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/SmallSet.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/Statistic.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/IR/CallSite.h"
29 #include "llvm/IR/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/InstVisitor.h"
35 #include "llvm/IR/IntrinsicInst.h"
36 #include "llvm/IR/LLVMContext.h"
37 #include "llvm/IR/MDBuilder.h"
38 #include "llvm/IR/Module.h"
39 #include "llvm/IR/Type.h"
40 #include "llvm/Support/CommandLine.h"
41 #include "llvm/Support/DataTypes.h"
42 #include "llvm/Support/Debug.h"
43 #include "llvm/Support/Endian.h"
44 #include "llvm/Support/system_error.h"
45 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
46 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
47 #include "llvm/Transforms/Utils/Cloning.h"
48 #include "llvm/Transforms/Utils/Local.h"
49 #include "llvm/Transforms/Utils/ModuleUtils.h"
50 #include "llvm/Transforms/Utils/SpecialCaseList.h"
56 static const uint64_t kDefaultShadowScale = 3;
57 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
58 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
59 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
60 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
61 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
62 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
63 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
65 static const size_t kMinStackMallocSize = 1 << 6; // 64B
66 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
67 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
68 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
70 static const char *const kAsanModuleCtorName = "asan.module_ctor";
71 static const char *const kAsanModuleDtorName = "asan.module_dtor";
72 static const int kAsanCtorAndCtorPriority = 1;
73 static const char *const kAsanReportErrorTemplate = "__asan_report_";
74 static const char *const kAsanReportLoadN = "__asan_report_load_n";
75 static const char *const kAsanReportStoreN = "__asan_report_store_n";
76 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
77 static const char *const kAsanUnregisterGlobalsName =
78 "__asan_unregister_globals";
79 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
80 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
81 static const char *const kAsanInitName = "__asan_init_v3";
82 static const char *const kAsanCovName = "__sanitizer_cov";
83 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
84 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
85 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
86 static const int kMaxAsanStackMallocSizeClass = 10;
87 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
88 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
89 static const char *const kAsanGenPrefix = "__asan_gen_";
90 static const char *const kAsanPoisonStackMemoryName =
91 "__asan_poison_stack_memory";
92 static const char *const kAsanUnpoisonStackMemoryName =
93 "__asan_unpoison_stack_memory";
95 static const char *const kAsanOptionDetectUAR =
96 "__asan_option_detect_stack_use_after_return";
99 static const int kAsanStackAfterReturnMagic = 0xf5;
102 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
103 static const size_t kNumberOfAccessSizes = 5;
105 // Command-line flags.
107 // This flag may need to be replaced with -f[no-]asan-reads.
108 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
109 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
110 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
111 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
112 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
113 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
114 cl::Hidden, cl::init(true));
115 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
116 cl::desc("use instrumentation with slow path for all accesses"),
117 cl::Hidden, cl::init(false));
118 // This flag limits the number of instructions to be instrumented
119 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
120 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
122 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
124 cl::desc("maximal number of instructions to instrument in any given BB"),
126 // This flag may need to be replaced with -f[no]asan-stack.
127 static cl::opt<bool> ClStack("asan-stack",
128 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
129 // This flag may need to be replaced with -f[no]asan-use-after-return.
130 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
131 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
132 // This flag may need to be replaced with -f[no]asan-globals.
133 static cl::opt<bool> ClGlobals("asan-globals",
134 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
135 static cl::opt<int> ClCoverage("asan-coverage",
136 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"),
137 cl::Hidden, cl::init(false));
138 static cl::opt<int> ClCoverageBlockThreshold("asan-coverage-block-threshold",
139 cl::desc("Add coverage instrumentation only to the entry block if there "
140 "are more than this number of blocks."),
141 cl::Hidden, cl::init(1500));
142 static cl::opt<bool> ClInitializers("asan-initialization-order",
143 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
144 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
145 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
146 cl::Hidden, cl::init(false));
147 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
148 cl::desc("Realign stack to the value of this flag (power of two)"),
149 cl::Hidden, cl::init(32));
150 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
151 cl::desc("File containing the list of objects to ignore "
152 "during instrumentation"), cl::Hidden);
153 static cl::opt<int> ClInstrumentationWithCallsThreshold(
154 "asan-instrumentation-with-call-threshold",
155 cl::desc("If the function being instrumented contains more than "
156 "this number of memory accesses, use callbacks instead of "
157 "inline checks (-1 means never use callbacks)."),
158 cl::Hidden, cl::init(10000));
159 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
160 "asan-memory-access-callback-prefix",
161 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
162 cl::init("__asan_"));
164 // This is an experimental feature that will allow to choose between
165 // instrumented and non-instrumented code at link-time.
166 // If this option is on, just before instrumenting a function we create its
167 // clone; if the function is not changed by asan the clone is deleted.
168 // If we end up with a clone, we put the instrumented function into a section
169 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
171 // This is still a prototype, we need to figure out a way to keep two copies of
172 // a function so that the linker can easily choose one of them.
173 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
174 cl::desc("Keep uninstrumented copies of functions"),
175 cl::Hidden, cl::init(false));
177 // These flags allow to change the shadow mapping.
178 // The shadow mapping looks like
179 // Shadow = (Mem >> scale) + (1 << offset_log)
180 static cl::opt<int> ClMappingScale("asan-mapping-scale",
181 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
183 // Optimization flags. Not user visible, used mostly for testing
184 // and benchmarking the tool.
185 static cl::opt<bool> ClOpt("asan-opt",
186 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
187 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
188 cl::desc("Instrument the same temp just once"), cl::Hidden,
190 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
191 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
193 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
194 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
195 cl::Hidden, cl::init(false));
198 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
200 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
201 cl::Hidden, cl::init(0));
202 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
203 cl::Hidden, cl::desc("Debug func"));
204 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
205 cl::Hidden, cl::init(-1));
206 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
207 cl::Hidden, cl::init(-1));
209 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
210 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
211 STATISTIC(NumOptimizedAccessesToGlobalArray,
212 "Number of optimized accesses to global arrays");
213 STATISTIC(NumOptimizedAccessesToGlobalVar,
214 "Number of optimized accesses to global vars");
217 /// A set of dynamically initialized globals extracted from metadata.
218 class SetOfDynamicallyInitializedGlobals {
220 void Init(Module& M) {
221 // Clang generates metadata identifying all dynamically initialized globals.
222 NamedMDNode *DynamicGlobals =
223 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
226 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
227 MDNode *MDN = DynamicGlobals->getOperand(i);
228 assert(MDN->getNumOperands() == 1);
229 Value *VG = MDN->getOperand(0);
230 // The optimizer may optimize away a global entirely, in which case we
231 // cannot instrument access to it.
234 DynInitGlobals.insert(cast<GlobalVariable>(VG));
237 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
239 SmallSet<GlobalValue*, 32> DynInitGlobals;
242 /// This struct defines the shadow mapping using the rule:
243 /// shadow = (mem >> Scale) ADD-or-OR Offset.
244 struct ShadowMapping {
250 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
251 llvm::Triple TargetTriple(M.getTargetTriple());
252 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
253 // bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
254 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
255 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
256 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
257 TargetTriple.getArch() == llvm::Triple::ppc64le;
258 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
259 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
260 TargetTriple.getArch() == llvm::Triple::mipsel;
262 ShadowMapping Mapping;
264 if (LongSize == 32) {
268 Mapping.Offset = kMIPS32_ShadowOffset32;
270 Mapping.Offset = kFreeBSD_ShadowOffset32;
272 Mapping.Offset = kDefaultShadowOffset32;
273 } else { // LongSize == 64
275 Mapping.Offset = kPPC64_ShadowOffset64;
277 Mapping.Offset = kFreeBSD_ShadowOffset64;
278 else if (IsLinux && IsX86_64)
279 Mapping.Offset = kSmallX86_64ShadowOffset;
281 Mapping.Offset = kDefaultShadowOffset64;
284 Mapping.Scale = kDefaultShadowScale;
285 if (ClMappingScale) {
286 Mapping.Scale = ClMappingScale;
289 // OR-ing shadow offset if more efficient (at least on x86) if the offset
290 // is a power of two, but on ppc64 we have to use add since the shadow
291 // offset is not necessary 1/8-th of the address space.
292 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
297 static size_t RedzoneSizeForScale(int MappingScale) {
298 // Redzone used for stack and globals is at least 32 bytes.
299 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
300 return std::max(32U, 1U << MappingScale);
303 /// AddressSanitizer: instrument the code in module to find memory bugs.
304 struct AddressSanitizer : public FunctionPass {
305 AddressSanitizer(bool CheckInitOrder = true,
306 bool CheckUseAfterReturn = false,
307 bool CheckLifetime = false,
308 StringRef BlacklistFile = StringRef())
310 CheckInitOrder(CheckInitOrder || ClInitializers),
311 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
312 CheckLifetime(CheckLifetime || ClCheckLifetime),
313 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
315 const char *getPassName() const override {
316 return "AddressSanitizerFunctionPass";
318 void instrumentMop(Instruction *I, bool UseCalls);
319 void instrumentPointerComparisonOrSubtraction(Instruction *I);
320 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
321 Value *Addr, uint32_t TypeSize, bool IsWrite,
322 Value *SizeArgument, bool UseCalls);
323 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
324 Value *ShadowValue, uint32_t TypeSize);
325 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
326 bool IsWrite, size_t AccessSizeIndex,
327 Value *SizeArgument);
328 void instrumentMemIntrinsic(MemIntrinsic *MI);
329 void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
330 Value *Size, Instruction *InsertBefore,
331 bool IsWrite, bool UseCalls);
332 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
333 bool runOnFunction(Function &F) override;
334 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
335 bool doInitialization(Module &M) override;
336 static char ID; // Pass identification, replacement for typeid
339 void initializeCallbacks(Module &M);
341 bool LooksLikeCodeInBug11395(Instruction *I);
342 bool GlobalIsLinkerInitialized(GlobalVariable *G);
343 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks);
344 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
347 bool CheckUseAfterReturn;
349 SmallString<64> BlacklistFile;
352 const DataLayout *DL;
355 ShadowMapping Mapping;
356 Function *AsanCtorFunction;
357 Function *AsanInitFunction;
358 Function *AsanHandleNoReturnFunc;
359 Function *AsanCovFunction;
360 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
361 std::unique_ptr<SpecialCaseList> BL;
362 // This array is indexed by AccessIsWrite and log2(AccessSize).
363 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
364 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
365 // This array is indexed by AccessIsWrite.
366 Function *AsanErrorCallbackSized[2],
367 *AsanMemoryAccessCallbackSized[2];
368 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
370 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
372 friend struct FunctionStackPoisoner;
375 class AddressSanitizerModule : public ModulePass {
377 AddressSanitizerModule(bool CheckInitOrder = true,
378 StringRef BlacklistFile = StringRef())
380 CheckInitOrder(CheckInitOrder || ClInitializers),
381 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
383 bool runOnModule(Module &M) override;
384 static char ID; // Pass identification, replacement for typeid
385 const char *getPassName() const override {
386 return "AddressSanitizerModule";
390 void initializeCallbacks(Module &M);
392 bool ShouldInstrumentGlobal(GlobalVariable *G);
393 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
394 size_t MinRedzoneSizeForGlobal() const {
395 return RedzoneSizeForScale(Mapping.Scale);
399 SmallString<64> BlacklistFile;
401 std::unique_ptr<SpecialCaseList> BL;
402 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
405 const DataLayout *DL;
406 ShadowMapping Mapping;
407 Function *AsanPoisonGlobals;
408 Function *AsanUnpoisonGlobals;
409 Function *AsanRegisterGlobals;
410 Function *AsanUnregisterGlobals;
413 // Stack poisoning does not play well with exception handling.
414 // When an exception is thrown, we essentially bypass the code
415 // that unpoisones the stack. This is why the run-time library has
416 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
417 // stack in the interceptor. This however does not work inside the
418 // actual function which catches the exception. Most likely because the
419 // compiler hoists the load of the shadow value somewhere too high.
420 // This causes asan to report a non-existing bug on 453.povray.
421 // It sounds like an LLVM bug.
422 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
424 AddressSanitizer &ASan;
429 ShadowMapping Mapping;
431 SmallVector<AllocaInst*, 16> AllocaVec;
432 SmallVector<Instruction*, 8> RetVec;
433 unsigned StackAlignment;
435 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
436 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
437 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
439 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
440 struct AllocaPoisonCall {
441 IntrinsicInst *InsBefore;
446 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
448 // Maps Value to an AllocaInst from which the Value is originated.
449 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
450 AllocaForValueMapTy AllocaForValue;
452 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
453 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
454 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
455 Mapping(ASan.Mapping),
456 StackAlignment(1 << Mapping.Scale) {}
458 bool runOnFunction() {
459 if (!ClStack) return false;
460 // Collect alloca, ret, lifetime instructions etc.
461 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
464 if (AllocaVec.empty()) return false;
466 initializeCallbacks(*F.getParent());
476 // Finds all static Alloca instructions and puts
477 // poisoned red zones around all of them.
478 // Then unpoison everything back before the function returns.
481 // ----------------------- Visitors.
482 /// \brief Collect all Ret instructions.
483 void visitReturnInst(ReturnInst &RI) {
484 RetVec.push_back(&RI);
487 /// \brief Collect Alloca instructions we want (and can) handle.
488 void visitAllocaInst(AllocaInst &AI) {
489 if (!isInterestingAlloca(AI)) return;
491 StackAlignment = std::max(StackAlignment, AI.getAlignment());
492 AllocaVec.push_back(&AI);
495 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
497 void visitIntrinsicInst(IntrinsicInst &II) {
498 if (!ASan.CheckLifetime) return;
499 Intrinsic::ID ID = II.getIntrinsicID();
500 if (ID != Intrinsic::lifetime_start &&
501 ID != Intrinsic::lifetime_end)
503 // Found lifetime intrinsic, add ASan instrumentation if necessary.
504 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
505 // If size argument is undefined, don't do anything.
506 if (Size->isMinusOne()) return;
507 // Check that size doesn't saturate uint64_t and can
508 // be stored in IntptrTy.
509 const uint64_t SizeValue = Size->getValue().getLimitedValue();
510 if (SizeValue == ~0ULL ||
511 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
513 // Find alloca instruction that corresponds to llvm.lifetime argument.
514 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
516 bool DoPoison = (ID == Intrinsic::lifetime_end);
517 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
518 AllocaPoisonCallVec.push_back(APC);
521 // ---------------------- Helpers.
522 void initializeCallbacks(Module &M);
524 // Check if we want (and can) handle this alloca.
525 bool isInterestingAlloca(AllocaInst &AI) const {
526 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
527 AI.getAllocatedType()->isSized() &&
528 // alloca() may be called with 0 size, ignore it.
529 getAllocaSizeInBytes(&AI) > 0);
532 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
533 Type *Ty = AI->getAllocatedType();
534 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
537 /// Finds alloca where the value comes from.
538 AllocaInst *findAllocaForValue(Value *V);
539 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
540 Value *ShadowBase, bool DoPoison);
541 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
543 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
549 char AddressSanitizer::ID = 0;
550 INITIALIZE_PASS(AddressSanitizer, "asan",
551 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
553 FunctionPass *llvm::createAddressSanitizerFunctionPass(
554 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
555 StringRef BlacklistFile) {
556 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
557 CheckLifetime, BlacklistFile);
560 char AddressSanitizerModule::ID = 0;
561 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
562 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
563 "ModulePass", false, false)
564 ModulePass *llvm::createAddressSanitizerModulePass(
565 bool CheckInitOrder, StringRef BlacklistFile) {
566 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
569 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
570 size_t Res = countTrailingZeros(TypeSize / 8);
571 assert(Res < kNumberOfAccessSizes);
575 // \brief Create a constant for Str so that we can pass it to the run-time lib.
576 static GlobalVariable *createPrivateGlobalForString(
577 Module &M, StringRef Str, bool AllowMerging) {
578 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
579 // We use private linkage for module-local strings. If they can be merged
580 // with another one, we set the unnamed_addr attribute.
582 new GlobalVariable(M, StrConst->getType(), true,
583 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
585 GV->setUnnamedAddr(true);
586 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
590 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
591 return G->getName().find(kAsanGenPrefix) == 0;
594 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
596 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
597 if (Mapping.Offset == 0)
599 // (Shadow >> scale) | offset
600 if (Mapping.OrShadowOffset)
601 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
603 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
606 void AddressSanitizer::instrumentMemIntrinsicParam(Instruction *OrigIns,
607 Value *Addr, Value *Size,
608 Instruction *InsertBefore,
611 IRBuilder<> IRB(InsertBefore);
612 if (Size->getType() != IntptrTy)
613 Size = IRB.CreateIntCast(Size, IntptrTy, false);
614 // Check the first byte.
615 instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size, false);
616 // Check the last byte.
617 IRB.SetInsertPoint(InsertBefore);
618 Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
619 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
620 Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
621 instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size, false);
624 // Instrument memset/memmove/memcpy
625 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
627 Instruction *Call = 0;
628 if (isa<MemTransferInst>(MI)) {
629 Call = IRB.CreateCall3(
630 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
631 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
632 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
633 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
634 } else if (isa<MemSetInst>(MI)) {
635 Call = IRB.CreateCall3(
637 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
638 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
639 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
641 Call->setDebugLoc(MI->getDebugLoc());
642 MI->eraseFromParent();
645 // If I is an interesting memory access, return the PointerOperand
646 // and set IsWrite. Otherwise return NULL.
647 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
648 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
649 if (!ClInstrumentReads) return NULL;
651 return LI->getPointerOperand();
653 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
654 if (!ClInstrumentWrites) return NULL;
656 return SI->getPointerOperand();
658 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
659 if (!ClInstrumentAtomics) return NULL;
661 return RMW->getPointerOperand();
663 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
664 if (!ClInstrumentAtomics) return NULL;
666 return XCHG->getPointerOperand();
671 static bool isPointerOperand(Value *V) {
672 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
675 // This is a rough heuristic; it may cause both false positives and
676 // false negatives. The proper implementation requires cooperation with
678 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
679 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
680 if (!Cmp->isRelational())
682 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
683 if (BO->getOpcode() != Instruction::Sub)
688 if (!isPointerOperand(I->getOperand(0)) ||
689 !isPointerOperand(I->getOperand(1)))
694 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
695 // If a global variable does not have dynamic initialization we don't
696 // have to instrument it. However, if a global does not have initializer
697 // at all, we assume it has dynamic initializer (in other TU).
698 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
702 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
704 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
705 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
706 for (int i = 0; i < 2; i++) {
707 if (Param[i]->getType()->isPointerTy())
708 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
710 IRB.CreateCall2(F, Param[0], Param[1]);
713 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
714 bool IsWrite = false;
715 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
717 if (ClOpt && ClOptGlobals) {
718 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
719 // If initialization order checking is disabled, a simple access to a
720 // dynamically initialized global is always valid.
721 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
722 NumOptimizedAccessesToGlobalVar++;
726 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
727 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
728 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
729 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
730 NumOptimizedAccessesToGlobalArray++;
737 Type *OrigPtrTy = Addr->getType();
738 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
740 assert(OrigTy->isSized());
741 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
743 assert((TypeSize % 8) == 0);
746 NumInstrumentedWrites++;
748 NumInstrumentedReads++;
750 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
751 if (TypeSize == 8 || TypeSize == 16 ||
752 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
753 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0, UseCalls);
754 // Instrument unusual size (but still multiple of 8).
755 // We can not do it with a single check, so we do 1-byte check for the first
756 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
757 // to report the actual access size.
759 Value *LastByte = IRB.CreateIntToPtr(
760 IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
761 ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
763 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
764 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
765 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
768 // Validate the result of Module::getOrInsertFunction called for an interface
769 // function of AddressSanitizer. If the instrumented module defines a function
770 // with the same name, their prototypes must match, otherwise
771 // getOrInsertFunction returns a bitcast.
772 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
773 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
774 FuncOrBitcast->dump();
775 report_fatal_error("trying to redefine an AddressSanitizer "
776 "interface function");
779 Instruction *AddressSanitizer::generateCrashCode(
780 Instruction *InsertBefore, Value *Addr,
781 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
782 IRBuilder<> IRB(InsertBefore);
783 CallInst *Call = SizeArgument
784 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
785 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
787 // We don't do Call->setDoesNotReturn() because the BB already has
788 // UnreachableInst at the end.
789 // This EmptyAsm is required to avoid callback merge.
790 IRB.CreateCall(EmptyAsm);
794 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
797 size_t Granularity = 1 << Mapping.Scale;
798 // Addr & (Granularity - 1)
799 Value *LastAccessedByte = IRB.CreateAnd(
800 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
801 // (Addr & (Granularity - 1)) + size - 1
802 if (TypeSize / 8 > 1)
803 LastAccessedByte = IRB.CreateAdd(
804 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
805 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
806 LastAccessedByte = IRB.CreateIntCast(
807 LastAccessedByte, ShadowValue->getType(), false);
808 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
809 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
812 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
813 Instruction *InsertBefore, Value *Addr,
814 uint32_t TypeSize, bool IsWrite,
815 Value *SizeArgument, bool UseCalls) {
816 IRBuilder<> IRB(InsertBefore);
817 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
818 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
821 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
826 Type *ShadowTy = IntegerType::get(
827 *C, std::max(8U, TypeSize >> Mapping.Scale));
828 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
829 Value *ShadowPtr = memToShadow(AddrLong, IRB);
830 Value *CmpVal = Constant::getNullValue(ShadowTy);
831 Value *ShadowValue = IRB.CreateLoad(
832 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
834 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
835 size_t Granularity = 1 << Mapping.Scale;
836 TerminatorInst *CrashTerm = 0;
838 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
839 TerminatorInst *CheckTerm =
840 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
841 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
842 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
843 IRB.SetInsertPoint(CheckTerm);
844 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
845 BasicBlock *CrashBlock =
846 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
847 CrashTerm = new UnreachableInst(*C, CrashBlock);
848 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
849 ReplaceInstWithInst(CheckTerm, NewTerm);
851 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
854 Instruction *Crash = generateCrashCode(
855 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
856 Crash->setDebugLoc(OrigIns->getDebugLoc());
859 void AddressSanitizerModule::createInitializerPoisonCalls(
860 Module &M, GlobalValue *ModuleName) {
861 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
862 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
863 // If that function is not present, this TU contains no globals, or they have
864 // all been optimized away
868 // Set up the arguments to our poison/unpoison functions.
869 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
871 // Add a call to poison all external globals before the given function starts.
872 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
873 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
875 // Add calls to unpoison all globals before each return instruction.
876 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
878 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
879 CallInst::Create(AsanUnpoisonGlobals, "", RI);
884 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
885 Type *Ty = cast<PointerType>(G->getType())->getElementType();
886 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
888 if (BL->isIn(*G)) return false;
889 if (!Ty->isSized()) return false;
890 if (!G->hasInitializer()) return false;
891 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
892 // Touch only those globals that will not be defined in other modules.
893 // Don't handle ODR type linkages since other modules may be built w/o asan.
894 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
895 G->getLinkage() != GlobalVariable::PrivateLinkage &&
896 G->getLinkage() != GlobalVariable::InternalLinkage)
898 // Two problems with thread-locals:
899 // - The address of the main thread's copy can't be computed at link-time.
900 // - Need to poison all copies, not just the main thread's one.
901 if (G->isThreadLocal())
903 // For now, just ignore this Global if the alignment is large.
904 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
906 // Ignore all the globals with the names starting with "\01L_OBJC_".
907 // Many of those are put into the .cstring section. The linker compresses
908 // that section by removing the spare \0s after the string terminator, so
909 // our redzones get broken.
910 if ((G->getName().find("\01L_OBJC_") == 0) ||
911 (G->getName().find("\01l_OBJC_") == 0)) {
912 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
916 if (G->hasSection()) {
917 StringRef Section(G->getSection());
918 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
919 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
921 if ((Section.find("__OBJC,") == 0) ||
922 (Section.find("__DATA, __objc_") == 0)) {
923 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
926 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
927 // Constant CFString instances are compiled in the following way:
928 // -- the string buffer is emitted into
929 // __TEXT,__cstring,cstring_literals
930 // -- the constant NSConstantString structure referencing that buffer
931 // is placed into __DATA,__cfstring
932 // Therefore there's no point in placing redzones into __DATA,__cfstring.
933 // Moreover, it causes the linker to crash on OS X 10.7
934 if (Section.find("__DATA,__cfstring") == 0) {
935 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
938 // The linker merges the contents of cstring_literals and removes the
940 if (Section.find("__TEXT,__cstring,cstring_literals") == 0) {
941 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
944 // Globals from llvm.metadata aren't emitted, do not instrument them.
945 if (Section == "llvm.metadata") return false;
951 void AddressSanitizerModule::initializeCallbacks(Module &M) {
953 // Declare our poisoning and unpoisoning functions.
954 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
955 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
956 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
957 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
958 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
959 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
960 // Declare functions that register/unregister globals.
961 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
962 kAsanRegisterGlobalsName, IRB.getVoidTy(),
963 IntptrTy, IntptrTy, NULL));
964 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
965 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
966 kAsanUnregisterGlobalsName,
967 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
968 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
971 // This function replaces all global variables with new variables that have
972 // trailing redzones. It also creates a function that poisons
973 // redzones and inserts this function into llvm.global_ctors.
974 bool AddressSanitizerModule::runOnModule(Module &M) {
975 if (!ClGlobals) return false;
977 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
980 DL = &DLP->getDataLayout();
982 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
983 if (BL->isIn(M)) return false;
984 C = &(M.getContext());
985 int LongSize = DL->getPointerSizeInBits();
986 IntptrTy = Type::getIntNTy(*C, LongSize);
987 Mapping = getShadowMapping(M, LongSize);
988 initializeCallbacks(M);
989 DynamicallyInitializedGlobals.Init(M);
991 SmallVector<GlobalVariable *, 16> GlobalsToChange;
993 for (Module::GlobalListType::iterator G = M.global_begin(),
994 E = M.global_end(); G != E; ++G) {
995 if (ShouldInstrumentGlobal(G))
996 GlobalsToChange.push_back(G);
999 size_t n = GlobalsToChange.size();
1000 if (n == 0) return false;
1002 // A global is described by a structure
1005 // size_t size_with_redzone;
1006 // const char *name;
1007 // const char *module_name;
1008 // size_t has_dynamic_init;
1009 // We initialize an array of such structures and pass it to a run-time call.
1010 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
1012 IntptrTy, IntptrTy, NULL);
1013 SmallVector<Constant *, 16> Initializers(n);
1015 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1017 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1019 bool HasDynamicallyInitializedGlobals = false;
1021 // We shouldn't merge same module names, as this string serves as unique
1022 // module ID in runtime.
1023 GlobalVariable *ModuleName = createPrivateGlobalForString(
1024 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1026 for (size_t i = 0; i < n; i++) {
1027 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1028 GlobalVariable *G = GlobalsToChange[i];
1029 PointerType *PtrTy = cast<PointerType>(G->getType());
1030 Type *Ty = PtrTy->getElementType();
1031 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1032 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1033 // MinRZ <= RZ <= kMaxGlobalRedzone
1034 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1035 uint64_t RZ = std::max(MinRZ,
1036 std::min(kMaxGlobalRedzone,
1037 (SizeInBytes / MinRZ / 4) * MinRZ));
1038 uint64_t RightRedzoneSize = RZ;
1039 // Round up to MinRZ
1040 if (SizeInBytes % MinRZ)
1041 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1042 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1043 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1044 // Determine whether this global should be poisoned in initialization.
1045 bool GlobalHasDynamicInitializer =
1046 DynamicallyInitializedGlobals.Contains(G);
1047 // Don't check initialization order if this global is blacklisted.
1048 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
1050 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1051 Constant *NewInitializer = ConstantStruct::get(
1052 NewTy, G->getInitializer(),
1053 Constant::getNullValue(RightRedZoneTy), NULL);
1055 GlobalVariable *Name =
1056 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
1058 // Create a new global variable with enough space for a redzone.
1059 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1060 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1061 Linkage = GlobalValue::InternalLinkage;
1062 GlobalVariable *NewGlobal = new GlobalVariable(
1063 M, NewTy, G->isConstant(), Linkage,
1064 NewInitializer, "", G, G->getThreadLocalMode());
1065 NewGlobal->copyAttributesFrom(G);
1066 NewGlobal->setAlignment(MinRZ);
1069 Indices2[0] = IRB.getInt32(0);
1070 Indices2[1] = IRB.getInt32(0);
1072 G->replaceAllUsesWith(
1073 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1074 NewGlobal->takeName(G);
1075 G->eraseFromParent();
1077 Initializers[i] = ConstantStruct::get(
1079 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1080 ConstantInt::get(IntptrTy, SizeInBytes),
1081 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1082 ConstantExpr::getPointerCast(Name, IntptrTy),
1083 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1084 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1087 // Populate the first and last globals declared in this TU.
1088 if (CheckInitOrder && GlobalHasDynamicInitializer)
1089 HasDynamicallyInitializedGlobals = true;
1091 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1094 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1095 GlobalVariable *AllGlobals = new GlobalVariable(
1096 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1097 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1099 // Create calls for poisoning before initializers run and unpoisoning after.
1100 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1101 createInitializerPoisonCalls(M, ModuleName);
1102 IRB.CreateCall2(AsanRegisterGlobals,
1103 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1104 ConstantInt::get(IntptrTy, n));
1106 // We also need to unregister globals at the end, e.g. when a shared library
1108 Function *AsanDtorFunction = Function::Create(
1109 FunctionType::get(Type::getVoidTy(*C), false),
1110 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1111 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1112 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1113 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1114 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1115 ConstantInt::get(IntptrTy, n));
1116 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1122 void AddressSanitizer::initializeCallbacks(Module &M) {
1123 IRBuilder<> IRB(*C);
1124 // Create __asan_report* callbacks.
1125 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1126 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1127 AccessSizeIndex++) {
1128 // IsWrite and TypeSize are encoded in the function name.
1129 std::string Suffix =
1130 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1131 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1132 checkInterfaceFunction(
1133 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1134 IRB.getVoidTy(), IntptrTy, NULL));
1135 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1136 checkInterfaceFunction(
1137 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1138 IRB.getVoidTy(), IntptrTy, NULL));
1141 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1142 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1143 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1144 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1146 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1147 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1148 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1149 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1150 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1151 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1153 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1154 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1155 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1156 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1157 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1158 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1159 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1160 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1161 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1163 AsanHandleNoReturnFunc = checkInterfaceFunction(
1164 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1165 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1166 kAsanCovName, IRB.getVoidTy(), NULL));
1167 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1168 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1169 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1170 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1171 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1172 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1173 StringRef(""), StringRef(""),
1174 /*hasSideEffects=*/true);
1178 bool AddressSanitizer::doInitialization(Module &M) {
1179 // Initialize the private fields. No one has accessed them before.
1180 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1183 DL = &DLP->getDataLayout();
1185 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1186 DynamicallyInitializedGlobals.Init(M);
1188 C = &(M.getContext());
1189 LongSize = DL->getPointerSizeInBits();
1190 IntptrTy = Type::getIntNTy(*C, LongSize);
1192 AsanCtorFunction = Function::Create(
1193 FunctionType::get(Type::getVoidTy(*C), false),
1194 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1195 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1196 // call __asan_init in the module ctor.
1197 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1198 AsanInitFunction = checkInterfaceFunction(
1199 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1200 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1201 IRB.CreateCall(AsanInitFunction);
1203 Mapping = getShadowMapping(M, LongSize);
1205 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1209 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1210 // For each NSObject descendant having a +load method, this method is invoked
1211 // by the ObjC runtime before any of the static constructors is called.
1212 // Therefore we need to instrument such methods with a call to __asan_init
1213 // at the beginning in order to initialize our runtime before any access to
1214 // the shadow memory.
1215 // We cannot just ignore these methods, because they may call other
1216 // instrumented functions.
1217 if (F.getName().find(" load]") != std::string::npos) {
1218 IRBuilder<> IRB(F.begin()->begin());
1219 IRB.CreateCall(AsanInitFunction);
1225 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1226 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1227 // Skip static allocas at the top of the entry block so they don't become
1228 // dynamic when we split the block. If we used our optimized stack layout,
1229 // then there will only be one alloca and it will come first.
1230 for (; IP != BE; ++IP) {
1231 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1232 if (!AI || !AI->isStaticAlloca())
1236 IRBuilder<> IRB(IP);
1237 Type *Int8Ty = IRB.getInt8Ty();
1238 GlobalVariable *Guard = new GlobalVariable(
1239 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1240 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1241 LoadInst *Load = IRB.CreateLoad(Guard);
1242 Load->setAtomic(Monotonic);
1243 Load->setAlignment(1);
1244 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1245 Instruction *Ins = SplitBlockAndInsertIfThen(
1246 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1247 IRB.SetInsertPoint(Ins);
1248 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1249 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1250 Instruction *Call = IRB.CreateCall(AsanCovFunction);
1251 Call->setDebugLoc(IP->getDebugLoc());
1252 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1253 Store->setAtomic(Monotonic);
1254 Store->setAlignment(1);
1257 // Poor man's coverage that works with ASan.
1258 // We create a Guard boolean variable with the same linkage
1259 // as the function and inject this code into the entry block (-asan-coverage=1)
1260 // or all blocks (-asan-coverage=2):
1262 // __sanitizer_cov(&F);
1265 // The accesses to Guard are atomic. The rest of the logic is
1266 // in __sanitizer_cov (it's fine to call it more than once).
1268 // This coverage implementation provides very limited data:
1269 // it only tells if a given function (block) was ever executed.
1270 // No counters, no per-edge data.
1271 // But for many use cases this is what we need and the added slowdown
1272 // is negligible. This simple implementation will probably be obsoleted
1273 // by the upcoming Clang-based coverage implementation.
1274 // By having it here and now we hope to
1275 // a) get the functionality to users earlier and
1276 // b) collect usage statistics to help improve Clang coverage design.
1277 bool AddressSanitizer::InjectCoverage(Function &F,
1278 const ArrayRef<BasicBlock *> AllBlocks) {
1279 if (!ClCoverage) return false;
1281 if (ClCoverage == 1 ||
1282 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1283 InjectCoverageAtBlock(F, F.getEntryBlock());
1285 for (size_t i = 0, n = AllBlocks.size(); i < n; i++)
1286 InjectCoverageAtBlock(F, *AllBlocks[i]);
1291 bool AddressSanitizer::runOnFunction(Function &F) {
1292 if (BL->isIn(F)) return false;
1293 if (&F == AsanCtorFunction) return false;
1294 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1295 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1296 initializeCallbacks(*F.getParent());
1298 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1299 maybeInsertAsanInitAtFunctionEntry(F);
1301 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1304 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1307 // We want to instrument every address only once per basic block (unless there
1308 // are calls between uses).
1309 SmallSet<Value*, 16> TempsToInstrument;
1310 SmallVector<Instruction*, 16> ToInstrument;
1311 SmallVector<Instruction*, 8> NoReturnCalls;
1312 SmallVector<BasicBlock*, 16> AllBlocks;
1313 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1317 // Fill the set of memory operations to instrument.
1318 for (Function::iterator FI = F.begin(), FE = F.end();
1320 AllBlocks.push_back(FI);
1321 TempsToInstrument.clear();
1322 int NumInsnsPerBB = 0;
1323 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1325 if (LooksLikeCodeInBug11395(BI)) return false;
1326 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1327 if (ClOpt && ClOptSameTemp) {
1328 if (!TempsToInstrument.insert(Addr))
1329 continue; // We've seen this temp in the current BB.
1331 } else if (ClInvalidPointerPairs &&
1332 isInterestingPointerComparisonOrSubtraction(BI)) {
1333 PointerComparisonsOrSubtracts.push_back(BI);
1335 } else if (isa<MemIntrinsic>(BI)) {
1338 if (isa<AllocaInst>(BI))
1342 // A call inside BB.
1343 TempsToInstrument.clear();
1344 if (CS.doesNotReturn())
1345 NoReturnCalls.push_back(CS.getInstruction());
1349 ToInstrument.push_back(BI);
1351 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1356 Function *UninstrumentedDuplicate = 0;
1357 bool LikelyToInstrument =
1358 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1359 if (ClKeepUninstrumented && LikelyToInstrument) {
1360 ValueToValueMapTy VMap;
1361 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1362 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1363 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1364 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1367 bool UseCalls = false;
1368 if (ClInstrumentationWithCallsThreshold >= 0 &&
1369 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1373 int NumInstrumented = 0;
1374 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1375 Instruction *Inst = ToInstrument[i];
1376 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1377 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1378 if (isInterestingMemoryAccess(Inst, &IsWrite))
1379 instrumentMop(Inst, UseCalls);
1381 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1386 FunctionStackPoisoner FSP(F, *this);
1387 bool ChangedStack = FSP.runOnFunction();
1389 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1390 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1391 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1392 Instruction *CI = NoReturnCalls[i];
1393 IRBuilder<> IRB(CI);
1394 IRB.CreateCall(AsanHandleNoReturnFunc);
1397 for (size_t i = 0, n = PointerComparisonsOrSubtracts.size(); i != n; i++) {
1398 instrumentPointerComparisonOrSubtraction(PointerComparisonsOrSubtracts[i]);
1402 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1404 if (InjectCoverage(F, AllBlocks))
1407 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1409 if (ClKeepUninstrumented) {
1411 // No instrumentation is done, no need for the duplicate.
1412 if (UninstrumentedDuplicate)
1413 UninstrumentedDuplicate->eraseFromParent();
1415 // The function was instrumented. We must have the duplicate.
1416 assert(UninstrumentedDuplicate);
1417 UninstrumentedDuplicate->setSection("NOASAN");
1418 assert(!F.hasSection());
1419 F.setSection("ASAN");
1426 // Workaround for bug 11395: we don't want to instrument stack in functions
1427 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1428 // FIXME: remove once the bug 11395 is fixed.
1429 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1430 if (LongSize != 32) return false;
1431 CallInst *CI = dyn_cast<CallInst>(I);
1432 if (!CI || !CI->isInlineAsm()) return false;
1433 if (CI->getNumArgOperands() <= 5) return false;
1434 // We have inline assembly with quite a few arguments.
1438 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1439 IRBuilder<> IRB(*C);
1440 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1441 std::string Suffix = itostr(i);
1442 AsanStackMallocFunc[i] = checkInterfaceFunction(
1443 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1444 IntptrTy, IntptrTy, NULL));
1445 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1446 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1447 IntptrTy, IntptrTy, NULL));
1449 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1450 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1451 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1452 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1456 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1457 IRBuilder<> &IRB, Value *ShadowBase,
1459 size_t n = ShadowBytes.size();
1461 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1462 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1463 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1464 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1465 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1466 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1468 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1469 if (ASan.DL->isLittleEndian())
1470 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1472 Val = (Val << 8) | ShadowBytes[i + j];
1475 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1476 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1477 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1478 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1483 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1484 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1485 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1486 assert(LocalStackSize <= kMaxStackMallocSize);
1487 uint64_t MaxSize = kMinStackMallocSize;
1488 for (int i = 0; ; i++, MaxSize *= 2)
1489 if (LocalStackSize <= MaxSize)
1491 llvm_unreachable("impossible LocalStackSize");
1494 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1495 // We can not use MemSet intrinsic because it may end up calling the actual
1496 // memset. Size is a multiple of 8.
1497 // Currently this generates 8-byte stores on x86_64; it may be better to
1498 // generate wider stores.
1499 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1500 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1501 assert(!(Size % 8));
1502 assert(kAsanStackAfterReturnMagic == 0xf5);
1503 for (int i = 0; i < Size; i += 8) {
1504 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1505 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1506 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1510 void FunctionStackPoisoner::poisonStack() {
1511 int StackMallocIdx = -1;
1513 assert(AllocaVec.size() > 0);
1514 Instruction *InsBefore = AllocaVec[0];
1515 IRBuilder<> IRB(InsBefore);
1517 SmallVector<ASanStackVariableDescription, 16> SVD;
1518 SVD.reserve(AllocaVec.size());
1519 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1520 AllocaInst *AI = AllocaVec[i];
1521 ASanStackVariableDescription D = { AI->getName().data(),
1522 getAllocaSizeInBytes(AI),
1523 AI->getAlignment(), AI, 0};
1526 // Minimal header size (left redzone) is 4 pointers,
1527 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1528 size_t MinHeaderSize = ASan.LongSize / 2;
1529 ASanStackFrameLayout L;
1530 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1531 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1532 uint64_t LocalStackSize = L.FrameSize;
1533 bool DoStackMalloc =
1534 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1536 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1537 AllocaInst *MyAlloca =
1538 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1539 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1540 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1541 MyAlloca->setAlignment(FrameAlignment);
1542 assert(MyAlloca->isStaticAlloca());
1543 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1544 Value *LocalStackBase = OrigStackBase;
1546 if (DoStackMalloc) {
1547 // LocalStackBase = OrigStackBase
1548 // if (__asan_option_detect_stack_use_after_return)
1549 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1550 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1551 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1552 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1553 kAsanOptionDetectUAR, IRB.getInt32Ty());
1554 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1555 Constant::getNullValue(IRB.getInt32Ty()));
1556 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1557 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1558 IRBuilder<> IRBIf(Term);
1559 LocalStackBase = IRBIf.CreateCall2(
1560 AsanStackMallocFunc[StackMallocIdx],
1561 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1562 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1563 IRB.SetInsertPoint(InsBefore);
1564 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1565 Phi->addIncoming(OrigStackBase, CmpBlock);
1566 Phi->addIncoming(LocalStackBase, SetBlock);
1567 LocalStackBase = Phi;
1570 // Insert poison calls for lifetime intrinsics for alloca.
1571 bool HavePoisonedAllocas = false;
1572 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1573 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1574 assert(APC.InsBefore);
1576 IRBuilder<> IRB(APC.InsBefore);
1577 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1578 HavePoisonedAllocas |= APC.DoPoison;
1581 // Replace Alloca instructions with base+offset.
1582 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1583 AllocaInst *AI = SVD[i].AI;
1584 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1585 IRB.CreateAdd(LocalStackBase,
1586 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1588 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1589 AI->replaceAllUsesWith(NewAllocaPtr);
1592 // The left-most redzone has enough space for at least 4 pointers.
1593 // Write the Magic value to redzone[0].
1594 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1595 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1597 // Write the frame description constant to redzone[1].
1598 Value *BasePlus1 = IRB.CreateIntToPtr(
1599 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1601 GlobalVariable *StackDescriptionGlobal =
1602 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1603 /*AllowMerging*/true);
1604 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1606 IRB.CreateStore(Description, BasePlus1);
1607 // Write the PC to redzone[2].
1608 Value *BasePlus2 = IRB.CreateIntToPtr(
1609 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1610 2 * ASan.LongSize/8)),
1612 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1614 // Poison the stack redzones at the entry.
1615 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1616 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1618 // (Un)poison the stack before all ret instructions.
1619 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1620 Instruction *Ret = RetVec[i];
1621 IRBuilder<> IRBRet(Ret);
1622 // Mark the current frame as retired.
1623 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1625 if (DoStackMalloc) {
1626 assert(StackMallocIdx >= 0);
1627 // if LocalStackBase != OrigStackBase:
1628 // // In use-after-return mode, poison the whole stack frame.
1629 // if StackMallocIdx <= 4
1630 // // For small sizes inline the whole thing:
1631 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1632 // **SavedFlagPtr(LocalStackBase) = 0
1634 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1636 // <This is not a fake stack; unpoison the redzones>
1637 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1638 TerminatorInst *ThenTerm, *ElseTerm;
1639 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1641 IRBuilder<> IRBPoison(ThenTerm);
1642 if (StackMallocIdx <= 4) {
1643 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1644 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1645 ClassSize >> Mapping.Scale);
1646 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1648 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1649 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1650 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1651 IRBPoison.CreateStore(
1652 Constant::getNullValue(IRBPoison.getInt8Ty()),
1653 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1655 // For larger frames call __asan_stack_free_*.
1656 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1657 ConstantInt::get(IntptrTy, LocalStackSize),
1661 IRBuilder<> IRBElse(ElseTerm);
1662 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1663 } else if (HavePoisonedAllocas) {
1664 // If we poisoned some allocas in llvm.lifetime analysis,
1665 // unpoison whole stack frame now.
1666 assert(LocalStackBase == OrigStackBase);
1667 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1669 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1673 // We are done. Remove the old unused alloca instructions.
1674 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1675 AllocaVec[i]->eraseFromParent();
1678 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1679 IRBuilder<> &IRB, bool DoPoison) {
1680 // For now just insert the call to ASan runtime.
1681 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1682 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1683 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1684 : AsanUnpoisonStackMemoryFunc,
1688 // Handling llvm.lifetime intrinsics for a given %alloca:
1689 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1690 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1691 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1692 // could be poisoned by previous llvm.lifetime.end instruction, as the
1693 // variable may go in and out of scope several times, e.g. in loops).
1694 // (3) if we poisoned at least one %alloca in a function,
1695 // unpoison the whole stack frame at function exit.
1697 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1698 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1699 // We're intested only in allocas we can handle.
1700 return isInterestingAlloca(*AI) ? AI : 0;
1701 // See if we've already calculated (or started to calculate) alloca for a
1703 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1704 if (I != AllocaForValue.end())
1706 // Store 0 while we're calculating alloca for value V to avoid
1707 // infinite recursion if the value references itself.
1708 AllocaForValue[V] = 0;
1709 AllocaInst *Res = 0;
1710 if (CastInst *CI = dyn_cast<CastInst>(V))
1711 Res = findAllocaForValue(CI->getOperand(0));
1712 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1713 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1714 Value *IncValue = PN->getIncomingValue(i);
1715 // Allow self-referencing phi-nodes.
1716 if (IncValue == PN) continue;
1717 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1718 // AI for incoming values should exist and should all be equal.
1719 if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1725 AllocaForValue[V] = Res;