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/DepthFirstIterator.h"
22 #include "llvm/ADT/OwningPtr.h"
23 #include "llvm/ADT/SmallSet.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/DataLayout.h"
29 #include "llvm/DIBuilder.h"
30 #include "llvm/Function.h"
31 #include "llvm/IRBuilder.h"
32 #include "llvm/InlineAsm.h"
33 #include "llvm/InstVisitor.h"
34 #include "llvm/IntrinsicInst.h"
35 #include "llvm/LLVMContext.h"
36 #include "llvm/Module.h"
37 #include "llvm/Support/CommandLine.h"
38 #include "llvm/Support/DataTypes.h"
39 #include "llvm/Support/Debug.h"
40 #include "llvm/Support/raw_ostream.h"
41 #include "llvm/Support/system_error.h"
42 #include "llvm/Target/TargetMachine.h"
43 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
44 #include "llvm/Transforms/Utils/Local.h"
45 #include "llvm/Transforms/Utils/ModuleUtils.h"
46 #include "llvm/Type.h"
52 static const uint64_t kDefaultShadowScale = 3;
53 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
54 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
55 static const uint64_t kDefaultShadowOffsetAndroid = 0;
57 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
58 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
59 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
61 static const char *kAsanModuleCtorName = "asan.module_ctor";
62 static const char *kAsanModuleDtorName = "asan.module_dtor";
63 static const int kAsanCtorAndCtorPriority = 1;
64 static const char *kAsanReportErrorTemplate = "__asan_report_";
65 static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
66 static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
67 static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
68 static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
69 static const char *kAsanInitName = "__asan_init";
70 static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
71 static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
72 static const char *kAsanMappingScaleName = "__asan_mapping_scale";
73 static const char *kAsanStackMallocName = "__asan_stack_malloc";
74 static const char *kAsanStackFreeName = "__asan_stack_free";
75 static const char *kAsanGenPrefix = "__asan_gen_";
76 static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
77 static const char *kAsanUnpoisonStackMemoryName =
78 "__asan_unpoison_stack_memory";
80 static const int kAsanStackLeftRedzoneMagic = 0xf1;
81 static const int kAsanStackMidRedzoneMagic = 0xf2;
82 static const int kAsanStackRightRedzoneMagic = 0xf3;
83 static const int kAsanStackPartialRedzoneMagic = 0xf4;
85 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
86 static const size_t kNumberOfAccessSizes = 5;
88 // Command-line flags.
90 // This flag may need to be replaced with -f[no-]asan-reads.
91 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
92 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
93 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
94 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
95 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
96 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
97 cl::Hidden, cl::init(true));
98 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
99 cl::desc("use instrumentation with slow path for all accesses"),
100 cl::Hidden, cl::init(false));
101 // This flag limits the number of instructions to be instrumented
102 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
103 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
105 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
107 cl::desc("maximal number of instructions to instrument in any given BB"),
109 // This flag may need to be replaced with -f[no]asan-stack.
110 static cl::opt<bool> ClStack("asan-stack",
111 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
112 // This flag may need to be replaced with -f[no]asan-use-after-return.
113 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
114 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
115 // This flag may need to be replaced with -f[no]asan-globals.
116 static cl::opt<bool> ClGlobals("asan-globals",
117 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
118 static cl::opt<bool> ClInitializers("asan-initialization-order",
119 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
120 static cl::opt<bool> ClMemIntrin("asan-memintrin",
121 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
122 static cl::opt<bool> ClRealignStack("asan-realign-stack",
123 cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
124 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
125 cl::desc("File containing the list of objects to ignore "
126 "during instrumentation"), cl::Hidden);
128 // These flags allow to change the shadow mapping.
129 // The shadow mapping looks like
130 // Shadow = (Mem >> scale) + (1 << offset_log)
131 static cl::opt<int> ClMappingScale("asan-mapping-scale",
132 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
133 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
134 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
136 // Optimization flags. Not user visible, used mostly for testing
137 // and benchmarking the tool.
138 static cl::opt<bool> ClOpt("asan-opt",
139 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
140 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
141 cl::desc("Instrument the same temp just once"), cl::Hidden,
143 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
144 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
146 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
147 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
148 cl::Hidden, cl::init(false));
151 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
153 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
154 cl::Hidden, cl::init(0));
155 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
156 cl::Hidden, cl::desc("Debug func"));
157 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
158 cl::Hidden, cl::init(-1));
159 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
160 cl::Hidden, cl::init(-1));
163 /// A set of dynamically initialized globals extracted from metadata.
164 class SetOfDynamicallyInitializedGlobals {
166 void Init(Module& M) {
167 // Clang generates metadata identifying all dynamically initialized globals.
168 NamedMDNode *DynamicGlobals =
169 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
172 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
173 MDNode *MDN = DynamicGlobals->getOperand(i);
174 assert(MDN->getNumOperands() == 1);
175 Value *VG = MDN->getOperand(0);
176 // The optimizer may optimize away a global entirely, in which case we
177 // cannot instrument access to it.
180 DynInitGlobals.insert(cast<GlobalVariable>(VG));
183 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
185 SmallSet<GlobalValue*, 32> DynInitGlobals;
188 static int MappingScale() {
189 return ClMappingScale ? ClMappingScale : kDefaultShadowScale;
192 static size_t RedzoneSize() {
193 // Redzone used for stack and globals is at least 32 bytes.
194 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
195 return std::max(32U, 1U << MappingScale());
198 /// AddressSanitizer: instrument the code in module to find memory bugs.
199 struct AddressSanitizer : public FunctionPass {
200 AddressSanitizer(bool CheckInitOrder = false,
201 bool CheckUseAfterReturn = false,
202 bool CheckLifetime = false,
203 StringRef BlacklistFile = StringRef())
205 CheckInitOrder(CheckInitOrder || ClInitializers),
206 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
207 CheckLifetime(CheckLifetime || ClCheckLifetime),
208 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
210 virtual const char *getPassName() const {
211 return "AddressSanitizerFunctionPass";
213 void instrumentMop(Instruction *I);
214 void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
215 Value *Addr, uint32_t TypeSize, bool IsWrite);
216 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
217 Value *ShadowValue, uint32_t TypeSize);
218 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
219 bool IsWrite, size_t AccessSizeIndex);
220 bool instrumentMemIntrinsic(MemIntrinsic *MI);
221 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
223 Instruction *InsertBefore, bool IsWrite);
224 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
225 bool runOnFunction(Function &F);
226 void createInitializerPoisonCalls(Module &M,
227 Value *FirstAddr, Value *LastAddr);
228 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
229 virtual bool doInitialization(Module &M);
230 static char ID; // Pass identification, replacement for typeid
233 void initializeCallbacks(Module &M);
235 bool ShouldInstrumentGlobal(GlobalVariable *G);
236 bool LooksLikeCodeInBug11395(Instruction *I);
237 void FindDynamicInitializers(Module &M);
240 bool CheckUseAfterReturn;
244 uint64_t MappingOffset;
247 Function *AsanCtorFunction;
248 Function *AsanInitFunction;
249 Function *AsanHandleNoReturnFunc;
250 SmallString<64> BlacklistFile;
251 OwningPtr<BlackList> BL;
252 // This array is indexed by AccessIsWrite and log2(AccessSize).
253 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
255 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
257 friend struct FunctionStackPoisoner;
260 class AddressSanitizerModule : public ModulePass {
262 AddressSanitizerModule(bool CheckInitOrder = false,
263 StringRef BlacklistFile = StringRef())
265 CheckInitOrder(CheckInitOrder || ClInitializers),
266 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
268 bool runOnModule(Module &M);
269 static char ID; // Pass identification, replacement for typeid
270 virtual const char *getPassName() const {
271 return "AddressSanitizerModule";
275 bool ShouldInstrumentGlobal(GlobalVariable *G);
276 void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
280 SmallString<64> BlacklistFile;
281 OwningPtr<BlackList> BL;
282 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
288 // Stack poisoning does not play well with exception handling.
289 // When an exception is thrown, we essentially bypass the code
290 // that unpoisones the stack. This is why the run-time library has
291 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
292 // stack in the interceptor. This however does not work inside the
293 // actual function which catches the exception. Most likely because the
294 // compiler hoists the load of the shadow value somewhere too high.
295 // This causes asan to report a non-existing bug on 453.povray.
296 // It sounds like an LLVM bug.
297 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
299 AddressSanitizer &ASan;
305 SmallVector<AllocaInst*, 16> AllocaVec;
306 SmallVector<Instruction*, 8> RetVec;
307 uint64_t TotalStackSize;
308 unsigned StackAlignment;
310 Function *AsanStackMallocFunc, *AsanStackFreeFunc;
311 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
313 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
314 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
315 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
316 TotalStackSize(0), StackAlignment(1 << MappingScale()) {}
318 bool runOnFunction() {
319 if (!ClStack) return false;
320 // Collect alloca, ret, lifetime instructions etc.
321 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
322 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
323 BasicBlock *BB = *DI;
326 if (AllocaVec.empty()) return false;
328 initializeCallbacks(*F.getParent());
338 // Finds all static Alloca instructions and puts
339 // poisoned red zones around all of them.
340 // Then unpoison everything back before the function returns.
343 // ----------------------- Visitors.
344 /// \brief Collect all Ret instructions.
345 void visitReturnInst(ReturnInst &RI) {
346 RetVec.push_back(&RI);
349 /// \brief Collect Alloca instructions we want (and can) handle.
350 void visitAllocaInst(AllocaInst &AI) {
351 if (AI.isArrayAllocation()) return;
352 if (!AI.isStaticAlloca()) return;
353 if (!AI.getAllocatedType()->isSized()) return;
355 StackAlignment = std::max(StackAlignment, AI.getAlignment());
356 AllocaVec.push_back(&AI);
357 uint64_t AlignedSize = getAlignedAllocaSize(&AI);
358 TotalStackSize += AlignedSize;
361 // ---------------------- Helpers.
362 void initializeCallbacks(Module &M);
364 uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
365 Type *Ty = AI->getAllocatedType();
366 uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
369 uint64_t getAlignedSize(uint64_t SizeInBytes) {
370 size_t RZ = RedzoneSize();
371 return ((SizeInBytes + RZ - 1) / RZ) * RZ;
373 uint64_t getAlignedAllocaSize(AllocaInst *AI) {
374 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
375 return getAlignedSize(SizeInBytes);
377 void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
378 Value *ShadowBase, bool DoPoison);
379 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
380 /// Analyze lifetime intrinsics for given alloca. Use Value* instead of
381 /// AllocaInst* here, as we call this method after we merge all allocas into a
382 /// single one. Returns true if ASan added some instrumentation.
383 bool handleAllocaLifetime(Value *Alloca);
384 /// Analyze lifetime intrinsics for a specific value, casted from alloca.
385 /// Returns true if if ASan added some instrumentation.
386 bool handleValueLifetime(Value *V);
391 char AddressSanitizer::ID = 0;
392 INITIALIZE_PASS(AddressSanitizer, "asan",
393 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
395 FunctionPass *llvm::createAddressSanitizerFunctionPass(
396 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
397 StringRef BlacklistFile) {
398 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
399 CheckLifetime, BlacklistFile);
402 char AddressSanitizerModule::ID = 0;
403 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
404 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
405 "ModulePass", false, false)
406 ModulePass *llvm::createAddressSanitizerModulePass(
407 bool CheckInitOrder, StringRef BlacklistFile) {
408 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
411 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
412 size_t Res = CountTrailingZeros_32(TypeSize / 8);
413 assert(Res < kNumberOfAccessSizes);
417 // Create a constant for Str so that we can pass it to the run-time lib.
418 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
419 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
420 return new GlobalVariable(M, StrConst->getType(), true,
421 GlobalValue::PrivateLinkage, StrConst,
425 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
426 return G->getName().find(kAsanGenPrefix) == 0;
429 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
431 Shadow = IRB.CreateLShr(Shadow, MappingScale());
432 if (MappingOffset == 0)
434 // (Shadow >> scale) | offset
435 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
439 void AddressSanitizer::instrumentMemIntrinsicParam(
440 Instruction *OrigIns,
441 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
442 // Check the first byte.
444 IRBuilder<> IRB(InsertBefore);
445 instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
447 // Check the last byte.
449 IRBuilder<> IRB(InsertBefore);
450 Value *SizeMinusOne = IRB.CreateSub(
451 Size, ConstantInt::get(Size->getType(), 1));
452 SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
453 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
454 Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
455 instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
459 // Instrument memset/memmove/memcpy
460 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
461 Value *Dst = MI->getDest();
462 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
463 Value *Src = MemTran ? MemTran->getSource() : 0;
464 Value *Length = MI->getLength();
466 Constant *ConstLength = dyn_cast<Constant>(Length);
467 Instruction *InsertBefore = MI;
469 if (ConstLength->isNullValue()) return false;
471 // The size is not a constant so it could be zero -- check at run-time.
472 IRBuilder<> IRB(InsertBefore);
474 Value *Cmp = IRB.CreateICmpNE(Length,
475 Constant::getNullValue(Length->getType()));
476 InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
479 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
481 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
485 // If I is an interesting memory access, return the PointerOperand
486 // and set IsWrite. Otherwise return NULL.
487 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
488 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
489 if (!ClInstrumentReads) return NULL;
491 return LI->getPointerOperand();
493 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
494 if (!ClInstrumentWrites) return NULL;
496 return SI->getPointerOperand();
498 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
499 if (!ClInstrumentAtomics) return NULL;
501 return RMW->getPointerOperand();
503 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
504 if (!ClInstrumentAtomics) return NULL;
506 return XCHG->getPointerOperand();
511 void AddressSanitizer::instrumentMop(Instruction *I) {
512 bool IsWrite = false;
513 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
515 if (ClOpt && ClOptGlobals) {
516 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
517 // If initialization order checking is disabled, a simple access to a
518 // dynamically initialized global is always valid.
521 // If a global variable does not have dynamic initialization we don't
522 // have to instrument it. However, if a global does not have initailizer
523 // at all, we assume it has dynamic initializer (in other TU).
524 if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
529 Type *OrigPtrTy = Addr->getType();
530 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
532 assert(OrigTy->isSized());
533 uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
535 if (TypeSize != 8 && TypeSize != 16 &&
536 TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
537 // Ignore all unusual sizes.
542 instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
545 // Validate the result of Module::getOrInsertFunction called for an interface
546 // function of AddressSanitizer. If the instrumented module defines a function
547 // with the same name, their prototypes must match, otherwise
548 // getOrInsertFunction returns a bitcast.
549 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
550 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
551 FuncOrBitcast->dump();
552 report_fatal_error("trying to redefine an AddressSanitizer "
553 "interface function");
556 Instruction *AddressSanitizer::generateCrashCode(
557 Instruction *InsertBefore, Value *Addr,
558 bool IsWrite, size_t AccessSizeIndex) {
559 IRBuilder<> IRB(InsertBefore);
560 CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
562 // We don't do Call->setDoesNotReturn() because the BB already has
563 // UnreachableInst at the end.
564 // This EmptyAsm is required to avoid callback merge.
565 IRB.CreateCall(EmptyAsm);
569 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
572 size_t Granularity = 1 << MappingScale();
573 // Addr & (Granularity - 1)
574 Value *LastAccessedByte = IRB.CreateAnd(
575 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
576 // (Addr & (Granularity - 1)) + size - 1
577 if (TypeSize / 8 > 1)
578 LastAccessedByte = IRB.CreateAdd(
579 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
580 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
581 LastAccessedByte = IRB.CreateIntCast(
582 LastAccessedByte, ShadowValue->getType(), false);
583 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
584 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
587 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
588 IRBuilder<> &IRB, Value *Addr,
589 uint32_t TypeSize, bool IsWrite) {
590 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
592 Type *ShadowTy = IntegerType::get(
593 *C, std::max(8U, TypeSize >> MappingScale()));
594 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
595 Value *ShadowPtr = memToShadow(AddrLong, IRB);
596 Value *CmpVal = Constant::getNullValue(ShadowTy);
597 Value *ShadowValue = IRB.CreateLoad(
598 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
600 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
601 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
602 size_t Granularity = 1 << MappingScale();
603 TerminatorInst *CrashTerm = 0;
605 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
606 TerminatorInst *CheckTerm =
607 SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
608 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
609 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
610 IRB.SetInsertPoint(CheckTerm);
611 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
612 BasicBlock *CrashBlock =
613 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
614 CrashTerm = new UnreachableInst(*C, CrashBlock);
615 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
616 ReplaceInstWithInst(CheckTerm, NewTerm);
618 CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
622 generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
623 Crash->setDebugLoc(OrigIns->getDebugLoc());
626 void AddressSanitizerModule::createInitializerPoisonCalls(
627 Module &M, Value *FirstAddr, Value *LastAddr) {
628 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
629 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
630 // If that function is not present, this TU contains no globals, or they have
631 // all been optimized away
635 // Set up the arguments to our poison/unpoison functions.
636 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
638 // Declare our poisoning and unpoisoning functions.
639 Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
640 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
641 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
642 Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
643 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
644 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
646 // Add a call to poison all external globals before the given function starts.
647 IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
649 // Add calls to unpoison all globals before each return instruction.
650 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
652 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
653 CallInst::Create(AsanUnpoisonGlobals, "", RI);
658 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
659 Type *Ty = cast<PointerType>(G->getType())->getElementType();
660 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
662 if (BL->isIn(*G)) return false;
663 if (!Ty->isSized()) return false;
664 if (!G->hasInitializer()) return false;
665 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
666 // Touch only those globals that will not be defined in other modules.
667 // Don't handle ODR type linkages since other modules may be built w/o asan.
668 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
669 G->getLinkage() != GlobalVariable::PrivateLinkage &&
670 G->getLinkage() != GlobalVariable::InternalLinkage)
672 // Two problems with thread-locals:
673 // - The address of the main thread's copy can't be computed at link-time.
674 // - Need to poison all copies, not just the main thread's one.
675 if (G->isThreadLocal())
677 // For now, just ignore this Alloca if the alignment is large.
678 if (G->getAlignment() > RedzoneSize()) return false;
680 // Ignore all the globals with the names starting with "\01L_OBJC_".
681 // Many of those are put into the .cstring section. The linker compresses
682 // that section by removing the spare \0s after the string terminator, so
683 // our redzones get broken.
684 if ((G->getName().find("\01L_OBJC_") == 0) ||
685 (G->getName().find("\01l_OBJC_") == 0)) {
686 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
690 if (G->hasSection()) {
691 StringRef Section(G->getSection());
692 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
693 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
695 if ((Section.find("__OBJC,") == 0) ||
696 (Section.find("__DATA, __objc_") == 0)) {
697 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
700 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
701 // Constant CFString instances are compiled in the following way:
702 // -- the string buffer is emitted into
703 // __TEXT,__cstring,cstring_literals
704 // -- the constant NSConstantString structure referencing that buffer
705 // is placed into __DATA,__cfstring
706 // Therefore there's no point in placing redzones into __DATA,__cfstring.
707 // Moreover, it causes the linker to crash on OS X 10.7
708 if (Section.find("__DATA,__cfstring") == 0) {
709 DEBUG(dbgs() << "Ignoring CFString: " << *G);
717 // This function replaces all global variables with new variables that have
718 // trailing redzones. It also creates a function that poisons
719 // redzones and inserts this function into llvm.global_ctors.
720 bool AddressSanitizerModule::runOnModule(Module &M) {
721 if (!ClGlobals) return false;
722 TD = getAnalysisIfAvailable<DataLayout>();
725 BL.reset(new BlackList(BlacklistFile));
726 if (BL->isIn(M)) return false;
727 DynamicallyInitializedGlobals.Init(M);
728 C = &(M.getContext());
729 IntptrTy = Type::getIntNTy(*C, TD->getPointerSizeInBits());
731 SmallVector<GlobalVariable *, 16> GlobalsToChange;
733 for (Module::GlobalListType::iterator G = M.global_begin(),
734 E = M.global_end(); G != E; ++G) {
735 if (ShouldInstrumentGlobal(G))
736 GlobalsToChange.push_back(G);
739 size_t n = GlobalsToChange.size();
740 if (n == 0) return false;
742 // A global is described by a structure
745 // size_t size_with_redzone;
747 // size_t has_dynamic_init;
748 // We initialize an array of such structures and pass it to a run-time call.
749 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
752 SmallVector<Constant *, 16> Initializers(n), DynamicInit;
755 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
757 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
759 // The addresses of the first and last dynamically initialized globals in
760 // this TU. Used in initialization order checking.
761 Value *FirstDynamic = 0, *LastDynamic = 0;
763 for (size_t i = 0; i < n; i++) {
764 GlobalVariable *G = GlobalsToChange[i];
765 PointerType *PtrTy = cast<PointerType>(G->getType());
766 Type *Ty = PtrTy->getElementType();
767 uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
768 size_t RZ = RedzoneSize();
769 uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
770 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
771 // Determine whether this global should be poisoned in initialization.
772 bool GlobalHasDynamicInitializer =
773 DynamicallyInitializedGlobals.Contains(G);
774 // Don't check initialization order if this global is blacklisted.
775 GlobalHasDynamicInitializer &= !BL->isInInit(*G);
777 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
778 Constant *NewInitializer = ConstantStruct::get(
779 NewTy, G->getInitializer(),
780 Constant::getNullValue(RightRedZoneTy), NULL);
782 SmallString<2048> DescriptionOfGlobal = G->getName();
783 DescriptionOfGlobal += " (";
784 DescriptionOfGlobal += M.getModuleIdentifier();
785 DescriptionOfGlobal += ")";
786 GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
788 // Create a new global variable with enough space for a redzone.
789 GlobalVariable *NewGlobal = new GlobalVariable(
790 M, NewTy, G->isConstant(), G->getLinkage(),
791 NewInitializer, "", G, G->getThreadLocalMode());
792 NewGlobal->copyAttributesFrom(G);
793 NewGlobal->setAlignment(RZ);
796 Indices2[0] = IRB.getInt32(0);
797 Indices2[1] = IRB.getInt32(0);
799 G->replaceAllUsesWith(
800 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
801 NewGlobal->takeName(G);
802 G->eraseFromParent();
804 Initializers[i] = ConstantStruct::get(
806 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
807 ConstantInt::get(IntptrTy, SizeInBytes),
808 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
809 ConstantExpr::getPointerCast(Name, IntptrTy),
810 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
813 // Populate the first and last globals declared in this TU.
814 if (CheckInitOrder && GlobalHasDynamicInitializer) {
815 LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
816 if (FirstDynamic == 0)
817 FirstDynamic = LastDynamic;
820 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
823 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
824 GlobalVariable *AllGlobals = new GlobalVariable(
825 M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
826 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
828 // Create calls for poisoning before initializers run and unpoisoning after.
829 if (CheckInitOrder && FirstDynamic && LastDynamic)
830 createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
832 Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
833 kAsanRegisterGlobalsName, IRB.getVoidTy(),
834 IntptrTy, IntptrTy, NULL));
835 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
837 IRB.CreateCall2(AsanRegisterGlobals,
838 IRB.CreatePointerCast(AllGlobals, IntptrTy),
839 ConstantInt::get(IntptrTy, n));
841 // We also need to unregister globals at the end, e.g. when a shared library
843 Function *AsanDtorFunction = Function::Create(
844 FunctionType::get(Type::getVoidTy(*C), false),
845 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
846 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
847 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
848 Function *AsanUnregisterGlobals =
849 checkInterfaceFunction(M.getOrInsertFunction(
850 kAsanUnregisterGlobalsName,
851 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
852 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
854 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
855 IRB.CreatePointerCast(AllGlobals, IntptrTy),
856 ConstantInt::get(IntptrTy, n));
857 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
863 void AddressSanitizer::initializeCallbacks(Module &M) {
865 // Create __asan_report* callbacks.
866 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
867 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
869 // IsWrite and TypeSize are encoded in the function name.
870 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
871 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
872 // If we are merging crash callbacks, they have two parameters.
873 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
874 checkInterfaceFunction(M.getOrInsertFunction(
875 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
879 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
880 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
881 // We insert an empty inline asm after __asan_report* to avoid callback merge.
882 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
883 StringRef(""), StringRef(""),
884 /*hasSideEffects=*/true);
888 bool AddressSanitizer::doInitialization(Module &M) {
889 // Initialize the private fields. No one has accessed them before.
890 TD = getAnalysisIfAvailable<DataLayout>();
894 BL.reset(new BlackList(BlacklistFile));
895 DynamicallyInitializedGlobals.Init(M);
897 C = &(M.getContext());
898 LongSize = TD->getPointerSizeInBits();
899 IntptrTy = Type::getIntNTy(*C, LongSize);
901 AsanCtorFunction = Function::Create(
902 FunctionType::get(Type::getVoidTy(*C), false),
903 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
904 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
905 // call __asan_init in the module ctor.
906 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
907 AsanInitFunction = checkInterfaceFunction(
908 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
909 AsanInitFunction->setLinkage(Function::ExternalLinkage);
910 IRB.CreateCall(AsanInitFunction);
912 llvm::Triple targetTriple(M.getTargetTriple());
913 bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
915 MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
916 (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
917 if (ClMappingOffsetLog >= 0) {
918 if (ClMappingOffsetLog == 0) {
922 MappingOffset = 1ULL << ClMappingOffsetLog;
927 if (ClMappingOffsetLog >= 0) {
928 // Tell the run-time the current values of mapping offset and scale.
929 GlobalValue *asan_mapping_offset =
930 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
931 ConstantInt::get(IntptrTy, MappingOffset),
932 kAsanMappingOffsetName);
933 // Read the global, otherwise it may be optimized away.
934 IRB.CreateLoad(asan_mapping_offset, true);
936 if (ClMappingScale) {
937 GlobalValue *asan_mapping_scale =
938 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
939 ConstantInt::get(IntptrTy, MappingScale()),
940 kAsanMappingScaleName);
941 // Read the global, otherwise it may be optimized away.
942 IRB.CreateLoad(asan_mapping_scale, true);
945 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
950 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
951 // For each NSObject descendant having a +load method, this method is invoked
952 // by the ObjC runtime before any of the static constructors is called.
953 // Therefore we need to instrument such methods with a call to __asan_init
954 // at the beginning in order to initialize our runtime before any access to
955 // the shadow memory.
956 // We cannot just ignore these methods, because they may call other
957 // instrumented functions.
958 if (F.getName().find(" load]") != std::string::npos) {
959 IRBuilder<> IRB(F.begin()->begin());
960 IRB.CreateCall(AsanInitFunction);
966 bool AddressSanitizer::runOnFunction(Function &F) {
967 if (BL->isIn(F)) return false;
968 if (&F == AsanCtorFunction) return false;
969 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
970 initializeCallbacks(*F.getParent());
972 // If needed, insert __asan_init before checking for AddressSafety attr.
973 maybeInsertAsanInitAtFunctionEntry(F);
975 if (!F.getFnAttributes().hasAttribute(Attribute::AddressSafety))
978 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
981 // We want to instrument every address only once per basic block (unless there
982 // are calls between uses).
983 SmallSet<Value*, 16> TempsToInstrument;
984 SmallVector<Instruction*, 16> ToInstrument;
985 SmallVector<Instruction*, 8> NoReturnCalls;
988 // Fill the set of memory operations to instrument.
989 for (Function::iterator FI = F.begin(), FE = F.end();
991 TempsToInstrument.clear();
992 int NumInsnsPerBB = 0;
993 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
995 if (LooksLikeCodeInBug11395(BI)) return false;
996 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
997 if (ClOpt && ClOptSameTemp) {
998 if (!TempsToInstrument.insert(Addr))
999 continue; // We've seen this temp in the current BB.
1001 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1004 if (CallInst *CI = dyn_cast<CallInst>(BI)) {
1005 // A call inside BB.
1006 TempsToInstrument.clear();
1007 if (CI->doesNotReturn()) {
1008 NoReturnCalls.push_back(CI);
1013 ToInstrument.push_back(BI);
1015 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1021 int NumInstrumented = 0;
1022 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1023 Instruction *Inst = ToInstrument[i];
1024 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1025 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1026 if (isInterestingMemoryAccess(Inst, &IsWrite))
1027 instrumentMop(Inst);
1029 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1034 FunctionStackPoisoner FSP(F, *this);
1035 bool ChangedStack = FSP.runOnFunction();
1037 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1038 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1039 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1040 Instruction *CI = NoReturnCalls[i];
1041 IRBuilder<> IRB(CI);
1042 IRB.CreateCall(AsanHandleNoReturnFunc);
1044 DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1046 return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1049 static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1050 if (ShadowRedzoneSize == 1) return PoisonByte;
1051 if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1052 if (ShadowRedzoneSize == 4)
1053 return (PoisonByte << 24) + (PoisonByte << 16) +
1054 (PoisonByte << 8) + (PoisonByte);
1055 llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1058 static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1061 size_t ShadowGranularity,
1063 for (size_t i = 0; i < RZSize;
1064 i+= ShadowGranularity, Shadow++) {
1065 if (i + ShadowGranularity <= Size) {
1066 *Shadow = 0; // fully addressable
1067 } else if (i >= Size) {
1068 *Shadow = Magic; // unaddressable
1070 *Shadow = Size - i; // first Size-i bytes are addressable
1075 // Workaround for bug 11395: we don't want to instrument stack in functions
1076 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1077 // FIXME: remove once the bug 11395 is fixed.
1078 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1079 if (LongSize != 32) return false;
1080 CallInst *CI = dyn_cast<CallInst>(I);
1081 if (!CI || !CI->isInlineAsm()) return false;
1082 if (CI->getNumArgOperands() <= 5) return false;
1083 // We have inline assembly with quite a few arguments.
1087 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1088 IRBuilder<> IRB(*C);
1089 AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1090 kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1091 AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1092 kAsanStackFreeName, IRB.getVoidTy(),
1093 IntptrTy, IntptrTy, IntptrTy, NULL));
1094 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1095 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1096 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1097 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1100 void FunctionStackPoisoner::poisonRedZones(
1101 const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1103 size_t ShadowRZSize = RedzoneSize() >> MappingScale();
1104 assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1105 Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1106 Type *RZPtrTy = PointerType::get(RZTy, 0);
1108 Value *PoisonLeft = ConstantInt::get(RZTy,
1109 ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1110 Value *PoisonMid = ConstantInt::get(RZTy,
1111 ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1112 Value *PoisonRight = ConstantInt::get(RZTy,
1113 ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1115 // poison the first red zone.
1116 IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1118 // poison all other red zones.
1119 uint64_t Pos = RedzoneSize();
1120 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1121 AllocaInst *AI = AllocaVec[i];
1122 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1123 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1124 assert(AlignedSize - SizeInBytes < RedzoneSize());
1129 assert(ShadowBase->getType() == IntptrTy);
1130 if (SizeInBytes < AlignedSize) {
1131 // Poison the partial redzone at right
1132 Ptr = IRB.CreateAdd(
1133 ShadowBase, ConstantInt::get(IntptrTy,
1134 (Pos >> MappingScale()) - ShadowRZSize));
1135 size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1136 uint32_t Poison = 0;
1138 PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1140 1ULL << MappingScale(),
1141 kAsanStackPartialRedzoneMagic);
1143 Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1144 IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1147 // Poison the full redzone at right.
1148 Ptr = IRB.CreateAdd(ShadowBase,
1149 ConstantInt::get(IntptrTy, Pos >> MappingScale()));
1150 Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1151 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1153 Pos += RedzoneSize();
1157 void FunctionStackPoisoner::poisonStack() {
1158 bool HavePoisonedAllocas = false;
1159 uint64_t LocalStackSize = TotalStackSize +
1160 (AllocaVec.size() + 1) * RedzoneSize();
1162 bool DoStackMalloc = ASan.CheckUseAfterReturn
1163 && LocalStackSize <= kMaxStackMallocSize;
1165 Instruction *InsBefore = AllocaVec[0];
1166 IRBuilder<> IRB(InsBefore);
1169 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1170 AllocaInst *MyAlloca =
1171 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1172 if (ClRealignStack && StackAlignment < RedzoneSize())
1173 StackAlignment = RedzoneSize();
1174 MyAlloca->setAlignment(StackAlignment);
1175 assert(MyAlloca->isStaticAlloca());
1176 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1177 Value *LocalStackBase = OrigStackBase;
1179 if (DoStackMalloc) {
1180 LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1181 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1184 // This string will be parsed by the run-time (DescribeStackAddress).
1185 SmallString<2048> StackDescriptionStorage;
1186 raw_svector_ostream StackDescription(StackDescriptionStorage);
1187 StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1189 uint64_t Pos = RedzoneSize();
1190 // Replace Alloca instructions with base+offset.
1191 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1192 AllocaInst *AI = AllocaVec[i];
1193 uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1194 StringRef Name = AI->getName();
1195 StackDescription << Pos << " " << SizeInBytes << " "
1196 << Name.size() << " " << Name << " ";
1197 uint64_t AlignedSize = getAlignedAllocaSize(AI);
1198 assert((AlignedSize % RedzoneSize()) == 0);
1199 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1200 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1202 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1203 AI->replaceAllUsesWith(NewAllocaPtr);
1204 // Analyze lifetime intrinsics only for static allocas we handle.
1205 if (ASan.CheckLifetime)
1206 HavePoisonedAllocas |= handleAllocaLifetime(NewAllocaPtr);
1207 Pos += AlignedSize + RedzoneSize();
1209 assert(Pos == LocalStackSize);
1211 // Write the Magic value and the frame description constant to the redzone.
1212 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1213 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1215 Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1216 ConstantInt::get(IntptrTy,
1218 BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1219 GlobalVariable *StackDescriptionGlobal =
1220 createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1221 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1223 IRB.CreateStore(Description, BasePlus1);
1225 // Poison the stack redzones at the entry.
1226 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1227 poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1229 // Unpoison the stack before all ret instructions.
1230 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1231 Instruction *Ret = RetVec[i];
1232 IRBuilder<> IRBRet(Ret);
1233 // Mark the current frame as retired.
1234 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1236 // Unpoison the stack.
1237 poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1238 if (DoStackMalloc) {
1239 // In use-after-return mode, mark the whole stack frame unaddressable.
1240 IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1241 ConstantInt::get(IntptrTy, LocalStackSize),
1243 } else if (HavePoisonedAllocas) {
1244 // If we poisoned some allocas in llvm.lifetime analysis,
1245 // unpoison whole stack frame now.
1246 assert(LocalStackBase == OrigStackBase);
1247 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1251 // We are done. Remove the old unused alloca instructions.
1252 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1253 AllocaVec[i]->eraseFromParent();
1256 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1257 IRBuilder<> IRB, bool DoPoison) {
1258 // For now just insert the call to ASan runtime.
1259 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1260 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1261 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1262 : AsanUnpoisonStackMemoryFunc,
1266 // Handling llvm.lifetime intrinsics for a given %alloca:
1267 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1268 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1269 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1270 // could be poisoned by previous llvm.lifetime.end instruction, as the
1271 // variable may go in and out of scope several times, e.g. in loops).
1272 // (3) if we poisoned at least one %alloca in a function,
1273 // unpoison the whole stack frame at function exit.
1274 bool FunctionStackPoisoner::handleAllocaLifetime(Value *Alloca) {
1275 assert(ASan.CheckLifetime);
1276 Type *AllocaType = Alloca->getType();
1277 Type *Int8PtrTy = Type::getInt8PtrTy(AllocaType->getContext());
1280 // Typical code looks like this:
1281 // %alloca = alloca <type>, <alignment>
1282 // ... some code ...
1283 // %val1 = bitcast <type>* %alloca to i8*
1284 // call void @llvm.lifetime.start(i64 <size>, i8* %val1)
1285 // ... more code ...
1286 // %val2 = bitcast <type>* %alloca to i8*
1287 // call void @llvm.lifetime.start(i64 <size>, i8* %val2)
1288 // That is, to handle %alloca we must find all its casts to
1289 // i8* values, and find lifetime instructions for these values.
1290 if (AllocaType == Int8PtrTy)
1291 Res |= handleValueLifetime(Alloca);
1292 for (Value::use_iterator UI = Alloca->use_begin(), UE = Alloca->use_end();
1294 if (UI->getType() != Int8PtrTy) continue;
1295 if (UI->stripPointerCasts() != Alloca) continue;
1296 Res |= handleValueLifetime(*UI);
1301 bool FunctionStackPoisoner::handleValueLifetime(Value *V) {
1302 assert(ASan.CheckLifetime);
1304 for (Value::use_iterator UI = V->use_begin(), UE = V->use_end(); UI != UE;
1306 IntrinsicInst *II = dyn_cast<IntrinsicInst>(*UI);
1308 Intrinsic::ID ID = II->getIntrinsicID();
1309 if (ID != Intrinsic::lifetime_start &&
1310 ID != Intrinsic::lifetime_end)
1312 if (V != II->getArgOperand(1))
1314 // Found lifetime intrinsic, add ASan instrumentation if necessary.
1315 ConstantInt *Size = dyn_cast<ConstantInt>(II->getArgOperand(0));
1316 // If size argument is undefined, don't do anything.
1317 if (Size->isMinusOne())
1319 // Check that size doesn't saturate uint64_t and can
1320 // be stored in IntptrTy.
1321 const uint64_t SizeValue = Size->getValue().getLimitedValue();
1322 if (SizeValue == ~0ULL ||
1323 !ConstantInt::isValueValidForType(IntptrTy, SizeValue)) {
1326 IRBuilder<> IRB(II);
1327 bool DoPoison = (ID == Intrinsic::lifetime_end);
1328 poisonAlloca(V, SizeValue, IRB, DoPoison);