AllocaForValue.end())
1658 // Store 0 while we're calculating alloca for value V to avoid
1659 // infinite recursion if the value references itself.
1660 AllocaForValue[V] = 0;
1661 AllocaInst *Res = 0;
1662 if (CastInst *CI = dyn_cast<CastInst>(V))
1663 Res = findAllocaForValue(CI->getOperand(0));
1664 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1665 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1666 Value *IncValue = PN->getIncomingValue(i);
1667 // Allow self-referencing phi-nodes.
1668 if (IncValue == PN) continue;
1669 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1670 // AI for incoming values should exist and should all be equal.
1671 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1677 AllocaForValue[V] = Res;