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 #include "llvm/Transforms/Instrumentation.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/DepthFirstIterator.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/ADT/SmallString.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/ADT/Statistic.h"
24 #include "llvm/ADT/StringExtras.h"
25 #include "llvm/ADT/Triple.h"
26 #include "llvm/IR/CallSite.h"
27 #include "llvm/IR/DIBuilder.h"
28 #include "llvm/IR/DataLayout.h"
29 #include "llvm/IR/Function.h"
30 #include "llvm/IR/IRBuilder.h"
31 #include "llvm/IR/InlineAsm.h"
32 #include "llvm/IR/InstVisitor.h"
33 #include "llvm/IR/IntrinsicInst.h"
34 #include "llvm/IR/LLVMContext.h"
35 #include "llvm/IR/MDBuilder.h"
36 #include "llvm/IR/Module.h"
37 #include "llvm/IR/Type.h"
38 #include "llvm/Support/CommandLine.h"
39 #include "llvm/Support/DataTypes.h"
40 #include "llvm/Support/Debug.h"
41 #include "llvm/Support/Endian.h"
42 #include "llvm/Support/system_error.h"
43 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
44 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
45 #include "llvm/Transforms/Utils/Cloning.h"
46 #include "llvm/Transforms/Utils/Local.h"
47 #include "llvm/Transforms/Utils/ModuleUtils.h"
48 #include "llvm/Transforms/Utils/SpecialCaseList.h"
54 #define DEBUG_TYPE "asan"
56 static const uint64_t kDefaultShadowScale = 3;
57 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
58 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
59 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
60 static const uint64_t kSmallX86_64ShadowOffset = 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 kAsanPtrCmp = "__sanitizer_ptr_cmp";
85 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
86 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
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<int> ClCoverageBlockThreshold("asan-coverage-block-threshold",
140 cl::desc("Add coverage instrumentation only to the entry block if there "
141 "are more than this number of blocks."),
142 cl::Hidden, cl::init(1500));
143 static cl::opt<bool> ClInitializers("asan-initialization-order",
144 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
145 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
146 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
147 cl::Hidden, cl::init(false));
148 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
149 cl::desc("Realign stack to the value of this flag (power of two)"),
150 cl::Hidden, cl::init(32));
151 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
152 cl::desc("File containing the list of objects to ignore "
153 "during instrumentation"), cl::Hidden);
154 static cl::opt<int> ClInstrumentationWithCallsThreshold(
155 "asan-instrumentation-with-call-threshold",
156 cl::desc("If the function being instrumented contains more than "
157 "this number of memory accesses, use callbacks instead of "
158 "inline checks (-1 means never use callbacks)."),
159 cl::Hidden, cl::init(10000));
160 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
161 "asan-memory-access-callback-prefix",
162 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
163 cl::init("__asan_"));
165 // This is an experimental feature that will allow to choose between
166 // instrumented and non-instrumented code at link-time.
167 // If this option is on, just before instrumenting a function we create its
168 // clone; if the function is not changed by asan the clone is deleted.
169 // If we end up with a clone, we put the instrumented function into a section
170 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
172 // This is still a prototype, we need to figure out a way to keep two copies of
173 // a function so that the linker can easily choose one of them.
174 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
175 cl::desc("Keep uninstrumented copies of functions"),
176 cl::Hidden, cl::init(false));
178 // These flags allow to change the shadow mapping.
179 // The shadow mapping looks like
180 // Shadow = (Mem >> scale) + (1 << offset_log)
181 static cl::opt<int> ClMappingScale("asan-mapping-scale",
182 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
184 // Optimization flags. Not user visible, used mostly for testing
185 // and benchmarking the tool.
186 static cl::opt<bool> ClOpt("asan-opt",
187 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
188 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
189 cl::desc("Instrument the same temp just once"), cl::Hidden,
191 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
192 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
194 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
195 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
196 cl::Hidden, cl::init(false));
199 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
201 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
202 cl::Hidden, cl::init(0));
203 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
204 cl::Hidden, cl::desc("Debug func"));
205 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
206 cl::Hidden, cl::init(-1));
207 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
208 cl::Hidden, cl::init(-1));
210 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
211 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
212 STATISTIC(NumOptimizedAccessesToGlobalArray,
213 "Number of optimized accesses to global arrays");
214 STATISTIC(NumOptimizedAccessesToGlobalVar,
215 "Number of optimized accesses to global vars");
218 /// A set of dynamically initialized globals extracted from metadata.
219 class SetOfDynamicallyInitializedGlobals {
221 void Init(Module& M) {
222 // Clang generates metadata identifying all dynamically initialized globals.
223 NamedMDNode *DynamicGlobals =
224 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
227 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
228 MDNode *MDN = DynamicGlobals->getOperand(i);
229 assert(MDN->getNumOperands() == 1);
230 Value *VG = MDN->getOperand(0);
231 // The optimizer may optimize away a global entirely, in which case we
232 // cannot instrument access to it.
235 DynInitGlobals.insert(cast<GlobalVariable>(VG));
238 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
240 SmallSet<GlobalValue*, 32> DynInitGlobals;
243 /// This struct defines the shadow mapping using the rule:
244 /// shadow = (mem >> Scale) ADD-or-OR Offset.
245 struct ShadowMapping {
251 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
252 llvm::Triple TargetTriple(M.getTargetTriple());
253 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
254 bool IsIOS = TargetTriple.getOS() == llvm::Triple::IOS;
255 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
256 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
257 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
258 TargetTriple.getArch() == llvm::Triple::ppc64le;
259 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
260 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
261 TargetTriple.getArch() == llvm::Triple::mipsel;
263 ShadowMapping Mapping;
265 if (LongSize == 32) {
269 Mapping.Offset = kMIPS32_ShadowOffset32;
271 Mapping.Offset = kFreeBSD_ShadowOffset32;
273 Mapping.Offset = kIOSShadowOffset32;
275 Mapping.Offset = kDefaultShadowOffset32;
276 } else { // LongSize == 64
278 Mapping.Offset = kPPC64_ShadowOffset64;
280 Mapping.Offset = kFreeBSD_ShadowOffset64;
281 else if (IsLinux && IsX86_64)
282 Mapping.Offset = kSmallX86_64ShadowOffset;
284 Mapping.Offset = kDefaultShadowOffset64;
287 Mapping.Scale = kDefaultShadowScale;
288 if (ClMappingScale) {
289 Mapping.Scale = ClMappingScale;
292 // OR-ing shadow offset if more efficient (at least on x86) if the offset
293 // is a power of two, but on ppc64 we have to use add since the shadow
294 // offset is not necessary 1/8-th of the address space.
295 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
300 static size_t RedzoneSizeForScale(int MappingScale) {
301 // Redzone used for stack and globals is at least 32 bytes.
302 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
303 return std::max(32U, 1U << MappingScale);
306 /// AddressSanitizer: instrument the code in module to find memory bugs.
307 struct AddressSanitizer : public FunctionPass {
308 AddressSanitizer(bool CheckInitOrder = true,
309 bool CheckUseAfterReturn = false,
310 bool CheckLifetime = false,
311 StringRef BlacklistFile = StringRef())
313 CheckInitOrder(CheckInitOrder || ClInitializers),
314 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
315 CheckLifetime(CheckLifetime || ClCheckLifetime),
316 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
318 const char *getPassName() const override {
319 return "AddressSanitizerFunctionPass";
321 void instrumentMop(Instruction *I, bool UseCalls);
322 void instrumentPointerComparisonOrSubtraction(Instruction *I);
323 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
324 Value *Addr, uint32_t TypeSize, bool IsWrite,
325 Value *SizeArgument, bool UseCalls);
326 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
327 Value *ShadowValue, uint32_t TypeSize);
328 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
329 bool IsWrite, size_t AccessSizeIndex,
330 Value *SizeArgument);
331 void instrumentMemIntrinsic(MemIntrinsic *MI);
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 // Instrument memset/memmove/memcpy
607 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
609 Instruction *Call = nullptr;
610 if (isa<MemTransferInst>(MI)) {
611 Call = IRB.CreateCall3(
612 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
613 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
614 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
615 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
616 } else if (isa<MemSetInst>(MI)) {
617 Call = IRB.CreateCall3(
619 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
620 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
621 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
623 Call->setDebugLoc(MI->getDebugLoc());
624 MI->eraseFromParent();
627 // If I is an interesting memory access, return the PointerOperand
628 // and set IsWrite. Otherwise return NULL.
629 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
630 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
631 if (!ClInstrumentReads) return nullptr;
633 return LI->getPointerOperand();
635 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
636 if (!ClInstrumentWrites) return nullptr;
638 return SI->getPointerOperand();
640 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
641 if (!ClInstrumentAtomics) return nullptr;
643 return RMW->getPointerOperand();
645 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
646 if (!ClInstrumentAtomics) return nullptr;
648 return XCHG->getPointerOperand();
653 static bool isPointerOperand(Value *V) {
654 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
657 // This is a rough heuristic; it may cause both false positives and
658 // false negatives. The proper implementation requires cooperation with
660 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
661 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
662 if (!Cmp->isRelational())
664 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
665 if (BO->getOpcode() != Instruction::Sub)
670 if (!isPointerOperand(I->getOperand(0)) ||
671 !isPointerOperand(I->getOperand(1)))
676 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
677 // If a global variable does not have dynamic initialization we don't
678 // have to instrument it. However, if a global does not have initializer
679 // at all, we assume it has dynamic initializer (in other TU).
680 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
684 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
686 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
687 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
688 for (int i = 0; i < 2; i++) {
689 if (Param[i]->getType()->isPointerTy())
690 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
692 IRB.CreateCall2(F, Param[0], Param[1]);
695 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
696 bool IsWrite = false;
697 Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
699 if (ClOpt && ClOptGlobals) {
700 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
701 // If initialization order checking is disabled, a simple access to a
702 // dynamically initialized global is always valid.
703 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
704 NumOptimizedAccessesToGlobalVar++;
708 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
709 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
710 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
711 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
712 NumOptimizedAccessesToGlobalArray++;
719 Type *OrigPtrTy = Addr->getType();
720 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
722 assert(OrigTy->isSized());
723 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
725 assert((TypeSize % 8) == 0);
728 NumInstrumentedWrites++;
730 NumInstrumentedReads++;
732 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
733 if (TypeSize == 8 || TypeSize == 16 ||
734 TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
735 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
736 // Instrument unusual size (but still multiple of 8).
737 // We can not do it with a single check, so we do 1-byte check for the first
738 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
739 // to report the actual access size.
741 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
742 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
745 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
746 Check->setDebugLoc(I->getDebugLoc());
748 Value *LastByte = IRB.CreateIntToPtr(
749 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
751 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
752 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
756 // Validate the result of Module::getOrInsertFunction called for an interface
757 // function of AddressSanitizer. If the instrumented module defines a function
758 // with the same name, their prototypes must match, otherwise
759 // getOrInsertFunction returns a bitcast.
760 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
761 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
762 FuncOrBitcast->dump();
763 report_fatal_error("trying to redefine an AddressSanitizer "
764 "interface function");
767 Instruction *AddressSanitizer::generateCrashCode(
768 Instruction *InsertBefore, Value *Addr,
769 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
770 IRBuilder<> IRB(InsertBefore);
771 CallInst *Call = SizeArgument
772 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
773 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
775 // We don't do Call->setDoesNotReturn() because the BB already has
776 // UnreachableInst at the end.
777 // This EmptyAsm is required to avoid callback merge.
778 IRB.CreateCall(EmptyAsm);
782 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
785 size_t Granularity = 1 << Mapping.Scale;
786 // Addr & (Granularity - 1)
787 Value *LastAccessedByte = IRB.CreateAnd(
788 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
789 // (Addr & (Granularity - 1)) + size - 1
790 if (TypeSize / 8 > 1)
791 LastAccessedByte = IRB.CreateAdd(
792 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
793 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
794 LastAccessedByte = IRB.CreateIntCast(
795 LastAccessedByte, ShadowValue->getType(), false);
796 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
797 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
800 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
801 Instruction *InsertBefore, Value *Addr,
802 uint32_t TypeSize, bool IsWrite,
803 Value *SizeArgument, bool UseCalls) {
804 IRBuilder<> IRB(InsertBefore);
805 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
806 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
809 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
814 Type *ShadowTy = IntegerType::get(
815 *C, std::max(8U, TypeSize >> Mapping.Scale));
816 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
817 Value *ShadowPtr = memToShadow(AddrLong, IRB);
818 Value *CmpVal = Constant::getNullValue(ShadowTy);
819 Value *ShadowValue = IRB.CreateLoad(
820 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
822 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
823 size_t Granularity = 1 << Mapping.Scale;
824 TerminatorInst *CrashTerm = nullptr;
826 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
827 TerminatorInst *CheckTerm =
828 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
829 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
830 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
831 IRB.SetInsertPoint(CheckTerm);
832 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
833 BasicBlock *CrashBlock =
834 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
835 CrashTerm = new UnreachableInst(*C, CrashBlock);
836 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
837 ReplaceInstWithInst(CheckTerm, NewTerm);
839 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
842 Instruction *Crash = generateCrashCode(
843 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
844 Crash->setDebugLoc(OrigIns->getDebugLoc());
847 void AddressSanitizerModule::createInitializerPoisonCalls(
848 Module &M, GlobalValue *ModuleName) {
849 // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
850 Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
851 // If that function is not present, this TU contains no globals, or they have
852 // all been optimized away
856 // Set up the arguments to our poison/unpoison functions.
857 IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
859 // Add a call to poison all external globals before the given function starts.
860 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
861 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
863 // Add calls to unpoison all globals before each return instruction.
864 for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
866 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
867 CallInst::Create(AsanUnpoisonGlobals, "", RI);
872 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
873 Type *Ty = cast<PointerType>(G->getType())->getElementType();
874 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
876 if (BL->isIn(*G)) return false;
877 if (!Ty->isSized()) return false;
878 if (!G->hasInitializer()) return false;
879 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
880 // Touch only those globals that will not be defined in other modules.
881 // Don't handle ODR type linkages since other modules may be built w/o asan.
882 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
883 G->getLinkage() != GlobalVariable::PrivateLinkage &&
884 G->getLinkage() != GlobalVariable::InternalLinkage)
886 // Two problems with thread-locals:
887 // - The address of the main thread's copy can't be computed at link-time.
888 // - Need to poison all copies, not just the main thread's one.
889 if (G->isThreadLocal())
891 // For now, just ignore this Global if the alignment is large.
892 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
894 // Ignore all the globals with the names starting with "\01L_OBJC_".
895 // Many of those are put into the .cstring section. The linker compresses
896 // that section by removing the spare \0s after the string terminator, so
897 // our redzones get broken.
898 if ((G->getName().find("\01L_OBJC_") == 0) ||
899 (G->getName().find("\01l_OBJC_") == 0)) {
900 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
904 if (G->hasSection()) {
905 StringRef Section(G->getSection());
906 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
907 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
909 if ((Section.find("__OBJC,") == 0) ||
910 (Section.find("__DATA, __objc_") == 0)) {
911 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
914 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
915 // Constant CFString instances are compiled in the following way:
916 // -- the string buffer is emitted into
917 // __TEXT,__cstring,cstring_literals
918 // -- the constant NSConstantString structure referencing that buffer
919 // is placed into __DATA,__cfstring
920 // Therefore there's no point in placing redzones into __DATA,__cfstring.
921 // Moreover, it causes the linker to crash on OS X 10.7
922 if (Section.find("__DATA,__cfstring") == 0) {
923 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
926 // The linker merges the contents of cstring_literals and removes the
928 if (Section.find("__TEXT,__cstring,cstring_literals") == 0) {
929 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
932 // Globals from llvm.metadata aren't emitted, do not instrument them.
933 if (Section == "llvm.metadata") return false;
939 void AddressSanitizerModule::initializeCallbacks(Module &M) {
941 // Declare our poisoning and unpoisoning functions.
942 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
943 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
944 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
945 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
946 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
947 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
948 // Declare functions that register/unregister globals.
949 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
950 kAsanRegisterGlobalsName, IRB.getVoidTy(),
951 IntptrTy, IntptrTy, NULL));
952 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
953 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
954 kAsanUnregisterGlobalsName,
955 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
956 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
959 // This function replaces all global variables with new variables that have
960 // trailing redzones. It also creates a function that poisons
961 // redzones and inserts this function into llvm.global_ctors.
962 bool AddressSanitizerModule::runOnModule(Module &M) {
963 if (!ClGlobals) return false;
965 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
968 DL = &DLP->getDataLayout();
970 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
971 if (BL->isIn(M)) return false;
972 C = &(M.getContext());
973 int LongSize = DL->getPointerSizeInBits();
974 IntptrTy = Type::getIntNTy(*C, LongSize);
975 Mapping = getShadowMapping(M, LongSize);
976 initializeCallbacks(M);
977 DynamicallyInitializedGlobals.Init(M);
979 SmallVector<GlobalVariable *, 16> GlobalsToChange;
981 for (Module::GlobalListType::iterator G = M.global_begin(),
982 E = M.global_end(); G != E; ++G) {
983 if (ShouldInstrumentGlobal(G))
984 GlobalsToChange.push_back(G);
987 size_t n = GlobalsToChange.size();
988 if (n == 0) return false;
990 // A global is described by a structure
993 // size_t size_with_redzone;
995 // const char *module_name;
996 // size_t has_dynamic_init;
997 // We initialize an array of such structures and pass it to a run-time call.
998 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
1000 IntptrTy, IntptrTy, NULL);
1001 SmallVector<Constant *, 16> Initializers(n);
1003 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1005 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1007 bool HasDynamicallyInitializedGlobals = false;
1009 // We shouldn't merge same module names, as this string serves as unique
1010 // module ID in runtime.
1011 GlobalVariable *ModuleName = createPrivateGlobalForString(
1012 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1014 for (size_t i = 0; i < n; i++) {
1015 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1016 GlobalVariable *G = GlobalsToChange[i];
1017 PointerType *PtrTy = cast<PointerType>(G->getType());
1018 Type *Ty = PtrTy->getElementType();
1019 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1020 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1021 // MinRZ <= RZ <= kMaxGlobalRedzone
1022 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1023 uint64_t RZ = std::max(MinRZ,
1024 std::min(kMaxGlobalRedzone,
1025 (SizeInBytes / MinRZ / 4) * MinRZ));
1026 uint64_t RightRedzoneSize = RZ;
1027 // Round up to MinRZ
1028 if (SizeInBytes % MinRZ)
1029 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1030 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1031 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1032 // Determine whether this global should be poisoned in initialization.
1033 bool GlobalHasDynamicInitializer =
1034 DynamicallyInitializedGlobals.Contains(G);
1035 // Don't check initialization order if this global is blacklisted.
1036 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
1038 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1039 Constant *NewInitializer = ConstantStruct::get(
1040 NewTy, G->getInitializer(),
1041 Constant::getNullValue(RightRedZoneTy), NULL);
1043 GlobalVariable *Name =
1044 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
1046 // Create a new global variable with enough space for a redzone.
1047 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1048 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1049 Linkage = GlobalValue::InternalLinkage;
1050 GlobalVariable *NewGlobal = new GlobalVariable(
1051 M, NewTy, G->isConstant(), Linkage,
1052 NewInitializer, "", G, G->getThreadLocalMode());
1053 NewGlobal->copyAttributesFrom(G);
1054 NewGlobal->setAlignment(MinRZ);
1057 Indices2[0] = IRB.getInt32(0);
1058 Indices2[1] = IRB.getInt32(0);
1060 G->replaceAllUsesWith(
1061 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1062 NewGlobal->takeName(G);
1063 G->eraseFromParent();
1065 Initializers[i] = ConstantStruct::get(
1067 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1068 ConstantInt::get(IntptrTy, SizeInBytes),
1069 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1070 ConstantExpr::getPointerCast(Name, IntptrTy),
1071 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1072 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1075 // Populate the first and last globals declared in this TU.
1076 if (CheckInitOrder && GlobalHasDynamicInitializer)
1077 HasDynamicallyInitializedGlobals = true;
1079 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1082 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1083 GlobalVariable *AllGlobals = new GlobalVariable(
1084 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1085 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1087 // Create calls for poisoning before initializers run and unpoisoning after.
1088 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1089 createInitializerPoisonCalls(M, ModuleName);
1090 IRB.CreateCall2(AsanRegisterGlobals,
1091 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1092 ConstantInt::get(IntptrTy, n));
1094 // We also need to unregister globals at the end, e.g. when a shared library
1096 Function *AsanDtorFunction = Function::Create(
1097 FunctionType::get(Type::getVoidTy(*C), false),
1098 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1099 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1100 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1101 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1102 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1103 ConstantInt::get(IntptrTy, n));
1104 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1110 void AddressSanitizer::initializeCallbacks(Module &M) {
1111 IRBuilder<> IRB(*C);
1112 // Create __asan_report* callbacks.
1113 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1114 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1115 AccessSizeIndex++) {
1116 // IsWrite and TypeSize are encoded in the function name.
1117 std::string Suffix =
1118 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1119 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1120 checkInterfaceFunction(
1121 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1122 IRB.getVoidTy(), IntptrTy, NULL));
1123 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1124 checkInterfaceFunction(
1125 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1126 IRB.getVoidTy(), IntptrTy, NULL));
1129 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1130 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1131 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1132 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1134 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1135 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1136 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1137 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1138 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1139 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1141 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1142 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1143 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1144 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1145 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1146 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1147 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1148 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1149 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1151 AsanHandleNoReturnFunc = checkInterfaceFunction(
1152 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1153 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1154 kAsanCovName, IRB.getVoidTy(), NULL));
1155 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1156 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1157 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1158 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1159 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1160 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1161 StringRef(""), StringRef(""),
1162 /*hasSideEffects=*/true);
1166 bool AddressSanitizer::doInitialization(Module &M) {
1167 // Initialize the private fields. No one has accessed them before.
1168 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1170 report_fatal_error("data layout missing");
1171 DL = &DLP->getDataLayout();
1173 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1174 DynamicallyInitializedGlobals.Init(M);
1176 C = &(M.getContext());
1177 LongSize = DL->getPointerSizeInBits();
1178 IntptrTy = Type::getIntNTy(*C, LongSize);
1180 AsanCtorFunction = Function::Create(
1181 FunctionType::get(Type::getVoidTy(*C), false),
1182 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1183 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1184 // call __asan_init in the module ctor.
1185 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1186 AsanInitFunction = checkInterfaceFunction(
1187 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1188 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1189 IRB.CreateCall(AsanInitFunction);
1191 Mapping = getShadowMapping(M, LongSize);
1193 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1197 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1198 // For each NSObject descendant having a +load method, this method is invoked
1199 // by the ObjC runtime before any of the static constructors is called.
1200 // Therefore we need to instrument such methods with a call to __asan_init
1201 // at the beginning in order to initialize our runtime before any access to
1202 // the shadow memory.
1203 // We cannot just ignore these methods, because they may call other
1204 // instrumented functions.
1205 if (F.getName().find(" load]") != std::string::npos) {
1206 IRBuilder<> IRB(F.begin()->begin());
1207 IRB.CreateCall(AsanInitFunction);
1213 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1214 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1215 // Skip static allocas at the top of the entry block so they don't become
1216 // dynamic when we split the block. If we used our optimized stack layout,
1217 // then there will only be one alloca and it will come first.
1218 for (; IP != BE; ++IP) {
1219 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1220 if (!AI || !AI->isStaticAlloca())
1224 IRBuilder<> IRB(IP);
1225 Type *Int8Ty = IRB.getInt8Ty();
1226 GlobalVariable *Guard = new GlobalVariable(
1227 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1228 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1229 LoadInst *Load = IRB.CreateLoad(Guard);
1230 Load->setAtomic(Monotonic);
1231 Load->setAlignment(1);
1232 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1233 Instruction *Ins = SplitBlockAndInsertIfThen(
1234 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1235 IRB.SetInsertPoint(Ins);
1236 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1237 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1238 Instruction *Call = IRB.CreateCall(AsanCovFunction);
1239 Call->setDebugLoc(IP->getDebugLoc());
1240 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1241 Store->setAtomic(Monotonic);
1242 Store->setAlignment(1);
1245 // Poor man's coverage that works with ASan.
1246 // We create a Guard boolean variable with the same linkage
1247 // as the function and inject this code into the entry block (-asan-coverage=1)
1248 // or all blocks (-asan-coverage=2):
1250 // __sanitizer_cov(&F);
1253 // The accesses to Guard are atomic. The rest of the logic is
1254 // in __sanitizer_cov (it's fine to call it more than once).
1256 // This coverage implementation provides very limited data:
1257 // it only tells if a given function (block) was ever executed.
1258 // No counters, no per-edge data.
1259 // But for many use cases this is what we need and the added slowdown
1260 // is negligible. This simple implementation will probably be obsoleted
1261 // by the upcoming Clang-based coverage implementation.
1262 // By having it here and now we hope to
1263 // a) get the functionality to users earlier and
1264 // b) collect usage statistics to help improve Clang coverage design.
1265 bool AddressSanitizer::InjectCoverage(Function &F,
1266 const ArrayRef<BasicBlock *> AllBlocks) {
1267 if (!ClCoverage) return false;
1269 if (ClCoverage == 1 ||
1270 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1271 InjectCoverageAtBlock(F, F.getEntryBlock());
1273 for (size_t i = 0, n = AllBlocks.size(); i < n; i++)
1274 InjectCoverageAtBlock(F, *AllBlocks[i]);
1279 bool AddressSanitizer::runOnFunction(Function &F) {
1280 if (BL->isIn(F)) return false;
1281 if (&F == AsanCtorFunction) return false;
1282 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1283 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1284 initializeCallbacks(*F.getParent());
1286 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1287 maybeInsertAsanInitAtFunctionEntry(F);
1289 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1292 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1295 // We want to instrument every address only once per basic block (unless there
1296 // are calls between uses).
1297 SmallSet<Value*, 16> TempsToInstrument;
1298 SmallVector<Instruction*, 16> ToInstrument;
1299 SmallVector<Instruction*, 8> NoReturnCalls;
1300 SmallVector<BasicBlock*, 16> AllBlocks;
1301 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1305 // Fill the set of memory operations to instrument.
1306 for (Function::iterator FI = F.begin(), FE = F.end();
1308 AllBlocks.push_back(FI);
1309 TempsToInstrument.clear();
1310 int NumInsnsPerBB = 0;
1311 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1313 if (LooksLikeCodeInBug11395(BI)) return false;
1314 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1315 if (ClOpt && ClOptSameTemp) {
1316 if (!TempsToInstrument.insert(Addr))
1317 continue; // We've seen this temp in the current BB.
1319 } else if (ClInvalidPointerPairs &&
1320 isInterestingPointerComparisonOrSubtraction(BI)) {
1321 PointerComparisonsOrSubtracts.push_back(BI);
1323 } else if (isa<MemIntrinsic>(BI)) {
1326 if (isa<AllocaInst>(BI))
1330 // A call inside BB.
1331 TempsToInstrument.clear();
1332 if (CS.doesNotReturn())
1333 NoReturnCalls.push_back(CS.getInstruction());
1337 ToInstrument.push_back(BI);
1339 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1344 Function *UninstrumentedDuplicate = nullptr;
1345 bool LikelyToInstrument =
1346 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1347 if (ClKeepUninstrumented && LikelyToInstrument) {
1348 ValueToValueMapTy VMap;
1349 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1350 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1351 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1352 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1355 bool UseCalls = false;
1356 if (ClInstrumentationWithCallsThreshold >= 0 &&
1357 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1361 int NumInstrumented = 0;
1362 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1363 Instruction *Inst = ToInstrument[i];
1364 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1365 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1366 if (isInterestingMemoryAccess(Inst, &IsWrite))
1367 instrumentMop(Inst, UseCalls);
1369 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1374 FunctionStackPoisoner FSP(F, *this);
1375 bool ChangedStack = FSP.runOnFunction();
1377 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1378 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1379 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1380 Instruction *CI = NoReturnCalls[i];
1381 IRBuilder<> IRB(CI);
1382 IRB.CreateCall(AsanHandleNoReturnFunc);
1385 for (size_t i = 0, n = PointerComparisonsOrSubtracts.size(); i != n; i++) {
1386 instrumentPointerComparisonOrSubtraction(PointerComparisonsOrSubtracts[i]);
1390 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1392 if (InjectCoverage(F, AllBlocks))
1395 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1397 if (ClKeepUninstrumented) {
1399 // No instrumentation is done, no need for the duplicate.
1400 if (UninstrumentedDuplicate)
1401 UninstrumentedDuplicate->eraseFromParent();
1403 // The function was instrumented. We must have the duplicate.
1404 assert(UninstrumentedDuplicate);
1405 UninstrumentedDuplicate->setSection("NOASAN");
1406 assert(!F.hasSection());
1407 F.setSection("ASAN");
1414 // Workaround for bug 11395: we don't want to instrument stack in functions
1415 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1416 // FIXME: remove once the bug 11395 is fixed.
1417 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1418 if (LongSize != 32) return false;
1419 CallInst *CI = dyn_cast<CallInst>(I);
1420 if (!CI || !CI->isInlineAsm()) return false;
1421 if (CI->getNumArgOperands() <= 5) return false;
1422 // We have inline assembly with quite a few arguments.
1426 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1427 IRBuilder<> IRB(*C);
1428 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1429 std::string Suffix = itostr(i);
1430 AsanStackMallocFunc[i] = checkInterfaceFunction(
1431 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1432 IntptrTy, IntptrTy, NULL));
1433 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1434 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1435 IntptrTy, IntptrTy, NULL));
1437 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1438 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1439 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1440 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1444 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1445 IRBuilder<> &IRB, Value *ShadowBase,
1447 size_t n = ShadowBytes.size();
1449 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1450 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1451 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1452 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1453 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1454 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1456 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1457 if (ASan.DL->isLittleEndian())
1458 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1460 Val = (Val << 8) | ShadowBytes[i + j];
1463 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1464 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1465 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1466 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1471 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1472 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1473 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1474 assert(LocalStackSize <= kMaxStackMallocSize);
1475 uint64_t MaxSize = kMinStackMallocSize;
1476 for (int i = 0; ; i++, MaxSize *= 2)
1477 if (LocalStackSize <= MaxSize)
1479 llvm_unreachable("impossible LocalStackSize");
1482 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1483 // We can not use MemSet intrinsic because it may end up calling the actual
1484 // memset. Size is a multiple of 8.
1485 // Currently this generates 8-byte stores on x86_64; it may be better to
1486 // generate wider stores.
1487 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1488 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1489 assert(!(Size % 8));
1490 assert(kAsanStackAfterReturnMagic == 0xf5);
1491 for (int i = 0; i < Size; i += 8) {
1492 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1493 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1494 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1498 void FunctionStackPoisoner::poisonStack() {
1499 int StackMallocIdx = -1;
1501 assert(AllocaVec.size() > 0);
1502 Instruction *InsBefore = AllocaVec[0];
1503 IRBuilder<> IRB(InsBefore);
1505 SmallVector<ASanStackVariableDescription, 16> SVD;
1506 SVD.reserve(AllocaVec.size());
1507 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1508 AllocaInst *AI = AllocaVec[i];
1509 ASanStackVariableDescription D = { AI->getName().data(),
1510 getAllocaSizeInBytes(AI),
1511 AI->getAlignment(), AI, 0};
1514 // Minimal header size (left redzone) is 4 pointers,
1515 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1516 size_t MinHeaderSize = ASan.LongSize / 2;
1517 ASanStackFrameLayout L;
1518 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1519 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1520 uint64_t LocalStackSize = L.FrameSize;
1521 bool DoStackMalloc =
1522 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1524 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1525 AllocaInst *MyAlloca =
1526 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1527 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1528 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1529 MyAlloca->setAlignment(FrameAlignment);
1530 assert(MyAlloca->isStaticAlloca());
1531 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1532 Value *LocalStackBase = OrigStackBase;
1534 if (DoStackMalloc) {
1535 // LocalStackBase = OrigStackBase
1536 // if (__asan_option_detect_stack_use_after_return)
1537 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1538 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1539 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1540 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1541 kAsanOptionDetectUAR, IRB.getInt32Ty());
1542 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1543 Constant::getNullValue(IRB.getInt32Ty()));
1544 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1545 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1546 IRBuilder<> IRBIf(Term);
1547 LocalStackBase = IRBIf.CreateCall2(
1548 AsanStackMallocFunc[StackMallocIdx],
1549 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1550 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1551 IRB.SetInsertPoint(InsBefore);
1552 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1553 Phi->addIncoming(OrigStackBase, CmpBlock);
1554 Phi->addIncoming(LocalStackBase, SetBlock);
1555 LocalStackBase = Phi;
1558 // Insert poison calls for lifetime intrinsics for alloca.
1559 bool HavePoisonedAllocas = false;
1560 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1561 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1562 assert(APC.InsBefore);
1564 IRBuilder<> IRB(APC.InsBefore);
1565 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1566 HavePoisonedAllocas |= APC.DoPoison;
1569 // Replace Alloca instructions with base+offset.
1570 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1571 AllocaInst *AI = SVD[i].AI;
1572 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1573 IRB.CreateAdd(LocalStackBase,
1574 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1576 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1577 AI->replaceAllUsesWith(NewAllocaPtr);
1580 // The left-most redzone has enough space for at least 4 pointers.
1581 // Write the Magic value to redzone[0].
1582 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1583 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1585 // Write the frame description constant to redzone[1].
1586 Value *BasePlus1 = IRB.CreateIntToPtr(
1587 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1589 GlobalVariable *StackDescriptionGlobal =
1590 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1591 /*AllowMerging*/true);
1592 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1594 IRB.CreateStore(Description, BasePlus1);
1595 // Write the PC to redzone[2].
1596 Value *BasePlus2 = IRB.CreateIntToPtr(
1597 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1598 2 * ASan.LongSize/8)),
1600 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1602 // Poison the stack redzones at the entry.
1603 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1604 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1606 // (Un)poison the stack before all ret instructions.
1607 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1608 Instruction *Ret = RetVec[i];
1609 IRBuilder<> IRBRet(Ret);
1610 // Mark the current frame as retired.
1611 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1613 if (DoStackMalloc) {
1614 assert(StackMallocIdx >= 0);
1615 // if LocalStackBase != OrigStackBase:
1616 // // In use-after-return mode, poison the whole stack frame.
1617 // if StackMallocIdx <= 4
1618 // // For small sizes inline the whole thing:
1619 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1620 // **SavedFlagPtr(LocalStackBase) = 0
1622 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1624 // <This is not a fake stack; unpoison the redzones>
1625 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1626 TerminatorInst *ThenTerm, *ElseTerm;
1627 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1629 IRBuilder<> IRBPoison(ThenTerm);
1630 if (StackMallocIdx <= 4) {
1631 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1632 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1633 ClassSize >> Mapping.Scale);
1634 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1636 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1637 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1638 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1639 IRBPoison.CreateStore(
1640 Constant::getNullValue(IRBPoison.getInt8Ty()),
1641 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1643 // For larger frames call __asan_stack_free_*.
1644 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1645 ConstantInt::get(IntptrTy, LocalStackSize),
1649 IRBuilder<> IRBElse(ElseTerm);
1650 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1651 } else if (HavePoisonedAllocas) {
1652 // If we poisoned some allocas in llvm.lifetime analysis,
1653 // unpoison whole stack frame now.
1654 assert(LocalStackBase == OrigStackBase);
1655 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1657 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1661 // We are done. Remove the old unused alloca instructions.
1662 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1663 AllocaVec[i]->eraseFromParent();
1666 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1667 IRBuilder<> &IRB, bool DoPoison) {
1668 // For now just insert the call to ASan runtime.
1669 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1670 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1671 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1672 : AsanUnpoisonStackMemoryFunc,
1676 // Handling llvm.lifetime intrinsics for a given %alloca:
1677 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1678 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1679 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1680 // could be poisoned by previous llvm.lifetime.end instruction, as the
1681 // variable may go in and out of scope several times, e.g. in loops).
1682 // (3) if we poisoned at least one %alloca in a function,
1683 // unpoison the whole stack frame at function exit.
1685 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1686 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1687 // We're intested only in allocas we can handle.
1688 return isInterestingAlloca(*AI) ? AI : nullptr;
1689 // See if we've already calculated (or started to calculate) alloca for a
1691 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1692 if (I != AllocaForValue.end())
1694 // Store 0 while we're calculating alloca for value V to avoid
1695 // infinite recursion if the value references itself.
1696 AllocaForValue[V] = nullptr;
1697 AllocaInst *Res = nullptr;
1698 if (CastInst *CI = dyn_cast<CastInst>(V))
1699 Res = findAllocaForValue(CI->getOperand(0));
1700 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1701 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1702 Value *IncValue = PN->getIncomingValue(i);
1703 // Allow self-referencing phi-nodes.
1704 if (IncValue == PN) continue;
1705 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1706 // AI for incoming values should exist and should all be equal.
1707 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1713 AllocaForValue[V] = Res;