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/DenseSet.h"
20 #include "llvm/ADT/DepthFirstIterator.h"
21 #include "llvm/ADT/SmallSet.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/Statistic.h"
25 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/ADT/Triple.h"
27 #include "llvm/IR/CallSite.h"
28 #include "llvm/IR/DIBuilder.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/Function.h"
31 #include "llvm/IR/IRBuilder.h"
32 #include "llvm/IR/InlineAsm.h"
33 #include "llvm/IR/InstVisitor.h"
34 #include "llvm/IR/IntrinsicInst.h"
35 #include "llvm/IR/LLVMContext.h"
36 #include "llvm/IR/MDBuilder.h"
37 #include "llvm/IR/Module.h"
38 #include "llvm/IR/Type.h"
39 #include "llvm/Support/CommandLine.h"
40 #include "llvm/Support/DataTypes.h"
41 #include "llvm/Support/Debug.h"
42 #include "llvm/Support/Endian.h"
43 #include "llvm/Transforms/Scalar.h"
44 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/Cloning.h"
47 #include "llvm/Transforms/Utils/Local.h"
48 #include "llvm/Transforms/Utils/ModuleUtils.h"
51 #include <system_error>
55 #define DEBUG_TYPE "asan"
57 static const uint64_t kDefaultShadowScale = 3;
58 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
59 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
60 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
61 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
62 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
63 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
64 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 36;
65 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
66 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
68 static const size_t kMinStackMallocSize = 1 << 6; // 64B
69 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
70 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
71 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
73 static const char *const kAsanModuleCtorName = "asan.module_ctor";
74 static const char *const kAsanModuleDtorName = "asan.module_dtor";
75 static const uint64_t kAsanCtorAndDtorPriority = 1;
76 static const char *const kAsanReportErrorTemplate = "__asan_report_";
77 static const char *const kAsanReportLoadN = "__asan_report_load_n";
78 static const char *const kAsanReportStoreN = "__asan_report_store_n";
79 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
80 static const char *const kAsanUnregisterGlobalsName =
81 "__asan_unregister_globals";
82 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
83 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
84 static const char *const kAsanInitName = "__asan_init_v4";
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 kSanCovGenPrefix = "__sancov_gen_";
93 static const char *const kAsanPoisonStackMemoryName =
94 "__asan_poison_stack_memory";
95 static const char *const kAsanUnpoisonStackMemoryName =
96 "__asan_unpoison_stack_memory";
98 static const char *const kAsanOptionDetectUAR =
99 "__asan_option_detect_stack_use_after_return";
102 static const int kAsanStackAfterReturnMagic = 0xf5;
105 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
106 static const size_t kNumberOfAccessSizes = 5;
108 // Command-line flags.
110 // This flag may need to be replaced with -f[no-]asan-reads.
111 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
112 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
113 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
114 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
115 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
116 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
117 cl::Hidden, cl::init(true));
118 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
119 cl::desc("use instrumentation with slow path for all accesses"),
120 cl::Hidden, cl::init(false));
121 // This flag limits the number of instructions to be instrumented
122 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
123 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
125 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
127 cl::desc("maximal number of instructions to instrument in any given BB"),
129 // This flag may need to be replaced with -f[no]asan-stack.
130 static cl::opt<bool> ClStack("asan-stack",
131 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
132 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
133 cl::desc("Check return-after-free"), cl::Hidden, cl::init(true));
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<bool> ClInitializers("asan-initialization-order",
138 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(true));
139 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
140 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
141 cl::Hidden, cl::init(false));
142 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
143 cl::desc("Realign stack to the value of this flag (power of two)"),
144 cl::Hidden, cl::init(32));
145 static cl::opt<int> ClInstrumentationWithCallsThreshold(
146 "asan-instrumentation-with-call-threshold",
147 cl::desc("If the function being instrumented contains more than "
148 "this number of memory accesses, use callbacks instead of "
149 "inline checks (-1 means never use callbacks)."),
150 cl::Hidden, cl::init(7000));
151 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
152 "asan-memory-access-callback-prefix",
153 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
154 cl::init("__asan_"));
156 // This is an experimental feature that will allow to choose between
157 // instrumented and non-instrumented code at link-time.
158 // If this option is on, just before instrumenting a function we create its
159 // clone; if the function is not changed by asan the clone is deleted.
160 // If we end up with a clone, we put the instrumented function into a section
161 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
163 // This is still a prototype, we need to figure out a way to keep two copies of
164 // a function so that the linker can easily choose one of them.
165 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
166 cl::desc("Keep uninstrumented copies of functions"),
167 cl::Hidden, cl::init(false));
169 // These flags allow to change the shadow mapping.
170 // The shadow mapping looks like
171 // Shadow = (Mem >> scale) + (1 << offset_log)
172 static cl::opt<int> ClMappingScale("asan-mapping-scale",
173 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
175 // Optimization flags. Not user visible, used mostly for testing
176 // and benchmarking the tool.
177 static cl::opt<bool> ClOpt("asan-opt",
178 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
179 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
180 cl::desc("Instrument the same temp just once"), cl::Hidden,
182 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
183 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
185 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
186 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
187 cl::Hidden, cl::init(false));
190 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
192 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
193 cl::Hidden, cl::init(0));
194 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
195 cl::Hidden, cl::desc("Debug func"));
196 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
197 cl::Hidden, cl::init(-1));
198 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
199 cl::Hidden, cl::init(-1));
201 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
202 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
203 STATISTIC(NumOptimizedAccessesToGlobalArray,
204 "Number of optimized accesses to global arrays");
205 STATISTIC(NumOptimizedAccessesToGlobalVar,
206 "Number of optimized accesses to global vars");
209 /// Frontend-provided metadata for source location.
210 struct LocationMetadata {
215 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
217 bool empty() const { return Filename.empty(); }
219 void parse(MDNode *MDN) {
220 assert(MDN->getNumOperands() == 3);
221 MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
222 Filename = MDFilename->getString();
223 LineNo = cast<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
224 ColumnNo = cast<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
228 /// Frontend-provided metadata for global variables.
229 class GlobalsMetadata {
233 : SourceLoc(), Name(), IsDynInit(false),
234 IsBlacklisted(false) {}
235 LocationMetadata SourceLoc;
241 GlobalsMetadata() : inited_(false) {}
243 void init(Module& M) {
246 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
249 for (auto MDN : Globals->operands()) {
250 // Metadata node contains the global and the fields of "Entry".
251 assert(MDN->getNumOperands() == 5);
252 Value *V = MDN->getOperand(0);
253 // The optimizer may optimize away a global entirely.
256 GlobalVariable *GV = cast<GlobalVariable>(V);
257 // We can already have an entry for GV if it was merged with another
259 Entry &E = Entries[GV];
260 if (Value *Loc = MDN->getOperand(1))
261 E.SourceLoc.parse(cast<MDNode>(Loc));
262 if (Value *Name = MDN->getOperand(2)) {
263 MDString *MDName = cast<MDString>(Name);
264 E.Name = MDName->getString();
266 ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(3));
267 E.IsDynInit |= IsDynInit->isOne();
268 ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(4));
269 E.IsBlacklisted |= IsBlacklisted->isOne();
273 /// Returns metadata entry for a given global.
274 Entry get(GlobalVariable *G) const {
275 auto Pos = Entries.find(G);
276 return (Pos != Entries.end()) ? Pos->second : Entry();
281 DenseMap<GlobalVariable*, Entry> Entries;
284 /// This struct defines the shadow mapping using the rule:
285 /// shadow = (mem >> Scale) ADD-or-OR Offset.
286 struct ShadowMapping {
292 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
293 llvm::Triple TargetTriple(M.getTargetTriple());
294 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
295 bool IsIOS = TargetTriple.isiOS();
296 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
297 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
298 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
299 TargetTriple.getArch() == llvm::Triple::ppc64le;
300 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
301 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
302 TargetTriple.getArch() == llvm::Triple::mipsel;
303 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
304 TargetTriple.getArch() == llvm::Triple::mips64el;
306 ShadowMapping Mapping;
308 if (LongSize == 32) {
312 Mapping.Offset = kMIPS32_ShadowOffset32;
314 Mapping.Offset = kFreeBSD_ShadowOffset32;
316 Mapping.Offset = kIOSShadowOffset32;
318 Mapping.Offset = kDefaultShadowOffset32;
319 } else { // LongSize == 64
321 Mapping.Offset = kPPC64_ShadowOffset64;
323 Mapping.Offset = kFreeBSD_ShadowOffset64;
324 else if (IsLinux && IsX86_64)
325 Mapping.Offset = kSmallX86_64ShadowOffset;
327 Mapping.Offset = kMIPS64_ShadowOffset64;
329 Mapping.Offset = kDefaultShadowOffset64;
332 Mapping.Scale = kDefaultShadowScale;
333 if (ClMappingScale) {
334 Mapping.Scale = ClMappingScale;
337 // OR-ing shadow offset if more efficient (at least on x86) if the offset
338 // is a power of two, but on ppc64 we have to use add since the shadow
339 // offset is not necessary 1/8-th of the address space.
340 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
345 static size_t RedzoneSizeForScale(int MappingScale) {
346 // Redzone used for stack and globals is at least 32 bytes.
347 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
348 return std::max(32U, 1U << MappingScale);
351 /// AddressSanitizer: instrument the code in module to find memory bugs.
352 struct AddressSanitizer : public FunctionPass {
353 AddressSanitizer() : FunctionPass(ID) {}
354 const char *getPassName() const override {
355 return "AddressSanitizerFunctionPass";
357 void instrumentMop(Instruction *I, bool UseCalls);
358 void instrumentPointerComparisonOrSubtraction(Instruction *I);
359 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
360 Value *Addr, uint32_t TypeSize, bool IsWrite,
361 Value *SizeArgument, bool UseCalls);
362 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
363 Value *ShadowValue, uint32_t TypeSize);
364 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
365 bool IsWrite, size_t AccessSizeIndex,
366 Value *SizeArgument);
367 void instrumentMemIntrinsic(MemIntrinsic *MI);
368 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
369 bool runOnFunction(Function &F) override;
370 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
371 bool doInitialization(Module &M) override;
372 static char ID; // Pass identification, replacement for typeid
375 void initializeCallbacks(Module &M);
377 bool LooksLikeCodeInBug11395(Instruction *I);
378 bool GlobalIsLinkerInitialized(GlobalVariable *G);
381 const DataLayout *DL;
384 ShadowMapping Mapping;
385 Function *AsanCtorFunction;
386 Function *AsanInitFunction;
387 Function *AsanHandleNoReturnFunc;
388 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
389 // This array is indexed by AccessIsWrite and log2(AccessSize).
390 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
391 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
392 // This array is indexed by AccessIsWrite.
393 Function *AsanErrorCallbackSized[2],
394 *AsanMemoryAccessCallbackSized[2];
395 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
397 GlobalsMetadata GlobalsMD;
399 friend struct FunctionStackPoisoner;
402 class AddressSanitizerModule : public ModulePass {
404 AddressSanitizerModule() : ModulePass(ID) {}
405 bool runOnModule(Module &M) override;
406 static char ID; // Pass identification, replacement for typeid
407 const char *getPassName() const override {
408 return "AddressSanitizerModule";
412 void initializeCallbacks(Module &M);
414 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
415 bool ShouldInstrumentGlobal(GlobalVariable *G);
416 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
417 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
418 size_t MinRedzoneSizeForGlobal() const {
419 return RedzoneSizeForScale(Mapping.Scale);
422 GlobalsMetadata GlobalsMD;
425 const DataLayout *DL;
426 ShadowMapping Mapping;
427 Function *AsanPoisonGlobals;
428 Function *AsanUnpoisonGlobals;
429 Function *AsanRegisterGlobals;
430 Function *AsanUnregisterGlobals;
433 // Stack poisoning does not play well with exception handling.
434 // When an exception is thrown, we essentially bypass the code
435 // that unpoisones the stack. This is why the run-time library has
436 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
437 // stack in the interceptor. This however does not work inside the
438 // actual function which catches the exception. Most likely because the
439 // compiler hoists the load of the shadow value somewhere too high.
440 // This causes asan to report a non-existing bug on 453.povray.
441 // It sounds like an LLVM bug.
442 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
444 AddressSanitizer &ASan;
449 ShadowMapping Mapping;
451 SmallVector<AllocaInst*, 16> AllocaVec;
452 SmallVector<Instruction*, 8> RetVec;
453 unsigned StackAlignment;
455 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
456 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
457 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
459 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
460 struct AllocaPoisonCall {
461 IntrinsicInst *InsBefore;
466 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
468 // Maps Value to an AllocaInst from which the Value is originated.
469 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
470 AllocaForValueMapTy AllocaForValue;
472 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
473 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
474 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
475 Mapping(ASan.Mapping),
476 StackAlignment(1 << Mapping.Scale) {}
478 bool runOnFunction() {
479 if (!ClStack) return false;
480 // Collect alloca, ret, lifetime instructions etc.
481 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
484 if (AllocaVec.empty()) return false;
486 initializeCallbacks(*F.getParent());
496 // Finds all static Alloca instructions and puts
497 // poisoned red zones around all of them.
498 // Then unpoison everything back before the function returns.
501 // ----------------------- Visitors.
502 /// \brief Collect all Ret instructions.
503 void visitReturnInst(ReturnInst &RI) {
504 RetVec.push_back(&RI);
507 /// \brief Collect Alloca instructions we want (and can) handle.
508 void visitAllocaInst(AllocaInst &AI) {
509 if (!isInterestingAlloca(AI)) return;
511 StackAlignment = std::max(StackAlignment, AI.getAlignment());
512 AllocaVec.push_back(&AI);
515 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
517 void visitIntrinsicInst(IntrinsicInst &II) {
518 if (!ClCheckLifetime) return;
519 Intrinsic::ID ID = II.getIntrinsicID();
520 if (ID != Intrinsic::lifetime_start &&
521 ID != Intrinsic::lifetime_end)
523 // Found lifetime intrinsic, add ASan instrumentation if necessary.
524 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
525 // If size argument is undefined, don't do anything.
526 if (Size->isMinusOne()) return;
527 // Check that size doesn't saturate uint64_t and can
528 // be stored in IntptrTy.
529 const uint64_t SizeValue = Size->getValue().getLimitedValue();
530 if (SizeValue == ~0ULL ||
531 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
533 // Find alloca instruction that corresponds to llvm.lifetime argument.
534 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
536 bool DoPoison = (ID == Intrinsic::lifetime_end);
537 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
538 AllocaPoisonCallVec.push_back(APC);
541 // ---------------------- Helpers.
542 void initializeCallbacks(Module &M);
544 // Check if we want (and can) handle this alloca.
545 bool isInterestingAlloca(AllocaInst &AI) const {
546 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
547 AI.getAllocatedType()->isSized() &&
548 // alloca() may be called with 0 size, ignore it.
549 getAllocaSizeInBytes(&AI) > 0);
552 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
553 Type *Ty = AI->getAllocatedType();
554 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
557 /// Finds alloca where the value comes from.
558 AllocaInst *findAllocaForValue(Value *V);
559 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
560 Value *ShadowBase, bool DoPoison);
561 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
563 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
569 char AddressSanitizer::ID = 0;
570 INITIALIZE_PASS(AddressSanitizer, "asan",
571 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
573 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
574 return new AddressSanitizer();
577 char AddressSanitizerModule::ID = 0;
578 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
579 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
580 "ModulePass", false, false)
581 ModulePass *llvm::createAddressSanitizerModulePass() {
582 return new AddressSanitizerModule();
585 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
586 size_t Res = countTrailingZeros(TypeSize / 8);
587 assert(Res < kNumberOfAccessSizes);
591 // \brief Create a constant for Str so that we can pass it to the run-time lib.
592 static GlobalVariable *createPrivateGlobalForString(
593 Module &M, StringRef Str, bool AllowMerging) {
594 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
595 // We use private linkage for module-local strings. If they can be merged
596 // with another one, we set the unnamed_addr attribute.
598 new GlobalVariable(M, StrConst->getType(), true,
599 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
601 GV->setUnnamedAddr(true);
602 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
606 /// \brief Create a global describing a source location.
607 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
608 LocationMetadata MD) {
609 Constant *LocData[] = {
610 createPrivateGlobalForString(M, MD.Filename, true),
611 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
612 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
614 auto LocStruct = ConstantStruct::getAnon(LocData);
615 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
616 GlobalValue::PrivateLinkage, LocStruct,
618 GV->setUnnamedAddr(true);
622 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
623 return G->getName().find(kAsanGenPrefix) == 0 ||
624 G->getName().find(kSanCovGenPrefix) == 0;
627 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
629 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
630 if (Mapping.Offset == 0)
632 // (Shadow >> scale) | offset
633 if (Mapping.OrShadowOffset)
634 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
636 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
639 // Instrument memset/memmove/memcpy
640 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
642 if (isa<MemTransferInst>(MI)) {
644 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
645 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
646 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
647 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
648 } else if (isa<MemSetInst>(MI)) {
651 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
652 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
653 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
655 MI->eraseFromParent();
658 // If I is an interesting memory access, return the PointerOperand
659 // and set IsWrite/Alignment. Otherwise return nullptr.
660 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
661 unsigned *Alignment) {
662 // Skip memory accesses inserted by another instrumentation.
663 if (I->getMetadata("nosanitize"))
665 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
666 if (!ClInstrumentReads) return nullptr;
668 *Alignment = LI->getAlignment();
669 return LI->getPointerOperand();
671 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
672 if (!ClInstrumentWrites) return nullptr;
674 *Alignment = SI->getAlignment();
675 return SI->getPointerOperand();
677 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
678 if (!ClInstrumentAtomics) return nullptr;
681 return RMW->getPointerOperand();
683 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
684 if (!ClInstrumentAtomics) return nullptr;
687 return XCHG->getPointerOperand();
692 static bool isPointerOperand(Value *V) {
693 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
696 // This is a rough heuristic; it may cause both false positives and
697 // false negatives. The proper implementation requires cooperation with
699 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
700 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
701 if (!Cmp->isRelational())
703 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
704 if (BO->getOpcode() != Instruction::Sub)
709 if (!isPointerOperand(I->getOperand(0)) ||
710 !isPointerOperand(I->getOperand(1)))
715 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
716 // If a global variable does not have dynamic initialization we don't
717 // have to instrument it. However, if a global does not have initializer
718 // at all, we assume it has dynamic initializer (in other TU).
719 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
723 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
725 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
726 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
727 for (int i = 0; i < 2; i++) {
728 if (Param[i]->getType()->isPointerTy())
729 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
731 IRB.CreateCall2(F, Param[0], Param[1]);
734 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
735 bool IsWrite = false;
736 unsigned Alignment = 0;
737 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
739 if (ClOpt && ClOptGlobals) {
740 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
741 // If initialization order checking is disabled, a simple access to a
742 // dynamically initialized global is always valid.
743 if (!ClInitializers || GlobalIsLinkerInitialized(G)) {
744 NumOptimizedAccessesToGlobalVar++;
748 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
749 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
750 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
751 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
752 NumOptimizedAccessesToGlobalArray++;
759 Type *OrigPtrTy = Addr->getType();
760 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
762 assert(OrigTy->isSized());
763 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
765 assert((TypeSize % 8) == 0);
768 NumInstrumentedWrites++;
770 NumInstrumentedReads++;
772 unsigned Granularity = 1 << Mapping.Scale;
773 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
774 // if the data is properly aligned.
775 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
777 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
778 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
779 // Instrument unusual size or unusual alignment.
780 // We can not do it with a single check, so we do 1-byte check for the first
781 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
782 // to report the actual access size.
784 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
785 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
787 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
789 Value *LastByte = IRB.CreateIntToPtr(
790 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
792 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
793 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
797 // Validate the result of Module::getOrInsertFunction called for an interface
798 // function of AddressSanitizer. If the instrumented module defines a function
799 // with the same name, their prototypes must match, otherwise
800 // getOrInsertFunction returns a bitcast.
801 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
802 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
803 FuncOrBitcast->dump();
804 report_fatal_error("trying to redefine an AddressSanitizer "
805 "interface function");
808 Instruction *AddressSanitizer::generateCrashCode(
809 Instruction *InsertBefore, Value *Addr,
810 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
811 IRBuilder<> IRB(InsertBefore);
812 CallInst *Call = SizeArgument
813 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
814 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
816 // We don't do Call->setDoesNotReturn() because the BB already has
817 // UnreachableInst at the end.
818 // This EmptyAsm is required to avoid callback merge.
819 IRB.CreateCall(EmptyAsm);
823 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
826 size_t Granularity = 1 << Mapping.Scale;
827 // Addr & (Granularity - 1)
828 Value *LastAccessedByte = IRB.CreateAnd(
829 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
830 // (Addr & (Granularity - 1)) + size - 1
831 if (TypeSize / 8 > 1)
832 LastAccessedByte = IRB.CreateAdd(
833 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
834 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
835 LastAccessedByte = IRB.CreateIntCast(
836 LastAccessedByte, ShadowValue->getType(), false);
837 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
838 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
841 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
842 Instruction *InsertBefore, Value *Addr,
843 uint32_t TypeSize, bool IsWrite,
844 Value *SizeArgument, bool UseCalls) {
845 IRBuilder<> IRB(InsertBefore);
846 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
847 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
850 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
855 Type *ShadowTy = IntegerType::get(
856 *C, std::max(8U, TypeSize >> Mapping.Scale));
857 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
858 Value *ShadowPtr = memToShadow(AddrLong, IRB);
859 Value *CmpVal = Constant::getNullValue(ShadowTy);
860 Value *ShadowValue = IRB.CreateLoad(
861 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
863 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
864 size_t Granularity = 1 << Mapping.Scale;
865 TerminatorInst *CrashTerm = nullptr;
867 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
868 // We use branch weights for the slow path check, to indicate that the slow
869 // path is rarely taken. This seems to be the case for SPEC benchmarks.
870 TerminatorInst *CheckTerm =
871 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false,
872 MDBuilder(*C).createBranchWeights(1, 100000));
873 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
874 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
875 IRB.SetInsertPoint(CheckTerm);
876 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
877 BasicBlock *CrashBlock =
878 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
879 CrashTerm = new UnreachableInst(*C, CrashBlock);
880 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
881 ReplaceInstWithInst(CheckTerm, NewTerm);
883 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
886 Instruction *Crash = generateCrashCode(
887 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
888 Crash->setDebugLoc(OrigIns->getDebugLoc());
891 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
892 GlobalValue *ModuleName) {
893 // Set up the arguments to our poison/unpoison functions.
894 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
896 // Add a call to poison all external globals before the given function starts.
897 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
898 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
900 // Add calls to unpoison all globals before each return instruction.
901 for (auto &BB : GlobalInit.getBasicBlockList())
902 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
903 CallInst::Create(AsanUnpoisonGlobals, "", RI);
906 void AddressSanitizerModule::createInitializerPoisonCalls(
907 Module &M, GlobalValue *ModuleName) {
908 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
910 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
911 for (Use &OP : CA->operands()) {
912 if (isa<ConstantAggregateZero>(OP))
914 ConstantStruct *CS = cast<ConstantStruct>(OP);
916 // Must have a function or null ptr.
917 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
918 if (F->getName() == kAsanModuleCtorName) continue;
919 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
920 // Don't instrument CTORs that will run before asan.module_ctor.
921 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
922 poisonOneInitializer(*F, ModuleName);
927 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
928 Type *Ty = cast<PointerType>(G->getType())->getElementType();
929 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
931 if (GlobalsMD.get(G).IsBlacklisted) return false;
932 if (!Ty->isSized()) return false;
933 if (!G->hasInitializer()) return false;
934 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
935 // Touch only those globals that will not be defined in other modules.
936 // Don't handle ODR linkage types and COMDATs since other modules may be built
938 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
939 G->getLinkage() != GlobalVariable::PrivateLinkage &&
940 G->getLinkage() != GlobalVariable::InternalLinkage)
944 // Two problems with thread-locals:
945 // - The address of the main thread's copy can't be computed at link-time.
946 // - Need to poison all copies, not just the main thread's one.
947 if (G->isThreadLocal())
949 // For now, just ignore this Global if the alignment is large.
950 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
952 if (G->hasSection()) {
953 StringRef Section(G->getSection());
954 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
955 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
957 if (Section.startswith("__OBJC,") ||
958 Section.startswith("__DATA, __objc_")) {
959 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
962 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
963 // Constant CFString instances are compiled in the following way:
964 // -- the string buffer is emitted into
965 // __TEXT,__cstring,cstring_literals
966 // -- the constant NSConstantString structure referencing that buffer
967 // is placed into __DATA,__cfstring
968 // Therefore there's no point in placing redzones into __DATA,__cfstring.
969 // Moreover, it causes the linker to crash on OS X 10.7
970 if (Section.startswith("__DATA,__cfstring")) {
971 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
974 // The linker merges the contents of cstring_literals and removes the
976 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
977 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
980 if (Section.startswith("__TEXT,__objc_methname,cstring_literals")) {
981 DEBUG(dbgs() << "Ignoring objc_methname cstring global: " << *G << "\n");
986 // Callbacks put into the CRT initializer/terminator sections
987 // should not be instrumented.
988 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
989 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
990 if (Section.startswith(".CRT")) {
991 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
995 // Globals from llvm.metadata aren't emitted, do not instrument them.
996 if (Section == "llvm.metadata") return false;
1002 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1003 IRBuilder<> IRB(*C);
1004 // Declare our poisoning and unpoisoning functions.
1005 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1006 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1007 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1008 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1009 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1010 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1011 // Declare functions that register/unregister globals.
1012 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1013 kAsanRegisterGlobalsName, IRB.getVoidTy(),
1014 IntptrTy, IntptrTy, nullptr));
1015 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1016 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1017 kAsanUnregisterGlobalsName,
1018 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1019 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1022 // This function replaces all global variables with new variables that have
1023 // trailing redzones. It also creates a function that poisons
1024 // redzones and inserts this function into llvm.global_ctors.
1025 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1028 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1030 for (auto &G : M.globals()) {
1031 if (ShouldInstrumentGlobal(&G))
1032 GlobalsToChange.push_back(&G);
1035 size_t n = GlobalsToChange.size();
1036 if (n == 0) return false;
1038 // A global is described by a structure
1041 // size_t size_with_redzone;
1042 // const char *name;
1043 // const char *module_name;
1044 // size_t has_dynamic_init;
1045 // void *source_location;
1046 // We initialize an array of such structures and pass it to a run-time call.
1047 StructType *GlobalStructTy =
1048 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1049 IntptrTy, IntptrTy, nullptr);
1050 SmallVector<Constant *, 16> Initializers(n);
1052 bool HasDynamicallyInitializedGlobals = false;
1054 // We shouldn't merge same module names, as this string serves as unique
1055 // module ID in runtime.
1056 GlobalVariable *ModuleName = createPrivateGlobalForString(
1057 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1059 for (size_t i = 0; i < n; i++) {
1060 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1061 GlobalVariable *G = GlobalsToChange[i];
1063 auto MD = GlobalsMD.get(G);
1064 // Create string holding the global name (use global name from metadata
1065 // if it's available, otherwise just write the name of global variable).
1066 GlobalVariable *Name = createPrivateGlobalForString(
1067 M, MD.Name.empty() ? G->getName() : MD.Name,
1068 /*AllowMerging*/ true);
1070 PointerType *PtrTy = cast<PointerType>(G->getType());
1071 Type *Ty = PtrTy->getElementType();
1072 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1073 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1074 // MinRZ <= RZ <= kMaxGlobalRedzone
1075 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1076 uint64_t RZ = std::max(MinRZ,
1077 std::min(kMaxGlobalRedzone,
1078 (SizeInBytes / MinRZ / 4) * MinRZ));
1079 uint64_t RightRedzoneSize = RZ;
1080 // Round up to MinRZ
1081 if (SizeInBytes % MinRZ)
1082 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1083 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1084 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1086 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1087 Constant *NewInitializer = ConstantStruct::get(
1088 NewTy, G->getInitializer(),
1089 Constant::getNullValue(RightRedZoneTy), nullptr);
1091 // Create a new global variable with enough space for a redzone.
1092 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1093 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1094 Linkage = GlobalValue::InternalLinkage;
1095 GlobalVariable *NewGlobal = new GlobalVariable(
1096 M, NewTy, G->isConstant(), Linkage,
1097 NewInitializer, "", G, G->getThreadLocalMode());
1098 NewGlobal->copyAttributesFrom(G);
1099 NewGlobal->setAlignment(MinRZ);
1102 Indices2[0] = IRB.getInt32(0);
1103 Indices2[1] = IRB.getInt32(0);
1105 G->replaceAllUsesWith(
1106 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1107 NewGlobal->takeName(G);
1108 G->eraseFromParent();
1110 Constant *SourceLoc;
1111 if (!MD.SourceLoc.empty()) {
1112 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1113 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1115 SourceLoc = ConstantInt::get(IntptrTy, 0);
1118 Initializers[i] = ConstantStruct::get(
1119 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1120 ConstantInt::get(IntptrTy, SizeInBytes),
1121 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1122 ConstantExpr::getPointerCast(Name, IntptrTy),
1123 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1124 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1126 if (ClInitializers && MD.IsDynInit)
1127 HasDynamicallyInitializedGlobals = true;
1129 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1132 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1133 GlobalVariable *AllGlobals = new GlobalVariable(
1134 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1135 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1137 // Create calls for poisoning before initializers run and unpoisoning after.
1138 if (HasDynamicallyInitializedGlobals)
1139 createInitializerPoisonCalls(M, ModuleName);
1140 IRB.CreateCall2(AsanRegisterGlobals,
1141 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1142 ConstantInt::get(IntptrTy, n));
1144 // We also need to unregister globals at the end, e.g. when a shared library
1146 Function *AsanDtorFunction = Function::Create(
1147 FunctionType::get(Type::getVoidTy(*C), false),
1148 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1149 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1150 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1151 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1152 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1153 ConstantInt::get(IntptrTy, n));
1154 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1160 bool AddressSanitizerModule::runOnModule(Module &M) {
1161 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1164 DL = &DLP->getDataLayout();
1165 C = &(M.getContext());
1166 int LongSize = DL->getPointerSizeInBits();
1167 IntptrTy = Type::getIntNTy(*C, LongSize);
1168 Mapping = getShadowMapping(M, LongSize);
1169 initializeCallbacks(M);
1171 bool Changed = false;
1173 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1175 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1178 Changed |= InstrumentGlobals(IRB, M);
1183 void AddressSanitizer::initializeCallbacks(Module &M) {
1184 IRBuilder<> IRB(*C);
1185 // Create __asan_report* callbacks.
1186 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1187 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1188 AccessSizeIndex++) {
1189 // IsWrite and TypeSize are encoded in the function name.
1190 std::string Suffix =
1191 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1192 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1193 checkInterfaceFunction(
1194 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1195 IRB.getVoidTy(), IntptrTy, nullptr));
1196 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1197 checkInterfaceFunction(
1198 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1199 IRB.getVoidTy(), IntptrTy, nullptr));
1202 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1203 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1204 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1205 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1207 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1208 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1209 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1210 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1211 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1212 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1214 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1215 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1216 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1217 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1218 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1219 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1220 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1221 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1222 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1224 AsanHandleNoReturnFunc = checkInterfaceFunction(
1225 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1227 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1228 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1229 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1230 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1231 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1232 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1233 StringRef(""), StringRef(""),
1234 /*hasSideEffects=*/true);
1238 bool AddressSanitizer::doInitialization(Module &M) {
1239 // Initialize the private fields. No one has accessed them before.
1240 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1242 report_fatal_error("data layout missing");
1243 DL = &DLP->getDataLayout();
1247 C = &(M.getContext());
1248 LongSize = DL->getPointerSizeInBits();
1249 IntptrTy = Type::getIntNTy(*C, LongSize);
1251 AsanCtorFunction = Function::Create(
1252 FunctionType::get(Type::getVoidTy(*C), false),
1253 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1254 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1255 // call __asan_init in the module ctor.
1256 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1257 AsanInitFunction = checkInterfaceFunction(
1258 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr));
1259 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1260 IRB.CreateCall(AsanInitFunction);
1262 Mapping = getShadowMapping(M, LongSize);
1264 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1268 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1269 // For each NSObject descendant having a +load method, this method is invoked
1270 // by the ObjC runtime before any of the static constructors is called.
1271 // Therefore we need to instrument such methods with a call to __asan_init
1272 // at the beginning in order to initialize our runtime before any access to
1273 // the shadow memory.
1274 // We cannot just ignore these methods, because they may call other
1275 // instrumented functions.
1276 if (F.getName().find(" load]") != std::string::npos) {
1277 IRBuilder<> IRB(F.begin()->begin());
1278 IRB.CreateCall(AsanInitFunction);
1284 bool AddressSanitizer::runOnFunction(Function &F) {
1285 if (&F == AsanCtorFunction) return false;
1286 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1287 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1288 initializeCallbacks(*F.getParent());
1290 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1291 maybeInsertAsanInitAtFunctionEntry(F);
1293 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1296 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1299 // We want to instrument every address only once per basic block (unless there
1300 // are calls between uses).
1301 SmallSet<Value*, 16> TempsToInstrument;
1302 SmallVector<Instruction*, 16> ToInstrument;
1303 SmallVector<Instruction*, 8> NoReturnCalls;
1304 SmallVector<BasicBlock*, 16> AllBlocks;
1305 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1310 // Fill the set of memory operations to instrument.
1311 for (auto &BB : F) {
1312 AllBlocks.push_back(&BB);
1313 TempsToInstrument.clear();
1314 int NumInsnsPerBB = 0;
1315 for (auto &Inst : BB) {
1316 if (LooksLikeCodeInBug11395(&Inst)) return false;
1318 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1319 if (ClOpt && ClOptSameTemp) {
1320 if (!TempsToInstrument.insert(Addr).second)
1321 continue; // We've seen this temp in the current BB.
1323 } else if (ClInvalidPointerPairs &&
1324 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1325 PointerComparisonsOrSubtracts.push_back(&Inst);
1327 } else if (isa<MemIntrinsic>(Inst)) {
1330 if (isa<AllocaInst>(Inst))
1334 // A call inside BB.
1335 TempsToInstrument.clear();
1336 if (CS.doesNotReturn())
1337 NoReturnCalls.push_back(CS.getInstruction());
1341 ToInstrument.push_back(&Inst);
1343 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1348 Function *UninstrumentedDuplicate = nullptr;
1349 bool LikelyToInstrument =
1350 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1351 if (ClKeepUninstrumented && LikelyToInstrument) {
1352 ValueToValueMapTy VMap;
1353 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1354 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1355 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1356 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1359 bool UseCalls = false;
1360 if (ClInstrumentationWithCallsThreshold >= 0 &&
1361 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1365 int NumInstrumented = 0;
1366 for (auto Inst : ToInstrument) {
1367 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1368 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1369 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1370 instrumentMop(Inst, UseCalls);
1372 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1377 FunctionStackPoisoner FSP(F, *this);
1378 bool ChangedStack = FSP.runOnFunction();
1380 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1381 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1382 for (auto CI : NoReturnCalls) {
1383 IRBuilder<> IRB(CI);
1384 IRB.CreateCall(AsanHandleNoReturnFunc);
1387 for (auto Inst : PointerComparisonsOrSubtracts) {
1388 instrumentPointerComparisonOrSubtraction(Inst);
1392 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1394 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1396 if (ClKeepUninstrumented) {
1398 // No instrumentation is done, no need for the duplicate.
1399 if (UninstrumentedDuplicate)
1400 UninstrumentedDuplicate->eraseFromParent();
1402 // The function was instrumented. We must have the duplicate.
1403 assert(UninstrumentedDuplicate);
1404 UninstrumentedDuplicate->setSection("NOASAN");
1405 assert(!F.hasSection());
1406 F.setSection("ASAN");
1413 // Workaround for bug 11395: we don't want to instrument stack in functions
1414 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1415 // FIXME: remove once the bug 11395 is fixed.
1416 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1417 if (LongSize != 32) return false;
1418 CallInst *CI = dyn_cast<CallInst>(I);
1419 if (!CI || !CI->isInlineAsm()) return false;
1420 if (CI->getNumArgOperands() <= 5) return false;
1421 // We have inline assembly with quite a few arguments.
1425 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1426 IRBuilder<> IRB(*C);
1427 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1428 std::string Suffix = itostr(i);
1429 AsanStackMallocFunc[i] = checkInterfaceFunction(
1430 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1431 IntptrTy, IntptrTy, nullptr));
1432 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1433 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1434 IntptrTy, IntptrTy, nullptr));
1436 AsanPoisonStackMemoryFunc = checkInterfaceFunction(
1437 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1438 IntptrTy, IntptrTy, nullptr));
1439 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(
1440 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1441 IntptrTy, IntptrTy, nullptr));
1445 FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1446 IRBuilder<> &IRB, Value *ShadowBase,
1448 size_t n = ShadowBytes.size();
1450 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1451 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1452 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1453 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1454 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1455 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1457 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1458 if (ASan.DL->isLittleEndian())
1459 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1461 Val = (Val << 8) | ShadowBytes[i + j];
1464 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1465 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1466 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1467 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1472 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1473 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1474 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1475 assert(LocalStackSize <= kMaxStackMallocSize);
1476 uint64_t MaxSize = kMinStackMallocSize;
1477 for (int i = 0; ; i++, MaxSize *= 2)
1478 if (LocalStackSize <= MaxSize)
1480 llvm_unreachable("impossible LocalStackSize");
1483 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1484 // We can not use MemSet intrinsic because it may end up calling the actual
1485 // memset. Size is a multiple of 8.
1486 // Currently this generates 8-byte stores on x86_64; it may be better to
1487 // generate wider stores.
1488 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1489 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1490 assert(!(Size % 8));
1491 assert(kAsanStackAfterReturnMagic == 0xf5);
1492 for (int i = 0; i < Size; i += 8) {
1493 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1494 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1495 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1499 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1500 for (const auto &Inst : F.getEntryBlock())
1501 if (!isa<AllocaInst>(Inst))
1502 return Inst.getDebugLoc();
1506 void FunctionStackPoisoner::poisonStack() {
1507 int StackMallocIdx = -1;
1508 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1510 assert(AllocaVec.size() > 0);
1511 Instruction *InsBefore = AllocaVec[0];
1512 IRBuilder<> IRB(InsBefore);
1513 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1515 SmallVector<ASanStackVariableDescription, 16> SVD;
1516 SVD.reserve(AllocaVec.size());
1517 for (AllocaInst *AI : AllocaVec) {
1518 ASanStackVariableDescription D = { AI->getName().data(),
1519 getAllocaSizeInBytes(AI),
1520 AI->getAlignment(), AI, 0};
1523 // Minimal header size (left redzone) is 4 pointers,
1524 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1525 size_t MinHeaderSize = ASan.LongSize / 2;
1526 ASanStackFrameLayout L;
1527 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1528 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1529 uint64_t LocalStackSize = L.FrameSize;
1530 bool DoStackMalloc =
1531 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1533 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1534 AllocaInst *MyAlloca =
1535 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1536 MyAlloca->setDebugLoc(EntryDebugLocation);
1537 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1538 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1539 MyAlloca->setAlignment(FrameAlignment);
1540 assert(MyAlloca->isStaticAlloca());
1541 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1542 Value *LocalStackBase = OrigStackBase;
1544 if (DoStackMalloc) {
1545 // LocalStackBase = OrigStackBase
1546 // if (__asan_option_detect_stack_use_after_return)
1547 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1548 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1549 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1550 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1551 kAsanOptionDetectUAR, IRB.getInt32Ty());
1552 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1553 Constant::getNullValue(IRB.getInt32Ty()));
1554 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1555 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1556 IRBuilder<> IRBIf(Term);
1557 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1558 LocalStackBase = IRBIf.CreateCall2(
1559 AsanStackMallocFunc[StackMallocIdx],
1560 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1561 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1562 IRB.SetInsertPoint(InsBefore);
1563 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1564 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1565 Phi->addIncoming(OrigStackBase, CmpBlock);
1566 Phi->addIncoming(LocalStackBase, SetBlock);
1567 LocalStackBase = Phi;
1570 // Insert poison calls for lifetime intrinsics for alloca.
1571 bool HavePoisonedAllocas = false;
1572 for (const auto &APC : AllocaPoisonCallVec) {
1573 assert(APC.InsBefore);
1575 IRBuilder<> IRB(APC.InsBefore);
1576 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1577 HavePoisonedAllocas |= APC.DoPoison;
1580 // Replace Alloca instructions with base+offset.
1581 for (const auto &Desc : SVD) {
1582 AllocaInst *AI = Desc.AI;
1583 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1584 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1586 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1587 AI->replaceAllUsesWith(NewAllocaPtr);
1590 // The left-most redzone has enough space for at least 4 pointers.
1591 // Write the Magic value to redzone[0].
1592 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1593 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1595 // Write the frame description constant to redzone[1].
1596 Value *BasePlus1 = IRB.CreateIntToPtr(
1597 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1599 GlobalVariable *StackDescriptionGlobal =
1600 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1601 /*AllowMerging*/true);
1602 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1604 IRB.CreateStore(Description, BasePlus1);
1605 // Write the PC to redzone[2].
1606 Value *BasePlus2 = IRB.CreateIntToPtr(
1607 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1608 2 * ASan.LongSize/8)),
1610 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1612 // Poison the stack redzones at the entry.
1613 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1614 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1616 // (Un)poison the stack before all ret instructions.
1617 for (auto Ret : RetVec) {
1618 IRBuilder<> IRBRet(Ret);
1619 // Mark the current frame as retired.
1620 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1622 if (DoStackMalloc) {
1623 assert(StackMallocIdx >= 0);
1624 // if LocalStackBase != OrigStackBase:
1625 // // In use-after-return mode, poison the whole stack frame.
1626 // if StackMallocIdx <= 4
1627 // // For small sizes inline the whole thing:
1628 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1629 // **SavedFlagPtr(LocalStackBase) = 0
1631 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1633 // <This is not a fake stack; unpoison the redzones>
1634 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1635 TerminatorInst *ThenTerm, *ElseTerm;
1636 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1638 IRBuilder<> IRBPoison(ThenTerm);
1639 if (StackMallocIdx <= 4) {
1640 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1641 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1642 ClassSize >> Mapping.Scale);
1643 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1645 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1646 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1647 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1648 IRBPoison.CreateStore(
1649 Constant::getNullValue(IRBPoison.getInt8Ty()),
1650 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1652 // For larger frames call __asan_stack_free_*.
1653 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1654 ConstantInt::get(IntptrTy, LocalStackSize),
1658 IRBuilder<> IRBElse(ElseTerm);
1659 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1660 } else if (HavePoisonedAllocas) {
1661 // If we poisoned some allocas in llvm.lifetime analysis,
1662 // unpoison whole stack frame now.
1663 assert(LocalStackBase == OrigStackBase);
1664 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1666 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1670 // We are done. Remove the old unused alloca instructions.
1671 for (auto AI : AllocaVec)
1672 AI->eraseFromParent();
1675 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1676 IRBuilder<> &IRB, bool DoPoison) {
1677 // For now just insert the call to ASan runtime.
1678 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1679 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1680 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1681 : AsanUnpoisonStackMemoryFunc,
1685 // Handling llvm.lifetime intrinsics for a given %alloca:
1686 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1687 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1688 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1689 // could be poisoned by previous llvm.lifetime.end instruction, as the
1690 // variable may go in and out of scope several times, e.g. in loops).
1691 // (3) if we poisoned at least one %alloca in a function,
1692 // unpoison the whole stack frame at function exit.
1694 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1695 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1696 // We're intested only in allocas we can handle.
1697 return isInterestingAlloca(*AI) ? AI : nullptr;
1698 // See if we've already calculated (or started to calculate) alloca for a
1700 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1701 if (I != AllocaForValue.end())
1703 // Store 0 while we're calculating alloca for value V to avoid
1704 // infinite recursion if the value references itself.
1705 AllocaForValue[V] = nullptr;
1706 AllocaInst *Res = nullptr;
1707 if (CastInst *CI = dyn_cast<CastInst>(V))
1708 Res = findAllocaForValue(CI->getOperand(0));
1709 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1710 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1711 Value *IncValue = PN->getIncomingValue(i);
1712 // Allow self-referencing phi-nodes.
1713 if (IncValue == PN) continue;
1714 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1715 // AI for incoming values should exist and should all be equal.
1716 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1722 AllocaForValue[V] = Res;