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/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"
50 #include <system_error>
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_v4";
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 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
132 cl::desc("Check return-after-free"), cl::Hidden, cl::init(true));
133 // This flag may need to be replaced with -f[no]asan-globals.
134 static cl::opt<bool> ClGlobals("asan-globals",
135 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
136 static cl::opt<int> ClCoverage("asan-coverage",
137 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"),
138 cl::Hidden, cl::init(false));
139 static cl::opt<int> ClCoverageBlockThreshold("asan-coverage-block-threshold",
140 cl::desc("Add coverage instrumentation only to the entry block if there "
141 "are more than this number of blocks."),
142 cl::Hidden, cl::init(1500));
143 static cl::opt<bool> ClInitializers("asan-initialization-order",
144 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(true));
145 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
146 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
147 cl::Hidden, cl::init(false));
148 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
149 cl::desc("Realign stack to the value of this flag (power of two)"),
150 cl::Hidden, cl::init(32));
151 static cl::opt<int> ClInstrumentationWithCallsThreshold(
152 "asan-instrumentation-with-call-threshold",
153 cl::desc("If the function being instrumented contains more than "
154 "this number of memory accesses, use callbacks instead of "
155 "inline checks (-1 means never use callbacks)."),
156 cl::Hidden, cl::init(7000));
157 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
158 "asan-memory-access-callback-prefix",
159 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
160 cl::init("__asan_"));
162 // This is an experimental feature that will allow to choose between
163 // instrumented and non-instrumented code at link-time.
164 // If this option is on, just before instrumenting a function we create its
165 // clone; if the function is not changed by asan the clone is deleted.
166 // If we end up with a clone, we put the instrumented function into a section
167 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
169 // This is still a prototype, we need to figure out a way to keep two copies of
170 // a function so that the linker can easily choose one of them.
171 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
172 cl::desc("Keep uninstrumented copies of functions"),
173 cl::Hidden, cl::init(false));
175 // These flags allow to change the shadow mapping.
176 // The shadow mapping looks like
177 // Shadow = (Mem >> scale) + (1 << offset_log)
178 static cl::opt<int> ClMappingScale("asan-mapping-scale",
179 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
181 // Optimization flags. Not user visible, used mostly for testing
182 // and benchmarking the tool.
183 static cl::opt<bool> ClOpt("asan-opt",
184 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
185 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
186 cl::desc("Instrument the same temp just once"), cl::Hidden,
188 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
189 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
191 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
192 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
193 cl::Hidden, cl::init(false));
196 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
198 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
199 cl::Hidden, cl::init(0));
200 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
201 cl::Hidden, cl::desc("Debug func"));
202 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
203 cl::Hidden, cl::init(-1));
204 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
205 cl::Hidden, cl::init(-1));
207 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
208 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
209 STATISTIC(NumOptimizedAccessesToGlobalArray,
210 "Number of optimized accesses to global arrays");
211 STATISTIC(NumOptimizedAccessesToGlobalVar,
212 "Number of optimized accesses to global vars");
215 /// Frontend-provided metadata for global variables.
216 class GlobalsMetadata {
220 : SourceLoc(nullptr), Name(nullptr), IsDynInit(false),
221 IsBlacklisted(false) {}
222 GlobalVariable *SourceLoc;
223 GlobalVariable *Name;
228 GlobalsMetadata() : inited_(false) {}
230 void init(Module& M) {
233 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
236 for (auto MDN : Globals->operands()) {
237 // Metadata node contains the global and the fields of "Entry".
238 assert(MDN->getNumOperands() == 5);
239 Value *V = MDN->getOperand(0);
240 // The optimizer may optimize away a global entirely.
243 GlobalVariable *GV = cast<GlobalVariable>(V);
244 // We can already have an entry for GV if it was merged with another
246 Entry &E = Entries[GV];
247 if (Value *Loc = MDN->getOperand(1)) {
248 GlobalVariable *GVLoc = cast<GlobalVariable>(Loc);
250 addSourceLocationGlobal(GVLoc);
252 if (Value *Name = MDN->getOperand(2)) {
253 GlobalVariable *GVName = cast<GlobalVariable>(Name);
255 InstrumentationGlobals.insert(GVName);
257 ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(3));
258 E.IsDynInit |= IsDynInit->isOne();
259 ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(4));
260 E.IsBlacklisted |= IsBlacklisted->isOne();
264 /// Returns metadata entry for a given global.
265 Entry get(GlobalVariable *G) const {
266 auto Pos = Entries.find(G);
267 return (Pos != Entries.end()) ? Pos->second : Entry();
270 /// Check if the global was generated by the instrumentation
271 /// (we don't want to instrument it again in this case).
272 bool isInstrumentationGlobal(GlobalVariable *G) const {
273 return InstrumentationGlobals.count(G);
278 DenseMap<GlobalVariable*, Entry> Entries;
279 // Globals generated by the frontend instrumentation.
280 DenseSet<GlobalVariable*> InstrumentationGlobals;
282 void addSourceLocationGlobal(GlobalVariable *SourceLocGV) {
283 // Source location global is a struct with layout:
287 // i32 column_number,
289 InstrumentationGlobals.insert(SourceLocGV);
290 ConstantStruct *Contents =
291 cast<ConstantStruct>(SourceLocGV->getInitializer());
292 GlobalVariable *FilenameGV = cast<GlobalVariable>(Contents->getOperand(0));
293 InstrumentationGlobals.insert(FilenameGV);
297 /// This struct defines the shadow mapping using the rule:
298 /// shadow = (mem >> Scale) ADD-or-OR Offset.
299 struct ShadowMapping {
305 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
306 llvm::Triple TargetTriple(M.getTargetTriple());
307 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
308 bool IsIOS = TargetTriple.getOS() == llvm::Triple::IOS;
309 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
310 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
311 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
312 TargetTriple.getArch() == llvm::Triple::ppc64le;
313 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
314 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
315 TargetTriple.getArch() == llvm::Triple::mipsel;
317 ShadowMapping Mapping;
319 if (LongSize == 32) {
323 Mapping.Offset = kMIPS32_ShadowOffset32;
325 Mapping.Offset = kFreeBSD_ShadowOffset32;
327 Mapping.Offset = kIOSShadowOffset32;
329 Mapping.Offset = kDefaultShadowOffset32;
330 } else { // LongSize == 64
332 Mapping.Offset = kPPC64_ShadowOffset64;
334 Mapping.Offset = kFreeBSD_ShadowOffset64;
335 else if (IsLinux && IsX86_64)
336 Mapping.Offset = kSmallX86_64ShadowOffset;
338 Mapping.Offset = kDefaultShadowOffset64;
341 Mapping.Scale = kDefaultShadowScale;
342 if (ClMappingScale) {
343 Mapping.Scale = ClMappingScale;
346 // OR-ing shadow offset if more efficient (at least on x86) if the offset
347 // is a power of two, but on ppc64 we have to use add since the shadow
348 // offset is not necessary 1/8-th of the address space.
349 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
354 static size_t RedzoneSizeForScale(int MappingScale) {
355 // Redzone used for stack and globals is at least 32 bytes.
356 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
357 return std::max(32U, 1U << MappingScale);
360 /// AddressSanitizer: instrument the code in module to find memory bugs.
361 struct AddressSanitizer : public FunctionPass {
362 AddressSanitizer() : FunctionPass(ID) {}
363 const char *getPassName() const override {
364 return "AddressSanitizerFunctionPass";
366 void instrumentMop(Instruction *I, bool UseCalls);
367 void instrumentPointerComparisonOrSubtraction(Instruction *I);
368 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
369 Value *Addr, uint32_t TypeSize, bool IsWrite,
370 Value *SizeArgument, bool UseCalls);
371 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
372 Value *ShadowValue, uint32_t TypeSize);
373 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
374 bool IsWrite, size_t AccessSizeIndex,
375 Value *SizeArgument);
376 void instrumentMemIntrinsic(MemIntrinsic *MI);
377 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
378 bool runOnFunction(Function &F) override;
379 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
380 bool doInitialization(Module &M) override;
381 static char ID; // Pass identification, replacement for typeid
384 void initializeCallbacks(Module &M);
386 bool LooksLikeCodeInBug11395(Instruction *I);
387 bool GlobalIsLinkerInitialized(GlobalVariable *G);
388 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks);
389 void InjectCoverageAtBlock(Function &F, BasicBlock &BB);
392 const DataLayout *DL;
395 ShadowMapping Mapping;
396 Function *AsanCtorFunction;
397 Function *AsanInitFunction;
398 Function *AsanHandleNoReturnFunc;
399 Function *AsanCovFunction;
400 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
401 // This array is indexed by AccessIsWrite and log2(AccessSize).
402 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
403 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
404 // This array is indexed by AccessIsWrite.
405 Function *AsanErrorCallbackSized[2],
406 *AsanMemoryAccessCallbackSized[2];
407 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
409 GlobalsMetadata GlobalsMD;
411 friend struct FunctionStackPoisoner;
414 class AddressSanitizerModule : public ModulePass {
416 AddressSanitizerModule() : ModulePass(ID) {}
417 bool runOnModule(Module &M) override;
418 static char ID; // Pass identification, replacement for typeid
419 const char *getPassName() const override {
420 return "AddressSanitizerModule";
424 void initializeCallbacks(Module &M);
426 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
427 bool ShouldInstrumentGlobal(GlobalVariable *G);
428 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
429 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
430 size_t MinRedzoneSizeForGlobal() const {
431 return RedzoneSizeForScale(Mapping.Scale);
434 GlobalsMetadata GlobalsMD;
437 const DataLayout *DL;
438 ShadowMapping Mapping;
439 Function *AsanPoisonGlobals;
440 Function *AsanUnpoisonGlobals;
441 Function *AsanRegisterGlobals;
442 Function *AsanUnregisterGlobals;
443 Function *AsanCovModuleInit;
446 // Stack poisoning does not play well with exception handling.
447 // When an exception is thrown, we essentially bypass the code
448 // that unpoisones the stack. This is why the run-time library has
449 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
450 // stack in the interceptor. This however does not work inside the
451 // actual function which catches the exception. Most likely because the
452 // compiler hoists the load of the shadow value somewhere too high.
453 // This causes asan to report a non-existing bug on 453.povray.
454 // It sounds like an LLVM bug.
455 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
457 AddressSanitizer &ASan;
462 ShadowMapping Mapping;
464 SmallVector<AllocaInst*, 16> AllocaVec;
465 SmallVector<Instruction*, 8> RetVec;
466 unsigned StackAlignment;
468 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
469 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
470 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
472 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
473 struct AllocaPoisonCall {
474 IntrinsicInst *InsBefore;
479 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
481 // Maps Value to an AllocaInst from which the Value is originated.
482 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
483 AllocaForValueMapTy AllocaForValue;
485 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
486 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
487 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
488 Mapping(ASan.Mapping),
489 StackAlignment(1 << Mapping.Scale) {}
491 bool runOnFunction() {
492 if (!ClStack) return false;
493 // Collect alloca, ret, lifetime instructions etc.
494 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
497 if (AllocaVec.empty()) return false;
499 initializeCallbacks(*F.getParent());
509 // Finds all static Alloca instructions and puts
510 // poisoned red zones around all of them.
511 // Then unpoison everything back before the function returns.
514 // ----------------------- Visitors.
515 /// \brief Collect all Ret instructions.
516 void visitReturnInst(ReturnInst &RI) {
517 RetVec.push_back(&RI);
520 /// \brief Collect Alloca instructions we want (and can) handle.
521 void visitAllocaInst(AllocaInst &AI) {
522 if (!isInterestingAlloca(AI)) return;
524 StackAlignment = std::max(StackAlignment, AI.getAlignment());
525 AllocaVec.push_back(&AI);
528 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
530 void visitIntrinsicInst(IntrinsicInst &II) {
531 if (!ClCheckLifetime) return;
532 Intrinsic::ID ID = II.getIntrinsicID();
533 if (ID != Intrinsic::lifetime_start &&
534 ID != Intrinsic::lifetime_end)
536 // Found lifetime intrinsic, add ASan instrumentation if necessary.
537 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
538 // If size argument is undefined, don't do anything.
539 if (Size->isMinusOne()) return;
540 // Check that size doesn't saturate uint64_t and can
541 // be stored in IntptrTy.
542 const uint64_t SizeValue = Size->getValue().getLimitedValue();
543 if (SizeValue == ~0ULL ||
544 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
546 // Find alloca instruction that corresponds to llvm.lifetime argument.
547 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
549 bool DoPoison = (ID == Intrinsic::lifetime_end);
550 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
551 AllocaPoisonCallVec.push_back(APC);
554 // ---------------------- Helpers.
555 void initializeCallbacks(Module &M);
557 // Check if we want (and can) handle this alloca.
558 bool isInterestingAlloca(AllocaInst &AI) const {
559 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
560 AI.getAllocatedType()->isSized() &&
561 // alloca() may be called with 0 size, ignore it.
562 getAllocaSizeInBytes(&AI) > 0);
565 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
566 Type *Ty = AI->getAllocatedType();
567 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
570 /// Finds alloca where the value comes from.
571 AllocaInst *findAllocaForValue(Value *V);
572 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
573 Value *ShadowBase, bool DoPoison);
574 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
576 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
582 char AddressSanitizer::ID = 0;
583 INITIALIZE_PASS(AddressSanitizer, "asan",
584 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
586 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
587 return new AddressSanitizer();
590 char AddressSanitizerModule::ID = 0;
591 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
592 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
593 "ModulePass", false, false)
594 ModulePass *llvm::createAddressSanitizerModulePass() {
595 return new AddressSanitizerModule();
598 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
599 size_t Res = countTrailingZeros(TypeSize / 8);
600 assert(Res < kNumberOfAccessSizes);
604 // \brief Create a constant for Str so that we can pass it to the run-time lib.
605 static GlobalVariable *createPrivateGlobalForString(
606 Module &M, StringRef Str, bool AllowMerging) {
607 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
608 // We use private linkage for module-local strings. If they can be merged
609 // with another one, we set the unnamed_addr attribute.
611 new GlobalVariable(M, StrConst->getType(), true,
612 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
614 GV->setUnnamedAddr(true);
615 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
619 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
620 return G->getName().find(kAsanGenPrefix) == 0;
623 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
625 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
626 if (Mapping.Offset == 0)
628 // (Shadow >> scale) | offset
629 if (Mapping.OrShadowOffset)
630 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
632 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
635 // Instrument memset/memmove/memcpy
636 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
638 if (isa<MemTransferInst>(MI)) {
640 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
641 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
642 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
643 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
644 } else if (isa<MemSetInst>(MI)) {
647 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
648 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
649 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
651 MI->eraseFromParent();
654 // If I is an interesting memory access, return the PointerOperand
655 // and set IsWrite/Alignment. Otherwise return NULL.
656 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
657 unsigned *Alignment) {
658 // Skip memory accesses inserted by another instrumentation.
659 if (I->getMetadata("nosanitize"))
661 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
662 if (!ClInstrumentReads) return nullptr;
664 *Alignment = LI->getAlignment();
665 return LI->getPointerOperand();
667 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
668 if (!ClInstrumentWrites) return nullptr;
670 *Alignment = SI->getAlignment();
671 return SI->getPointerOperand();
673 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
674 if (!ClInstrumentAtomics) return nullptr;
677 return RMW->getPointerOperand();
679 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
680 if (!ClInstrumentAtomics) return nullptr;
683 return XCHG->getPointerOperand();
688 static bool isPointerOperand(Value *V) {
689 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
692 // This is a rough heuristic; it may cause both false positives and
693 // false negatives. The proper implementation requires cooperation with
695 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
696 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
697 if (!Cmp->isRelational())
699 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
700 if (BO->getOpcode() != Instruction::Sub)
705 if (!isPointerOperand(I->getOperand(0)) ||
706 !isPointerOperand(I->getOperand(1)))
711 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
712 // If a global variable does not have dynamic initialization we don't
713 // have to instrument it. However, if a global does not have initializer
714 // at all, we assume it has dynamic initializer (in other TU).
715 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
719 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
721 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
722 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
723 for (int i = 0; i < 2; i++) {
724 if (Param[i]->getType()->isPointerTy())
725 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
727 IRB.CreateCall2(F, Param[0], Param[1]);
730 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
731 bool IsWrite = false;
732 unsigned Alignment = 0;
733 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
735 if (ClOpt && ClOptGlobals) {
736 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
737 // If initialization order checking is disabled, a simple access to a
738 // dynamically initialized global is always valid.
739 if (!ClInitializers || GlobalIsLinkerInitialized(G)) {
740 NumOptimizedAccessesToGlobalVar++;
744 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
745 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
746 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
747 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
748 NumOptimizedAccessesToGlobalArray++;
755 Type *OrigPtrTy = Addr->getType();
756 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
758 assert(OrigTy->isSized());
759 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
761 assert((TypeSize % 8) == 0);
764 NumInstrumentedWrites++;
766 NumInstrumentedReads++;
768 unsigned Granularity = 1 << Mapping.Scale;
769 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
770 // if the data is properly aligned.
771 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
773 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
774 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
775 // Instrument unusual size or unusual alignment.
776 // We can not do it with a single check, so we do 1-byte check for the first
777 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
778 // to report the actual access size.
780 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
781 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
783 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
785 Value *LastByte = IRB.CreateIntToPtr(
786 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
788 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
789 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
793 // Validate the result of Module::getOrInsertFunction called for an interface
794 // function of AddressSanitizer. If the instrumented module defines a function
795 // with the same name, their prototypes must match, otherwise
796 // getOrInsertFunction returns a bitcast.
797 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
798 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
799 FuncOrBitcast->dump();
800 report_fatal_error("trying to redefine an AddressSanitizer "
801 "interface function");
804 Instruction *AddressSanitizer::generateCrashCode(
805 Instruction *InsertBefore, Value *Addr,
806 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
807 IRBuilder<> IRB(InsertBefore);
808 CallInst *Call = SizeArgument
809 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
810 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
812 // We don't do Call->setDoesNotReturn() because the BB already has
813 // UnreachableInst at the end.
814 // This EmptyAsm is required to avoid callback merge.
815 IRB.CreateCall(EmptyAsm);
819 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
822 size_t Granularity = 1 << Mapping.Scale;
823 // Addr & (Granularity - 1)
824 Value *LastAccessedByte = IRB.CreateAnd(
825 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
826 // (Addr & (Granularity - 1)) + size - 1
827 if (TypeSize / 8 > 1)
828 LastAccessedByte = IRB.CreateAdd(
829 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
830 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
831 LastAccessedByte = IRB.CreateIntCast(
832 LastAccessedByte, ShadowValue->getType(), false);
833 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
834 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
837 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
838 Instruction *InsertBefore, Value *Addr,
839 uint32_t TypeSize, bool IsWrite,
840 Value *SizeArgument, bool UseCalls) {
841 IRBuilder<> IRB(InsertBefore);
842 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
843 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
846 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
851 Type *ShadowTy = IntegerType::get(
852 *C, std::max(8U, TypeSize >> Mapping.Scale));
853 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
854 Value *ShadowPtr = memToShadow(AddrLong, IRB);
855 Value *CmpVal = Constant::getNullValue(ShadowTy);
856 Value *ShadowValue = IRB.CreateLoad(
857 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
859 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
860 size_t Granularity = 1 << Mapping.Scale;
861 TerminatorInst *CrashTerm = nullptr;
863 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
864 TerminatorInst *CheckTerm =
865 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false);
866 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
867 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
868 IRB.SetInsertPoint(CheckTerm);
869 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
870 BasicBlock *CrashBlock =
871 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
872 CrashTerm = new UnreachableInst(*C, CrashBlock);
873 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
874 ReplaceInstWithInst(CheckTerm, NewTerm);
876 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
879 Instruction *Crash = generateCrashCode(
880 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
881 Crash->setDebugLoc(OrigIns->getDebugLoc());
884 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
885 GlobalValue *ModuleName) {
886 // Set up the arguments to our poison/unpoison functions.
887 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
889 // Add a call to poison all external globals before the given function starts.
890 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
891 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
893 // Add calls to unpoison all globals before each return instruction.
894 for (auto &BB : GlobalInit.getBasicBlockList())
895 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
896 CallInst::Create(AsanUnpoisonGlobals, "", RI);
899 void AddressSanitizerModule::createInitializerPoisonCalls(
900 Module &M, GlobalValue *ModuleName) {
901 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
903 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
904 for (Use &OP : CA->operands()) {
905 if (isa<ConstantAggregateZero>(OP))
907 ConstantStruct *CS = cast<ConstantStruct>(OP);
909 // Must have a function or null ptr.
910 // (CS->getOperand(0) is the init priority.)
911 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
912 if (F->getName() != kAsanModuleCtorName)
913 poisonOneInitializer(*F, ModuleName);
918 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
919 Type *Ty = cast<PointerType>(G->getType())->getElementType();
920 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
922 if (GlobalsMD.get(G).IsBlacklisted) return false;
923 if (GlobalsMD.isInstrumentationGlobal(G)) return false;
924 if (!Ty->isSized()) return false;
925 if (!G->hasInitializer()) return false;
926 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
927 // Touch only those globals that will not be defined in other modules.
928 // Don't handle ODR linkage types and COMDATs since other modules may be built
930 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
931 G->getLinkage() != GlobalVariable::PrivateLinkage &&
932 G->getLinkage() != GlobalVariable::InternalLinkage)
936 // Two problems with thread-locals:
937 // - The address of the main thread's copy can't be computed at link-time.
938 // - Need to poison all copies, not just the main thread's one.
939 if (G->isThreadLocal())
941 // For now, just ignore this Global if the alignment is large.
942 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
944 // Ignore all the globals with the names starting with "\01L_OBJC_".
945 // Many of those are put into the .cstring section. The linker compresses
946 // that section by removing the spare \0s after the string terminator, so
947 // our redzones get broken.
948 if ((G->getName().find("\01L_OBJC_") == 0) ||
949 (G->getName().find("\01l_OBJC_") == 0)) {
950 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n");
954 if (G->hasSection()) {
955 StringRef Section(G->getSection());
956 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
957 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
959 if (Section.startswith("__OBJC,") ||
960 Section.startswith("__DATA, __objc_")) {
961 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
964 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
965 // Constant CFString instances are compiled in the following way:
966 // -- the string buffer is emitted into
967 // __TEXT,__cstring,cstring_literals
968 // -- the constant NSConstantString structure referencing that buffer
969 // is placed into __DATA,__cfstring
970 // Therefore there's no point in placing redzones into __DATA,__cfstring.
971 // Moreover, it causes the linker to crash on OS X 10.7
972 if (Section.startswith("__DATA,__cfstring")) {
973 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
976 // The linker merges the contents of cstring_literals and removes the
978 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
979 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
983 // Callbacks put into the CRT initializer/terminator sections
984 // should not be instrumented.
985 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
986 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
987 if (Section.startswith(".CRT")) {
988 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
992 // Globals from llvm.metadata aren't emitted, do not instrument them.
993 if (Section == "llvm.metadata") return false;
999 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1000 IRBuilder<> IRB(*C);
1001 // Declare our poisoning and unpoisoning functions.
1002 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1003 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
1004 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1005 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1006 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
1007 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1008 // Declare functions that register/unregister globals.
1009 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1010 kAsanRegisterGlobalsName, IRB.getVoidTy(),
1011 IntptrTy, IntptrTy, NULL));
1012 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1013 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1014 kAsanUnregisterGlobalsName,
1015 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1016 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1017 AsanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction(
1018 kAsanCovModuleInitName,
1019 IRB.getVoidTy(), IntptrTy, NULL));
1020 AsanCovModuleInit->setLinkage(Function::ExternalLinkage);
1023 // This function replaces all global variables with new variables that have
1024 // trailing redzones. It also creates a function that poisons
1025 // redzones and inserts this function into llvm.global_ctors.
1026 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1029 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1031 for (auto &G : M.globals()) {
1032 if (ShouldInstrumentGlobal(&G))
1033 GlobalsToChange.push_back(&G);
1036 size_t n = GlobalsToChange.size();
1037 if (n == 0) return false;
1039 // A global is described by a structure
1042 // size_t size_with_redzone;
1043 // const char *name;
1044 // const char *module_name;
1045 // size_t has_dynamic_init;
1046 // void *source_location;
1047 // We initialize an array of such structures and pass it to a run-time call.
1048 StructType *GlobalStructTy =
1049 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1050 IntptrTy, IntptrTy, NULL);
1051 SmallVector<Constant *, 16> Initializers(n);
1053 bool HasDynamicallyInitializedGlobals = false;
1055 // We shouldn't merge same module names, as this string serves as unique
1056 // module ID in runtime.
1057 GlobalVariable *ModuleName = createPrivateGlobalForString(
1058 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1060 for (size_t i = 0; i < n; i++) {
1061 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1062 GlobalVariable *G = GlobalsToChange[i];
1064 auto MD = GlobalsMD.get(G);
1065 // Create string holding the global name unless it was provided by
1067 GlobalVariable *Name =
1068 MD.Name ? MD.Name : createPrivateGlobalForString(M, G->getName(),
1069 /*AllowMerging*/ true);
1071 PointerType *PtrTy = cast<PointerType>(G->getType());
1072 Type *Ty = PtrTy->getElementType();
1073 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1074 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1075 // MinRZ <= RZ <= kMaxGlobalRedzone
1076 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1077 uint64_t RZ = std::max(MinRZ,
1078 std::min(kMaxGlobalRedzone,
1079 (SizeInBytes / MinRZ / 4) * MinRZ));
1080 uint64_t RightRedzoneSize = RZ;
1081 // Round up to MinRZ
1082 if (SizeInBytes % MinRZ)
1083 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1084 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1085 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1087 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1088 Constant *NewInitializer = ConstantStruct::get(
1089 NewTy, G->getInitializer(),
1090 Constant::getNullValue(RightRedZoneTy), NULL);
1092 // Create a new global variable with enough space for a redzone.
1093 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1094 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1095 Linkage = GlobalValue::InternalLinkage;
1096 GlobalVariable *NewGlobal = new GlobalVariable(
1097 M, NewTy, G->isConstant(), Linkage,
1098 NewInitializer, "", G, G->getThreadLocalMode());
1099 NewGlobal->copyAttributesFrom(G);
1100 NewGlobal->setAlignment(MinRZ);
1103 Indices2[0] = IRB.getInt32(0);
1104 Indices2[1] = IRB.getInt32(0);
1106 G->replaceAllUsesWith(
1107 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1108 NewGlobal->takeName(G);
1109 G->eraseFromParent();
1111 Initializers[i] = ConstantStruct::get(
1112 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1113 ConstantInt::get(IntptrTy, SizeInBytes),
1114 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1115 ConstantExpr::getPointerCast(Name, IntptrTy),
1116 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1117 ConstantInt::get(IntptrTy, MD.IsDynInit),
1118 MD.SourceLoc ? ConstantExpr::getPointerCast(MD.SourceLoc, IntptrTy)
1119 : ConstantInt::get(IntptrTy, 0),
1122 if (ClInitializers && MD.IsDynInit)
1123 HasDynamicallyInitializedGlobals = true;
1125 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1128 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1129 GlobalVariable *AllGlobals = new GlobalVariable(
1130 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1131 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1133 // Create calls for poisoning before initializers run and unpoisoning after.
1134 if (HasDynamicallyInitializedGlobals)
1135 createInitializerPoisonCalls(M, ModuleName);
1136 IRB.CreateCall2(AsanRegisterGlobals,
1137 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1138 ConstantInt::get(IntptrTy, n));
1140 // We also need to unregister globals at the end, e.g. when a shared library
1142 Function *AsanDtorFunction = Function::Create(
1143 FunctionType::get(Type::getVoidTy(*C), false),
1144 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1145 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1146 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1147 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1148 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1149 ConstantInt::get(IntptrTy, n));
1150 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1156 bool AddressSanitizerModule::runOnModule(Module &M) {
1157 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1160 DL = &DLP->getDataLayout();
1161 C = &(M.getContext());
1162 int LongSize = DL->getPointerSizeInBits();
1163 IntptrTy = Type::getIntNTy(*C, LongSize);
1164 Mapping = getShadowMapping(M, LongSize);
1165 initializeCallbacks(M);
1167 bool Changed = false;
1169 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1171 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1173 if (ClCoverage > 0) {
1174 Function *CovFunc = M.getFunction(kAsanCovName);
1175 int nCov = CovFunc ? CovFunc->getNumUses() : 0;
1176 IRB.CreateCall(AsanCovModuleInit, ConstantInt::get(IntptrTy, nCov));
1181 Changed |= InstrumentGlobals(IRB, M);
1186 void AddressSanitizer::initializeCallbacks(Module &M) {
1187 IRBuilder<> IRB(*C);
1188 // Create __asan_report* callbacks.
1189 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1190 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1191 AccessSizeIndex++) {
1192 // IsWrite and TypeSize are encoded in the function name.
1193 std::string Suffix =
1194 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1195 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1196 checkInterfaceFunction(
1197 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1198 IRB.getVoidTy(), IntptrTy, NULL));
1199 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1200 checkInterfaceFunction(
1201 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1202 IRB.getVoidTy(), IntptrTy, NULL));
1205 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1206 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1207 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1208 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1210 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1211 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1212 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1213 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1214 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1215 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1217 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1218 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1219 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1220 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1221 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1222 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1223 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1224 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1225 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1227 AsanHandleNoReturnFunc = checkInterfaceFunction(
1228 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1229 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction(
1230 kAsanCovName, IRB.getVoidTy(), NULL));
1231 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1232 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1233 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1234 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1235 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1236 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1237 StringRef(""), StringRef(""),
1238 /*hasSideEffects=*/true);
1242 bool AddressSanitizer::doInitialization(Module &M) {
1243 // Initialize the private fields. No one has accessed them before.
1244 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1246 report_fatal_error("data layout missing");
1247 DL = &DLP->getDataLayout();
1251 C = &(M.getContext());
1252 LongSize = DL->getPointerSizeInBits();
1253 IntptrTy = Type::getIntNTy(*C, LongSize);
1255 AsanCtorFunction = Function::Create(
1256 FunctionType::get(Type::getVoidTy(*C), false),
1257 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1258 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1259 // call __asan_init in the module ctor.
1260 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1261 AsanInitFunction = checkInterfaceFunction(
1262 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1263 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1264 IRB.CreateCall(AsanInitFunction);
1266 Mapping = getShadowMapping(M, LongSize);
1268 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1272 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1273 // For each NSObject descendant having a +load method, this method is invoked
1274 // by the ObjC runtime before any of the static constructors is called.
1275 // Therefore we need to instrument such methods with a call to __asan_init
1276 // at the beginning in order to initialize our runtime before any access to
1277 // the shadow memory.
1278 // We cannot just ignore these methods, because they may call other
1279 // instrumented functions.
1280 if (F.getName().find(" load]") != std::string::npos) {
1281 IRBuilder<> IRB(F.begin()->begin());
1282 IRB.CreateCall(AsanInitFunction);
1288 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) {
1289 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end();
1290 // Skip static allocas at the top of the entry block so they don't become
1291 // dynamic when we split the block. If we used our optimized stack layout,
1292 // then there will only be one alloca and it will come first.
1293 for (; IP != BE; ++IP) {
1294 AllocaInst *AI = dyn_cast<AllocaInst>(IP);
1295 if (!AI || !AI->isStaticAlloca())
1299 DebugLoc EntryLoc = IP->getDebugLoc().getFnDebugLoc(*C);
1300 IRBuilder<> IRB(IP);
1301 IRB.SetCurrentDebugLocation(EntryLoc);
1302 Type *Int8Ty = IRB.getInt8Ty();
1303 GlobalVariable *Guard = new GlobalVariable(
1304 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage,
1305 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName());
1306 LoadInst *Load = IRB.CreateLoad(Guard);
1307 Load->setAtomic(Monotonic);
1308 Load->setAlignment(1);
1309 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load);
1310 Instruction *Ins = SplitBlockAndInsertIfThen(
1311 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000));
1312 IRB.SetInsertPoint(Ins);
1313 IRB.SetCurrentDebugLocation(EntryLoc);
1314 // We pass &F to __sanitizer_cov. We could avoid this and rely on
1315 // GET_CALLER_PC, but having the PC of the first instruction is just nice.
1316 IRB.CreateCall(AsanCovFunction);
1317 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard);
1318 Store->setAtomic(Monotonic);
1319 Store->setAlignment(1);
1322 // Poor man's coverage that works with ASan.
1323 // We create a Guard boolean variable with the same linkage
1324 // as the function and inject this code into the entry block (-asan-coverage=1)
1325 // or all blocks (-asan-coverage=2):
1327 // __sanitizer_cov(&F);
1330 // The accesses to Guard are atomic. The rest of the logic is
1331 // in __sanitizer_cov (it's fine to call it more than once).
1333 // This coverage implementation provides very limited data:
1334 // it only tells if a given function (block) was ever executed.
1335 // No counters, no per-edge data.
1336 // But for many use cases this is what we need and the added slowdown
1337 // is negligible. This simple implementation will probably be obsoleted
1338 // by the upcoming Clang-based coverage implementation.
1339 // By having it here and now we hope to
1340 // a) get the functionality to users earlier and
1341 // b) collect usage statistics to help improve Clang coverage design.
1342 bool AddressSanitizer::InjectCoverage(Function &F,
1343 const ArrayRef<BasicBlock *> AllBlocks) {
1344 if (!ClCoverage) return false;
1346 if (ClCoverage == 1 ||
1347 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) {
1348 InjectCoverageAtBlock(F, F.getEntryBlock());
1350 for (auto BB : AllBlocks)
1351 InjectCoverageAtBlock(F, *BB);
1356 bool AddressSanitizer::runOnFunction(Function &F) {
1357 if (&F == AsanCtorFunction) return false;
1358 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1359 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1360 initializeCallbacks(*F.getParent());
1362 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1363 maybeInsertAsanInitAtFunctionEntry(F);
1365 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1368 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1371 // We want to instrument every address only once per basic block (unless there
1372 // are calls between uses).
1373 SmallSet<Value*, 16> TempsToInstrument;
1374 SmallVector<Instruction*, 16> ToInstrument;
1375 SmallVector<Instruction*, 8> NoReturnCalls;
1376 SmallVector<BasicBlock*, 16> AllBlocks;
1377 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1382 // Fill the set of memory operations to instrument.
1383 for (auto &BB : F) {
1384 AllBlocks.push_back(&BB);
1385 TempsToInstrument.clear();
1386 int NumInsnsPerBB = 0;
1387 for (auto &Inst : BB) {
1388 if (LooksLikeCodeInBug11395(&Inst)) return false;
1390 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1391 if (ClOpt && ClOptSameTemp) {
1392 if (!TempsToInstrument.insert(Addr))
1393 continue; // We've seen this temp in the current BB.
1395 } else if (ClInvalidPointerPairs &&
1396 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1397 PointerComparisonsOrSubtracts.push_back(&Inst);
1399 } else if (isa<MemIntrinsic>(Inst)) {
1402 if (isa<AllocaInst>(Inst))
1406 // A call inside BB.
1407 TempsToInstrument.clear();
1408 if (CS.doesNotReturn())
1409 NoReturnCalls.push_back(CS.getInstruction());
1413 ToInstrument.push_back(&Inst);
1415 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1420 Function *UninstrumentedDuplicate = nullptr;
1421 bool LikelyToInstrument =
1422 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1423 if (ClKeepUninstrumented && LikelyToInstrument) {
1424 ValueToValueMapTy VMap;
1425 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1426 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1427 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1428 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1431 bool UseCalls = false;
1432 if (ClInstrumentationWithCallsThreshold >= 0 &&
1433 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1437 int NumInstrumented = 0;
1438 for (auto Inst : ToInstrument) {
1439 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1440 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1441 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1442 instrumentMop(Inst, UseCalls);
1444 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1449 FunctionStackPoisoner FSP(F, *this);
1450 bool ChangedStack = FSP.runOnFunction();
1452 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1453 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1454 for (auto CI : NoReturnCalls) {
1455 IRBuilder<> IRB(CI);
1456 IRB.CreateCall(AsanHandleNoReturnFunc);
1459 for (auto Inst : PointerComparisonsOrSubtracts) {
1460 instrumentPointerComparisonOrSubtraction(Inst);
1464 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1466 if (InjectCoverage(F, AllBlocks))
1469 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1471 if (ClKeepUninstrumented) {
1473 // No instrumentation is done, no need for the duplicate.
1474 if (UninstrumentedDuplicate)
1475 UninstrumentedDuplicate->eraseFromParent();
1477 // The function was instrumented. We must have the duplicate.
1478 assert(UninstrumentedDuplicate);
1479 UninstrumentedDuplicate->setSection("NOASAN");
1480 assert(!F.hasSection());
1481 F.setSection("ASAN");
1488 // Workaround for bug 11395: we don't want to instrument stack in functions
1489 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1490 // FIXME: remove once the bug 11395 is fixed.
1491 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1492 if (LongSize != 32) return false;
1493 CallInst *CI = dyn_cast<CallInst>(I);
1494 if (!CI || !CI->isInlineAsm()) return false;
1495 if (CI->getNumArgOperands() <= 5) return false;
1496 // We have inline assembly with quite a few arguments.
1500 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1501 IRBuilder<> IRB(*C);
1502 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1503 std::string Suffix = itostr(i);
1504 AsanStackMallocFunc[i] = checkInterfaceFunction(
1505 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1506 IntptrTy, IntptrTy, NULL));
1507 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1508 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1509 IntptrTy, IntptrTy, NULL));
1511 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1512 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1513 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1514 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1518 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes,
1519 IRBuilder<> &IRB, Value *ShadowBase,
1521 size_t n = ShadowBytes.size();
1523 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1524 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1525 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1526 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1527 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1528 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1530 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1531 if (ASan.DL->isLittleEndian())
1532 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1534 Val = (Val << 8) | ShadowBytes[i + j];
1537 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1538 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1539 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1540 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1545 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1546 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1547 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1548 assert(LocalStackSize <= kMaxStackMallocSize);
1549 uint64_t MaxSize = kMinStackMallocSize;
1550 for (int i = 0; ; i++, MaxSize *= 2)
1551 if (LocalStackSize <= MaxSize)
1553 llvm_unreachable("impossible LocalStackSize");
1556 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1557 // We can not use MemSet intrinsic because it may end up calling the actual
1558 // memset. Size is a multiple of 8.
1559 // Currently this generates 8-byte stores on x86_64; it may be better to
1560 // generate wider stores.
1561 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1562 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1563 assert(!(Size % 8));
1564 assert(kAsanStackAfterReturnMagic == 0xf5);
1565 for (int i = 0; i < Size; i += 8) {
1566 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1567 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1568 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1572 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1573 for (const auto &Inst : F.getEntryBlock())
1574 if (!isa<AllocaInst>(Inst))
1575 return Inst.getDebugLoc();
1579 void FunctionStackPoisoner::poisonStack() {
1580 int StackMallocIdx = -1;
1581 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1583 assert(AllocaVec.size() > 0);
1584 Instruction *InsBefore = AllocaVec[0];
1585 IRBuilder<> IRB(InsBefore);
1586 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1588 SmallVector<ASanStackVariableDescription, 16> SVD;
1589 SVD.reserve(AllocaVec.size());
1590 for (AllocaInst *AI : AllocaVec) {
1591 ASanStackVariableDescription D = { AI->getName().data(),
1592 getAllocaSizeInBytes(AI),
1593 AI->getAlignment(), AI, 0};
1596 // Minimal header size (left redzone) is 4 pointers,
1597 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1598 size_t MinHeaderSize = ASan.LongSize / 2;
1599 ASanStackFrameLayout L;
1600 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1601 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1602 uint64_t LocalStackSize = L.FrameSize;
1603 bool DoStackMalloc =
1604 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1606 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1607 AllocaInst *MyAlloca =
1608 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1609 MyAlloca->setDebugLoc(EntryDebugLocation);
1610 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1611 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1612 MyAlloca->setAlignment(FrameAlignment);
1613 assert(MyAlloca->isStaticAlloca());
1614 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1615 Value *LocalStackBase = OrigStackBase;
1617 if (DoStackMalloc) {
1618 // LocalStackBase = OrigStackBase
1619 // if (__asan_option_detect_stack_use_after_return)
1620 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1621 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1622 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1623 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1624 kAsanOptionDetectUAR, IRB.getInt32Ty());
1625 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1626 Constant::getNullValue(IRB.getInt32Ty()));
1627 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1628 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1629 IRBuilder<> IRBIf(Term);
1630 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1631 LocalStackBase = IRBIf.CreateCall2(
1632 AsanStackMallocFunc[StackMallocIdx],
1633 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1634 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1635 IRB.SetInsertPoint(InsBefore);
1636 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1637 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1638 Phi->addIncoming(OrigStackBase, CmpBlock);
1639 Phi->addIncoming(LocalStackBase, SetBlock);
1640 LocalStackBase = Phi;
1643 // Insert poison calls for lifetime intrinsics for alloca.
1644 bool HavePoisonedAllocas = false;
1645 for (const auto &APC : AllocaPoisonCallVec) {
1646 assert(APC.InsBefore);
1648 IRBuilder<> IRB(APC.InsBefore);
1649 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1650 HavePoisonedAllocas |= APC.DoPoison;
1653 // Replace Alloca instructions with base+offset.
1654 for (const auto &Desc : SVD) {
1655 AllocaInst *AI = Desc.AI;
1656 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1657 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1659 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1660 AI->replaceAllUsesWith(NewAllocaPtr);
1663 // The left-most redzone has enough space for at least 4 pointers.
1664 // Write the Magic value to redzone[0].
1665 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1666 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1668 // Write the frame description constant to redzone[1].
1669 Value *BasePlus1 = IRB.CreateIntToPtr(
1670 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1672 GlobalVariable *StackDescriptionGlobal =
1673 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1674 /*AllowMerging*/true);
1675 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1677 IRB.CreateStore(Description, BasePlus1);
1678 // Write the PC to redzone[2].
1679 Value *BasePlus2 = IRB.CreateIntToPtr(
1680 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1681 2 * ASan.LongSize/8)),
1683 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1685 // Poison the stack redzones at the entry.
1686 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1687 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1689 // (Un)poison the stack before all ret instructions.
1690 for (auto Ret : RetVec) {
1691 IRBuilder<> IRBRet(Ret);
1692 // Mark the current frame as retired.
1693 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1695 if (DoStackMalloc) {
1696 assert(StackMallocIdx >= 0);
1697 // if LocalStackBase != OrigStackBase:
1698 // // In use-after-return mode, poison the whole stack frame.
1699 // if StackMallocIdx <= 4
1700 // // For small sizes inline the whole thing:
1701 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1702 // **SavedFlagPtr(LocalStackBase) = 0
1704 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1706 // <This is not a fake stack; unpoison the redzones>
1707 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1708 TerminatorInst *ThenTerm, *ElseTerm;
1709 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1711 IRBuilder<> IRBPoison(ThenTerm);
1712 if (StackMallocIdx <= 4) {
1713 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1714 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1715 ClassSize >> Mapping.Scale);
1716 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1718 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1719 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1720 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1721 IRBPoison.CreateStore(
1722 Constant::getNullValue(IRBPoison.getInt8Ty()),
1723 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1725 // For larger frames call __asan_stack_free_*.
1726 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1727 ConstantInt::get(IntptrTy, LocalStackSize),
1731 IRBuilder<> IRBElse(ElseTerm);
1732 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1733 } else if (HavePoisonedAllocas) {
1734 // If we poisoned some allocas in llvm.lifetime analysis,
1735 // unpoison whole stack frame now.
1736 assert(LocalStackBase == OrigStackBase);
1737 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1739 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1743 // We are done. Remove the old unused alloca instructions.
1744 for (auto AI : AllocaVec)
1745 AI->eraseFromParent();
1748 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1749 IRBuilder<> &IRB, bool DoPoison) {
1750 // For now just insert the call to ASan runtime.
1751 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1752 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1753 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1754 : AsanUnpoisonStackMemoryFunc,
1758 // Handling llvm.lifetime intrinsics for a given %alloca:
1759 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1760 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1761 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1762 // could be poisoned by previous llvm.lifetime.end instruction, as the
1763 // variable may go in and out of scope several times, e.g. in loops).
1764 // (3) if we poisoned at least one %alloca in a function,
1765 // unpoison the whole stack frame at function exit.
1767 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1768 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1769 // We're intested only in allocas we can handle.
1770 return isInterestingAlloca(*AI) ? AI : nullptr;
1771 // See if we've already calculated (or started to calculate) alloca for a
1773 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1774 if (I != AllocaForValue.end())
1776 // Store 0 while we're calculating alloca for value V to avoid
1777 // infinite recursion if the value references itself.
1778 AllocaForValue[V] = nullptr;
1779 AllocaInst *Res = nullptr;
1780 if (CastInst *CI = dyn_cast<CastInst>(V))
1781 Res = findAllocaForValue(CI->getOperand(0));
1782 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1783 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1784 Value *IncValue = PN->getIncomingValue(i);
1785 // Allow self-referencing phi-nodes.
1786 if (IncValue == PN) continue;
1787 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1788 // AI for incoming values should exist and should all be equal.
1789 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1795 AllocaForValue[V] = Res;