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 kDefaultShadowOffsetAndroid = 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 static int MappingScale() {
190 return ClMappingScale ? ClMappingScale : kDefaultShadowScale;
193 static size_t RedzoneSize() {
194 // Redzone used for stack and globals is at least 32 bytes.
195 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
196 return std::max(32U, 1U << MappingScale());
199 /// AddressSanitizer: instrument the code in module to find memory bugs.
200 struct AddressSanitizer : public FunctionPass {
201 AddressSanitizer(bool CheckInitOrder = false,
202 bool CheckUseAfterReturn = false,
203 bool CheckLifetime = false,
204 StringRef BlacklistFile = StringRef())
206 CheckInitOrder(CheckInitOrder || ClInitializers),
207 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
208 CheckLifetime(CheckLifetime || ClCheckLifetime),
209 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
211 virtual const char *getPassName() const {
212 return "AddressSanitizerFunctionPass";
214 void instrumentMop(Instruction *I);
215 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
216 Value *Addr, uint32_t TypeSize, bool IsWrite);
217 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
218 Value *ShadowValue, uint32_t TypeSize);
219 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
220 bool IsWrite, size_t AccessSizeIndex);
221 bool instrumentMemIntrinsic(MemIntrinsic *MI);
222 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
224 Instruction *InsertBefore, bool IsWrite);
225 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
226 bool runOnFunction(Function &F);
227 void createInitializerPoisonCalls(Module &M,
228 Value *FirstAddr, Value *LastAddr);
229 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
230 virtual bool doInitialization(Module &M);
231 static char ID; // Pass identification, replacement for typeid
234 void initializeCallbacks(Module &M);
236 bool ShouldInstrumentGlobal(GlobalVariable *G);
237 bool LooksLikeCodeInBug11395(Instruction *I);
238 void FindDynamicInitializers(Module &M);
241 bool CheckUseAfterReturn;
245 uint64_t MappingOffset;
248 Function *AsanCtorFunction;
249 Function *AsanInitFunction;
250 Function *AsanHandleNoReturnFunc;
251 SmallString<64> BlacklistFile;
252 OwningPtr<BlackList> BL;
253 // This array is indexed by AccessIsWrite and log2(AccessSize).
254 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
256 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
258 friend struct FunctionStackPoisoner;
261 class AddressSanitizerModule : public ModulePass {
263 AddressSanitizerModule(bool CheckInitOrder = false,
264 StringRef BlacklistFile = StringRef())
266 CheckInitOrder(CheckInitOrder || ClInitializers),
267 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
269 bool runOnModule(Module &M);
270 static char ID; // Pass identification, replacement for typeid
271 virtual const char *getPassName() const {
272 return "AddressSanitizerModule";
276 void initializeCallbacks(Module &M);
278 bool ShouldInstrumentGlobal(GlobalVariable *G);
279 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
283 SmallString<64> BlacklistFile;
284 OwningPtr<BlackList> BL;
285 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
289 Function *AsanPoisonGlobals;
290 Function *AsanUnpoisonGlobals;
291 Function *AsanRegisterGlobals;
292 Function *AsanUnregisterGlobals;
295 // Stack poisoning does not play well with exception handling.
296 // When an exception is thrown, we essentially bypass the code
297 // that unpoisones the stack. This is why the run-time library has
298 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
299 // stack in the interceptor. This however does not work inside the
300 // actual function which catches the exception. Most likely because the
301 // compiler hoists the load of the shadow value somewhere too high.
302 // This causes asan to report a non-existing bug on 453.povray.
303 // It sounds like an LLVM bug.
304 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
306 AddressSanitizer &ASan;
312 SmallVector<AllocaInst*, 16> AllocaVec;
313 SmallVector<Instruction*, 8> RetVec;
314 uint64_t TotalStackSize;
315 unsigned StackAlignment;
317 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
318 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
320 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
321 struct AllocaPoisonCall {
322 IntrinsicInst *InsBefore;
326 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
328 // Maps Value to an AllocaInst from which the Value is originated.
329 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
330 AllocaForValueMapTy AllocaForValue;
332 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
333 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
334 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
335 TotalStackSize(0), StackAlignment(1 << MappingScale()) {}
337 bool runOnFunction() {
338 if (!ClStack) return false;
339 // Collect alloca, ret, lifetime instructions etc.
340 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
341 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
342 BasicBlock *BB = *DI;
345 if (AllocaVec.empty()) return false;
347 initializeCallbacks(*F.getParent());
357 // Finds all static Alloca instructions and puts
358 // poisoned red zones around all of them.
359 // Then unpoison everything back before the function returns.
362 // ----------------------- Visitors.
363 /// \brief Collect all Ret instructions.
364 void visitReturnInst(ReturnInst &RI) {
365 RetVec.push_back(&RI);
368 /// \brief Collect Alloca instructions we want (and can) handle.
369 void visitAllocaInst(AllocaInst &AI) {
370 if (!isInterestingAlloca(AI)) return;
372 StackAlignment = std::max(StackAlignment, AI.getAlignment());
373 AllocaVec.push_back(&AI);
374 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
375 TotalStackSize += AlignedSize;
378 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
380 void visitIntrinsicInst(IntrinsicInst &II) {
381 if (!ASan.CheckLifetime) return;
382 Intrinsic::ID ID = II.getIntrinsicID();
383 if (ID != Intrinsic::lifetime_start &&
384 ID != Intrinsic::lifetime_end)
386 // Found lifetime intrinsic, add ASan instrumentation if necessary.
387 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
388 // If size argument is undefined, don't do anything.
389 if (Size->isMinusOne()) return;
390 // Check that size doesn't saturate uint64_t and can
391 // be stored in IntptrTy.
392 const uint64_t SizeValue = Size->getValue().getLimitedValue();
393 if (SizeValue == ~0ULL ||
394 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
396 // Find alloca instruction that corresponds to llvm.lifetime argument.
397 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
399 bool DoPoison = (ID == Intrinsic::lifetime_end);
400 AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
401 AllocaPoisonCallVec.push_back(APC);
404 // ---------------------- Helpers.
405 void initializeCallbacks(Module &M);
407 // Check if we want (and can) handle this alloca.
408 bool isInterestingAlloca(AllocaInst &AI) {
409 return (!AI.isArrayAllocation() &&
410 AI.isStaticAlloca() &&
411 AI.getAllocatedType()->isSized());
414 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
415 Type *Ty = AI->getAllocatedType();
416 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
419 uint64_t getAlignedSize(uint64_t SizeInBytes) {
420 size_t RZ = RedzoneSize();
421 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
423 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
424 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
425 return getAlignedSize(SizeInBytes);
427 /// Finds alloca where the value comes from.
428 AllocaInst *findAllocaForValue(Value *V);
429 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
430 Value *ShadowBase, bool DoPoison);
431 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
436 char AddressSanitizer::ID = 0;
437 INITIALIZE_PASS(AddressSanitizer, "asan",
438 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
440 FunctionPass *llvm::createAddressSanitizerFunctionPass(
441 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
442 StringRef BlacklistFile) {
443 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
444 CheckLifetime, BlacklistFile);
447 char AddressSanitizerModule::ID = 0;
448 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
449 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
450 "ModulePass", false, false)
451 ModulePass *llvm::createAddressSanitizerModulePass(
452 bool CheckInitOrder, StringRef BlacklistFile) {
453 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
456 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
457 size_t Res = CountTrailingZeros_32(TypeSize / 8);
458 assert(Res < kNumberOfAccessSizes);
462 // Create a constant for Str so that we can pass it to the run-time lib.
463 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
464 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
465 return new GlobalVariable(M, StrConst->getType(), true,
466 GlobalValue::PrivateLinkage, StrConst,
470 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
471 return G->getName().find(kAsanGenPrefix) == 0;
474 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
476 Shadow = IRB.CreateLShr(Shadow, MappingScale());
477 if (MappingOffset == 0)
479 // (Shadow >> scale) | offset
480 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
484 void AddressSanitizer::instrumentMemIntrinsicParam(
485 Instruction *OrigIns,
486 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
487 // Check the first byte.
489 IRBuilder<> IRB(InsertBefore);
490 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
492 // Check the last byte.
494 IRBuilder<> IRB(InsertBefore);
495 Value *SizeMinusOne = IRB.CreateSub(
496 Size, ConstantInt::get(Size->getType(), 1));
497 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
498 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
499 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
500 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
504 // Instrument memset/memmove/memcpy
505 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
506 Value *Dst = MI->getDest();
507 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
508 Value *Src = MemTran ? MemTran->getSource() : 0;
509 Value *Length = MI->getLength();
511 Constant *ConstLength = dyn_cast<Constant>(Length);
512 Instruction *InsertBefore = MI;
514 if (ConstLength->isNullValue()) return false;
516 // The size is not a constant so it could be zero -- check at run-time.
517 IRBuilder<> IRB(InsertBefore);
519 Value *Cmp = IRB.CreateICmpNE(Length,
520 Constant::getNullValue(Length->getType()));
521 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
524 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
526 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
530 // If I is an interesting memory access, return the PointerOperand
531 // and set IsWrite. Otherwise return NULL.
532 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
533 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
534 if (!ClInstrumentReads) return NULL;
536 return LI->getPointerOperand();
538 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
539 if (!ClInstrumentWrites) return NULL;
541 return SI->getPointerOperand();
543 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
544 if (!ClInstrumentAtomics) return NULL;
546 return RMW->getPointerOperand();
548 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
549 if (!ClInstrumentAtomics) return NULL;
551 return XCHG->getPointerOperand();
556 void AddressSanitizer::instrumentMop(Instruction *I) {
557 bool IsWrite = false;
558 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
560 if (ClOpt && ClOptGlobals) {
561 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
562 // If initialization order checking is disabled, a simple access to a
563 // dynamically initialized global is always valid.
566 // If a global variable does not have dynamic initialization we don't
567 // have to instrument it. However, if a global does not have initailizer
568 // at all, we assume it has dynamic initializer (in other TU).
569 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
574 Type *OrigPtrTy = Addr->getType();
575 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
577 assert(OrigTy->isSized());
578 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
580 if (TypeSize != 8 && TypeSize != 16 &&
581 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
582 // Ignore all unusual sizes.
587 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
590 // Validate the result of Module::getOrInsertFunction called for an interface
591 // function of AddressSanitizer. If the instrumented module defines a function
592 // with the same name, their prototypes must match, otherwise
593 // getOrInsertFunction returns a bitcast.
594 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
595 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
596 FuncOrBitcast->dump();
597 report_fatal_error("trying to redefine an AddressSanitizer "
598 "interface function");
601 Instruction *AddressSanitizer::generateCrashCode(
602 Instruction *InsertBefore, Value *Addr,
603 bool IsWrite, size_t AccessSizeIndex) {
604 IRBuilder<> IRB(InsertBefore);
605 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
607 // We don't do Call->setDoesNotReturn() because the BB already has
608 // UnreachableInst at the end.
609 // This EmptyAsm is required to avoid callback merge.
610 IRB.CreateCall(EmptyAsm);
614 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
617 size_t Granularity = 1 << MappingScale();
618 // Addr & (Granularity - 1)
619 Value *LastAccessedByte = IRB.CreateAnd(
620 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
621 // (Addr & (Granularity - 1)) + size - 1
622 if (TypeSize / 8 > 1)
623 LastAccessedByte = IRB.CreateAdd(
624 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
625 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
626 LastAccessedByte = IRB.CreateIntCast(
627 LastAccessedByte, ShadowValue->getType(), false);
628 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
629 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
632 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
633 IRBuilder<> &IRB, Value *Addr,
634 uint32_t TypeSize, bool IsWrite) {
635 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
637 Type *ShadowTy = IntegerType::get(
638 *C, std::max(8U, TypeSize >> MappingScale()));
639 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
640 Value *ShadowPtr = memToShadow(AddrLong, IRB);
641 Value *CmpVal = Constant::getNullValue(ShadowTy);
642 Value *ShadowValue = IRB.CreateLoad(
643 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
645 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
646 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
647 size_t Granularity = 1 << MappingScale();
648 TerminatorInst *CrashTerm = 0;
650 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
651 TerminatorInst *CheckTerm =
652 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
653 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
654 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
655 IRB.SetInsertPoint(CheckTerm);
656 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
657 BasicBlock *CrashBlock =
658 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
659 CrashTerm = new UnreachableInst(*C, CrashBlock);
660 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
661 ReplaceInstWithInst(CheckTerm, NewTerm);
663 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
667 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
668 Crash->setDebugLoc(OrigIns->getDebugLoc());
671 void AddressSanitizerModule::createInitializerPoisonCalls(
672 Module &M, Value *FirstAddr, Value *LastAddr) {
673 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
674 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
675 // If that function is not present, this TU contains no globals, or they have
676 // all been optimized away
680 // Set up the arguments to our poison/unpoison functions.
681 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
683 // Add a call to poison all external globals before the given function starts.
684 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
686 // Add calls to unpoison all globals before each return instruction.
687 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
689 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
690 CallInst::Create(AsanUnpoisonGlobals, "", RI);
695 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
696 Type *Ty = cast<PointerType>(G->getType())->getElementType();
697 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
699 if (BL->isIn(*G)) return false;
700 if (!Ty->isSized()) return false;
701 if (!G->hasInitializer()) return false;
702 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
703 // Touch only those globals that will not be defined in other modules.
704 // Don't handle ODR type linkages since other modules may be built w/o asan.
705 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
706 G->getLinkage() != GlobalVariable::PrivateLinkage &&
707 G->getLinkage() != GlobalVariable::InternalLinkage)
709 // Two problems with thread-locals:
710 // - The address of the main thread's copy can't be computed at link-time.
711 // - Need to poison all copies, not just the main thread's one.
712 if (G->isThreadLocal())
714 // For now, just ignore this Alloca if the alignment is large.
715 if (G->getAlignment() > RedzoneSize()) return false;
717 // Ignore all the globals with the names starting with "\01L_OBJC_".
718 // Many of those are put into the .cstring section. The linker compresses
719 // that section by removing the spare \0s after the string terminator, so
720 // our redzones get broken.
721 if ((G->getName().find("\01L_OBJC_") == 0) ||
722 (G->getName().find("\01l_OBJC_") == 0)) {
723 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
727 if (G->hasSection()) {
728 StringRef Section(G->getSection());
729 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
730 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
732 if ((Section.find("__OBJC,") == 0) ||
733 (Section.find("__DATA, __objc_") == 0)) {
734 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
737 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
738 // Constant CFString instances are compiled in the following way:
739 // -- the string buffer is emitted into
740 // __TEXT,__cstring,cstring_literals
741 // -- the constant NSConstantString structure referencing that buffer
742 // is placed into __DATA,__cfstring
743 // Therefore there's no point in placing redzones into __DATA,__cfstring.
744 // Moreover, it causes the linker to crash on OS X 10.7
745 if (Section.find("__DATA,__cfstring") == 0) {
746 DEBUG(dbgs() << "Ignoring CFString: " << *G);
754 void AddressSanitizerModule::initializeCallbacks(Module &M) {
756 // Declare our poisoning and unpoisoning functions.
757 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
758 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
759 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
760 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
761 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
762 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
763 // Declare functions that register/unregister globals.
764 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
765 kAsanRegisterGlobalsName, IRB.getVoidTy(),
766 IntptrTy, IntptrTy, NULL));
767 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
768 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
769 kAsanUnregisterGlobalsName,
770 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
771 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
774 // This function replaces all global variables with new variables that have
775 // trailing redzones. It also creates a function that poisons
776 // redzones and inserts this function into llvm.global_ctors.
777 bool AddressSanitizerModule::runOnModule(Module &M) {
778 if (!ClGlobals) return false;
779 TD = getAnalysisIfAvailable<DataLayout>();
782 BL.reset(new BlackList(BlacklistFile));
783 if (BL->isIn(M)) return false;
784 C = &(M.getContext());
785 IntptrTy = Type::getIntNTy(*C, TD->getPointerSizeInBits());
786 initializeCallbacks(M);
787 DynamicallyInitializedGlobals.Init(M);
789 SmallVector<GlobalVariable *, 16> GlobalsToChange;
791 for (Module::GlobalListType::iterator G = M.global_begin(),
792 E = M.global_end(); G != E; ++G) {
793 if (ShouldInstrumentGlobal(G))
794 GlobalsToChange.push_back(G);
797 size_t n = GlobalsToChange.size();
798 if (n == 0) return false;
800 // A global is described by a structure
803 // size_t size_with_redzone;
805 // size_t has_dynamic_init;
806 // We initialize an array of such structures and pass it to a run-time call.
807 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
810 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
813 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
815 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
817 // The addresses of the first and last dynamically initialized globals in
818 // this TU. Used in initialization order checking.
819 Value *FirstDynamic = 0, *LastDynamic = 0;
821 for (size_t i = 0; i < n; i++) {
822 GlobalVariable *G = GlobalsToChange[i];
823 PointerType *PtrTy = cast<PointerType>(G->getType());
824 Type *Ty = PtrTy->getElementType();
825 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
826 size_t RZ = RedzoneSize();
827 uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
828 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
829 // Determine whether this global should be poisoned in initialization.
830 bool GlobalHasDynamicInitializer =
831 DynamicallyInitializedGlobals.Contains(G);
832 // Don't check initialization order if this global is blacklisted.
833 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
835 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
836 Constant *NewInitializer = ConstantStruct::get(
837 NewTy, G->getInitializer(),
838 Constant::getNullValue(RightRedZoneTy), NULL);
840 SmallString<2048> DescriptionOfGlobal = G->getName();
841 DescriptionOfGlobal += " (";
842 DescriptionOfGlobal += M.getModuleIdentifier();
843 DescriptionOfGlobal += ")";
844 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
846 // Create a new global variable with enough space for a redzone.
847 GlobalVariable *NewGlobal = new GlobalVariable(
848 M, NewTy, G->isConstant(), G->getLinkage(),
849 NewInitializer, "", G, G->getThreadLocalMode());
850 NewGlobal->copyAttributesFrom(G);
851 NewGlobal->setAlignment(RZ);
854 Indices2[0] = IRB.getInt32(0);
855 Indices2[1] = IRB.getInt32(0);
857 G->replaceAllUsesWith(
858 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
859 NewGlobal->takeName(G);
860 G->eraseFromParent();
862 Initializers[i] = ConstantStruct::get(
864 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
865 ConstantInt::get(IntptrTy, SizeInBytes),
866 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
867 ConstantExpr::getPointerCast(Name, IntptrTy),
868 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
871 // Populate the first and last globals declared in this TU.
872 if (CheckInitOrder && GlobalHasDynamicInitializer) {
873 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
874 if (FirstDynamic == 0)
875 FirstDynamic = LastDynamic;
878 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
881 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
882 GlobalVariable *AllGlobals = new GlobalVariable(
883 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
884 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
886 // Create calls for poisoning before initializers run and unpoisoning after.
887 if (CheckInitOrder && FirstDynamic && LastDynamic)
888 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
889 IRB.CreateCall2(AsanRegisterGlobals,
890 IRB.CreatePointerCast(AllGlobals, IntptrTy),
891 ConstantInt::get(IntptrTy, n));
893 // We also need to unregister globals at the end, e.g. when a shared library
895 Function *AsanDtorFunction = Function::Create(
896 FunctionType::get(Type::getVoidTy(*C), false),
897 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
898 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
899 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
900 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
901 IRB.CreatePointerCast(AllGlobals, IntptrTy),
902 ConstantInt::get(IntptrTy, n));
903 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
909 void AddressSanitizer::initializeCallbacks(Module &M) {
911 // Create __asan_report* callbacks.
912 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
913 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
915 // IsWrite and TypeSize are encoded in the function name.
916 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
917 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
918 // If we are merging crash callbacks, they have two parameters.
919 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
920 checkInterfaceFunction(M.getOrInsertFunction(
921 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
925 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
926 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
927 // We insert an empty inline asm after __asan_report* to avoid callback merge.
928 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
929 StringRef(""), StringRef(""),
930 /*hasSideEffects=*/true);
934 bool AddressSanitizer::doInitialization(Module &M) {
935 // Initialize the private fields. No one has accessed them before.
936 TD = getAnalysisIfAvailable<DataLayout>();
940 BL.reset(new BlackList(BlacklistFile));
941 DynamicallyInitializedGlobals.Init(M);
943 C = &(M.getContext());
944 LongSize = TD->getPointerSizeInBits();
945 IntptrTy = Type::getIntNTy(*C, LongSize);
947 AsanCtorFunction = Function::Create(
948 FunctionType::get(Type::getVoidTy(*C), false),
949 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
950 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
951 // call __asan_init in the module ctor.
952 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
953 AsanInitFunction = checkInterfaceFunction(
954 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
955 AsanInitFunction->setLinkage(Function::ExternalLinkage);
956 IRB.CreateCall(AsanInitFunction);
958 llvm::Triple targetTriple(M.getTargetTriple());
959 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
961 MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
962 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
963 if (ClMappingOffsetLog >= 0) {
964 if (ClMappingOffsetLog == 0) {
968 MappingOffset = 1ULL << ClMappingOffsetLog;
973 if (ClMappingOffsetLog >= 0) {
974 // Tell the run-time the current values of mapping offset and scale.
975 GlobalValue *asan_mapping_offset =
976 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
977 ConstantInt::get(IntptrTy, MappingOffset),
978 kAsanMappingOffsetName);
979 // Read the global, otherwise it may be optimized away.
980 IRB.CreateLoad(asan_mapping_offset, true);
982 if (ClMappingScale) {
983 GlobalValue *asan_mapping_scale =
984 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
985 ConstantInt::get(IntptrTy, MappingScale()),
986 kAsanMappingScaleName);
987 // Read the global, otherwise it may be optimized away.
988 IRB.CreateLoad(asan_mapping_scale, true);
991 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
996 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
997 // For each NSObject descendant having a +load method, this method is invoked
998 // by the ObjC runtime before any of the static constructors is called.
999 // Therefore we need to instrument such methods with a call to __asan_init
1000 // at the beginning in order to initialize our runtime before any access to
1001 // the shadow memory.
1002 // We cannot just ignore these methods, because they may call other
1003 // instrumented functions.
1004 if (F.getName().find(" load]") != std::string::npos) {
1005 IRBuilder<> IRB(F.begin()->begin());
1006 IRB.CreateCall(AsanInitFunction);
1012 bool AddressSanitizer::runOnFunction(Function &F) {
1013 if (BL->isIn(F)) return false;
1014 if (&F == AsanCtorFunction) return false;
1015 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1016 initializeCallbacks(*F.getParent());
1018 // If needed, insert __asan_init before checking for AddressSafety attr.
1019 maybeInsertAsanInitAtFunctionEntry(F);
1021 if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1022 Attribute::AddressSafety))
1025 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1028 // We want to instrument every address only once per basic block (unless there
1029 // are calls between uses).
1030 SmallSet<Value*, 16> TempsToInstrument;
1031 SmallVector<Instruction*, 16> ToInstrument;
1032 SmallVector<Instruction*, 8> NoReturnCalls;
1035 // Fill the set of memory operations to instrument.
1036 for (Function::iterator FI = F.begin(), FE = F.end();
1038 TempsToInstrument.clear();
1039 int NumInsnsPerBB = 0;
1040 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1042 if (LooksLikeCodeInBug11395(BI)) return false;
1043 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1044 if (ClOpt && ClOptSameTemp) {
1045 if (!TempsToInstrument.insert(Addr))
1046 continue; // We've seen this temp in the current BB.
1048 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1051 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
1052 // A call inside BB.
1053 TempsToInstrument.clear();
1054 if (CI->doesNotReturn()) {
1055 NoReturnCalls.push_back(CI);
1060 ToInstrument.push_back(BI);
1062 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1068 int NumInstrumented = 0;
1069 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1070 Instruction *Inst = ToInstrument[i];
1071 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1072 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1073 if (isInterestingMemoryAccess(Inst, &IsWrite))
1074 instrumentMop(Inst);
1076 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1081 FunctionStackPoisoner FSP(F, *this);
1082 bool ChangedStack = FSP.runOnFunction();
1084 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1085 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1086 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1087 Instruction *CI = NoReturnCalls[i];
1088 IRBuilder<> IRB(CI);
1089 IRB.CreateCall(AsanHandleNoReturnFunc);
1091 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1093 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1096 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1097 if (ShadowRedzoneSize == 1) return PoisonByte;
1098 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1099 if (ShadowRedzoneSize == 4)
1100 return (PoisonByte << 24) + (PoisonByte << 16) +
1101 (PoisonByte << 8) + (PoisonByte);
1102 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1105 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1108 size_t ShadowGranularity,
1110 for (size_t i = 0; i < RZSize;
1111 i+= ShadowGranularity, Shadow++) {
1112 if (i + ShadowGranularity <= Size) {
1113 *Shadow = 0; // fully addressable
1114 } else if (i >= Size) {
1115 *Shadow = Magic; // unaddressable
1117 *Shadow = Size - i; // first Size-i bytes are addressable
1122 // Workaround for bug 11395: we don't want to instrument stack in functions
1123 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1124 // FIXME: remove once the bug 11395 is fixed.
1125 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1126 if (LongSize != 32) return false;
1127 CallInst *CI = dyn_cast<CallInst>(I);
1128 if (!CI || !CI->isInlineAsm()) return false;
1129 if (CI->getNumArgOperands() <= 5) return false;
1130 // We have inline assembly with quite a few arguments.
1134 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1135 IRBuilder<> IRB(*C);
1136 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1137 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1138 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1139 kAsanStackFreeName, IRB.getVoidTy(),
1140 IntptrTy, IntptrTy, IntptrTy, NULL));
1141 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1142 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1143 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1144 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1147 void FunctionStackPoisoner::poisonRedZones(
1148 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1150 size_t ShadowRZSize = RedzoneSize() >> MappingScale();
1151 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1152 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1153 Type *RZPtrTy = PointerType::get(RZTy, 0);
1155 Value *PoisonLeft = ConstantInt::get(RZTy,
1156 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1157 Value *PoisonMid = ConstantInt::get(RZTy,
1158 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1159 Value *PoisonRight = ConstantInt::get(RZTy,
1160 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1162 // poison the first red zone.
1163 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1165 // poison all other red zones.
1166 uint64_t Pos = RedzoneSize();
1167 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1168 AllocaInst *AI = AllocaVec[i];
1169 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1170 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1171 assert(AlignedSize - SizeInBytes < RedzoneSize());
1176 assert(ShadowBase->getType() == IntptrTy);
1177 if (SizeInBytes < AlignedSize) {
1178 // Poison the partial redzone at right
1179 Ptr = IRB.CreateAdd(
1180 ShadowBase, ConstantInt::get(IntptrTy,
1181 (Pos >> MappingScale()) - ShadowRZSize));
1182 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1183 uint32_t Poison = 0;
1185 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1187 1ULL << MappingScale(),
1188 kAsanStackPartialRedzoneMagic);
1190 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1191 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1194 // Poison the full redzone at right.
1195 Ptr = IRB.CreateAdd(ShadowBase,
1196 ConstantInt::get(IntptrTy, Pos >> MappingScale()));
1197 bool LastAlloca = (i == AllocaVec.size() - 1);
1198 Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1199 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1201 Pos += RedzoneSize();
1205 void FunctionStackPoisoner::poisonStack() {
1206 uint64_t LocalStackSize = TotalStackSize +
1207 (AllocaVec.size() + 1) * RedzoneSize();
1209 bool DoStackMalloc = ASan.CheckUseAfterReturn
1210 && LocalStackSize <= kMaxStackMallocSize;
1212 assert(AllocaVec.size() > 0);
1213 Instruction *InsBefore = AllocaVec[0];
1214 IRBuilder<> IRB(InsBefore);
1217 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1218 AllocaInst *MyAlloca =
1219 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1220 if (ClRealignStack && StackAlignment < RedzoneSize())
1221 StackAlignment = RedzoneSize();
1222 MyAlloca->setAlignment(StackAlignment);
1223 assert(MyAlloca->isStaticAlloca());
1224 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1225 Value *LocalStackBase = OrigStackBase;
1227 if (DoStackMalloc) {
1228 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1229 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1232 // This string will be parsed by the run-time (DescribeStackAddress).
1233 SmallString<2048> StackDescriptionStorage;
1234 raw_svector_ostream StackDescription(StackDescriptionStorage);
1235 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1237 // Insert poison calls for lifetime intrinsics for alloca.
1238 bool HavePoisonedAllocas = false;
1239 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1240 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1241 IntrinsicInst *II = APC.InsBefore;
1242 AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1244 IRBuilder<> IRB(II);
1245 poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1246 HavePoisonedAllocas |= APC.DoPoison;
1249 uint64_t Pos = RedzoneSize();
1250 // Replace Alloca instructions with base+offset.
1251 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1252 AllocaInst *AI = AllocaVec[i];
1253 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1254 StringRef Name = AI->getName();
1255 StackDescription << Pos << " " << SizeInBytes << " "
1256 << Name.size() << " " << Name << " ";
1257 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1258 assert((AlignedSize % RedzoneSize()) == 0);
1259 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1260 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1262 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1263 AI->replaceAllUsesWith(NewAllocaPtr);
1264 Pos += AlignedSize + RedzoneSize();
1266 assert(Pos == LocalStackSize);
1268 // Write the Magic value and the frame description constant to the redzone.
1269 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1270 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1272 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1273 ConstantInt::get(IntptrTy,
1275 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1276 GlobalVariable *StackDescriptionGlobal =
1277 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1278 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1280 IRB.CreateStore(Description, BasePlus1);
1282 // Poison the stack redzones at the entry.
1283 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1284 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1286 // Unpoison the stack before all ret instructions.
1287 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1288 Instruction *Ret = RetVec[i];
1289 IRBuilder<> IRBRet(Ret);
1290 // Mark the current frame as retired.
1291 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1293 // Unpoison the stack.
1294 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1295 if (DoStackMalloc) {
1296 // In use-after-return mode, mark the whole stack frame unaddressable.
1297 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1298 ConstantInt::get(IntptrTy, LocalStackSize),
1300 } else if (HavePoisonedAllocas) {
1301 // If we poisoned some allocas in llvm.lifetime analysis,
1302 // unpoison whole stack frame now.
1303 assert(LocalStackBase == OrigStackBase);
1304 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1308 // We are done. Remove the old unused alloca instructions.
1309 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1310 AllocaVec[i]->eraseFromParent();
1313 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1314 IRBuilder<> IRB, bool DoPoison) {
1315 // For now just insert the call to ASan runtime.
1316 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1317 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1318 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1319 : AsanUnpoisonStackMemoryFunc,
1323 // Handling llvm.lifetime intrinsics for a given %alloca:
1324 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1325 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1326 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1327 // could be poisoned by previous llvm.lifetime.end instruction, as the
1328 // variable may go in and out of scope several times, e.g. in loops).
1329 // (3) if we poisoned at least one %alloca in a function,
1330 // unpoison the whole stack frame at function exit.
1332 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1333 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1334 // We're intested only in allocas we can handle.
1335 return isInterestingAlloca(*AI) ? AI : 0;
1336 // See if we've already calculated (or started to calculate) alloca for a
1338 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1339 if (I != AllocaForValue.end())
1341 // Store 0 while we're calculating alloca for value V to avoid
1342 // infinite recursion if the value references itself.
1343 AllocaForValue[V] = 0;
1344 AllocaInst *Res = 0;
1345 if (CastInst *CI = dyn_cast<CastInst>(V))
1346 Res = findAllocaForValue(CI->getOperand(0));
1347 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1348 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1349 Value *IncValue = PN->getIncomingValue(i);
1350 // Allow self-referencing phi-nodes.
1351 if (IncValue == PN) continue;
1352 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1353 // AI for incoming values should exist and should all be equal.
1354 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1360 AllocaForValue[V] = Res;