1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 // Details of the algorithm:
12 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
14 //===----------------------------------------------------------------------===//
16 #define DEBUG_TYPE "asan"
18 #include "llvm/Transforms/Instrumentation.h"
19 #include "llvm/ADT/ArrayRef.h"
20 #include "llvm/ADT/DenseMap.h"
21 #include "llvm/ADT/DepthFirstIterator.h"
22 #include "llvm/ADT/OwningPtr.h"
23 #include "llvm/ADT/SmallSet.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/ADT/SmallVector.h"
26 #include "llvm/ADT/Statistic.h"
27 #include "llvm/ADT/StringExtras.h"
28 #include "llvm/ADT/Triple.h"
29 #include "llvm/DIBuilder.h"
30 #include "llvm/IR/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/MDBuilder.h"
37 #include "llvm/IR/Module.h"
38 #include "llvm/IR/Type.h"
39 #include "llvm/InstVisitor.h"
40 #include "llvm/Support/CallSite.h"
41 #include "llvm/Support/CommandLine.h"
42 #include "llvm/Support/DataTypes.h"
43 #include "llvm/Support/Debug.h"
44 #include "llvm/Support/Endian.h"
45 #include "llvm/Support/system_error.h"
46 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
47 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
48 #include "llvm/Transforms/Utils/Cloning.h"
49 #include "llvm/Transforms/Utils/Local.h"
50 #include "llvm/Transforms/Utils/ModuleUtils.h"
51 #include "llvm/Transforms/Utils/SpecialCaseList.h"
57 static const uint64_t kDefaultShadowScale = 3;
58 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
59 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
60 static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000; // < 2G.
61 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
62 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
63 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
64 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
66 static const size_t kMinStackMallocSize = 1 << 6; // 64B
67 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
68 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
69 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
71 static const char *const kAsanModuleCtorName = "asan.module_ctor";
72 static const char *const kAsanModuleDtorName = "asan.module_dtor";
73 static const int kAsanCtorAndCtorPriority = 1;
74 static const char *const kAsanReportErrorTemplate = "__asan_report_";
75 static const char *const kAsanReportLoadN = "__asan_report_load_n";
76 static const char *const kAsanReportStoreN = "__asan_report_store_n";
77 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
78 static const char *const kAsanUnregisterGlobalsName =
79 "__asan_unregister_globals";
80 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
81 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
82 static const char *const kAsanInitName = "__asan_init_v3";
83 static const char *const kAsanCovName = "__sanitizer_cov";
84 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
85 static const char *const kAsanMappingOffsetName = "__asan_mapping_offset";
86 static const char *const kAsanMappingScaleName = "__asan_mapping_scale";
87 static const int kMaxAsanStackMallocSizeClass = 10;
88 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
89 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
90 static const char *const kAsanGenPrefix = "__asan_gen_";
91 static const char *const kAsanPoisonStackMemoryName =
92 "__asan_poison_stack_memory";
93 static const char *const kAsanUnpoisonStackMemoryName =
94 "__asan_unpoison_stack_memory";
96 static const char *const kAsanOptionDetectUAR =
97 "__asan_option_detect_stack_use_after_return";
100 static const int kAsanStackAfterReturnMagic = 0xf5;
103 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
104 static const size_t kNumberOfAccessSizes = 5;
106 // Command-line flags.
108 // This flag may need to be replaced with -f[no-]asan-reads.
109 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
110 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
111 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
112 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
113 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
114 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
115 cl::Hidden, cl::init(true));
116 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
117 cl::desc("use instrumentation with slow path for all accesses"),
118 cl::Hidden, cl::init(false));
119 // This flag limits the number of instructions to be instrumented
120 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
121 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
123 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
125 cl::desc("maximal number of instructions to instrument in any given BB"),
127 // This flag may need to be replaced with -f[no]asan-stack.
128 static cl::opt<bool> ClStack("asan-stack",
129 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
130 // This flag may need to be replaced with -f[no]asan-use-after-return.
131 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
132 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
133 // This flag may need to be replaced with -f[no]asan-globals.
134 static cl::opt<bool> ClGlobals("asan-globals",
135 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
136 static cl::opt<int> ClCoverage("asan-coverage",
137 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"),
138 cl::Hidden, cl::init(false));
139 static cl::opt<bool> ClInitializers("asan-initialization-order",
140 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
141 static cl::opt<bool> ClMemIntrin("asan-memintrin",
142 cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
143 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
144 cl::desc("Realign stack to the value of this flag (power of two)"),
145 cl::Hidden, cl::init(32));
146 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
147 cl::desc("File containing the list of objects to ignore "
148 "during instrumentation"), cl::Hidden);
150 // This is an experimental feature that will allow to choose between
151 // instrumented and non-instrumented code at link-time.
152 // If this option is on, just before instrumenting a function we create its
153 // clone; if the function is not changed by asan the clone is deleted.
154 // If we end up with a clone, we put the instrumented function into a section
155 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
157 // This is still a prototype, we need to figure out a way to keep two copies of
158 // a function so that the linker can easily choose one of them.
159 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
160 cl::desc("Keep uninstrumented copies of functions"),
161 cl::Hidden, cl::init(false));
163 // These flags allow to change the shadow mapping.
164 // The shadow mapping looks like
165 // Shadow = (Mem >> scale) + (1 << offset_log)
166 static cl::opt<int> ClMappingScale("asan-mapping-scale",
167 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
168 static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
169 cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
170 static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
171 cl::desc("Use short immediate constant as the mapping offset for 64bit"),
172 cl::Hidden, cl::init(true));
174 // Optimization flags. Not user visible, used mostly for testing
175 // and benchmarking the tool.
176 static cl::opt<bool> ClOpt("asan-opt",
177 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
178 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
179 cl::desc("Instrument the same temp just once"), cl::Hidden,
181 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
182 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
184 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
185 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
186 cl::Hidden, cl::init(false));
189 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
191 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
192 cl::Hidden, cl::init(0));
193 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
194 cl::Hidden, cl::desc("Debug func"));
195 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
196 cl::Hidden, cl::init(-1));
197 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
198 cl::Hidden, cl::init(-1));
200 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
201 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
202 STATISTIC(NumOptimizedAccessesToGlobalArray,
203 "Number of optimized accesses to global arrays");
204 STATISTIC(NumOptimizedAccessesToGlobalVar,
205 "Number of optimized accesses to global vars");
208 /// A set of dynamically initialized globals extracted from metadata.
209 class SetOfDynamicallyInitializedGlobals {
211 void Init(Module& M) {
212 // Clang generates metadata identifying all dynamically initialized globals.
213 NamedMDNode *DynamicGlobals =
214 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
217 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
218 MDNode *MDN = DynamicGlobals->getOperand(i);
219 assert(MDN->getNumOperands() == 1);
220 Value *VG = MDN->getOperand(0);
221 // The optimizer may optimize away a global entirely, in which case we
222 // cannot instrument access to it.
225 DynInitGlobals.insert(cast<GlobalVariable>(VG));
228 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
230 SmallSet<GlobalValue*, 32> DynInitGlobals;
233 /// This struct defines the shadow mapping using the rule:
234 /// shadow = (mem >> Scale) ADD-or-OR Offset.
235 struct ShadowMapping {
241 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
242 llvm::Triple TargetTriple(M.getTargetTriple());
243 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
244 bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
245 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
246 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
247 TargetTriple.getArch() == llvm::Triple::ppc64le;
248 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
249 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
250 TargetTriple.getArch() == llvm::Triple::mipsel;
252 ShadowMapping Mapping;
254 // OR-ing shadow offset if more efficient (at least on x86),
255 // but on ppc64 we have to use add since the shadow offset is not necessary
256 // 1/8-th of the address space.
257 Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
259 Mapping.Offset = IsAndroid ? 0 :
261 (IsMIPS32 ? kMIPS32_ShadowOffset32 :
262 (IsFreeBSD ? kFreeBSD_ShadowOffset32 : kDefaultShadowOffset32)) :
263 IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
264 if (!IsAndroid && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
265 assert(LongSize == 64);
266 Mapping.Offset = (IsFreeBSD ?
267 kFreeBSD_ShadowOffset64 : kDefaultShort64bitShadowOffset);
269 if (!IsAndroid && ClMappingOffsetLog >= 0) {
270 // Zero offset log is the special case.
271 Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
274 Mapping.Scale = kDefaultShadowScale;
275 if (ClMappingScale) {
276 Mapping.Scale = ClMappingScale;
282 static size_t RedzoneSizeForScale(int MappingScale) {
283 // Redzone used for stack and globals is at least 32 bytes.
284 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
285 return std::max(32U, 1U << MappingScale);
288 /// AddressSanitizer: instrument the code in module to find memory bugs.
289 struct AddressSanitizer : public FunctionPass {
290 AddressSanitizer(bool CheckInitOrder = true,
291 bool CheckUseAfterReturn = false,
292 bool CheckLifetime = false,
293 StringRef BlacklistFile = StringRef())
295 CheckInitOrder(CheckInitOrder || ClInitializers),
296 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
297 CheckLifetime(CheckLifetime || ClCheckLifetime),
298 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
300 virtual const char *getPassName() const {
301 return "AddressSanitizerFunctionPass";
303 void instrumentMop(Instruction *I);
304 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
305 Value *Addr, uint32_t TypeSize, bool IsWrite,
306 Value *SizeArgument);
307 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
308 Value *ShadowValue, uint32_t TypeSize);
309 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
310 bool IsWrite, size_t AccessSizeIndex,
311 Value *SizeArgument);
312 bool instrumentMemIntrinsic(MemIntrinsic *MI);
313 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
315 Instruction *InsertBefore, bool IsWrite);
316 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
317 bool runOnFunction(Function &F);
318 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
319 void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
320 virtual bool doInitialization(Module &M);
321 static char ID; // Pass identification, replacement for typeid
324 void initializeCallbacks(Module &M);
326 bool ShouldInstrumentGlobal(GlobalVariable *G);
327 bool LooksLikeCodeInBug11395(Instruction *I);
328 void FindDynamicInitializers(Module &M);
329 bool GlobalIsLinkerInitialized(GlobalVariable *G);
330 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks);
331 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
334 bool CheckUseAfterReturn;
336 SmallString<64> BlacklistFile;
342 ShadowMapping Mapping;
343 Function *AsanCtorFunction;
344 Function *AsanInitFunction;
345 Function *AsanHandleNoReturnFunc;
346 Function *AsanCovFunction;
347 OwningPtr<SpecialCaseList> BL;
348 // This array is indexed by AccessIsWrite and log2(AccessSize).
349 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
350 // This array is indexed by AccessIsWrite.
351 Function *AsanErrorCallbackSized[2];
353 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
355 friend struct FunctionStackPoisoner;
358 class AddressSanitizerModule : public ModulePass {
360 AddressSanitizerModule(bool CheckInitOrder = true,
361 StringRef BlacklistFile = StringRef())
363 CheckInitOrder(CheckInitOrder || ClInitializers),
364 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
366 bool runOnModule(Module &M);
367 static char ID; // Pass identification, replacement for typeid
368 virtual const char *getPassName() const {
369 return "AddressSanitizerModule";
373 void initializeCallbacks(Module &M);
375 bool ShouldInstrumentGlobal(GlobalVariable *G);
376 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
377 size_t MinRedzoneSizeForGlobal() const {
378 return RedzoneSizeForScale(Mapping.Scale);
382 SmallString<64> BlacklistFile;
384 OwningPtr<SpecialCaseList> BL;
385 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
389 ShadowMapping Mapping;
390 Function *AsanPoisonGlobals;
391 Function *AsanUnpoisonGlobals;
392 Function *AsanRegisterGlobals;
393 Function *AsanUnregisterGlobals;
396 // Stack poisoning does not play well with exception handling.
397 // When an exception is thrown, we essentially bypass the code
398 // that unpoisones the stack. This is why the run-time library has
399 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
400 // stack in the interceptor. This however does not work inside the
401 // actual function which catches the exception. Most likely because the
402 // compiler hoists the load of the shadow value somewhere too high.
403 // This causes asan to report a non-existing bug on 453.povray.
404 // It sounds like an LLVM bug.
405 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
407 AddressSanitizer &ASan;
412 ShadowMapping Mapping;
414 SmallVector<AllocaInst*, 16> AllocaVec;
415 SmallVector<Instruction*, 8> RetVec;
416 unsigned StackAlignment;
418 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
419 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
420 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
422 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
423 struct AllocaPoisonCall {
424 IntrinsicInst *InsBefore;
429 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
431 // Maps Value to an AllocaInst from which the Value is originated.
432 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
433 AllocaForValueMapTy AllocaForValue;
435 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
436 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
437 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
438 Mapping(ASan.Mapping),
439 StackAlignment(1 << Mapping.Scale) {}
441 bool runOnFunction() {
442 if (!ClStack) return false;
443 // Collect alloca, ret, lifetime instructions etc.
444 for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
445 DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
446 BasicBlock *BB = *DI;
449 if (AllocaVec.empty()) return false;
451 initializeCallbacks(*F.getParent());
461 // Finds all static Alloca instructions and puts
462 // poisoned red zones around all of them.
463 // Then unpoison everything back before the function returns.
466 // ----------------------- Visitors.
467 /// \brief Collect all Ret instructions.
468 void visitReturnInst(ReturnInst &RI) {
469 RetVec.push_back(&RI);
472 /// \brief Collect Alloca instructions we want (and can) handle.
473 void visitAllocaInst(AllocaInst &AI) {
474 if (!isInterestingAlloca(AI)) return;
476 StackAlignment = std::max(StackAlignment, AI.getAlignment());
477 AllocaVec.push_back(&AI);
480 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
482 void visitIntrinsicInst(IntrinsicInst &II) {
483 if (!ASan.CheckLifetime) return;
484 Intrinsic::ID ID = II.getIntrinsicID();
485 if (ID != Intrinsic::lifetime_start &&
486 ID != Intrinsic::lifetime_end)
488 // Found lifetime intrinsic, add ASan instrumentation if necessary.
489 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
490 // If size argument is undefined, don't do anything.
491 if (Size->isMinusOne()) return;
492 // Check that size doesn't saturate uint64_t and can
493 // be stored in IntptrTy.
494 const uint64_t SizeValue = Size->getValue().getLimitedValue();
495 if (SizeValue == ~0ULL ||
496 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
498 // Find alloca instruction that corresponds to llvm.lifetime argument.
499 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
501 bool DoPoison = (ID == Intrinsic::lifetime_end);
502 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
503 AllocaPoisonCallVec.push_back(APC);
506 // ---------------------- Helpers.
507 void initializeCallbacks(Module &M);
509 // Check if we want (and can) handle this alloca.
510 bool isInterestingAlloca(AllocaInst &AI) const {
511 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
512 AI.getAllocatedType()->isSized() &&
513 // alloca() may be called with 0 size, ignore it.
514 getAllocaSizeInBytes(&AI) > 0);
517 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
518 Type *Ty = AI->getAllocatedType();
519 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
522 /// Finds alloca where the value comes from.
523 AllocaInst *findAllocaForValue(Value *V);
524 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
525 Value *ShadowBase, bool DoPoison);
526 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
528 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
534 char AddressSanitizer::ID = 0;
535 INITIALIZE_PASS(AddressSanitizer, "asan",
536 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
538 FunctionPass *llvm::createAddressSanitizerFunctionPass(
539 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
540 StringRef BlacklistFile) {
541 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
542 CheckLifetime, BlacklistFile);
545 char AddressSanitizerModule::ID = 0;
546 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
547 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
548 "ModulePass", false, false)
549 ModulePass *llvm::createAddressSanitizerModulePass(
550 bool CheckInitOrder, StringRef BlacklistFile) {
551 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
554 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
555 size_t Res = countTrailingZeros(TypeSize / 8);
556 assert(Res < kNumberOfAccessSizes);
560 // \brief Create a constant for Str so that we can pass it to the run-time lib.
561 static GlobalVariable *createPrivateGlobalForString(
562 Module &M, StringRef Str, bool AllowMerging) {
563 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
564 // We use private linkage for module-local strings. If they can be merged
565 // with another one, we set the unnamed_addr attribute.
567 new GlobalVariable(M, StrConst->getType(), true,
568 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
570 GV->setUnnamedAddr(true);
571 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
575 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
576 return G->getName().find(kAsanGenPrefix) == 0;
579 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
581 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
582 if (Mapping.Offset == 0)
584 // (Shadow >> scale) | offset
585 if (Mapping.OrShadowOffset)
586 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
588 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
591 void AddressSanitizer::instrumentMemIntrinsicParam(
592 Instruction *OrigIns,
593 Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
594 IRBuilder<> IRB(InsertBefore);
595 if (Size->getType() != IntptrTy)
596 Size = IRB.CreateIntCast(Size, IntptrTy, false);
597 // Check the first byte.
598 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
599 // Check the last byte.
600 IRB.SetInsertPoint(InsertBefore);
601 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
602 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
603 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
604 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
607 // Instrument memset/memmove/memcpy
608 bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
609 Value *Dst = MI->getDest();
610 MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
611 Value *Src = MemTran ? MemTran->getSource() : 0;
612 Value *Length = MI->getLength();
614 Constant *ConstLength = dyn_cast<Constant>(Length);
615 Instruction *InsertBefore = MI;
617 if (ConstLength->isNullValue()) return false;
619 // The size is not a constant so it could be zero -- check at run-time.
620 IRBuilder<> IRB(InsertBefore);
622 Value *Cmp = IRB.CreateICmpNE(Length,
623 Constant::getNullValue(Length->getType()));
624 InsertBefore = SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
627 instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
629 instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
633 // If I is an interesting memory access, return the PointerOperand
634 // and set IsWrite. Otherwise return NULL.
635 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
636 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
637 if (!ClInstrumentReads) return NULL;
639 return LI->getPointerOperand();
641 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
642 if (!ClInstrumentWrites) return NULL;
644 return SI->getPointerOperand();
646 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
647 if (!ClInstrumentAtomics) return NULL;
649 return RMW->getPointerOperand();
651 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
652 if (!ClInstrumentAtomics) return NULL;
654 return XCHG->getPointerOperand();
659 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
660 // If a global variable does not have dynamic initialization we don't
661 // have to instrument it. However, if a global does not have initializer
662 // at all, we assume it has dynamic initializer (in other TU).
663 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
666 void AddressSanitizer::instrumentMop(Instruction *I) {
667 bool IsWrite = false;
668 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
670 if (ClOpt && ClOptGlobals) {
671 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
672 // If initialization order checking is disabled, a simple access to a
673 // dynamically initialized global is always valid.
674 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
675 NumOptimizedAccessesToGlobalVar++;
679 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
680 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
681 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
682 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
683 NumOptimizedAccessesToGlobalArray++;
690 Type *OrigPtrTy = Addr->getType();
691 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
693 assert(OrigTy->isSized());
694 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
696 assert((TypeSize % 8) == 0);
699 NumInstrumentedWrites++;
701 NumInstrumentedReads++;
703 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
704 if (TypeSize == 8 || TypeSize == 16 ||
705 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
706 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
707 // Instrument unusual size (but still multiple of 8).
708 // We can not do it with a single check, so we do 1-byte check for the first
709 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
710 // to report the actual access size.
712 Value *LastByte = IRB.CreateIntToPtr(
713 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
714 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
716 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
717 instrumentAddress(I, I, Addr, 8, IsWrite, Size);
718 instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
721 // Validate the result of Module::getOrInsertFunction called for an interface
722 // function of AddressSanitizer. If the instrumented module defines a function
723 // with the same name, their prototypes must match, otherwise
724 // getOrInsertFunction returns a bitcast.
725 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
726 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
727 FuncOrBitcast->dump();
728 report_fatal_error("trying to redefine an AddressSanitizer "
729 "interface function");
732 Instruction *AddressSanitizer::generateCrashCode(
733 Instruction *InsertBefore, Value *Addr,
734 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
735 IRBuilder<> IRB(InsertBefore);
736 CallInst *Call = SizeArgument
737 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
738 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
740 // We don't do Call->setDoesNotReturn() because the BB already has
741 // UnreachableInst at the end.
742 // This EmptyAsm is required to avoid callback merge.
743 IRB.CreateCall(EmptyAsm);
747 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
750 size_t Granularity = 1 << Mapping.Scale;
751 // Addr & (Granularity - 1)
752 Value *LastAccessedByte = IRB.CreateAnd(
753 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
754 // (Addr & (Granularity - 1)) + size - 1
755 if (TypeSize / 8 > 1)
756 LastAccessedByte = IRB.CreateAdd(
757 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
758 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
759 LastAccessedByte = IRB.CreateIntCast(
760 LastAccessedByte, ShadowValue->getType(), false);
761 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
762 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
765 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
766 Instruction *InsertBefore,
767 Value *Addr, uint32_t TypeSize,
768 bool IsWrite, Value *SizeArgument) {
769 IRBuilder<> IRB(InsertBefore);
770 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
772 Type *ShadowTy = IntegerType::get(
773 *C, std::max(8U, TypeSize >> Mapping.Scale));
774 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
775 Value *ShadowPtr = memToShadow(AddrLong, IRB);
776 Value *CmpVal = Constant::getNullValue(ShadowTy);
777 Value *ShadowValue = IRB.CreateLoad(
778 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
780 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
781 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
782 size_t Granularity = 1 << Mapping.Scale;
783 TerminatorInst *CrashTerm = 0;
785 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
786 TerminatorInst *CheckTerm =
787 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
788 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
789 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
790 IRB.SetInsertPoint(CheckTerm);
791 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
792 BasicBlock *CrashBlock =
793 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
794 CrashTerm = new UnreachableInst(*C, CrashBlock);
795 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
796 ReplaceInstWithInst(CheckTerm, NewTerm);
798 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
801 Instruction *Crash = generateCrashCode(
802 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
803 Crash->setDebugLoc(OrigIns->getDebugLoc());
806 void AddressSanitizerModule::createInitializerPoisonCalls(
807 Module &M, GlobalValue *ModuleName) {
808 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
809 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
810 // If that function is not present, this TU contains no globals, or they have
811 // all been optimized away
815 // Set up the arguments to our poison/unpoison functions.
816 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
818 // Add a call to poison all external globals before the given function starts.
819 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
820 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
822 // Add calls to unpoison all globals before each return instruction.
823 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
825 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
826 CallInst::Create(AsanUnpoisonGlobals, "", RI);
831 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
832 Type *Ty = cast<PointerType>(G->getType())->getElementType();
833 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
835 if (BL->isIn(*G)) return false;
836 if (!Ty->isSized()) return false;
837 if (!G->hasInitializer()) return false;
838 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
839 // Touch only those globals that will not be defined in other modules.
840 // Don't handle ODR type linkages since other modules may be built w/o asan.
841 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
842 G->getLinkage() != GlobalVariable::PrivateLinkage &&
843 G->getLinkage() != GlobalVariable::InternalLinkage)
845 // Two problems with thread-locals:
846 // - The address of the main thread's copy can't be computed at link-time.
847 // - Need to poison all copies, not just the main thread's one.
848 if (G->isThreadLocal())
850 // For now, just ignore this Global if the alignment is large.
851 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
853 // Ignore all the globals with the names starting with "\01L_OBJC_".
854 // Many of those are put into the .cstring section. The linker compresses
855 // that section by removing the spare \0s after the string terminator, so
856 // our redzones get broken.
857 if ((G->getName().find("\01L_OBJC_") == 0) ||
858 (G->getName().find("\01l_OBJC_") == 0)) {
859 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
863 if (G->hasSection()) {
864 StringRef Section(G->getSection());
865 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
866 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
868 if ((Section.find("__OBJC,") == 0) ||
869 (Section.find("__DATA, __objc_") == 0)) {
870 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
873 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
874 // Constant CFString instances are compiled in the following way:
875 // -- the string buffer is emitted into
876 // __TEXT,__cstring,cstring_literals
877 // -- the constant NSConstantString structure referencing that buffer
878 // is placed into __DATA,__cfstring
879 // Therefore there's no point in placing redzones into __DATA,__cfstring.
880 // Moreover, it causes the linker to crash on OS X 10.7
881 if (Section.find("__DATA,__cfstring") == 0) {
882 DEBUG(dbgs() << "Ignoring CFString: " << *G);
890 void AddressSanitizerModule::initializeCallbacks(Module &M) {
892 // Declare our poisoning and unpoisoning functions.
893 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
894 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
895 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
896 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
897 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
898 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
899 // Declare functions that register/unregister globals.
900 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
901 kAsanRegisterGlobalsName, IRB.getVoidTy(),
902 IntptrTy, IntptrTy, NULL));
903 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
904 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
905 kAsanUnregisterGlobalsName,
906 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
907 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
910 // This function replaces all global variables with new variables that have
911 // trailing redzones. It also creates a function that poisons
912 // redzones and inserts this function into llvm.global_ctors.
913 bool AddressSanitizerModule::runOnModule(Module &M) {
914 if (!ClGlobals) return false;
915 DL = getAnalysisIfAvailable<DataLayout>();
918 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
919 if (BL->isIn(M)) return false;
920 C = &(M.getContext());
921 int LongSize = DL->getPointerSizeInBits();
922 IntptrTy = Type::getIntNTy(*C, LongSize);
923 Mapping = getShadowMapping(M, LongSize);
924 initializeCallbacks(M);
925 DynamicallyInitializedGlobals.Init(M);
927 SmallVector<GlobalVariable *, 16> GlobalsToChange;
929 for (Module::GlobalListType::iterator G = M.global_begin(),
930 E = M.global_end(); G != E; ++G) {
931 if (ShouldInstrumentGlobal(G))
932 GlobalsToChange.push_back(G);
935 size_t n = GlobalsToChange.size();
936 if (n == 0) return false;
938 // A global is described by a structure
941 // size_t size_with_redzone;
943 // const char *module_name;
944 // size_t has_dynamic_init;
945 // We initialize an array of such structures and pass it to a run-time call.
946 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
948 IntptrTy, IntptrTy, NULL);
949 SmallVector<Constant *, 16> Initializers(n);
951 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
953 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
955 bool HasDynamicallyInitializedGlobals = false;
957 // We shouldn't merge same module names, as this string serves as unique
958 // module ID in runtime.
959 GlobalVariable *ModuleName = createPrivateGlobalForString(
960 M, M.getModuleIdentifier(), /*AllowMerging*/false);
962 for (size_t i = 0; i < n; i++) {
963 static const uint64_t kMaxGlobalRedzone = 1 << 18;
964 GlobalVariable *G = GlobalsToChange[i];
965 PointerType *PtrTy = cast<PointerType>(G->getType());
966 Type *Ty = PtrTy->getElementType();
967 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
968 uint64_t MinRZ = MinRedzoneSizeForGlobal();
969 // MinRZ <= RZ <= kMaxGlobalRedzone
970 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
971 uint64_t RZ = std::max(MinRZ,
972 std::min(kMaxGlobalRedzone,
973 (SizeInBytes / MinRZ / 4) * MinRZ));
974 uint64_t RightRedzoneSize = RZ;
976 if (SizeInBytes % MinRZ)
977 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
978 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
979 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
980 // Determine whether this global should be poisoned in initialization.
981 bool GlobalHasDynamicInitializer =
982 DynamicallyInitializedGlobals.Contains(G);
983 // Don't check initialization order if this global is blacklisted.
984 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
986 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
987 Constant *NewInitializer = ConstantStruct::get(
988 NewTy, G->getInitializer(),
989 Constant::getNullValue(RightRedZoneTy), NULL);
991 GlobalVariable *Name =
992 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
994 // Create a new global variable with enough space for a redzone.
995 GlobalValue::LinkageTypes Linkage = G->getLinkage();
996 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
997 Linkage = GlobalValue::InternalLinkage;
998 GlobalVariable *NewGlobal = new GlobalVariable(
999 M, NewTy, G->isConstant(), Linkage,
1000 NewInitializer, "", G, G->getThreadLocalMode());
1001 NewGlobal->copyAttributesFrom(G);
1002 NewGlobal->setAlignment(MinRZ);
1005 Indices2[0] = IRB.getInt32(0);
1006 Indices2[1] = IRB.getInt32(0);
1008 G->replaceAllUsesWith(
1009 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1010 NewGlobal->takeName(G);
1011 G->eraseFromParent();
1013 Initializers[i] = ConstantStruct::get(
1015 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1016 ConstantInt::get(IntptrTy, SizeInBytes),
1017 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1018 ConstantExpr::getPointerCast(Name, IntptrTy),
1019 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1020 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1023 // Populate the first and last globals declared in this TU.
1024 if (CheckInitOrder && GlobalHasDynamicInitializer)
1025 HasDynamicallyInitializedGlobals = true;
1027 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1030 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1031 GlobalVariable *AllGlobals = new GlobalVariable(
1032 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1033 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1035 // Create calls for poisoning before initializers run and unpoisoning after.
1036 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1037 createInitializerPoisonCalls(M, ModuleName);
1038 IRB.CreateCall2(AsanRegisterGlobals,
1039 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1040 ConstantInt::get(IntptrTy, n));
1042 // We also need to unregister globals at the end, e.g. when a shared library
1044 Function *AsanDtorFunction = Function::Create(
1045 FunctionType::get(Type::getVoidTy(*C), false),
1046 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1047 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1048 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1049 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1050 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1051 ConstantInt::get(IntptrTy, n));
1052 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1058 void AddressSanitizer::initializeCallbacks(Module &M) {
1059 IRBuilder<> IRB(*C);
1060 // Create __asan_report* callbacks.
1061 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1062 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1063 AccessSizeIndex++) {
1064 // IsWrite and TypeSize are encoded in the function name.
1065 std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1066 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1067 // If we are merging crash callbacks, they have two parameters.
1068 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1069 checkInterfaceFunction(M.getOrInsertFunction(
1070 FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1073 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1074 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1075 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1076 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1078 AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1079 kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1080 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1081 kAsanCovName, IRB.getVoidTy(), NULL));
1082 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1083 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1084 StringRef(""), StringRef(""),
1085 /*hasSideEffects=*/true);
1088 void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1089 // Tell the values of mapping offset and scale to the run-time.
1090 GlobalValue *asan_mapping_offset =
1091 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1092 ConstantInt::get(IntptrTy, Mapping.Offset),
1093 kAsanMappingOffsetName);
1094 // Read the global, otherwise it may be optimized away.
1095 IRB.CreateLoad(asan_mapping_offset, true);
1097 GlobalValue *asan_mapping_scale =
1098 new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1099 ConstantInt::get(IntptrTy, Mapping.Scale),
1100 kAsanMappingScaleName);
1101 // Read the global, otherwise it may be optimized away.
1102 IRB.CreateLoad(asan_mapping_scale, true);
1106 bool AddressSanitizer::doInitialization(Module &M) {
1107 // Initialize the private fields. No one has accessed them before.
1108 DL = getAnalysisIfAvailable<DataLayout>();
1112 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1113 DynamicallyInitializedGlobals.Init(M);
1115 C = &(M.getContext());
1116 LongSize = DL->getPointerSizeInBits();
1117 IntptrTy = Type::getIntNTy(*C, LongSize);
1119 AsanCtorFunction = Function::Create(
1120 FunctionType::get(Type::getVoidTy(*C), false),
1121 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1122 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1123 // call __asan_init in the module ctor.
1124 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1125 AsanInitFunction = checkInterfaceFunction(
1126 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1127 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1128 IRB.CreateCall(AsanInitFunction);
1130 Mapping = getShadowMapping(M, LongSize);
1131 emitShadowMapping(M, IRB);
1133 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1137 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1138 // For each NSObject descendant having a +load method, this method is invoked
1139 // by the ObjC runtime before any of the static constructors is called.
1140 // Therefore we need to instrument such methods with a call to __asan_init
1141 // at the beginning in order to initialize our runtime before any access to
1142 // the shadow memory.
1143 // We cannot just ignore these methods, because they may call other
1144 // instrumented functions.
1145 if (F.getName().find(" load]") != std::string::npos) {
1146 IRBuilder<> IRB(F.begin()->begin());
1147 IRB.CreateCall(AsanInitFunction);
1153 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1154 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1155 // Skip static allocas at the top of the entry block so they don't become
1156 // dynamic when we split the block. If we used our optimized stack layout,
1157 // then there will only be one alloca and it will come first.
1158 for (; IP != BE; ++IP) {
1159 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1160 if (!AI || !AI->isStaticAlloca())
1164 IRBuilder<> IRB(IP);
1165 Type *Int8Ty = IRB.getInt8Ty();
1166 GlobalVariable *Guard = new GlobalVariable(
1167 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1168 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1169 LoadInst *Load = IRB.CreateLoad(Guard);
1170 Load->setAtomic(Monotonic);
1171 Load->setAlignment(1);
1172 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1173 Instruction *Ins = SplitBlockAndInsertIfThen(
1174 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1175 IRB.SetInsertPoint(Ins);
1176 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1177 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1178 Instruction *Call = IRB.CreateCall(AsanCovFunction);
1179 Call->setDebugLoc(IP->getDebugLoc());
1180 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1181 Store->setAtomic(Monotonic);
1182 Store->setAlignment(1);
1185 // Poor man's coverage that works with ASan.
1186 // We create a Guard boolean variable with the same linkage
1187 // as the function and inject this code into the entry block (-asan-coverage=1)
1188 // or all blocks (-asan-coverage=2):
1190 // __sanitizer_cov(&F);
1193 // The accesses to Guard are atomic. The rest of the logic is
1194 // in __sanitizer_cov (it's fine to call it more than once).
1196 // This coverage implementation provides very limited data:
1197 // it only tells if a given function (block) was ever executed.
1198 // No counters, no per-edge data.
1199 // But for many use cases this is what we need and the added slowdown
1200 // is negligible. This simple implementation will probably be obsoleted
1201 // by the upcoming Clang-based coverage implementation.
1202 // By having it here and now we hope to
1203 // a) get the functionality to users earlier and
1204 // b) collect usage statistics to help improve Clang coverage design.
1205 bool AddressSanitizer::InjectCoverage(Function &F,
1206 const ArrayRef<BasicBlock *> AllBlocks) {
1207 if (!ClCoverage) return false;
1209 if (ClCoverage == 1) {
1210 InjectCoverageAtBlock(F, F.getEntryBlock());
1212 for (size_t i = 0, n = AllBlocks.size(); i < n; i++)
1213 InjectCoverageAtBlock(F, *AllBlocks[i]);
1218 bool AddressSanitizer::runOnFunction(Function &F) {
1219 if (BL->isIn(F)) return false;
1220 if (&F == AsanCtorFunction) return false;
1221 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1222 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1223 initializeCallbacks(*F.getParent());
1225 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1226 maybeInsertAsanInitAtFunctionEntry(F);
1228 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1231 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1234 // We want to instrument every address only once per basic block (unless there
1235 // are calls between uses).
1236 SmallSet<Value*, 16> TempsToInstrument;
1237 SmallVector<Instruction*, 16> ToInstrument;
1238 SmallVector<Instruction*, 8> NoReturnCalls;
1239 SmallVector<BasicBlock*, 16> AllBlocks;
1243 // Fill the set of memory operations to instrument.
1244 for (Function::iterator FI = F.begin(), FE = F.end();
1246 AllBlocks.push_back(FI);
1247 TempsToInstrument.clear();
1248 int NumInsnsPerBB = 0;
1249 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1251 if (LooksLikeCodeInBug11395(BI)) return false;
1252 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1253 if (ClOpt && ClOptSameTemp) {
1254 if (!TempsToInstrument.insert(Addr))
1255 continue; // We've seen this temp in the current BB.
1257 } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1260 if (isa<AllocaInst>(BI))
1264 // A call inside BB.
1265 TempsToInstrument.clear();
1266 if (CS.doesNotReturn())
1267 NoReturnCalls.push_back(CS.getInstruction());
1271 ToInstrument.push_back(BI);
1273 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1278 Function *UninstrumentedDuplicate = 0;
1279 bool LikelyToInstrument =
1280 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1281 if (ClKeepUninstrumented && LikelyToInstrument) {
1282 ValueToValueMapTy VMap;
1283 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1284 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1285 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1286 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1290 int NumInstrumented = 0;
1291 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1292 Instruction *Inst = ToInstrument[i];
1293 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1294 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1295 if (isInterestingMemoryAccess(Inst, &IsWrite))
1296 instrumentMop(Inst);
1298 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1303 FunctionStackPoisoner FSP(F, *this);
1304 bool ChangedStack = FSP.runOnFunction();
1306 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1307 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1308 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1309 Instruction *CI = NoReturnCalls[i];
1310 IRBuilder<> IRB(CI);
1311 IRB.CreateCall(AsanHandleNoReturnFunc);
1314 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1316 if (InjectCoverage(F, AllBlocks))
1319 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1321 if (ClKeepUninstrumented) {
1323 // No instrumentation is done, no need for the duplicate.
1324 if (UninstrumentedDuplicate)
1325 UninstrumentedDuplicate->eraseFromParent();
1327 // The function was instrumented. We must have the duplicate.
1328 assert(UninstrumentedDuplicate);
1329 UninstrumentedDuplicate->setSection("NOASAN");
1330 assert(!F.hasSection());
1331 F.setSection("ASAN");
1338 // Workaround for bug 11395: we don't want to instrument stack in functions
1339 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1340 // FIXME: remove once the bug 11395 is fixed.
1341 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1342 if (LongSize != 32) return false;
1343 CallInst *CI = dyn_cast<CallInst>(I);
1344 if (!CI || !CI->isInlineAsm()) return false;
1345 if (CI->getNumArgOperands() <= 5) return false;
1346 // We have inline assembly with quite a few arguments.
1350 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1351 IRBuilder<> IRB(*C);
1352 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1353 std::string Suffix = itostr(i);
1354 AsanStackMallocFunc[i] = checkInterfaceFunction(
1355 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1356 IntptrTy, IntptrTy, NULL));
1357 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1358 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1359 IntptrTy, IntptrTy, NULL));
1361 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1362 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1363 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1364 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1368 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1369 IRBuilder<> &IRB, Value *ShadowBase,
1371 size_t n = ShadowBytes.size();
1373 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1374 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1375 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1376 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1377 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1378 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1380 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1381 if (ASan.DL->isLittleEndian())
1382 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1384 Val = (Val << 8) | ShadowBytes[i + j];
1387 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1388 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1389 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1390 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1395 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1396 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1397 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1398 assert(LocalStackSize <= kMaxStackMallocSize);
1399 uint64_t MaxSize = kMinStackMallocSize;
1400 for (int i = 0; ; i++, MaxSize *= 2)
1401 if (LocalStackSize <= MaxSize)
1403 llvm_unreachable("impossible LocalStackSize");
1406 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1407 // We can not use MemSet intrinsic because it may end up calling the actual
1408 // memset. Size is a multiple of 8.
1409 // Currently this generates 8-byte stores on x86_64; it may be better to
1410 // generate wider stores.
1411 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1412 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1413 assert(!(Size % 8));
1414 assert(kAsanStackAfterReturnMagic == 0xf5);
1415 for (int i = 0; i < Size; i += 8) {
1416 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1417 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1418 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1422 void FunctionStackPoisoner::poisonStack() {
1423 int StackMallocIdx = -1;
1425 assert(AllocaVec.size() > 0);
1426 Instruction *InsBefore = AllocaVec[0];
1427 IRBuilder<> IRB(InsBefore);
1429 SmallVector<ASanStackVariableDescription, 16> SVD;
1430 SVD.reserve(AllocaVec.size());
1431 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1432 AllocaInst *AI = AllocaVec[i];
1433 ASanStackVariableDescription D = { AI->getName().data(),
1434 getAllocaSizeInBytes(AI),
1435 AI->getAlignment(), AI, 0};
1438 // Minimal header size (left redzone) is 4 pointers,
1439 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1440 size_t MinHeaderSize = ASan.LongSize / 2;
1441 ASanStackFrameLayout L;
1442 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1443 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1444 uint64_t LocalStackSize = L.FrameSize;
1445 bool DoStackMalloc =
1446 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1448 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1449 AllocaInst *MyAlloca =
1450 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1451 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1452 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1453 MyAlloca->setAlignment(FrameAlignment);
1454 assert(MyAlloca->isStaticAlloca());
1455 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1456 Value *LocalStackBase = OrigStackBase;
1458 if (DoStackMalloc) {
1459 // LocalStackBase = OrigStackBase
1460 // if (__asan_option_detect_stack_use_after_return)
1461 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1462 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1463 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1464 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1465 kAsanOptionDetectUAR, IRB.getInt32Ty());
1466 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1467 Constant::getNullValue(IRB.getInt32Ty()));
1468 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1469 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1470 IRBuilder<> IRBIf(Term);
1471 LocalStackBase = IRBIf.CreateCall2(
1472 AsanStackMallocFunc[StackMallocIdx],
1473 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1474 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1475 IRB.SetInsertPoint(InsBefore);
1476 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1477 Phi->addIncoming(OrigStackBase, CmpBlock);
1478 Phi->addIncoming(LocalStackBase, SetBlock);
1479 LocalStackBase = Phi;
1482 // Insert poison calls for lifetime intrinsics for alloca.
1483 bool HavePoisonedAllocas = false;
1484 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1485 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1486 assert(APC.InsBefore);
1488 IRBuilder<> IRB(APC.InsBefore);
1489 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1490 HavePoisonedAllocas |= APC.DoPoison;
1493 // Replace Alloca instructions with base+offset.
1494 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1495 AllocaInst *AI = SVD[i].AI;
1496 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1497 IRB.CreateAdd(LocalStackBase,
1498 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1500 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1501 AI->replaceAllUsesWith(NewAllocaPtr);
1504 // The left-most redzone has enough space for at least 4 pointers.
1505 // Write the Magic value to redzone[0].
1506 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1507 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1509 // Write the frame description constant to redzone[1].
1510 Value *BasePlus1 = IRB.CreateIntToPtr(
1511 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1513 GlobalVariable *StackDescriptionGlobal =
1514 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1515 /*AllowMerging*/true);
1516 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1518 IRB.CreateStore(Description, BasePlus1);
1519 // Write the PC to redzone[2].
1520 Value *BasePlus2 = IRB.CreateIntToPtr(
1521 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1522 2 * ASan.LongSize/8)),
1524 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1526 // Poison the stack redzones at the entry.
1527 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1528 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1530 // (Un)poison the stack before all ret instructions.
1531 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1532 Instruction *Ret = RetVec[i];
1533 IRBuilder<> IRBRet(Ret);
1534 // Mark the current frame as retired.
1535 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1537 if (DoStackMalloc) {
1538 assert(StackMallocIdx >= 0);
1539 // if LocalStackBase != OrigStackBase:
1540 // // In use-after-return mode, poison the whole stack frame.
1541 // if StackMallocIdx <= 4
1542 // // For small sizes inline the whole thing:
1543 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1544 // **SavedFlagPtr(LocalStackBase) = 0
1546 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1548 // <This is not a fake stack; unpoison the redzones>
1549 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1550 TerminatorInst *ThenTerm, *ElseTerm;
1551 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1553 IRBuilder<> IRBPoison(ThenTerm);
1554 if (StackMallocIdx <= 4) {
1555 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1556 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1557 ClassSize >> Mapping.Scale);
1558 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1560 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1561 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1562 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1563 IRBPoison.CreateStore(
1564 Constant::getNullValue(IRBPoison.getInt8Ty()),
1565 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1567 // For larger frames call __asan_stack_free_*.
1568 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1569 ConstantInt::get(IntptrTy, LocalStackSize),
1573 IRBuilder<> IRBElse(ElseTerm);
1574 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1575 } else if (HavePoisonedAllocas) {
1576 // If we poisoned some allocas in llvm.lifetime analysis,
1577 // unpoison whole stack frame now.
1578 assert(LocalStackBase == OrigStackBase);
1579 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1581 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1585 // We are done. Remove the old unused alloca instructions.
1586 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1587 AllocaVec[i]->eraseFromParent();
1590 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1591 IRBuilder<> &IRB, bool DoPoison) {
1592 // For now just insert the call to ASan runtime.
1593 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1594 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1595 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1596 : AsanUnpoisonStackMemoryFunc,
1600 // Handling llvm.lifetime intrinsics for a given %alloca:
1601 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1602 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1603 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1604 // could be poisoned by previous llvm.lifetime.end instruction, as the
1605 // variable may go in and out of scope several times, e.g. in loops).
1606 // (3) if we poisoned at least one %alloca in a function,
1607 // unpoison the whole stack frame at function exit.
1609 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1610 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1611 // We're intested only in allocas we can handle.
1612 return isInterestingAlloca(*AI) ? AI : 0;
1613 // See if we've already calculated (or started to calculate) alloca for a
1615 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1616 if (I != AllocaForValue.end())
1618 // Store 0 while we're calculating alloca for value V to avoid
1619 // infinite recursion if the value references itself.
1620 AllocaForValue[V] = 0;
1621 AllocaInst *Res = 0;
1622 if (CastInst *CI = dyn_cast<CastInst>(V))
1623 Res = findAllocaForValue(CI->getOperand(0));
1624 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1625 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1626 Value *IncValue = PN->getIncomingValue(i);
1627 // Allow self-referencing phi-nodes.
1628 if (IncValue == PN) continue;
1629 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1630 // AI for incoming values should exist and should all be equal.
1631 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1637 AllocaForValue[V] = Res;