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 "BlackList.h"
20 #include "llvm/ADT/ArrayRef.h"
21 #include "llvm/ADT/DenseMap.h"
22 #include "llvm/ADT/DepthFirstIterator.h"
23 #include "llvm/ADT/OwningPtr.h"
24 #include "llvm/ADT/SmallSet.h"
25 #include "llvm/ADT/SmallString.h"
26 #include "llvm/ADT/SmallVector.h"
27 #include "llvm/ADT/StringExtras.h"
28 #include "llvm/ADT/Triple.h"
29 #include "llvm/DIBuilder.h"
30 #include "llvm/IR/DataLayout.h"
31 #include "llvm/IR/Function.h"
32 #include "llvm/IR/IRBuilder.h"
33 #include "llvm/IR/InlineAsm.h"
34 #include "llvm/IR/IntrinsicInst.h"
35 #include "llvm/IR/LLVMContext.h"
36 #include "llvm/IR/Module.h"
37 #include "llvm/IR/Type.h"
38 #include "llvm/InstVisitor.h"
39 #include "llvm/Support/CommandLine.h"
40 #include "llvm/Support/DataTypes.h"
41 #include "llvm/Support/Debug.h"
42 #include "llvm/Support/raw_ostream.h"
43 #include "llvm/Support/system_error.h"
44 #include "llvm/Target/TargetMachine.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Transforms/Utils/ModuleUtils.h"
53 static const uint64_t kDefaultShadowScale = 3;
54 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
55 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
56 static const uint64_t kDefaultShadowOffsetPie = 0;
58 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
59 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
60 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
62 static const char *kAsanModuleCtorName = "asan.module_ctor";
63 static const char *kAsanModuleDtorName = "asan.module_dtor";
64 static const int kAsanCtorAndCtorPriority = 1;
65 static const char *kAsanReportErrorTemplate = "__asan_report_";
66 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
67 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
68 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
69 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
70 static const char *kAsanInitName = "__asan_init";
71 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
72 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
73 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
74 static const char *kAsanStackMallocName = "__asan_stack_malloc";
75 static const char *kAsanStackFreeName = "__asan_stack_free";
76 static const char *kAsanGenPrefix = "__asan_gen_";
77 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
78 static const char *kAsanUnpoisonStackMemoryName =
79 "__asan_unpoison_stack_memory";
81 static const int kAsanStackLeftRedzoneMagic = 0xf1;
82 static const int kAsanStackMidRedzoneMagic = 0xf2;
83 static const int kAsanStackRightRedzoneMagic = 0xf3;
84 static const int kAsanStackPartialRedzoneMagic = 0xf4;
86 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
87 static const size_t kNumberOfAccessSizes = 5;
89 // Command-line flags.
91 // This flag may need to be replaced with -f[no-]asan-reads.
92 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
93 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
94 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
95 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
96 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
97 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
98 cl::Hidden, cl::init(true));
99 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
100 cl::desc("use instrumentation with slow path for all accesses"),
101 cl::Hidden, cl::init(false));
102 // This flag limits the number of instructions to be instrumented
103 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
104 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
106 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
108 cl::desc("maximal number of instructions to instrument in any given BB"),
110 // This flag may need to be replaced with -f[no]asan-stack.
111 static cl::opt<bool> ClStack("asan-stack",
112 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
113 // This flag may need to be replaced with -f[no]asan-use-after-return.
114 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
115 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
116 // This flag may need to be replaced with -f[no]asan-globals.
117 static cl::opt<bool> ClGlobals("asan-globals",
118 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
119 static cl::opt<bool> ClInitializers("asan-initialization-order",
120 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
121 static cl::opt<bool> ClMemIntrin("asan-memintrin",
122 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
123 static cl::opt<bool> ClRealignStack("asan-realign-stack",
124 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
125 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
126 cl::desc("File containing the list of objects to ignore "
127 "during instrumentation"), cl::Hidden);
129 // These flags allow to change the shadow mapping.
130 // The shadow mapping looks like
131 // Shadow = (Mem >> scale) + (1 << offset_log)
132 static cl::opt<int> ClMappingScale("asan-mapping-scale",
133 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
134 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
135 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
137 // Optimization flags. Not user visible, used mostly for testing
138 // and benchmarking the tool.
139 static cl::opt<bool> ClOpt("asan-opt",
140 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
141 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
142 cl::desc("Instrument the same temp just once"), cl::Hidden,
144 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
145 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
147 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
148 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
149 cl::Hidden, cl::init(false));
152 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
154 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
155 cl::Hidden, cl::init(0));
156 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
157 cl::Hidden, cl::desc("Debug func"));
158 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
159 cl::Hidden, cl::init(-1));
160 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
161 cl::Hidden, cl::init(-1));
164 /// A set of dynamically initialized globals extracted from metadata.
165 class SetOfDynamicallyInitializedGlobals {
167 void Init(Module& M) {
168 // Clang generates metadata identifying all dynamically initialized globals.
169 NamedMDNode *DynamicGlobals =
170 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
173 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
174 MDNode *MDN = DynamicGlobals->getOperand(i);
175 assert(MDN->getNumOperands() == 1);
176 Value *VG = MDN->getOperand(0);
177 // The optimizer may optimize away a global entirely, in which case we
178 // cannot instrument access to it.
181 DynInitGlobals.insert(cast<GlobalVariable>(VG));
184 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
186 SmallSet<GlobalValue*, 32> DynInitGlobals;
189 /// This struct defines the shadow mapping using the rule:
190 /// shadow = (mem >> Scale) + Offset.
191 struct ShadowMapping {
196 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
197 llvm::Triple targetTriple(M.getTargetTriple());
198 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
200 ShadowMapping Mapping;
202 Mapping.Offset = isAndroid ? kDefaultShadowOffsetPie :
203 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
204 if (ClMappingOffsetLog >= 0) {
205 // Zero offset log is the special case.
206 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
209 Mapping.Scale = kDefaultShadowScale;
210 if (ClMappingScale) {
211 Mapping.Scale = ClMappingScale;
217 static size_t RedzoneSizeForScale(int MappingScale) {
218 // Redzone used for stack and globals is at least 32 bytes.
219 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
220 return std::max(32U, 1U << MappingScale);
223 /// AddressSanitizer: instrument the code in module to find memory bugs.
224 struct AddressSanitizer : public FunctionPass {
225 AddressSanitizer(bool CheckInitOrder = false,
226 bool CheckUseAfterReturn = false,
227 bool CheckLifetime = false,
228 StringRef BlacklistFile = StringRef())
230 CheckInitOrder(CheckInitOrder || ClInitializers),
231 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
232 CheckLifetime(CheckLifetime || ClCheckLifetime),
233 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
235 virtual const char *getPassName() const {
236 return "AddressSanitizerFunctionPass";
238 void instrumentMop(Instruction *I);
239 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
240 Value *Addr, uint32_t TypeSize, bool IsWrite);
241 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
242 Value *ShadowValue, uint32_t TypeSize);
243 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
244 bool IsWrite, size_t AccessSizeIndex);
245 bool instrumentMemIntrinsic(MemIntrinsic *MI);
246 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
248 Instruction *InsertBefore, bool IsWrite);
249 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
250 bool runOnFunction(Function &F);
251 void createInitializerPoisonCalls(Module &M,
252 Value *FirstAddr, Value *LastAddr);
253 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
254 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
255 virtual bool doInitialization(Module &M);
256 static char ID; // Pass identification, replacement for typeid
259 void initializeCallbacks(Module &M);
261 bool ShouldInstrumentGlobal(GlobalVariable *G);
262 bool LooksLikeCodeInBug11395(Instruction *I);
263 void FindDynamicInitializers(Module &M);
266 bool CheckUseAfterReturn;
272 ShadowMapping Mapping;
273 Function *AsanCtorFunction;
274 Function *AsanInitFunction;
275 Function *AsanHandleNoReturnFunc;
276 SmallString<64> BlacklistFile;
277 OwningPtr<BlackList> BL;
278 // This array is indexed by AccessIsWrite and log2(AccessSize).
279 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
281 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
283 friend struct FunctionStackPoisoner;
286 class AddressSanitizerModule : public ModulePass {
288 AddressSanitizerModule(bool CheckInitOrder = false,
289 StringRef BlacklistFile = StringRef())
291 CheckInitOrder(CheckInitOrder || ClInitializers),
292 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
294 bool runOnModule(Module &M);
295 static char ID; // Pass identification, replacement for typeid
296 virtual const char *getPassName() const {
297 return "AddressSanitizerModule";
301 void initializeCallbacks(Module &M);
303 bool ShouldInstrumentGlobal(GlobalVariable *G);
304 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
306 size_t RedzoneSize() const {
307 return RedzoneSizeForScale(Mapping.Scale);
311 SmallString<64> BlacklistFile;
312 OwningPtr<BlackList> BL;
313 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
317 ShadowMapping Mapping;
318 Function *AsanPoisonGlobals;
319 Function *AsanUnpoisonGlobals;
320 Function *AsanRegisterGlobals;
321 Function *AsanUnregisterGlobals;
324 // Stack poisoning does not play well with exception handling.
325 // When an exception is thrown, we essentially bypass the code
326 // that unpoisones the stack. This is why the run-time library has
327 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
328 // stack in the interceptor. This however does not work inside the
329 // actual function which catches the exception. Most likely because the
330 // compiler hoists the load of the shadow value somewhere too high.
331 // This causes asan to report a non-existing bug on 453.povray.
332 // It sounds like an LLVM bug.
333 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
335 AddressSanitizer &ASan;
340 ShadowMapping Mapping;
342 SmallVector<AllocaInst*, 16> AllocaVec;
343 SmallVector<Instruction*, 8> RetVec;
344 uint64_t TotalStackSize;
345 unsigned StackAlignment;
347 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
348 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
350 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
351 struct AllocaPoisonCall {
352 IntrinsicInst *InsBefore;
356 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
358 // Maps Value to an AllocaInst from which the Value is originated.
359 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
360 AllocaForValueMapTy AllocaForValue;
362 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
363 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
364 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
365 Mapping(ASan.Mapping),
366 TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
368 bool runOnFunction() {
369 if (!ClStack) return false;
370 // Collect alloca, ret, lifetime instructions etc.
371 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
372 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
373 BasicBlock *BB = *DI;
376 if (AllocaVec.empty()) return false;
378 initializeCallbacks(*F.getParent());
388 // Finds all static Alloca instructions and puts
389 // poisoned red zones around all of them.
390 // Then unpoison everything back before the function returns.
393 // ----------------------- Visitors.
394 /// \brief Collect all Ret instructions.
395 void visitReturnInst(ReturnInst &RI) {
396 RetVec.push_back(&RI);
399 /// \brief Collect Alloca instructions we want (and can) handle.
400 void visitAllocaInst(AllocaInst &AI) {
401 if (!isInterestingAlloca(AI)) return;
403 StackAlignment = std::max(StackAlignment, AI.getAlignment());
404 AllocaVec.push_back(&AI);
405 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
406 TotalStackSize += AlignedSize;
409 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
411 void visitIntrinsicInst(IntrinsicInst &II) {
412 if (!ASan.CheckLifetime) return;
413 Intrinsic::ID ID = II.getIntrinsicID();
414 if (ID != Intrinsic::lifetime_start &&
415 ID != Intrinsic::lifetime_end)
417 // Found lifetime intrinsic, add ASan instrumentation if necessary.
418 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
419 // If size argument is undefined, don't do anything.
420 if (Size->isMinusOne()) return;
421 // Check that size doesn't saturate uint64_t and can
422 // be stored in IntptrTy.
423 const uint64_t SizeValue = Size->getValue().getLimitedValue();
424 if (SizeValue == ~0ULL ||
425 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
427 // Find alloca instruction that corresponds to llvm.lifetime argument.
428 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
430 bool DoPoison = (ID == Intrinsic::lifetime_end);
431 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
432 AllocaPoisonCallVec.push_back(APC);
435 // ---------------------- Helpers.
436 void initializeCallbacks(Module &M);
438 // Check if we want (and can) handle this alloca.
439 bool isInterestingAlloca(AllocaInst &AI) {
440 return (!AI.isArrayAllocation() &&
441 AI.isStaticAlloca() &&
442 AI.getAllocatedType()->isSized());
445 size_t RedzoneSize() const {
446 return RedzoneSizeForScale(Mapping.Scale);
448 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
449 Type *Ty = AI->getAllocatedType();
450 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
453 uint64_t getAlignedSize(uint64_t SizeInBytes) {
454 size_t RZ = RedzoneSize();
455 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
457 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
458 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
459 return getAlignedSize(SizeInBytes);
461 /// Finds alloca where the value comes from.
462 AllocaInst *findAllocaForValue(Value *V);
463 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
464 Value *ShadowBase, bool DoPoison);
465 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
470 char AddressSanitizer::ID = 0;
471 INITIALIZE_PASS(AddressSanitizer, "asan",
472 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
474 FunctionPass *llvm::createAddressSanitizerFunctionPass(
475 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
476 StringRef BlacklistFile) {
477 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
478 CheckLifetime, BlacklistFile);
481 char AddressSanitizerModule::ID = 0;
482 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
483 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
484 "ModulePass", false, false)
485 ModulePass *llvm::createAddressSanitizerModulePass(
486 bool CheckInitOrder, StringRef BlacklistFile) {
487 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
490 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
491 size_t Res = CountTrailingZeros_32(TypeSize / 8);
492 assert(Res < kNumberOfAccessSizes);
496 // Create a constant for Str so that we can pass it to the run-time lib.
497 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
498 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
499 return new GlobalVariable(M, StrConst->getType(), true,
500 GlobalValue::PrivateLinkage, StrConst,
504 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
505 return G->getName().find(kAsanGenPrefix) == 0;
508 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
510 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
511 if (Mapping.Offset == 0)
513 // (Shadow >> scale) | offset
514 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
518 void AddressSanitizer::instrumentMemIntrinsicParam(
519 Instruction *OrigIns,
520 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
521 // Check the first byte.
523 IRBuilder<> IRB(InsertBefore);
524 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
526 // Check the last byte.
528 IRBuilder<> IRB(InsertBefore);
529 Value *SizeMinusOne = IRB.CreateSub(
530 Size, ConstantInt::get(Size->getType(), 1));
531 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
532 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
533 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
534 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
538 // Instrument memset/memmove/memcpy
539 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
540 Value *Dst = MI->getDest();
541 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
542 Value *Src = MemTran ? MemTran->getSource() : 0;
543 Value *Length = MI->getLength();
545 Constant *ConstLength = dyn_cast<Constant>(Length);
546 Instruction *InsertBefore = MI;
548 if (ConstLength->isNullValue()) return false;
550 // The size is not a constant so it could be zero -- check at run-time.
551 IRBuilder<> IRB(InsertBefore);
553 Value *Cmp = IRB.CreateICmpNE(Length,
554 Constant::getNullValue(Length->getType()));
555 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
558 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
560 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
564 // If I is an interesting memory access, return the PointerOperand
565 // and set IsWrite. Otherwise return NULL.
566 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
567 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
568 if (!ClInstrumentReads) return NULL;
570 return LI->getPointerOperand();
572 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
573 if (!ClInstrumentWrites) return NULL;
575 return SI->getPointerOperand();
577 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
578 if (!ClInstrumentAtomics) return NULL;
580 return RMW->getPointerOperand();
582 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
583 if (!ClInstrumentAtomics) return NULL;
585 return XCHG->getPointerOperand();
590 void AddressSanitizer::instrumentMop(Instruction *I) {
591 bool IsWrite = false;
592 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
594 if (ClOpt && ClOptGlobals) {
595 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
596 // If initialization order checking is disabled, a simple access to a
597 // dynamically initialized global is always valid.
600 // If a global variable does not have dynamic initialization we don't
601 // have to instrument it. However, if a global does not have initailizer
602 // at all, we assume it has dynamic initializer (in other TU).
603 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
608 Type *OrigPtrTy = Addr->getType();
609 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
611 assert(OrigTy->isSized());
612 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
614 if (TypeSize != 8 && TypeSize != 16 &&
615 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
616 // Ignore all unusual sizes.
621 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
624 // Validate the result of Module::getOrInsertFunction called for an interface
625 // function of AddressSanitizer. If the instrumented module defines a function
626 // with the same name, their prototypes must match, otherwise
627 // getOrInsertFunction returns a bitcast.
628 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
629 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
630 FuncOrBitcast->dump();
631 report_fatal_error("trying to redefine an AddressSanitizer "
632 "interface function");
635 Instruction *AddressSanitizer::generateCrashCode(
636 Instruction *InsertBefore, Value *Addr,
637 bool IsWrite, size_t AccessSizeIndex) {
638 IRBuilder<> IRB(InsertBefore);
639 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
641 // We don't do Call->setDoesNotReturn() because the BB already has
642 // UnreachableInst at the end.
643 // This EmptyAsm is required to avoid callback merge.
644 IRB.CreateCall(EmptyAsm);
648 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
651 size_t Granularity = 1 << Mapping.Scale;
652 // Addr & (Granularity - 1)
653 Value *LastAccessedByte = IRB.CreateAnd(
654 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
655 // (Addr & (Granularity - 1)) + size - 1
656 if (TypeSize / 8 > 1)
657 LastAccessedByte = IRB.CreateAdd(
658 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
659 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
660 LastAccessedByte = IRB.CreateIntCast(
661 LastAccessedByte, ShadowValue->getType(), false);
662 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
663 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
666 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
667 IRBuilder<> &IRB, Value *Addr,
668 uint32_t TypeSize, bool IsWrite) {
669 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
671 Type *ShadowTy = IntegerType::get(
672 *C, std::max(8U, TypeSize >> Mapping.Scale));
673 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
674 Value *ShadowPtr = memToShadow(AddrLong, IRB);
675 Value *CmpVal = Constant::getNullValue(ShadowTy);
676 Value *ShadowValue = IRB.CreateLoad(
677 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
679 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
680 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
681 size_t Granularity = 1 << Mapping.Scale;
682 TerminatorInst *CrashTerm = 0;
684 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
685 TerminatorInst *CheckTerm =
686 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
687 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
688 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
689 IRB.SetInsertPoint(CheckTerm);
690 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
691 BasicBlock *CrashBlock =
692 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
693 CrashTerm = new UnreachableInst(*C, CrashBlock);
694 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
695 ReplaceInstWithInst(CheckTerm, NewTerm);
697 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
701 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
702 Crash->setDebugLoc(OrigIns->getDebugLoc());
705 void AddressSanitizerModule::createInitializerPoisonCalls(
706 Module &M, Value *FirstAddr, Value *LastAddr) {
707 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
708 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
709 // If that function is not present, this TU contains no globals, or they have
710 // all been optimized away
714 // Set up the arguments to our poison/unpoison functions.
715 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
717 // Add a call to poison all external globals before the given function starts.
718 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
720 // Add calls to unpoison all globals before each return instruction.
721 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
723 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
724 CallInst::Create(AsanUnpoisonGlobals, "", RI);
729 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
730 Type *Ty = cast<PointerType>(G->getType())->getElementType();
731 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
733 if (BL->isIn(*G)) return false;
734 if (!Ty->isSized()) return false;
735 if (!G->hasInitializer()) return false;
736 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
737 // Touch only those globals that will not be defined in other modules.
738 // Don't handle ODR type linkages since other modules may be built w/o asan.
739 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
740 G->getLinkage() != GlobalVariable::PrivateLinkage &&
741 G->getLinkage() != GlobalVariable::InternalLinkage)
743 // Two problems with thread-locals:
744 // - The address of the main thread's copy can't be computed at link-time.
745 // - Need to poison all copies, not just the main thread's one.
746 if (G->isThreadLocal())
748 // For now, just ignore this Alloca if the alignment is large.
749 if (G->getAlignment() > RedzoneSize()) return false;
751 // Ignore all the globals with the names starting with "\01L_OBJC_".
752 // Many of those are put into the .cstring section. The linker compresses
753 // that section by removing the spare \0s after the string terminator, so
754 // our redzones get broken.
755 if ((G->getName().find("\01L_OBJC_") == 0) ||
756 (G->getName().find("\01l_OBJC_") == 0)) {
757 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
761 if (G->hasSection()) {
762 StringRef Section(G->getSection());
763 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
764 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
766 if ((Section.find("__OBJC,") == 0) ||
767 (Section.find("__DATA, __objc_") == 0)) {
768 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
771 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
772 // Constant CFString instances are compiled in the following way:
773 // -- the string buffer is emitted into
774 // __TEXT,__cstring,cstring_literals
775 // -- the constant NSConstantString structure referencing that buffer
776 // is placed into __DATA,__cfstring
777 // Therefore there's no point in placing redzones into __DATA,__cfstring.
778 // Moreover, it causes the linker to crash on OS X 10.7
779 if (Section.find("__DATA,__cfstring") == 0) {
780 DEBUG(dbgs() << "Ignoring CFString: " << *G);
788 void AddressSanitizerModule::initializeCallbacks(Module &M) {
790 // Declare our poisoning and unpoisoning functions.
791 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
792 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
793 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
794 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
795 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
796 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
797 // Declare functions that register/unregister globals.
798 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
799 kAsanRegisterGlobalsName, IRB.getVoidTy(),
800 IntptrTy, IntptrTy, NULL));
801 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
802 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
803 kAsanUnregisterGlobalsName,
804 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
805 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
808 // This function replaces all global variables with new variables that have
809 // trailing redzones. It also creates a function that poisons
810 // redzones and inserts this function into llvm.global_ctors.
811 bool AddressSanitizerModule::runOnModule(Module &M) {
812 if (!ClGlobals) return false;
813 TD = getAnalysisIfAvailable<DataLayout>();
816 BL.reset(new BlackList(BlacklistFile));
817 if (BL->isIn(M)) return false;
818 C = &(M.getContext());
819 int LongSize = TD->getPointerSizeInBits();
820 IntptrTy = Type::getIntNTy(*C, LongSize);
821 Mapping = getShadowMapping(M, LongSize);
822 initializeCallbacks(M);
823 DynamicallyInitializedGlobals.Init(M);
825 SmallVector<GlobalVariable *, 16> GlobalsToChange;
827 for (Module::GlobalListType::iterator G = M.global_begin(),
828 E = M.global_end(); G != E; ++G) {
829 if (ShouldInstrumentGlobal(G))
830 GlobalsToChange.push_back(G);
833 size_t n = GlobalsToChange.size();
834 if (n == 0) return false;
836 // A global is described by a structure
839 // size_t size_with_redzone;
841 // size_t has_dynamic_init;
842 // We initialize an array of such structures and pass it to a run-time call.
843 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
846 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
849 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
851 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
853 // The addresses of the first and last dynamically initialized globals in
854 // this TU. Used in initialization order checking.
855 Value *FirstDynamic = 0, *LastDynamic = 0;
857 for (size_t i = 0; i < n; i++) {
858 GlobalVariable *G = GlobalsToChange[i];
859 PointerType *PtrTy = cast<PointerType>(G->getType());
860 Type *Ty = PtrTy->getElementType();
861 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
862 size_t RZ = RedzoneSize();
863 uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
864 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
865 // Determine whether this global should be poisoned in initialization.
866 bool GlobalHasDynamicInitializer =
867 DynamicallyInitializedGlobals.Contains(G);
868 // Don't check initialization order if this global is blacklisted.
869 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
871 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
872 Constant *NewInitializer = ConstantStruct::get(
873 NewTy, G->getInitializer(),
874 Constant::getNullValue(RightRedZoneTy), NULL);
876 SmallString<2048> DescriptionOfGlobal = G->getName();
877 DescriptionOfGlobal += " (";
878 DescriptionOfGlobal += M.getModuleIdentifier();
879 DescriptionOfGlobal += ")";
880 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
882 // Create a new global variable with enough space for a redzone.
883 GlobalVariable *NewGlobal = new GlobalVariable(
884 M, NewTy, G->isConstant(), G->getLinkage(),
885 NewInitializer, "", G, G->getThreadLocalMode());
886 NewGlobal->copyAttributesFrom(G);
887 NewGlobal->setAlignment(RZ);
890 Indices2[0] = IRB.getInt32(0);
891 Indices2[1] = IRB.getInt32(0);
893 G->replaceAllUsesWith(
894 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
895 NewGlobal->takeName(G);
896 G->eraseFromParent();
898 Initializers[i] = ConstantStruct::get(
900 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
901 ConstantInt::get(IntptrTy, SizeInBytes),
902 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
903 ConstantExpr::getPointerCast(Name, IntptrTy),
904 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
907 // Populate the first and last globals declared in this TU.
908 if (CheckInitOrder && GlobalHasDynamicInitializer) {
909 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
910 if (FirstDynamic == 0)
911 FirstDynamic = LastDynamic;
914 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
917 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
918 GlobalVariable *AllGlobals = new GlobalVariable(
919 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
920 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
922 // Create calls for poisoning before initializers run and unpoisoning after.
923 if (CheckInitOrder && FirstDynamic && LastDynamic)
924 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
925 IRB.CreateCall2(AsanRegisterGlobals,
926 IRB.CreatePointerCast(AllGlobals, IntptrTy),
927 ConstantInt::get(IntptrTy, n));
929 // We also need to unregister globals at the end, e.g. when a shared library
931 Function *AsanDtorFunction = Function::Create(
932 FunctionType::get(Type::getVoidTy(*C), false),
933 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
934 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
935 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
936 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
937 IRB.CreatePointerCast(AllGlobals, IntptrTy),
938 ConstantInt::get(IntptrTy, n));
939 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
945 void AddressSanitizer::initializeCallbacks(Module &M) {
947 // Create __asan_report* callbacks.
948 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
949 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
951 // IsWrite and TypeSize are encoded in the function name.
952 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
953 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
954 // If we are merging crash callbacks, they have two parameters.
955 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
956 checkInterfaceFunction(M.getOrInsertFunction(
957 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
961 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
962 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
963 // We insert an empty inline asm after __asan_report* to avoid callback merge.
964 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
965 StringRef(""), StringRef(""),
966 /*hasSideEffects=*/true);
969 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
970 // Tell the values of mapping offset and scale to the run-time if they are
971 // specified by command-line flags.
972 if (ClMappingOffsetLog >= 0) {
973 GlobalValue *asan_mapping_offset =
974 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
975 ConstantInt::get(IntptrTy, Mapping.Offset),
976 kAsanMappingOffsetName);
977 // Read the global, otherwise it may be optimized away.
978 IRB.CreateLoad(asan_mapping_offset, true);
981 if (ClMappingScale) {
982 GlobalValue *asan_mapping_scale =
983 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
984 ConstantInt::get(IntptrTy, Mapping.Scale),
985 kAsanMappingScaleName);
986 // Read the global, otherwise it may be optimized away.
987 IRB.CreateLoad(asan_mapping_scale, true);
992 bool AddressSanitizer::doInitialization(Module &M) {
993 // Initialize the private fields. No one has accessed them before.
994 TD = getAnalysisIfAvailable<DataLayout>();
998 BL.reset(new BlackList(BlacklistFile));
999 DynamicallyInitializedGlobals.Init(M);
1001 C = &(M.getContext());
1002 LongSize = TD->getPointerSizeInBits();
1003 IntptrTy = Type::getIntNTy(*C, LongSize);
1005 AsanCtorFunction = Function::Create(
1006 FunctionType::get(Type::getVoidTy(*C), false),
1007 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1008 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1009 // call __asan_init in the module ctor.
1010 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1011 AsanInitFunction = checkInterfaceFunction(
1012 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1013 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1014 IRB.CreateCall(AsanInitFunction);
1016 Mapping = getShadowMapping(M, LongSize);
1017 emitShadowMapping(M, IRB);
1019 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1023 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1024 // For each NSObject descendant having a +load method, this method is invoked
1025 // by the ObjC runtime before any of the static constructors is called.
1026 // Therefore we need to instrument such methods with a call to __asan_init
1027 // at the beginning in order to initialize our runtime before any access to
1028 // the shadow memory.
1029 // We cannot just ignore these methods, because they may call other
1030 // instrumented functions.
1031 if (F.getName().find(" load]") != std::string::npos) {
1032 IRBuilder<> IRB(F.begin()->begin());
1033 IRB.CreateCall(AsanInitFunction);
1039 bool AddressSanitizer::runOnFunction(Function &F) {
1040 if (BL->isIn(F)) return false;
1041 if (&F == AsanCtorFunction) return false;
1042 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1043 initializeCallbacks(*F.getParent());
1045 // If needed, insert __asan_init before checking for AddressSafety attr.
1046 maybeInsertAsanInitAtFunctionEntry(F);
1048 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1049 Attribute::AddressSafety))
1052 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1055 // We want to instrument every address only once per basic block (unless there
1056 // are calls between uses).
1057 SmallSet<Value*, 16> TempsToInstrument;
1058 SmallVector<Instruction*, 16> ToInstrument;
1059 SmallVector<Instruction*, 8> NoReturnCalls;
1062 // Fill the set of memory operations to instrument.
1063 for (Function::iterator FI = F.begin(), FE = F.end();
1065 TempsToInstrument.clear();
1066 int NumInsnsPerBB = 0;
1067 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1069 if (LooksLikeCodeInBug11395(BI)) return false;
1070 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1071 if (ClOpt && ClOptSameTemp) {
1072 if (!TempsToInstrument.insert(Addr))
1073 continue; // We've seen this temp in the current BB.
1075 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1078 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
1079 // A call inside BB.
1080 TempsToInstrument.clear();
1081 if (CI->doesNotReturn()) {
1082 NoReturnCalls.push_back(CI);
1087 ToInstrument.push_back(BI);
1089 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1095 int NumInstrumented = 0;
1096 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1097 Instruction *Inst = ToInstrument[i];
1098 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1099 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1100 if (isInterestingMemoryAccess(Inst, &IsWrite))
1101 instrumentMop(Inst);
1103 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1108 FunctionStackPoisoner FSP(F, *this);
1109 bool ChangedStack = FSP.runOnFunction();
1111 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1112 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1113 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1114 Instruction *CI = NoReturnCalls[i];
1115 IRBuilder<> IRB(CI);
1116 IRB.CreateCall(AsanHandleNoReturnFunc);
1118 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1120 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1123 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1124 if (ShadowRedzoneSize == 1) return PoisonByte;
1125 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1126 if (ShadowRedzoneSize == 4)
1127 return (PoisonByte << 24) + (PoisonByte << 16) +
1128 (PoisonByte << 8) + (PoisonByte);
1129 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1132 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1135 size_t ShadowGranularity,
1137 for (size_t i = 0; i < RZSize;
1138 i+= ShadowGranularity, Shadow++) {
1139 if (i + ShadowGranularity <= Size) {
1140 *Shadow = 0; // fully addressable
1141 } else if (i >= Size) {
1142 *Shadow = Magic; // unaddressable
1144 *Shadow = Size - i; // first Size-i bytes are addressable
1149 // Workaround for bug 11395: we don't want to instrument stack in functions
1150 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1151 // FIXME: remove once the bug 11395 is fixed.
1152 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1153 if (LongSize != 32) return false;
1154 CallInst *CI = dyn_cast<CallInst>(I);
1155 if (!CI || !CI->isInlineAsm()) return false;
1156 if (CI->getNumArgOperands() <= 5) return false;
1157 // We have inline assembly with quite a few arguments.
1161 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1162 IRBuilder<> IRB(*C);
1163 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1164 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1165 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1166 kAsanStackFreeName, IRB.getVoidTy(),
1167 IntptrTy, IntptrTy, IntptrTy, NULL));
1168 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1169 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1170 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1171 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1174 void FunctionStackPoisoner::poisonRedZones(
1175 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1177 size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1178 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1179 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1180 Type *RZPtrTy = PointerType::get(RZTy, 0);
1182 Value *PoisonLeft = ConstantInt::get(RZTy,
1183 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1184 Value *PoisonMid = ConstantInt::get(RZTy,
1185 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1186 Value *PoisonRight = ConstantInt::get(RZTy,
1187 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1189 // poison the first red zone.
1190 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1192 // poison all other red zones.
1193 uint64_t Pos = RedzoneSize();
1194 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1195 AllocaInst *AI = AllocaVec[i];
1196 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1197 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1198 assert(AlignedSize - SizeInBytes < RedzoneSize());
1203 assert(ShadowBase->getType() == IntptrTy);
1204 if (SizeInBytes < AlignedSize) {
1205 // Poison the partial redzone at right
1206 Ptr = IRB.CreateAdd(
1207 ShadowBase, ConstantInt::get(IntptrTy,
1208 (Pos >> Mapping.Scale) - ShadowRZSize));
1209 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1210 uint32_t Poison = 0;
1212 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1214 1ULL << Mapping.Scale,
1215 kAsanStackPartialRedzoneMagic);
1217 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1218 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1221 // Poison the full redzone at right.
1222 Ptr = IRB.CreateAdd(ShadowBase,
1223 ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1224 bool LastAlloca = (i == AllocaVec.size() - 1);
1225 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1226 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1228 Pos += RedzoneSize();
1232 void FunctionStackPoisoner::poisonStack() {
1233 uint64_t LocalStackSize = TotalStackSize +
1234 (AllocaVec.size() + 1) * RedzoneSize();
1236 bool DoStackMalloc = ASan.CheckUseAfterReturn
1237 && LocalStackSize <= kMaxStackMallocSize;
1239 assert(AllocaVec.size() > 0);
1240 Instruction *InsBefore = AllocaVec[0];
1241 IRBuilder<> IRB(InsBefore);
1244 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1245 AllocaInst *MyAlloca =
1246 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1247 if (ClRealignStack && StackAlignment < RedzoneSize())
1248 StackAlignment = RedzoneSize();
1249 MyAlloca->setAlignment(StackAlignment);
1250 assert(MyAlloca->isStaticAlloca());
1251 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1252 Value *LocalStackBase = OrigStackBase;
1254 if (DoStackMalloc) {
1255 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1256 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1259 // This string will be parsed by the run-time (DescribeStackAddress).
1260 SmallString<2048> StackDescriptionStorage;
1261 raw_svector_ostream StackDescription(StackDescriptionStorage);
1262 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1264 // Insert poison calls for lifetime intrinsics for alloca.
1265 bool HavePoisonedAllocas = false;
1266 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1267 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1268 IntrinsicInst *II = APC.InsBefore;
1269 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1271 IRBuilder<> IRB(II);
1272 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1273 HavePoisonedAllocas |= APC.DoPoison;
1276 uint64_t Pos = RedzoneSize();
1277 // Replace Alloca instructions with base+offset.
1278 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1279 AllocaInst *AI = AllocaVec[i];
1280 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1281 StringRef Name = AI->getName();
1282 StackDescription << Pos << " " << SizeInBytes << " "
1283 << Name.size() << " " << Name << " ";
1284 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1285 assert((AlignedSize % RedzoneSize()) == 0);
1286 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1287 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1289 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1290 AI->replaceAllUsesWith(NewAllocaPtr);
1291 Pos += AlignedSize + RedzoneSize();
1293 assert(Pos == LocalStackSize);
1295 // Write the Magic value and the frame description constant to the redzone.
1296 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1297 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1299 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1300 ConstantInt::get(IntptrTy,
1302 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1303 GlobalVariable *StackDescriptionGlobal =
1304 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1305 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1307 IRB.CreateStore(Description, BasePlus1);
1309 // Poison the stack redzones at the entry.
1310 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1311 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1313 // Unpoison the stack before all ret instructions.
1314 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1315 Instruction *Ret = RetVec[i];
1316 IRBuilder<> IRBRet(Ret);
1317 // Mark the current frame as retired.
1318 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1320 // Unpoison the stack.
1321 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1322 if (DoStackMalloc) {
1323 // In use-after-return mode, mark the whole stack frame unaddressable.
1324 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1325 ConstantInt::get(IntptrTy, LocalStackSize),
1327 } else if (HavePoisonedAllocas) {
1328 // If we poisoned some allocas in llvm.lifetime analysis,
1329 // unpoison whole stack frame now.
1330 assert(LocalStackBase == OrigStackBase);
1331 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1335 // We are done. Remove the old unused alloca instructions.
1336 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1337 AllocaVec[i]->eraseFromParent();
1340 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1341 IRBuilder<> IRB, bool DoPoison) {
1342 // For now just insert the call to ASan runtime.
1343 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1344 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1345 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1346 : AsanUnpoisonStackMemoryFunc,
1350 // Handling llvm.lifetime intrinsics for a given %alloca:
1351 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1352 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1353 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1354 // could be poisoned by previous llvm.lifetime.end instruction, as the
1355 // variable may go in and out of scope several times, e.g. in loops).
1356 // (3) if we poisoned at least one %alloca in a function,
1357 // unpoison the whole stack frame at function exit.
1359 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1360 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1361 // We're intested only in allocas we can handle.
1362 return isInterestingAlloca(*AI) ? AI : 0;
1363 // See if we've already calculated (or started to calculate) alloca for a
1365 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1366 if (I != AllocaForValue.end())
1368 // Store 0 while we're calculating alloca for value V to avoid
1369 // infinite recursion if the value references itself.
1370 AllocaForValue[V] = 0;
1371 AllocaInst *Res = 0;
1372 if (CastInst *CI = dyn_cast<CastInst>(V))
1373 Res = findAllocaForValue(CI->getOperand(0));
1374 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1375 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1376 Value *IncValue = PN->getIncomingValue(i);
1377 // Allow self-referencing phi-nodes.
1378 if (IncValue == PN) continue;
1379 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1380 // AI for incoming values should exist and should all be equal.
1381 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1387 AllocaForValue[V] = Res;