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 kAsanCtorAndDtorPriority = 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 kAsanCovModuleInitName = "__sanitizer_cov_module_init";
84 static const char *const kAsanCovName = "__sanitizer_cov";
85 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
86 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
87 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
88 static const int kMaxAsanStackMallocSizeClass = 10;
89 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
90 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
91 static const char *const kAsanGenPrefix = "__asan_gen_";
92 static const char *const kAsanPoisonStackMemoryName =
93 "__asan_poison_stack_memory";
94 static const char *const kAsanUnpoisonStackMemoryName =
95 "__asan_unpoison_stack_memory";
97 static const char *const kAsanOptionDetectUAR =
98 "__asan_option_detect_stack_use_after_return";
101 static const int kAsanStackAfterReturnMagic = 0xf5;
104 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
105 static const size_t kNumberOfAccessSizes = 5;
107 // Command-line flags.
109 // This flag may need to be replaced with -f[no-]asan-reads.
110 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
111 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
112 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
113 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
114 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
115 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
116 cl::Hidden, cl::init(true));
117 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
118 cl::desc("use instrumentation with slow path for all accesses"),
119 cl::Hidden, cl::init(false));
120 // This flag limits the number of instructions to be instrumented
121 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
122 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
124 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
126 cl::desc("maximal number of instructions to instrument in any given BB"),
128 // This flag may need to be replaced with -f[no]asan-stack.
129 static cl::opt<bool> ClStack("asan-stack",
130 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
131 // This flag may need to be replaced with -f[no]asan-use-after-return.
132 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
133 cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
134 // This flag may need to be replaced with -f[no]asan-globals.
135 static cl::opt<bool> ClGlobals("asan-globals",
136 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
137 static cl::opt<int> ClCoverage("asan-coverage",
138 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"),
139 cl::Hidden, cl::init(false));
140 static cl::opt<int> ClCoverageBlockThreshold("asan-coverage-block-threshold",
141 cl::desc("Add coverage instrumentation only to the entry block if there "
142 "are more than this number of blocks."),
143 cl::Hidden, cl::init(1500));
144 static cl::opt<bool> ClInitializers("asan-initialization-order",
145 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
146 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
147 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
148 cl::Hidden, cl::init(false));
149 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
150 cl::desc("Realign stack to the value of this flag (power of two)"),
151 cl::Hidden, cl::init(32));
152 static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
153 cl::desc("File containing the list of objects to ignore "
154 "during instrumentation"), cl::Hidden);
155 static cl::opt<int> ClInstrumentationWithCallsThreshold(
156 "asan-instrumentation-with-call-threshold",
157 cl::desc("If the function being instrumented contains more than "
158 "this number of memory accesses, use callbacks instead of "
159 "inline checks (-1 means never use callbacks)."),
160 cl::Hidden, cl::init(7000));
161 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
162 "asan-memory-access-callback-prefix",
163 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
164 cl::init("__asan_"));
166 // This is an experimental feature that will allow to choose between
167 // instrumented and non-instrumented code at link-time.
168 // If this option is on, just before instrumenting a function we create its
169 // clone; if the function is not changed by asan the clone is deleted.
170 // If we end up with a clone, we put the instrumented function into a section
171 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
173 // This is still a prototype, we need to figure out a way to keep two copies of
174 // a function so that the linker can easily choose one of them.
175 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
176 cl::desc("Keep uninstrumented copies of functions"),
177 cl::Hidden, cl::init(false));
179 // These flags allow to change the shadow mapping.
180 // The shadow mapping looks like
181 // Shadow = (Mem >> scale) + (1 << offset_log)
182 static cl::opt<int> ClMappingScale("asan-mapping-scale",
183 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
185 // Optimization flags. Not user visible, used mostly for testing
186 // and benchmarking the tool.
187 static cl::opt<bool> ClOpt("asan-opt",
188 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
189 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
190 cl::desc("Instrument the same temp just once"), cl::Hidden,
192 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
193 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
195 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
196 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
197 cl::Hidden, cl::init(false));
200 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
202 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
203 cl::Hidden, cl::init(0));
204 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
205 cl::Hidden, cl::desc("Debug func"));
206 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
207 cl::Hidden, cl::init(-1));
208 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
209 cl::Hidden, cl::init(-1));
211 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
212 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
213 STATISTIC(NumOptimizedAccessesToGlobalArray,
214 "Number of optimized accesses to global arrays");
215 STATISTIC(NumOptimizedAccessesToGlobalVar,
216 "Number of optimized accesses to global vars");
219 /// A set of dynamically initialized globals extracted from metadata.
220 class SetOfDynamicallyInitializedGlobals {
222 void Init(Module& M) {
223 // Clang generates metadata identifying all dynamically initialized globals.
224 NamedMDNode *DynamicGlobals =
225 M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
228 for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
229 MDNode *MDN = DynamicGlobals->getOperand(i);
230 assert(MDN->getNumOperands() == 1);
231 Value *VG = MDN->getOperand(0);
232 // The optimizer may optimize away a global entirely, in which case we
233 // cannot instrument access to it.
236 DynInitGlobals.insert(cast<GlobalVariable>(VG));
239 bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
241 SmallSet<GlobalValue*, 32> DynInitGlobals;
244 /// This struct defines the shadow mapping using the rule:
245 /// shadow = (mem >> Scale) ADD-or-OR Offset.
246 struct ShadowMapping {
252 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
253 llvm::Triple TargetTriple(M.getTargetTriple());
254 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
255 bool IsIOS = TargetTriple.getOS() == llvm::Triple::IOS;
256 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
257 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
258 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
259 TargetTriple.getArch() == llvm::Triple::ppc64le;
260 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
261 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
262 TargetTriple.getArch() == llvm::Triple::mipsel;
264 ShadowMapping Mapping;
266 if (LongSize == 32) {
270 Mapping.Offset = kMIPS32_ShadowOffset32;
272 Mapping.Offset = kFreeBSD_ShadowOffset32;
274 Mapping.Offset = kIOSShadowOffset32;
276 Mapping.Offset = kDefaultShadowOffset32;
277 } else { // LongSize == 64
279 Mapping.Offset = kPPC64_ShadowOffset64;
281 Mapping.Offset = kFreeBSD_ShadowOffset64;
282 else if (IsLinux && IsX86_64)
283 Mapping.Offset = kSmallX86_64ShadowOffset;
285 Mapping.Offset = kDefaultShadowOffset64;
288 Mapping.Scale = kDefaultShadowScale;
289 if (ClMappingScale) {
290 Mapping.Scale = ClMappingScale;
293 // OR-ing shadow offset if more efficient (at least on x86) if the offset
294 // is a power of two, but on ppc64 we have to use add since the shadow
295 // offset is not necessary 1/8-th of the address space.
296 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
301 static size_t RedzoneSizeForScale(int MappingScale) {
302 // Redzone used for stack and globals is at least 32 bytes.
303 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
304 return std::max(32U, 1U << MappingScale);
307 /// AddressSanitizer: instrument the code in module to find memory bugs.
308 struct AddressSanitizer : public FunctionPass {
309 AddressSanitizer(bool CheckInitOrder = true,
310 bool CheckUseAfterReturn = false,
311 bool CheckLifetime = false,
312 StringRef BlacklistFile = StringRef())
314 CheckInitOrder(CheckInitOrder || ClInitializers),
315 CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
316 CheckLifetime(CheckLifetime || ClCheckLifetime),
317 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
319 const char *getPassName() const override {
320 return "AddressSanitizerFunctionPass";
322 void instrumentMop(Instruction *I, bool UseCalls);
323 void instrumentPointerComparisonOrSubtraction(Instruction *I);
324 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
325 Value *Addr, uint32_t TypeSize, bool IsWrite,
326 Value *SizeArgument, bool UseCalls);
327 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
328 Value *ShadowValue, uint32_t TypeSize);
329 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
330 bool IsWrite, size_t AccessSizeIndex,
331 Value *SizeArgument);
332 void instrumentMemIntrinsic(MemIntrinsic *MI);
333 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
334 bool runOnFunction(Function &F) override;
335 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
336 bool doInitialization(Module &M) override;
337 static char ID; // Pass identification, replacement for typeid
340 void initializeCallbacks(Module &M);
342 bool LooksLikeCodeInBug11395(Instruction *I);
343 bool GlobalIsLinkerInitialized(GlobalVariable *G);
344 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks);
345 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
348 bool CheckUseAfterReturn;
350 SmallString<64> BlacklistFile;
353 const DataLayout *DL;
356 ShadowMapping Mapping;
357 Function *AsanCtorFunction;
358 Function *AsanInitFunction;
359 Function *AsanHandleNoReturnFunc;
360 Function *AsanCovFunction;
361 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
362 std::unique_ptr<SpecialCaseList> BL;
363 // This array is indexed by AccessIsWrite and log2(AccessSize).
364 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
365 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
366 // This array is indexed by AccessIsWrite.
367 Function *AsanErrorCallbackSized[2],
368 *AsanMemoryAccessCallbackSized[2];
369 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
371 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
373 friend struct FunctionStackPoisoner;
376 class AddressSanitizerModule : public ModulePass {
378 AddressSanitizerModule(bool CheckInitOrder = true,
379 StringRef BlacklistFile = StringRef())
381 CheckInitOrder(CheckInitOrder || ClInitializers),
382 BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
384 bool runOnModule(Module &M) override;
385 static char ID; // Pass identification, replacement for typeid
386 const char *getPassName() const override {
387 return "AddressSanitizerModule";
391 void initializeCallbacks(Module &M);
393 bool ShouldInstrumentGlobal(GlobalVariable *G);
394 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
395 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
396 size_t MinRedzoneSizeForGlobal() const {
397 return RedzoneSizeForScale(Mapping.Scale);
401 SmallString<64> BlacklistFile;
403 std::unique_ptr<SpecialCaseList> BL;
404 SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
407 const DataLayout *DL;
408 ShadowMapping Mapping;
409 Function *AsanPoisonGlobals;
410 Function *AsanUnpoisonGlobals;
411 Function *AsanRegisterGlobals;
412 Function *AsanUnregisterGlobals;
413 Function *AsanCovModuleInit;
416 // Stack poisoning does not play well with exception handling.
417 // When an exception is thrown, we essentially bypass the code
418 // that unpoisones the stack. This is why the run-time library has
419 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
420 // stack in the interceptor. This however does not work inside the
421 // actual function which catches the exception. Most likely because the
422 // compiler hoists the load of the shadow value somewhere too high.
423 // This causes asan to report a non-existing bug on 453.povray.
424 // It sounds like an LLVM bug.
425 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
427 AddressSanitizer &ASan;
432 ShadowMapping Mapping;
434 SmallVector<AllocaInst*, 16> AllocaVec;
435 SmallVector<Instruction*, 8> RetVec;
436 unsigned StackAlignment;
438 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
439 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
440 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
442 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
443 struct AllocaPoisonCall {
444 IntrinsicInst *InsBefore;
449 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
451 // Maps Value to an AllocaInst from which the Value is originated.
452 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
453 AllocaForValueMapTy AllocaForValue;
455 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
456 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
457 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
458 Mapping(ASan.Mapping),
459 StackAlignment(1 << Mapping.Scale) {}
461 bool runOnFunction() {
462 if (!ClStack) return false;
463 // Collect alloca, ret, lifetime instructions etc.
464 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
467 if (AllocaVec.empty()) return false;
469 initializeCallbacks(*F.getParent());
479 // Finds all static Alloca instructions and puts
480 // poisoned red zones around all of them.
481 // Then unpoison everything back before the function returns.
484 // ----------------------- Visitors.
485 /// \brief Collect all Ret instructions.
486 void visitReturnInst(ReturnInst &RI) {
487 RetVec.push_back(&RI);
490 /// \brief Collect Alloca instructions we want (and can) handle.
491 void visitAllocaInst(AllocaInst &AI) {
492 if (!isInterestingAlloca(AI)) return;
494 StackAlignment = std::max(StackAlignment, AI.getAlignment());
495 AllocaVec.push_back(&AI);
498 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
500 void visitIntrinsicInst(IntrinsicInst &II) {
501 if (!ASan.CheckLifetime) return;
502 Intrinsic::ID ID = II.getIntrinsicID();
503 if (ID != Intrinsic::lifetime_start &&
504 ID != Intrinsic::lifetime_end)
506 // Found lifetime intrinsic, add ASan instrumentation if necessary.
507 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
508 // If size argument is undefined, don't do anything.
509 if (Size->isMinusOne()) return;
510 // Check that size doesn't saturate uint64_t and can
511 // be stored in IntptrTy.
512 const uint64_t SizeValue = Size->getValue().getLimitedValue();
513 if (SizeValue == ~0ULL ||
514 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
516 // Find alloca instruction that corresponds to llvm.lifetime argument.
517 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
519 bool DoPoison = (ID == Intrinsic::lifetime_end);
520 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
521 AllocaPoisonCallVec.push_back(APC);
524 // ---------------------- Helpers.
525 void initializeCallbacks(Module &M);
527 // Check if we want (and can) handle this alloca.
528 bool isInterestingAlloca(AllocaInst &AI) const {
529 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
530 AI.getAllocatedType()->isSized() &&
531 // alloca() may be called with 0 size, ignore it.
532 getAllocaSizeInBytes(&AI) > 0);
535 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
536 Type *Ty = AI->getAllocatedType();
537 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
540 /// Finds alloca where the value comes from.
541 AllocaInst *findAllocaForValue(Value *V);
542 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
543 Value *ShadowBase, bool DoPoison);
544 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
546 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
552 char AddressSanitizer::ID = 0;
553 INITIALIZE_PASS(AddressSanitizer, "asan",
554 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
556 FunctionPass *llvm::createAddressSanitizerFunctionPass(
557 bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
558 StringRef BlacklistFile) {
559 return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
560 CheckLifetime, BlacklistFile);
563 char AddressSanitizerModule::ID = 0;
564 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
565 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
566 "ModulePass", false, false)
567 ModulePass *llvm::createAddressSanitizerModulePass(
568 bool CheckInitOrder, StringRef BlacklistFile) {
569 return new AddressSanitizerModule(CheckInitOrder, BlacklistFile);
572 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
573 size_t Res = countTrailingZeros(TypeSize / 8);
574 assert(Res < kNumberOfAccessSizes);
578 // \brief Create a constant for Str so that we can pass it to the run-time lib.
579 static GlobalVariable *createPrivateGlobalForString(
580 Module &M, StringRef Str, bool AllowMerging) {
581 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
582 // We use private linkage for module-local strings. If they can be merged
583 // with another one, we set the unnamed_addr attribute.
585 new GlobalVariable(M, StrConst->getType(), true,
586 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
588 GV->setUnnamedAddr(true);
589 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
593 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
594 return G->getName().find(kAsanGenPrefix) == 0;
597 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
599 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
600 if (Mapping.Offset == 0)
602 // (Shadow >> scale) | offset
603 if (Mapping.OrShadowOffset)
604 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
606 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
609 // Instrument memset/memmove/memcpy
610 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
612 if (isa<MemTransferInst>(MI)) {
614 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
615 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
616 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
617 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
618 } else if (isa<MemSetInst>(MI)) {
621 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
622 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
623 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
625 MI->eraseFromParent();
628 // If I is an interesting memory access, return the PointerOperand
629 // and set IsWrite/Alignment. Otherwise return NULL.
630 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
631 unsigned *Alignment) {
632 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
633 if (!ClInstrumentReads) return nullptr;
635 *Alignment = LI->getAlignment();
636 return LI->getPointerOperand();
638 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
639 if (!ClInstrumentWrites) return nullptr;
641 *Alignment = SI->getAlignment();
642 return SI->getPointerOperand();
644 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
645 if (!ClInstrumentAtomics) return nullptr;
648 return RMW->getPointerOperand();
650 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
651 if (!ClInstrumentAtomics) return nullptr;
654 return XCHG->getPointerOperand();
659 static bool isPointerOperand(Value *V) {
660 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
663 // This is a rough heuristic; it may cause both false positives and
664 // false negatives. The proper implementation requires cooperation with
666 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
667 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
668 if (!Cmp->isRelational())
670 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
671 if (BO->getOpcode() != Instruction::Sub)
676 if (!isPointerOperand(I->getOperand(0)) ||
677 !isPointerOperand(I->getOperand(1)))
682 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
683 // If a global variable does not have dynamic initialization we don't
684 // have to instrument it. However, if a global does not have initializer
685 // at all, we assume it has dynamic initializer (in other TU).
686 return G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G);
690 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
692 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
693 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
694 for (int i = 0; i < 2; i++) {
695 if (Param[i]->getType()->isPointerTy())
696 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
698 IRB.CreateCall2(F, Param[0], Param[1]);
701 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
702 bool IsWrite = false;
703 unsigned Alignment = 0;
704 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
706 if (ClOpt && ClOptGlobals) {
707 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
708 // If initialization order checking is disabled, a simple access to a
709 // dynamically initialized global is always valid.
710 if (!CheckInitOrder || GlobalIsLinkerInitialized(G)) {
711 NumOptimizedAccessesToGlobalVar++;
715 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
716 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
717 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
718 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
719 NumOptimizedAccessesToGlobalArray++;
726 Type *OrigPtrTy = Addr->getType();
727 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
729 assert(OrigTy->isSized());
730 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
732 assert((TypeSize % 8) == 0);
735 NumInstrumentedWrites++;
737 NumInstrumentedReads++;
739 unsigned Granularity = 1 << Mapping.Scale;
740 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
741 // if the data is properly aligned.
742 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
744 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
745 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
746 // Instrument unusual size or unusual alignment.
747 // We can not do it with a single check, so we do 1-byte check for the first
748 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
749 // to report the actual access size.
751 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
752 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
754 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
756 Value *LastByte = IRB.CreateIntToPtr(
757 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
759 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
760 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
764 // Validate the result of Module::getOrInsertFunction called for an interface
765 // function of AddressSanitizer. If the instrumented module defines a function
766 // with the same name, their prototypes must match, otherwise
767 // getOrInsertFunction returns a bitcast.
768 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
769 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
770 FuncOrBitcast->dump();
771 report_fatal_error("trying to redefine an AddressSanitizer "
772 "interface function");
775 Instruction *AddressSanitizer::generateCrashCode(
776 Instruction *InsertBefore, Value *Addr,
777 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
778 IRBuilder<> IRB(InsertBefore);
779 CallInst *Call = SizeArgument
780 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
781 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
783 // We don't do Call->setDoesNotReturn() because the BB already has
784 // UnreachableInst at the end.
785 // This EmptyAsm is required to avoid callback merge.
786 IRB.CreateCall(EmptyAsm);
790 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
793 size_t Granularity = 1 << Mapping.Scale;
794 // Addr & (Granularity - 1)
795 Value *LastAccessedByte = IRB.CreateAnd(
796 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
797 // (Addr & (Granularity - 1)) + size - 1
798 if (TypeSize / 8 > 1)
799 LastAccessedByte = IRB.CreateAdd(
800 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
801 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
802 LastAccessedByte = IRB.CreateIntCast(
803 LastAccessedByte, ShadowValue->getType(), false);
804 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
805 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
808 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
809 Instruction *InsertBefore, Value *Addr,
810 uint32_t TypeSize, bool IsWrite,
811 Value *SizeArgument, bool UseCalls) {
812 IRBuilder<> IRB(InsertBefore);
813 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
814 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
817 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
822 Type *ShadowTy = IntegerType::get(
823 *C, std::max(8U, TypeSize >> Mapping.Scale));
824 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
825 Value *ShadowPtr = memToShadow(AddrLong, IRB);
826 Value *CmpVal = Constant::getNullValue(ShadowTy);
827 Value *ShadowValue = IRB.CreateLoad(
828 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
830 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
831 size_t Granularity = 1 << Mapping.Scale;
832 TerminatorInst *CrashTerm = nullptr;
834 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
835 TerminatorInst *CheckTerm =
836 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
837 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
838 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
839 IRB.SetInsertPoint(CheckTerm);
840 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
841 BasicBlock *CrashBlock =
842 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
843 CrashTerm = new UnreachableInst(*C, CrashBlock);
844 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
845 ReplaceInstWithInst(CheckTerm, NewTerm);
847 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
850 Instruction *Crash = generateCrashCode(
851 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
852 Crash->setDebugLoc(OrigIns->getDebugLoc());
855 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
856 GlobalValue *ModuleName) {
857 // Set up the arguments to our poison/unpoison functions.
858 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
860 // Add a call to poison all external globals before the given function starts.
861 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
862 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
864 // Add calls to unpoison all globals before each return instruction.
865 for (auto &BB : GlobalInit.getBasicBlockList())
866 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
867 CallInst::Create(AsanUnpoisonGlobals, "", RI);
870 void AddressSanitizerModule::createInitializerPoisonCalls(
871 Module &M, GlobalValue *ModuleName) {
872 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
874 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
875 for (Use &OP : CA->operands()) {
876 if (isa<ConstantAggregateZero>(OP))
878 ConstantStruct *CS = cast<ConstantStruct>(OP);
880 // Must have a function or null ptr.
881 // (CS->getOperand(0) is the init priority.)
882 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
883 if (F->getName() != kAsanModuleCtorName)
884 poisonOneInitializer(*F, ModuleName);
889 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
890 Type *Ty = cast<PointerType>(G->getType())->getElementType();
891 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
893 if (BL->isIn(*G)) return false;
894 if (!Ty->isSized()) return false;
895 if (!G->hasInitializer()) return false;
896 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
897 // Touch only those globals that will not be defined in other modules.
898 // Don't handle ODR type linkages since other modules may be built w/o asan.
899 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
900 G->getLinkage() != GlobalVariable::PrivateLinkage &&
901 G->getLinkage() != GlobalVariable::InternalLinkage)
903 // Two problems with thread-locals:
904 // - The address of the main thread's copy can't be computed at link-time.
905 // - Need to poison all copies, not just the main thread's one.
906 if (G->isThreadLocal())
908 // For now, just ignore this Global if the alignment is large.
909 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
911 // Ignore all the globals with the names starting with "\01L_OBJC_".
912 // Many of those are put into the .cstring section. The linker compresses
913 // that section by removing the spare \0s after the string terminator, so
914 // our redzones get broken.
915 if ((G->getName().find("\01L_OBJC_") == 0) ||
916 (G->getName().find("\01l_OBJC_") == 0)) {
917 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
921 if (G->hasSection()) {
922 StringRef Section(G->getSection());
923 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
924 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
926 if (Section.startswith("__OBJC,") ||
927 Section.startswith("__DATA, __objc_")) {
928 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
931 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
932 // Constant CFString instances are compiled in the following way:
933 // -- the string buffer is emitted into
934 // __TEXT,__cstring,cstring_literals
935 // -- the constant NSConstantString structure referencing that buffer
936 // is placed into __DATA,__cfstring
937 // Therefore there's no point in placing redzones into __DATA,__cfstring.
938 // Moreover, it causes the linker to crash on OS X 10.7
939 if (Section.startswith("__DATA,__cfstring")) {
940 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
943 // The linker merges the contents of cstring_literals and removes the
945 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
946 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
950 // Callbacks put into the CRT initializer/terminator sections
951 // should not be instrumented.
952 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
953 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
954 if (Section.startswith(".CRT")) {
955 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
959 // Globals from llvm.metadata aren't emitted, do not instrument them.
960 if (Section == "llvm.metadata") return false;
966 void AddressSanitizerModule::initializeCallbacks(Module &M) {
968 // Declare our poisoning and unpoisoning functions.
969 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
970 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
971 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
972 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
973 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
974 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
975 // Declare functions that register/unregister globals.
976 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
977 kAsanRegisterGlobalsName, IRB.getVoidTy(),
978 IntptrTy, IntptrTy, NULL));
979 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
980 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
981 kAsanUnregisterGlobalsName,
982 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
983 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
984 AsanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction(
985 kAsanCovModuleInitName,
986 IRB.getVoidTy(), IntptrTy, NULL));
987 AsanCovModuleInit->setLinkage(Function::ExternalLinkage);
990 // This function replaces all global variables with new variables that have
991 // trailing redzones. It also creates a function that poisons
992 // redzones and inserts this function into llvm.global_ctors.
993 bool AddressSanitizerModule::runOnModule(Module &M) {
994 if (!ClGlobals) return false;
996 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
999 DL = &DLP->getDataLayout();
1001 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1002 if (BL->isIn(M)) return false;
1003 C = &(M.getContext());
1004 int LongSize = DL->getPointerSizeInBits();
1005 IntptrTy = Type::getIntNTy(*C, LongSize);
1006 Mapping = getShadowMapping(M, LongSize);
1007 initializeCallbacks(M);
1008 DynamicallyInitializedGlobals.Init(M);
1010 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1012 for (Module::GlobalListType::iterator G = M.global_begin(),
1013 E = M.global_end(); G != E; ++G) {
1014 if (ShouldInstrumentGlobal(G))
1015 GlobalsToChange.push_back(G);
1018 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1020 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1022 if (ClCoverage > 0) {
1023 Function *CovFunc = M.getFunction(kAsanCovName);
1024 int nCov = CovFunc ? CovFunc->getNumUses() : 0;
1025 IRB.CreateCall(AsanCovModuleInit, ConstantInt::get(IntptrTy, nCov));
1028 size_t n = GlobalsToChange.size();
1029 if (n == 0) return false;
1031 // A global is described by a structure
1034 // size_t size_with_redzone;
1035 // const char *name;
1036 // const char *module_name;
1037 // size_t has_dynamic_init;
1038 // We initialize an array of such structures and pass it to a run-time call.
1039 StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
1041 IntptrTy, IntptrTy, NULL);
1042 SmallVector<Constant *, 16> Initializers(n);
1044 bool HasDynamicallyInitializedGlobals = false;
1046 // We shouldn't merge same module names, as this string serves as unique
1047 // module ID in runtime.
1048 GlobalVariable *ModuleName = createPrivateGlobalForString(
1049 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1051 for (size_t i = 0; i < n; i++) {
1052 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1053 GlobalVariable *G = GlobalsToChange[i];
1054 PointerType *PtrTy = cast<PointerType>(G->getType());
1055 Type *Ty = PtrTy->getElementType();
1056 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1057 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1058 // MinRZ <= RZ <= kMaxGlobalRedzone
1059 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1060 uint64_t RZ = std::max(MinRZ,
1061 std::min(kMaxGlobalRedzone,
1062 (SizeInBytes / MinRZ / 4) * MinRZ));
1063 uint64_t RightRedzoneSize = RZ;
1064 // Round up to MinRZ
1065 if (SizeInBytes % MinRZ)
1066 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1067 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1068 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1069 // Determine whether this global should be poisoned in initialization.
1070 bool GlobalHasDynamicInitializer =
1071 DynamicallyInitializedGlobals.Contains(G);
1072 // Don't check initialization order if this global is blacklisted.
1073 GlobalHasDynamicInitializer &= !BL->isIn(*G, "init");
1075 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1076 Constant *NewInitializer = ConstantStruct::get(
1077 NewTy, G->getInitializer(),
1078 Constant::getNullValue(RightRedZoneTy), NULL);
1080 GlobalVariable *Name =
1081 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true);
1083 // Create a new global variable with enough space for a redzone.
1084 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1085 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1086 Linkage = GlobalValue::InternalLinkage;
1087 GlobalVariable *NewGlobal = new GlobalVariable(
1088 M, NewTy, G->isConstant(), Linkage,
1089 NewInitializer, "", G, G->getThreadLocalMode());
1090 NewGlobal->copyAttributesFrom(G);
1091 NewGlobal->setAlignment(MinRZ);
1094 Indices2[0] = IRB.getInt32(0);
1095 Indices2[1] = IRB.getInt32(0);
1097 G->replaceAllUsesWith(
1098 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1099 NewGlobal->takeName(G);
1100 G->eraseFromParent();
1102 Initializers[i] = ConstantStruct::get(
1104 ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1105 ConstantInt::get(IntptrTy, SizeInBytes),
1106 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1107 ConstantExpr::getPointerCast(Name, IntptrTy),
1108 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1109 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
1112 // Populate the first and last globals declared in this TU.
1113 if (CheckInitOrder && GlobalHasDynamicInitializer)
1114 HasDynamicallyInitializedGlobals = true;
1116 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1119 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1120 GlobalVariable *AllGlobals = new GlobalVariable(
1121 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1122 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1124 // Create calls for poisoning before initializers run and unpoisoning after.
1125 if (CheckInitOrder && HasDynamicallyInitializedGlobals)
1126 createInitializerPoisonCalls(M, ModuleName);
1127 IRB.CreateCall2(AsanRegisterGlobals,
1128 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1129 ConstantInt::get(IntptrTy, n));
1131 // We also need to unregister globals at the end, e.g. when a shared library
1133 Function *AsanDtorFunction = Function::Create(
1134 FunctionType::get(Type::getVoidTy(*C), false),
1135 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1136 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1137 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1138 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1139 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1140 ConstantInt::get(IntptrTy, n));
1141 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1147 void AddressSanitizer::initializeCallbacks(Module &M) {
1148 IRBuilder<> IRB(*C);
1149 // Create __asan_report* callbacks.
1150 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1151 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1152 AccessSizeIndex++) {
1153 // IsWrite and TypeSize are encoded in the function name.
1154 std::string Suffix =
1155 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1156 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1157 checkInterfaceFunction(
1158 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1159 IRB.getVoidTy(), IntptrTy, NULL));
1160 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1161 checkInterfaceFunction(
1162 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1163 IRB.getVoidTy(), IntptrTy, NULL));
1166 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1167 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1168 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1169 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1171 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1172 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1173 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1174 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1175 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1176 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1178 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1179 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1180 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1181 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1182 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1183 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1184 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1185 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1186 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1188 AsanHandleNoReturnFunc = checkInterfaceFunction(
1189 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1190 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1191 kAsanCovName, IRB.getVoidTy(), NULL));
1192 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1193 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1194 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1195 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1196 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1197 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1198 StringRef(""), StringRef(""),
1199 /*hasSideEffects=*/true);
1203 bool AddressSanitizer::doInitialization(Module &M) {
1204 // Initialize the private fields. No one has accessed them before.
1205 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1207 report_fatal_error("data layout missing");
1208 DL = &DLP->getDataLayout();
1210 BL.reset(SpecialCaseList::createOrDie(BlacklistFile));
1211 DynamicallyInitializedGlobals.Init(M);
1213 C = &(M.getContext());
1214 LongSize = DL->getPointerSizeInBits();
1215 IntptrTy = Type::getIntNTy(*C, LongSize);
1217 AsanCtorFunction = Function::Create(
1218 FunctionType::get(Type::getVoidTy(*C), false),
1219 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1220 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1221 // call __asan_init in the module ctor.
1222 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1223 AsanInitFunction = checkInterfaceFunction(
1224 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1225 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1226 IRB.CreateCall(AsanInitFunction);
1228 Mapping = getShadowMapping(M, LongSize);
1230 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1234 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1235 // For each NSObject descendant having a +load method, this method is invoked
1236 // by the ObjC runtime before any of the static constructors is called.
1237 // Therefore we need to instrument such methods with a call to __asan_init
1238 // at the beginning in order to initialize our runtime before any access to
1239 // the shadow memory.
1240 // We cannot just ignore these methods, because they may call other
1241 // instrumented functions.
1242 if (F.getName().find(" load]") != std::string::npos) {
1243 IRBuilder<> IRB(F.begin()->begin());
1244 IRB.CreateCall(AsanInitFunction);
1250 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1251 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1252 // Skip static allocas at the top of the entry block so they don't become
1253 // dynamic when we split the block. If we used our optimized stack layout,
1254 // then there will only be one alloca and it will come first.
1255 for (; IP != BE; ++IP) {
1256 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1257 if (!AI || !AI->isStaticAlloca())
1261 IRBuilder<> IRB(IP);
1262 Type *Int8Ty = IRB.getInt8Ty();
1263 GlobalVariable *Guard = new GlobalVariable(
1264 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1265 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1266 LoadInst *Load = IRB.CreateLoad(Guard);
1267 Load->setAtomic(Monotonic);
1268 Load->setAlignment(1);
1269 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1270 Instruction *Ins = SplitBlockAndInsertIfThen(
1271 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1272 IRB.SetInsertPoint(Ins);
1273 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1274 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1275 Instruction *Call = IRB.CreateCall(AsanCovFunction);
1276 Call->setDebugLoc(IP->getDebugLoc());
1277 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1278 Store->setAtomic(Monotonic);
1279 Store->setAlignment(1);
1282 // Poor man's coverage that works with ASan.
1283 // We create a Guard boolean variable with the same linkage
1284 // as the function and inject this code into the entry block (-asan-coverage=1)
1285 // or all blocks (-asan-coverage=2):
1287 // __sanitizer_cov(&F);
1290 // The accesses to Guard are atomic. The rest of the logic is
1291 // in __sanitizer_cov (it's fine to call it more than once).
1293 // This coverage implementation provides very limited data:
1294 // it only tells if a given function (block) was ever executed.
1295 // No counters, no per-edge data.
1296 // But for many use cases this is what we need and the added slowdown
1297 // is negligible. This simple implementation will probably be obsoleted
1298 // by the upcoming Clang-based coverage implementation.
1299 // By having it here and now we hope to
1300 // a) get the functionality to users earlier and
1301 // b) collect usage statistics to help improve Clang coverage design.
1302 bool AddressSanitizer::InjectCoverage(Function &F,
1303 const ArrayRef<BasicBlock *> AllBlocks) {
1304 if (!ClCoverage) return false;
1306 if (ClCoverage == 1 ||
1307 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1308 InjectCoverageAtBlock(F, F.getEntryBlock());
1310 for (size_t i = 0, n = AllBlocks.size(); i < n; i++)
1311 InjectCoverageAtBlock(F, *AllBlocks[i]);
1316 bool AddressSanitizer::runOnFunction(Function &F) {
1317 if (BL->isIn(F)) return false;
1318 if (&F == AsanCtorFunction) return false;
1319 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1320 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1321 initializeCallbacks(*F.getParent());
1323 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1324 maybeInsertAsanInitAtFunctionEntry(F);
1326 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1329 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1332 // We want to instrument every address only once per basic block (unless there
1333 // are calls between uses).
1334 SmallSet<Value*, 16> TempsToInstrument;
1335 SmallVector<Instruction*, 16> ToInstrument;
1336 SmallVector<Instruction*, 8> NoReturnCalls;
1337 SmallVector<BasicBlock*, 16> AllBlocks;
1338 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1343 // Fill the set of memory operations to instrument.
1344 for (Function::iterator FI = F.begin(), FE = F.end();
1346 AllBlocks.push_back(FI);
1347 TempsToInstrument.clear();
1348 int NumInsnsPerBB = 0;
1349 for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1351 if (LooksLikeCodeInBug11395(BI)) return false;
1352 if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite, &Alignment)) {
1353 if (ClOpt && ClOptSameTemp) {
1354 if (!TempsToInstrument.insert(Addr))
1355 continue; // We've seen this temp in the current BB.
1357 } else if (ClInvalidPointerPairs &&
1358 isInterestingPointerComparisonOrSubtraction(BI)) {
1359 PointerComparisonsOrSubtracts.push_back(BI);
1361 } else if (isa<MemIntrinsic>(BI)) {
1364 if (isa<AllocaInst>(BI))
1368 // A call inside BB.
1369 TempsToInstrument.clear();
1370 if (CS.doesNotReturn())
1371 NoReturnCalls.push_back(CS.getInstruction());
1375 ToInstrument.push_back(BI);
1377 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1382 Function *UninstrumentedDuplicate = nullptr;
1383 bool LikelyToInstrument =
1384 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1385 if (ClKeepUninstrumented && LikelyToInstrument) {
1386 ValueToValueMapTy VMap;
1387 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1388 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1389 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1390 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1393 bool UseCalls = false;
1394 if (ClInstrumentationWithCallsThreshold >= 0 &&
1395 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1399 int NumInstrumented = 0;
1400 for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1401 Instruction *Inst = ToInstrument[i];
1402 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1403 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1404 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1405 instrumentMop(Inst, UseCalls);
1407 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1412 FunctionStackPoisoner FSP(F, *this);
1413 bool ChangedStack = FSP.runOnFunction();
1415 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1416 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1417 for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1418 Instruction *CI = NoReturnCalls[i];
1419 IRBuilder<> IRB(CI);
1420 IRB.CreateCall(AsanHandleNoReturnFunc);
1423 for (size_t i = 0, n = PointerComparisonsOrSubtracts.size(); i != n; i++) {
1424 instrumentPointerComparisonOrSubtraction(PointerComparisonsOrSubtracts[i]);
1428 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1430 if (InjectCoverage(F, AllBlocks))
1433 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1435 if (ClKeepUninstrumented) {
1437 // No instrumentation is done, no need for the duplicate.
1438 if (UninstrumentedDuplicate)
1439 UninstrumentedDuplicate->eraseFromParent();
1441 // The function was instrumented. We must have the duplicate.
1442 assert(UninstrumentedDuplicate);
1443 UninstrumentedDuplicate->setSection("NOASAN");
1444 assert(!F.hasSection());
1445 F.setSection("ASAN");
1452 // Workaround for bug 11395: we don't want to instrument stack in functions
1453 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1454 // FIXME: remove once the bug 11395 is fixed.
1455 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1456 if (LongSize != 32) return false;
1457 CallInst *CI = dyn_cast<CallInst>(I);
1458 if (!CI || !CI->isInlineAsm()) return false;
1459 if (CI->getNumArgOperands() <= 5) return false;
1460 // We have inline assembly with quite a few arguments.
1464 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1465 IRBuilder<> IRB(*C);
1466 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1467 std::string Suffix = itostr(i);
1468 AsanStackMallocFunc[i] = checkInterfaceFunction(
1469 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1470 IntptrTy, IntptrTy, NULL));
1471 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1472 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1473 IntptrTy, IntptrTy, NULL));
1475 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1476 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1477 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1478 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1482 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1483 IRBuilder<> &IRB, Value *ShadowBase,
1485 size_t n = ShadowBytes.size();
1487 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1488 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1489 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1490 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1491 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1492 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1494 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1495 if (ASan.DL->isLittleEndian())
1496 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1498 Val = (Val << 8) | ShadowBytes[i + j];
1501 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1502 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1503 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1504 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1509 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1510 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1511 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1512 assert(LocalStackSize <= kMaxStackMallocSize);
1513 uint64_t MaxSize = kMinStackMallocSize;
1514 for (int i = 0; ; i++, MaxSize *= 2)
1515 if (LocalStackSize <= MaxSize)
1517 llvm_unreachable("impossible LocalStackSize");
1520 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1521 // We can not use MemSet intrinsic because it may end up calling the actual
1522 // memset. Size is a multiple of 8.
1523 // Currently this generates 8-byte stores on x86_64; it may be better to
1524 // generate wider stores.
1525 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1526 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1527 assert(!(Size % 8));
1528 assert(kAsanStackAfterReturnMagic == 0xf5);
1529 for (int i = 0; i < Size; i += 8) {
1530 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1531 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1532 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1536 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1537 BasicBlock::iterator I = F.getEntryBlock().begin(),
1538 E = F.getEntryBlock().end();
1540 if (!isa<AllocaInst>(I))
1542 return I->getDebugLoc();
1545 void FunctionStackPoisoner::poisonStack() {
1546 int StackMallocIdx = -1;
1547 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1549 assert(AllocaVec.size() > 0);
1550 Instruction *InsBefore = AllocaVec[0];
1551 IRBuilder<> IRB(InsBefore);
1552 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1554 SmallVector<ASanStackVariableDescription, 16> SVD;
1555 SVD.reserve(AllocaVec.size());
1556 for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1557 AllocaInst *AI = AllocaVec[i];
1558 ASanStackVariableDescription D = { AI->getName().data(),
1559 getAllocaSizeInBytes(AI),
1560 AI->getAlignment(), AI, 0};
1563 // Minimal header size (left redzone) is 4 pointers,
1564 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1565 size_t MinHeaderSize = ASan.LongSize / 2;
1566 ASanStackFrameLayout L;
1567 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1568 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1569 uint64_t LocalStackSize = L.FrameSize;
1570 bool DoStackMalloc =
1571 ASan.CheckUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1573 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1574 AllocaInst *MyAlloca =
1575 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1576 MyAlloca->setDebugLoc(EntryDebugLocation);
1577 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1578 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1579 MyAlloca->setAlignment(FrameAlignment);
1580 assert(MyAlloca->isStaticAlloca());
1581 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1582 Value *LocalStackBase = OrigStackBase;
1584 if (DoStackMalloc) {
1585 // LocalStackBase = OrigStackBase
1586 // if (__asan_option_detect_stack_use_after_return)
1587 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1588 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1589 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1590 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1591 kAsanOptionDetectUAR, IRB.getInt32Ty());
1592 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1593 Constant::getNullValue(IRB.getInt32Ty()));
1594 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1595 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1596 IRBuilder<> IRBIf(Term);
1597 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1598 LocalStackBase = IRBIf.CreateCall2(
1599 AsanStackMallocFunc[StackMallocIdx],
1600 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1601 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1602 IRB.SetInsertPoint(InsBefore);
1603 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1604 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1605 Phi->addIncoming(OrigStackBase, CmpBlock);
1606 Phi->addIncoming(LocalStackBase, SetBlock);
1607 LocalStackBase = Phi;
1610 // Insert poison calls for lifetime intrinsics for alloca.
1611 bool HavePoisonedAllocas = false;
1612 for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1613 const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1614 assert(APC.InsBefore);
1616 IRBuilder<> IRB(APC.InsBefore);
1617 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1618 HavePoisonedAllocas |= APC.DoPoison;
1621 // Replace Alloca instructions with base+offset.
1622 for (size_t i = 0, n = SVD.size(); i < n; i++) {
1623 AllocaInst *AI = SVD[i].AI;
1624 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1625 IRB.CreateAdd(LocalStackBase,
1626 ConstantInt::get(IntptrTy, SVD[i].Offset)),
1628 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1629 AI->replaceAllUsesWith(NewAllocaPtr);
1632 // The left-most redzone has enough space for at least 4 pointers.
1633 // Write the Magic value to redzone[0].
1634 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1635 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1637 // Write the frame description constant to redzone[1].
1638 Value *BasePlus1 = IRB.CreateIntToPtr(
1639 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1641 GlobalVariable *StackDescriptionGlobal =
1642 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1643 /*AllowMerging*/true);
1644 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1646 IRB.CreateStore(Description, BasePlus1);
1647 // Write the PC to redzone[2].
1648 Value *BasePlus2 = IRB.CreateIntToPtr(
1649 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1650 2 * ASan.LongSize/8)),
1652 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1654 // Poison the stack redzones at the entry.
1655 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1656 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1658 // (Un)poison the stack before all ret instructions.
1659 for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1660 Instruction *Ret = RetVec[i];
1661 IRBuilder<> IRBRet(Ret);
1662 // Mark the current frame as retired.
1663 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1665 if (DoStackMalloc) {
1666 assert(StackMallocIdx >= 0);
1667 // if LocalStackBase != OrigStackBase:
1668 // // In use-after-return mode, poison the whole stack frame.
1669 // if StackMallocIdx <= 4
1670 // // For small sizes inline the whole thing:
1671 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1672 // **SavedFlagPtr(LocalStackBase) = 0
1674 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1676 // <This is not a fake stack; unpoison the redzones>
1677 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1678 TerminatorInst *ThenTerm, *ElseTerm;
1679 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1681 IRBuilder<> IRBPoison(ThenTerm);
1682 if (StackMallocIdx <= 4) {
1683 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1684 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1685 ClassSize >> Mapping.Scale);
1686 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1688 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1689 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1690 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1691 IRBPoison.CreateStore(
1692 Constant::getNullValue(IRBPoison.getInt8Ty()),
1693 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1695 // For larger frames call __asan_stack_free_*.
1696 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1697 ConstantInt::get(IntptrTy, LocalStackSize),
1701 IRBuilder<> IRBElse(ElseTerm);
1702 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1703 } else if (HavePoisonedAllocas) {
1704 // If we poisoned some allocas in llvm.lifetime analysis,
1705 // unpoison whole stack frame now.
1706 assert(LocalStackBase == OrigStackBase);
1707 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1709 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1713 // We are done. Remove the old unused alloca instructions.
1714 for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1715 AllocaVec[i]->eraseFromParent();
1718 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1719 IRBuilder<> &IRB, bool DoPoison) {
1720 // For now just insert the call to ASan runtime.
1721 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1722 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1723 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1724 : AsanUnpoisonStackMemoryFunc,
1728 // Handling llvm.lifetime intrinsics for a given %alloca:
1729 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1730 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1731 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1732 // could be poisoned by previous llvm.lifetime.end instruction, as the
1733 // variable may go in and out of scope several times, e.g. in loops).
1734 // (3) if we poisoned at least one %alloca in a function,
1735 // unpoison the whole stack frame at function exit.
1737 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1738 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1739 // We're intested only in allocas we can handle.
1740 return isInterestingAlloca(*AI) ? AI : nullptr;
1741 // See if we've already calculated (or started to calculate) alloca for a
1743 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1744 if (I != AllocaForValue.end())
1746 // Store 0 while we're calculating alloca for value V to avoid
1747 // infinite recursion if the value references itself.
1748 AllocaForValue[V] = nullptr;
1749 AllocaInst *Res = nullptr;
1750 if (CastInst *CI = dyn_cast<CastInst>(V))
1751 Res = findAllocaForValue(CI->getOperand(0));
1752 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1753 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1754 Value *IncValue = PN->getIncomingValue(i);
1755 // Allow self-referencing phi-nodes.
1756 if (IncValue == PN) continue;
1757 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1758 // AI for incoming values should exist and should all be equal.
1759 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1765 AllocaForValue[V] = Res;