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/Analysis/MemoryBuiltins.h"
28 #include "llvm/Analysis/TargetLibraryInfo.h"
29 #include "llvm/Analysis/ValueTracking.h"
30 #include "llvm/IR/CallSite.h"
31 #include "llvm/IR/DIBuilder.h"
32 #include "llvm/IR/DataLayout.h"
33 #include "llvm/IR/Dominators.h"
34 #include "llvm/IR/Function.h"
35 #include "llvm/IR/IRBuilder.h"
36 #include "llvm/IR/InlineAsm.h"
37 #include "llvm/IR/InstVisitor.h"
38 #include "llvm/IR/IntrinsicInst.h"
39 #include "llvm/IR/LLVMContext.h"
40 #include "llvm/IR/MDBuilder.h"
41 #include "llvm/IR/Module.h"
42 #include "llvm/IR/Type.h"
43 #include "llvm/MC/MCSectionMachO.h"
44 #include "llvm/Support/CommandLine.h"
45 #include "llvm/Support/DataTypes.h"
46 #include "llvm/Support/Debug.h"
47 #include "llvm/Support/Endian.h"
48 #include "llvm/Support/SwapByteOrder.h"
49 #include "llvm/Support/raw_ostream.h"
50 #include "llvm/Transforms/Scalar.h"
51 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
52 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
53 #include "llvm/Transforms/Utils/Cloning.h"
54 #include "llvm/Transforms/Utils/Local.h"
55 #include "llvm/Transforms/Utils/ModuleUtils.h"
56 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
59 #include <system_error>
63 #define DEBUG_TYPE "asan"
65 static const uint64_t kDefaultShadowScale = 3;
66 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
67 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
68 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
69 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
70 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
71 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
72 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
73 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
74 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
75 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
76 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
78 static const size_t kMinStackMallocSize = 1 << 6; // 64B
79 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
80 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
81 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
83 static const char *const kAsanModuleCtorName = "asan.module_ctor";
84 static const char *const kAsanModuleDtorName = "asan.module_dtor";
85 static const uint64_t kAsanCtorAndDtorPriority = 1;
86 static const char *const kAsanReportErrorTemplate = "__asan_report_";
87 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
88 static const char *const kAsanUnregisterGlobalsName =
89 "__asan_unregister_globals";
90 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
91 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
92 static const char *const kAsanInitName = "__asan_init_v5";
93 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
94 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
95 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
96 static const int kMaxAsanStackMallocSizeClass = 10;
97 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
98 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
99 static const char *const kAsanGenPrefix = "__asan_gen_";
100 static const char *const kSanCovGenPrefix = "__sancov_gen_";
101 static const char *const kAsanPoisonStackMemoryName =
102 "__asan_poison_stack_memory";
103 static const char *const kAsanUnpoisonStackMemoryName =
104 "__asan_unpoison_stack_memory";
106 static const char *const kAsanOptionDetectUAR =
107 "__asan_option_detect_stack_use_after_return";
109 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
110 static const size_t kNumberOfAccessSizes = 5;
112 static const unsigned kAllocaRzSize = 32;
113 static const unsigned kAsanAllocaLeftMagic = 0xcacacacaU;
114 static const unsigned kAsanAllocaRightMagic = 0xcbcbcbcbU;
115 static const unsigned kAsanAllocaPartialVal1 = 0xcbcbcb00U;
116 static const unsigned kAsanAllocaPartialVal2 = 0x000000cbU;
118 // Command-line flags.
120 // This flag may need to be replaced with -f[no-]asan-reads.
121 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
122 cl::desc("instrument read instructions"),
123 cl::Hidden, cl::init(true));
124 static cl::opt<bool> ClInstrumentWrites(
125 "asan-instrument-writes", cl::desc("instrument write instructions"),
126 cl::Hidden, cl::init(true));
127 static cl::opt<bool> ClInstrumentAtomics(
128 "asan-instrument-atomics",
129 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
131 static cl::opt<bool> ClAlwaysSlowPath(
132 "asan-always-slow-path",
133 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
135 // This flag limits the number of instructions to be instrumented
136 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
137 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
139 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
140 "asan-max-ins-per-bb", cl::init(10000),
141 cl::desc("maximal number of instructions to instrument in any given BB"),
143 // This flag may need to be replaced with -f[no]asan-stack.
144 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
145 cl::Hidden, cl::init(true));
146 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
147 cl::desc("Check return-after-free"),
148 cl::Hidden, cl::init(true));
149 // This flag may need to be replaced with -f[no]asan-globals.
150 static cl::opt<bool> ClGlobals("asan-globals",
151 cl::desc("Handle global objects"), cl::Hidden,
153 static cl::opt<bool> ClInitializers("asan-initialization-order",
154 cl::desc("Handle C++ initializer order"),
155 cl::Hidden, cl::init(true));
156 static cl::opt<bool> ClInvalidPointerPairs(
157 "asan-detect-invalid-pointer-pair",
158 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
160 static cl::opt<unsigned> ClRealignStack(
161 "asan-realign-stack",
162 cl::desc("Realign stack to the value of this flag (power of two)"),
163 cl::Hidden, cl::init(32));
164 static cl::opt<int> ClInstrumentationWithCallsThreshold(
165 "asan-instrumentation-with-call-threshold",
167 "If the function being instrumented contains more than "
168 "this number of memory accesses, use callbacks instead of "
169 "inline checks (-1 means never use callbacks)."),
170 cl::Hidden, cl::init(7000));
171 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
172 "asan-memory-access-callback-prefix",
173 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
174 cl::init("__asan_"));
175 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
176 cl::desc("instrument dynamic allocas"),
177 cl::Hidden, cl::init(false));
178 static cl::opt<bool> ClSkipPromotableAllocas(
179 "asan-skip-promotable-allocas",
180 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
183 // These flags allow to change the shadow mapping.
184 // The shadow mapping looks like
185 // Shadow = (Mem >> scale) + (1 << offset_log)
186 static cl::opt<int> ClMappingScale("asan-mapping-scale",
187 cl::desc("scale of asan shadow mapping"),
188 cl::Hidden, cl::init(0));
190 // Optimization flags. Not user visible, used mostly for testing
191 // and benchmarking the tool.
192 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
193 cl::Hidden, cl::init(true));
194 static cl::opt<bool> ClOptSameTemp(
195 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
196 cl::Hidden, cl::init(true));
197 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
198 cl::desc("Don't instrument scalar globals"),
199 cl::Hidden, cl::init(true));
200 static cl::opt<bool> ClOptStack(
201 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
202 cl::Hidden, cl::init(false));
204 static cl::opt<bool> ClCheckLifetime(
205 "asan-check-lifetime",
206 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
209 static cl::opt<bool> ClDynamicAllocaStack(
210 "asan-stack-dynamic-alloca",
211 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
214 static cl::opt<uint32_t> ClForceExperiment(
215 "asan-force-experiment",
216 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
220 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
222 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
223 cl::Hidden, cl::init(0));
224 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
225 cl::desc("Debug func"));
226 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
227 cl::Hidden, cl::init(-1));
228 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
229 cl::Hidden, cl::init(-1));
231 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
232 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
233 STATISTIC(NumInstrumentedDynamicAllocas,
234 "Number of instrumented dynamic allocas");
235 STATISTIC(NumOptimizedAccessesToGlobalVar,
236 "Number of optimized accesses to global vars");
237 STATISTIC(NumOptimizedAccessesToStackVar,
238 "Number of optimized accesses to stack vars");
241 /// Frontend-provided metadata for source location.
242 struct LocationMetadata {
247 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
249 bool empty() const { return Filename.empty(); }
251 void parse(MDNode *MDN) {
252 assert(MDN->getNumOperands() == 3);
253 MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
254 Filename = MDFilename->getString();
256 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
258 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
262 /// Frontend-provided metadata for global variables.
263 class GlobalsMetadata {
266 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
267 LocationMetadata SourceLoc;
273 GlobalsMetadata() : inited_(false) {}
275 void init(Module &M) {
278 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
279 if (!Globals) return;
280 for (auto MDN : Globals->operands()) {
281 // Metadata node contains the global and the fields of "Entry".
282 assert(MDN->getNumOperands() == 5);
283 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
284 // The optimizer may optimize away a global entirely.
286 // We can already have an entry for GV if it was merged with another
288 Entry &E = Entries[GV];
289 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
290 E.SourceLoc.parse(Loc);
291 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
292 E.Name = Name->getString();
293 ConstantInt *IsDynInit =
294 mdconst::extract<ConstantInt>(MDN->getOperand(3));
295 E.IsDynInit |= IsDynInit->isOne();
296 ConstantInt *IsBlacklisted =
297 mdconst::extract<ConstantInt>(MDN->getOperand(4));
298 E.IsBlacklisted |= IsBlacklisted->isOne();
302 /// Returns metadata entry for a given global.
303 Entry get(GlobalVariable *G) const {
304 auto Pos = Entries.find(G);
305 return (Pos != Entries.end()) ? Pos->second : Entry();
310 DenseMap<GlobalVariable *, Entry> Entries;
313 /// This struct defines the shadow mapping using the rule:
314 /// shadow = (mem >> Scale) ADD-or-OR Offset.
315 struct ShadowMapping {
321 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) {
322 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
323 bool IsIOS = TargetTriple.isiOS();
324 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
325 bool IsLinux = TargetTriple.isOSLinux();
326 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
327 TargetTriple.getArch() == llvm::Triple::ppc64le;
328 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
329 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
330 TargetTriple.getArch() == llvm::Triple::mipsel;
331 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
332 TargetTriple.getArch() == llvm::Triple::mips64el;
333 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
334 bool IsWindows = TargetTriple.isOSWindows();
336 ShadowMapping Mapping;
338 if (LongSize == 32) {
342 Mapping.Offset = kMIPS32_ShadowOffset32;
344 Mapping.Offset = kFreeBSD_ShadowOffset32;
346 Mapping.Offset = kIOSShadowOffset32;
348 Mapping.Offset = kWindowsShadowOffset32;
350 Mapping.Offset = kDefaultShadowOffset32;
351 } else { // LongSize == 64
353 Mapping.Offset = kPPC64_ShadowOffset64;
355 Mapping.Offset = kFreeBSD_ShadowOffset64;
356 else if (IsLinux && IsX86_64)
357 Mapping.Offset = kSmallX86_64ShadowOffset;
359 Mapping.Offset = kMIPS64_ShadowOffset64;
361 Mapping.Offset = kAArch64_ShadowOffset64;
363 Mapping.Offset = kDefaultShadowOffset64;
366 Mapping.Scale = kDefaultShadowScale;
367 if (ClMappingScale) {
368 Mapping.Scale = ClMappingScale;
371 // OR-ing shadow offset if more efficient (at least on x86) if the offset
372 // is a power of two, but on ppc64 we have to use add since the shadow
373 // offset is not necessary 1/8-th of the address space.
374 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
379 static size_t RedzoneSizeForScale(int MappingScale) {
380 // Redzone used for stack and globals is at least 32 bytes.
381 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
382 return std::max(32U, 1U << MappingScale);
385 /// AddressSanitizer: instrument the code in module to find memory bugs.
386 struct AddressSanitizer : public FunctionPass {
387 AddressSanitizer() : FunctionPass(ID) {
388 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
390 const char *getPassName() const override {
391 return "AddressSanitizerFunctionPass";
393 void getAnalysisUsage(AnalysisUsage &AU) const override {
394 AU.addRequired<DominatorTreeWrapperPass>();
395 AU.addRequired<TargetLibraryInfoWrapperPass>();
397 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
398 Type *Ty = AI->getAllocatedType();
399 uint64_t SizeInBytes =
400 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
403 /// Check if we want (and can) handle this alloca.
404 bool isInterestingAlloca(AllocaInst &AI);
405 /// If it is an interesting memory access, return the PointerOperand
406 /// and set IsWrite/Alignment. Otherwise return nullptr.
407 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
409 unsigned *Alignment);
410 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
411 bool UseCalls, const DataLayout &DL);
412 void instrumentPointerComparisonOrSubtraction(Instruction *I);
413 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
414 Value *Addr, uint32_t TypeSize, bool IsWrite,
415 Value *SizeArgument, bool UseCalls, uint32_t Exp);
416 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
417 uint32_t TypeSize, bool IsWrite,
418 Value *SizeArgument, bool UseCalls,
420 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
421 Value *ShadowValue, uint32_t TypeSize);
422 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
423 bool IsWrite, size_t AccessSizeIndex,
424 Value *SizeArgument, uint32_t Exp);
425 void instrumentMemIntrinsic(MemIntrinsic *MI);
426 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
427 bool runOnFunction(Function &F) override;
428 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
429 bool doInitialization(Module &M) override;
430 static char ID; // Pass identification, replacement for typeid
432 DominatorTree &getDominatorTree() const { return *DT; }
435 void initializeCallbacks(Module &M);
437 bool LooksLikeCodeInBug11395(Instruction *I);
438 bool GlobalIsLinkerInitialized(GlobalVariable *G);
439 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
440 uint64_t TypeSize) const;
446 ShadowMapping Mapping;
448 Function *AsanCtorFunction;
449 Function *AsanInitFunction;
450 Function *AsanHandleNoReturnFunc;
451 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
452 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
453 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
454 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
455 // This array is indexed by AccessIsWrite and Experiment.
456 Function *AsanErrorCallbackSized[2][2];
457 Function *AsanMemoryAccessCallbackSized[2][2];
458 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
460 GlobalsMetadata GlobalsMD;
461 DenseMap<AllocaInst *, bool> ProcessedAllocas;
463 friend struct FunctionStackPoisoner;
466 class AddressSanitizerModule : public ModulePass {
468 AddressSanitizerModule() : ModulePass(ID) {}
469 bool runOnModule(Module &M) override;
470 static char ID; // Pass identification, replacement for typeid
471 const char *getPassName() const override { return "AddressSanitizerModule"; }
474 void initializeCallbacks(Module &M);
476 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
477 bool ShouldInstrumentGlobal(GlobalVariable *G);
478 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
479 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
480 size_t MinRedzoneSizeForGlobal() const {
481 return RedzoneSizeForScale(Mapping.Scale);
484 GlobalsMetadata GlobalsMD;
488 ShadowMapping Mapping;
489 Function *AsanPoisonGlobals;
490 Function *AsanUnpoisonGlobals;
491 Function *AsanRegisterGlobals;
492 Function *AsanUnregisterGlobals;
495 // Stack poisoning does not play well with exception handling.
496 // When an exception is thrown, we essentially bypass the code
497 // that unpoisones the stack. This is why the run-time library has
498 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
499 // stack in the interceptor. This however does not work inside the
500 // actual function which catches the exception. Most likely because the
501 // compiler hoists the load of the shadow value somewhere too high.
502 // This causes asan to report a non-existing bug on 453.povray.
503 // It sounds like an LLVM bug.
504 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
506 AddressSanitizer &ASan;
511 ShadowMapping Mapping;
513 SmallVector<AllocaInst *, 16> AllocaVec;
514 SmallVector<Instruction *, 8> RetVec;
515 unsigned StackAlignment;
517 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
518 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
519 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
521 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
522 struct AllocaPoisonCall {
523 IntrinsicInst *InsBefore;
528 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
530 // Stores left and right redzone shadow addresses for dynamic alloca
531 // and pointer to alloca instruction itself.
532 // LeftRzAddr is a shadow address for alloca left redzone.
533 // RightRzAddr is a shadow address for alloca right redzone.
534 struct DynamicAllocaCall {
539 explicit DynamicAllocaCall(AllocaInst *AI, Value *LeftRzAddr = nullptr,
540 Value *RightRzAddr = nullptr)
542 LeftRzAddr(LeftRzAddr),
543 RightRzAddr(RightRzAddr),
546 SmallVector<DynamicAllocaCall, 1> DynamicAllocaVec;
548 // Maps Value to an AllocaInst from which the Value is originated.
549 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
550 AllocaForValueMapTy AllocaForValue;
552 bool HasNonEmptyInlineAsm;
553 std::unique_ptr<CallInst> EmptyInlineAsm;
555 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
558 DIB(*F.getParent(), /*AllowUnresolved*/ false),
560 IntptrTy(ASan.IntptrTy),
561 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
562 Mapping(ASan.Mapping),
563 StackAlignment(1 << Mapping.Scale),
564 HasNonEmptyInlineAsm(false),
565 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
567 bool runOnFunction() {
568 if (!ClStack) return false;
569 // Collect alloca, ret, lifetime instructions etc.
570 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
572 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
574 initializeCallbacks(*F.getParent());
584 // Finds all Alloca instructions and puts
585 // poisoned red zones around all of them.
586 // Then unpoison everything back before the function returns.
589 // ----------------------- Visitors.
590 /// \brief Collect all Ret instructions.
591 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
593 // Unpoison dynamic allocas redzones.
594 void unpoisonDynamicAlloca(DynamicAllocaCall &AllocaCall) {
595 if (!AllocaCall.Poison) return;
596 for (auto Ret : RetVec) {
597 IRBuilder<> IRBRet(Ret);
598 PointerType *Int32PtrTy = PointerType::getUnqual(IRBRet.getInt32Ty());
599 Value *Zero = Constant::getNullValue(IRBRet.getInt32Ty());
600 Value *PartialRzAddr = IRBRet.CreateSub(AllocaCall.RightRzAddr,
601 ConstantInt::get(IntptrTy, 4));
603 Zero, IRBRet.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
604 IRBRet.CreateStore(Zero,
605 IRBRet.CreateIntToPtr(PartialRzAddr, Int32PtrTy));
607 Zero, IRBRet.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
611 // Right shift for BigEndian and left shift for LittleEndian.
612 Value *shiftAllocaMagic(Value *Val, IRBuilder<> &IRB, Value *Shift) {
613 auto &DL = F.getParent()->getDataLayout();
614 return DL.isLittleEndian() ? IRB.CreateShl(Val, Shift)
615 : IRB.CreateLShr(Val, Shift);
618 // Compute PartialRzMagic for dynamic alloca call. Since we don't know the
619 // size of requested memory until runtime, we should compute it dynamically.
620 // If PartialSize is 0, PartialRzMagic would contain kAsanAllocaRightMagic,
621 // otherwise it would contain the value that we will use to poison the
622 // partial redzone for alloca call.
623 Value *computePartialRzMagic(Value *PartialSize, IRBuilder<> &IRB);
625 // Deploy and poison redzones around dynamic alloca call. To do this, we
626 // should replace this call with another one with changed parameters and
627 // replace all its uses with new address, so
628 // addr = alloca type, old_size, align
630 // new_size = (old_size + additional_size) * sizeof(type)
631 // tmp = alloca i8, new_size, max(align, 32)
632 // addr = tmp + 32 (first 32 bytes are for the left redzone).
633 // Additional_size is added to make new memory allocation contain not only
634 // requested memory, but also left, partial and right redzones.
635 // After that, we should poison redzones:
636 // (1) Left redzone with kAsanAllocaLeftMagic.
637 // (2) Partial redzone with the value, computed in runtime by
638 // computePartialRzMagic function.
639 // (3) Right redzone with kAsanAllocaRightMagic.
640 void handleDynamicAllocaCall(DynamicAllocaCall &AllocaCall);
642 /// \brief Collect Alloca instructions we want (and can) handle.
643 void visitAllocaInst(AllocaInst &AI) {
644 if (!ASan.isInterestingAlloca(AI)) return;
646 StackAlignment = std::max(StackAlignment, AI.getAlignment());
647 if (isDynamicAlloca(AI))
648 DynamicAllocaVec.push_back(DynamicAllocaCall(&AI));
650 AllocaVec.push_back(&AI);
653 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
655 void visitIntrinsicInst(IntrinsicInst &II) {
656 if (!ClCheckLifetime) return;
657 Intrinsic::ID ID = II.getIntrinsicID();
658 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
660 // Found lifetime intrinsic, add ASan instrumentation if necessary.
661 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
662 // If size argument is undefined, don't do anything.
663 if (Size->isMinusOne()) return;
664 // Check that size doesn't saturate uint64_t and can
665 // be stored in IntptrTy.
666 const uint64_t SizeValue = Size->getValue().getLimitedValue();
667 if (SizeValue == ~0ULL ||
668 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
670 // Find alloca instruction that corresponds to llvm.lifetime argument.
671 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
673 bool DoPoison = (ID == Intrinsic::lifetime_end);
674 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
675 AllocaPoisonCallVec.push_back(APC);
678 void visitCallInst(CallInst &CI) {
679 HasNonEmptyInlineAsm |=
680 CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get());
683 // ---------------------- Helpers.
684 void initializeCallbacks(Module &M);
686 bool doesDominateAllExits(const Instruction *I) const {
687 for (auto Ret : RetVec) {
688 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
693 bool isDynamicAlloca(AllocaInst &AI) const {
694 return AI.isArrayAllocation() || !AI.isStaticAlloca();
696 /// Finds alloca where the value comes from.
697 AllocaInst *findAllocaForValue(Value *V);
698 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
699 Value *ShadowBase, bool DoPoison);
700 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
702 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
704 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
706 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
707 Instruction *ThenTerm, Value *ValueIfFalse);
712 char AddressSanitizer::ID = 0;
713 INITIALIZE_PASS_BEGIN(
714 AddressSanitizer, "asan",
715 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
717 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
719 AddressSanitizer, "asan",
720 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
722 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
723 return new AddressSanitizer();
726 char AddressSanitizerModule::ID = 0;
728 AddressSanitizerModule, "asan-module",
729 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
732 ModulePass *llvm::createAddressSanitizerModulePass() {
733 return new AddressSanitizerModule();
736 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
737 size_t Res = countTrailingZeros(TypeSize / 8);
738 assert(Res < kNumberOfAccessSizes);
742 // \brief Create a constant for Str so that we can pass it to the run-time lib.
743 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
745 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
746 // We use private linkage for module-local strings. If they can be merged
747 // with another one, we set the unnamed_addr attribute.
749 new GlobalVariable(M, StrConst->getType(), true,
750 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
751 if (AllowMerging) GV->setUnnamedAddr(true);
752 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
756 /// \brief Create a global describing a source location.
757 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
758 LocationMetadata MD) {
759 Constant *LocData[] = {
760 createPrivateGlobalForString(M, MD.Filename, true),
761 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
762 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
764 auto LocStruct = ConstantStruct::getAnon(LocData);
765 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
766 GlobalValue::PrivateLinkage, LocStruct,
768 GV->setUnnamedAddr(true);
772 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
773 return G->getName().find(kAsanGenPrefix) == 0 ||
774 G->getName().find(kSanCovGenPrefix) == 0;
777 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
779 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
780 if (Mapping.Offset == 0) return Shadow;
781 // (Shadow >> scale) | offset
782 if (Mapping.OrShadowOffset)
783 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
785 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
788 // Instrument memset/memmove/memcpy
789 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
791 if (isa<MemTransferInst>(MI)) {
793 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
794 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
795 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
796 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
797 } else if (isa<MemSetInst>(MI)) {
800 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
801 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
802 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
804 MI->eraseFromParent();
807 /// Check if we want (and can) handle this alloca.
808 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
809 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
811 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
812 return PreviouslySeenAllocaInfo->getSecond();
814 bool IsInteresting = (AI.getAllocatedType()->isSized() &&
815 // alloca() may be called with 0 size, ignore it.
816 getAllocaSizeInBytes(&AI) > 0 &&
817 // We are only interested in allocas not promotable to registers.
818 // Promotable allocas are common under -O0.
819 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)));
821 ProcessedAllocas[&AI] = IsInteresting;
822 return IsInteresting;
825 /// If I is an interesting memory access, return the PointerOperand
826 /// and set IsWrite/Alignment. Otherwise return nullptr.
827 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
830 unsigned *Alignment) {
831 // Skip memory accesses inserted by another instrumentation.
832 if (I->getMetadata("nosanitize")) return nullptr;
834 Value *PtrOperand = nullptr;
835 const DataLayout &DL = I->getModule()->getDataLayout();
836 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
837 if (!ClInstrumentReads) return nullptr;
839 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
840 *Alignment = LI->getAlignment();
841 PtrOperand = LI->getPointerOperand();
842 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
843 if (!ClInstrumentWrites) return nullptr;
845 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
846 *Alignment = SI->getAlignment();
847 PtrOperand = SI->getPointerOperand();
848 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
849 if (!ClInstrumentAtomics) return nullptr;
851 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
853 PtrOperand = RMW->getPointerOperand();
854 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
855 if (!ClInstrumentAtomics) return nullptr;
857 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
859 PtrOperand = XCHG->getPointerOperand();
862 // Treat memory accesses to promotable allocas as non-interesting since they
863 // will not cause memory violations. This greatly speeds up the instrumented
864 // executable at -O0.
865 if (ClSkipPromotableAllocas)
866 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
867 return isInterestingAlloca(*AI) ? AI : nullptr;
872 static bool isPointerOperand(Value *V) {
873 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
876 // This is a rough heuristic; it may cause both false positives and
877 // false negatives. The proper implementation requires cooperation with
879 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
880 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
881 if (!Cmp->isRelational()) return false;
882 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
883 if (BO->getOpcode() != Instruction::Sub) return false;
887 if (!isPointerOperand(I->getOperand(0)) ||
888 !isPointerOperand(I->getOperand(1)))
893 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
894 // If a global variable does not have dynamic initialization we don't
895 // have to instrument it. However, if a global does not have initializer
896 // at all, we assume it has dynamic initializer (in other TU).
897 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
900 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
903 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
904 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
905 for (int i = 0; i < 2; i++) {
906 if (Param[i]->getType()->isPointerTy())
907 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
909 IRB.CreateCall2(F, Param[0], Param[1]);
912 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
913 Instruction *I, bool UseCalls,
914 const DataLayout &DL) {
915 bool IsWrite = false;
916 unsigned Alignment = 0;
917 uint64_t TypeSize = 0;
918 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
921 // Optimization experiments.
922 // The experiments can be used to evaluate potential optimizations that remove
923 // instrumentation (assess false negatives). Instead of completely removing
924 // some instrumentation, you set Exp to a non-zero value (mask of optimization
925 // experiments that want to remove instrumentation of this instruction).
926 // If Exp is non-zero, this pass will emit special calls into runtime
927 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
928 // make runtime terminate the program in a special way (with a different
929 // exit status). Then you run the new compiler on a buggy corpus, collect
930 // the special terminations (ideally, you don't see them at all -- no false
931 // negatives) and make the decision on the optimization.
932 uint32_t Exp = ClForceExperiment;
934 if (ClOpt && ClOptGlobals) {
935 // If initialization order checking is disabled, a simple access to a
936 // dynamically initialized global is always valid.
937 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
938 if (G != NULL && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
939 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
940 NumOptimizedAccessesToGlobalVar++;
945 if (ClOpt && ClOptStack) {
946 // A direct inbounds access to a stack variable is always valid.
947 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
948 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
949 NumOptimizedAccessesToStackVar++;
955 NumInstrumentedWrites++;
957 NumInstrumentedReads++;
959 unsigned Granularity = 1 << Mapping.Scale;
960 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
961 // if the data is properly aligned.
962 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
964 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
965 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
967 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
971 // Validate the result of Module::getOrInsertFunction called for an interface
972 // function of AddressSanitizer. If the instrumented module defines a function
973 // with the same name, their prototypes must match, otherwise
974 // getOrInsertFunction returns a bitcast.
975 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
976 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
977 FuncOrBitcast->dump();
979 "trying to redefine an AddressSanitizer "
980 "interface function");
983 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
984 Value *Addr, bool IsWrite,
985 size_t AccessSizeIndex,
988 IRBuilder<> IRB(InsertBefore);
989 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
990 CallInst *Call = nullptr;
993 Call = IRB.CreateCall2(AsanErrorCallbackSized[IsWrite][0], Addr,
996 Call = IRB.CreateCall3(AsanErrorCallbackSized[IsWrite][1], Addr,
997 SizeArgument, ExpVal);
1001 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1003 Call = IRB.CreateCall2(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1007 // We don't do Call->setDoesNotReturn() because the BB already has
1008 // UnreachableInst at the end.
1009 // This EmptyAsm is required to avoid callback merge.
1010 IRB.CreateCall(EmptyAsm);
1014 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1016 uint32_t TypeSize) {
1017 size_t Granularity = 1 << Mapping.Scale;
1018 // Addr & (Granularity - 1)
1019 Value *LastAccessedByte =
1020 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1021 // (Addr & (Granularity - 1)) + size - 1
1022 if (TypeSize / 8 > 1)
1023 LastAccessedByte = IRB.CreateAdd(
1024 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1025 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1027 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1028 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1029 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1032 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1033 Instruction *InsertBefore, Value *Addr,
1034 uint32_t TypeSize, bool IsWrite,
1035 Value *SizeArgument, bool UseCalls,
1037 IRBuilder<> IRB(InsertBefore);
1038 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1039 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1043 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1046 IRB.CreateCall2(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1047 AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp));
1052 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1053 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1054 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1055 Value *CmpVal = Constant::getNullValue(ShadowTy);
1056 Value *ShadowValue =
1057 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1059 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1060 size_t Granularity = 1 << Mapping.Scale;
1061 TerminatorInst *CrashTerm = nullptr;
1063 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1064 // We use branch weights for the slow path check, to indicate that the slow
1065 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1066 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1067 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1068 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
1069 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1070 IRB.SetInsertPoint(CheckTerm);
1071 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1072 BasicBlock *CrashBlock =
1073 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1074 CrashTerm = new UnreachableInst(*C, CrashBlock);
1075 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1076 ReplaceInstWithInst(CheckTerm, NewTerm);
1078 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1081 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1082 AccessSizeIndex, SizeArgument, Exp);
1083 Crash->setDebugLoc(OrigIns->getDebugLoc());
1086 // Instrument unusual size or unusual alignment.
1087 // We can not do it with a single check, so we do 1-byte check for the first
1088 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1089 // to report the actual access size.
1090 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1091 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1092 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1094 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1095 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1098 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite][0], AddrLong,
1101 IRB.CreateCall3(AsanMemoryAccessCallbackSized[IsWrite][1], AddrLong, Size,
1102 ConstantInt::get(IRB.getInt32Ty(), Exp));
1104 Value *LastByte = IRB.CreateIntToPtr(
1105 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1107 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1108 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1112 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1113 GlobalValue *ModuleName) {
1114 // Set up the arguments to our poison/unpoison functions.
1115 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1117 // Add a call to poison all external globals before the given function starts.
1118 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1119 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1121 // Add calls to unpoison all globals before each return instruction.
1122 for (auto &BB : GlobalInit.getBasicBlockList())
1123 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1124 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1127 void AddressSanitizerModule::createInitializerPoisonCalls(
1128 Module &M, GlobalValue *ModuleName) {
1129 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1131 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1132 for (Use &OP : CA->operands()) {
1133 if (isa<ConstantAggregateZero>(OP)) continue;
1134 ConstantStruct *CS = cast<ConstantStruct>(OP);
1136 // Must have a function or null ptr.
1137 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1138 if (F->getName() == kAsanModuleCtorName) continue;
1139 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1140 // Don't instrument CTORs that will run before asan.module_ctor.
1141 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1142 poisonOneInitializer(*F, ModuleName);
1147 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1148 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1149 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1151 if (GlobalsMD.get(G).IsBlacklisted) return false;
1152 if (!Ty->isSized()) return false;
1153 if (!G->hasInitializer()) return false;
1154 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1155 // Touch only those globals that will not be defined in other modules.
1156 // Don't handle ODR linkage types and COMDATs since other modules may be built
1158 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1159 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1160 G->getLinkage() != GlobalVariable::InternalLinkage)
1162 if (G->hasComdat()) return false;
1163 // Two problems with thread-locals:
1164 // - The address of the main thread's copy can't be computed at link-time.
1165 // - Need to poison all copies, not just the main thread's one.
1166 if (G->isThreadLocal()) return false;
1167 // For now, just ignore this Global if the alignment is large.
1168 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1170 if (G->hasSection()) {
1171 StringRef Section(G->getSection());
1173 if (TargetTriple.isOSBinFormatMachO()) {
1174 StringRef ParsedSegment, ParsedSection;
1175 unsigned TAA = 0, StubSize = 0;
1177 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1178 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1179 if (!ErrorCode.empty()) {
1180 report_fatal_error("Invalid section specifier '" + ParsedSection +
1181 "': " + ErrorCode + ".");
1184 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1185 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1187 if (ParsedSegment == "__OBJC" ||
1188 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1189 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1192 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1193 // Constant CFString instances are compiled in the following way:
1194 // -- the string buffer is emitted into
1195 // __TEXT,__cstring,cstring_literals
1196 // -- the constant NSConstantString structure referencing that buffer
1197 // is placed into __DATA,__cfstring
1198 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1199 // Moreover, it causes the linker to crash on OS X 10.7
1200 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1201 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1204 // The linker merges the contents of cstring_literals and removes the
1206 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1207 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1212 // Callbacks put into the CRT initializer/terminator sections
1213 // should not be instrumented.
1214 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1215 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1216 if (Section.startswith(".CRT")) {
1217 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1221 // Globals from llvm.metadata aren't emitted, do not instrument them.
1222 if (Section == "llvm.metadata") return false;
1228 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1229 IRBuilder<> IRB(*C);
1230 // Declare our poisoning and unpoisoning functions.
1231 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1232 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1233 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1234 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1235 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1236 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1237 // Declare functions that register/unregister globals.
1238 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1239 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1240 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1241 AsanUnregisterGlobals = checkInterfaceFunction(
1242 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1243 IntptrTy, IntptrTy, nullptr));
1244 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1247 // This function replaces all global variables with new variables that have
1248 // trailing redzones. It also creates a function that poisons
1249 // redzones and inserts this function into llvm.global_ctors.
1250 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1253 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1255 for (auto &G : M.globals()) {
1256 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1259 size_t n = GlobalsToChange.size();
1260 if (n == 0) return false;
1262 // A global is described by a structure
1265 // size_t size_with_redzone;
1266 // const char *name;
1267 // const char *module_name;
1268 // size_t has_dynamic_init;
1269 // void *source_location;
1270 // We initialize an array of such structures and pass it to a run-time call.
1271 StructType *GlobalStructTy =
1272 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1273 IntptrTy, IntptrTy, nullptr);
1274 SmallVector<Constant *, 16> Initializers(n);
1276 bool HasDynamicallyInitializedGlobals = false;
1278 // We shouldn't merge same module names, as this string serves as unique
1279 // module ID in runtime.
1280 GlobalVariable *ModuleName = createPrivateGlobalForString(
1281 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1283 auto &DL = M.getDataLayout();
1284 for (size_t i = 0; i < n; i++) {
1285 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1286 GlobalVariable *G = GlobalsToChange[i];
1288 auto MD = GlobalsMD.get(G);
1289 // Create string holding the global name (use global name from metadata
1290 // if it's available, otherwise just write the name of global variable).
1291 GlobalVariable *Name = createPrivateGlobalForString(
1292 M, MD.Name.empty() ? G->getName() : MD.Name,
1293 /*AllowMerging*/ true);
1295 PointerType *PtrTy = cast<PointerType>(G->getType());
1296 Type *Ty = PtrTy->getElementType();
1297 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1298 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1299 // MinRZ <= RZ <= kMaxGlobalRedzone
1300 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1301 uint64_t RZ = std::max(
1302 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1303 uint64_t RightRedzoneSize = RZ;
1304 // Round up to MinRZ
1305 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1306 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1307 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1309 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1310 Constant *NewInitializer =
1311 ConstantStruct::get(NewTy, G->getInitializer(),
1312 Constant::getNullValue(RightRedZoneTy), nullptr);
1314 // Create a new global variable with enough space for a redzone.
1315 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1316 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1317 Linkage = GlobalValue::InternalLinkage;
1318 GlobalVariable *NewGlobal =
1319 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1320 "", G, G->getThreadLocalMode());
1321 NewGlobal->copyAttributesFrom(G);
1322 NewGlobal->setAlignment(MinRZ);
1325 Indices2[0] = IRB.getInt32(0);
1326 Indices2[1] = IRB.getInt32(0);
1328 G->replaceAllUsesWith(
1329 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1330 NewGlobal->takeName(G);
1331 G->eraseFromParent();
1333 Constant *SourceLoc;
1334 if (!MD.SourceLoc.empty()) {
1335 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1336 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1338 SourceLoc = ConstantInt::get(IntptrTy, 0);
1341 Initializers[i] = ConstantStruct::get(
1342 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1343 ConstantInt::get(IntptrTy, SizeInBytes),
1344 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1345 ConstantExpr::getPointerCast(Name, IntptrTy),
1346 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1347 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1349 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1351 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1354 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1355 GlobalVariable *AllGlobals = new GlobalVariable(
1356 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1357 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1359 // Create calls for poisoning before initializers run and unpoisoning after.
1360 if (HasDynamicallyInitializedGlobals)
1361 createInitializerPoisonCalls(M, ModuleName);
1362 IRB.CreateCall2(AsanRegisterGlobals,
1363 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1364 ConstantInt::get(IntptrTy, n));
1366 // We also need to unregister globals at the end, e.g. when a shared library
1368 Function *AsanDtorFunction =
1369 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1370 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1371 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1372 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1373 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1374 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1375 ConstantInt::get(IntptrTy, n));
1376 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1382 bool AddressSanitizerModule::runOnModule(Module &M) {
1383 C = &(M.getContext());
1384 int LongSize = M.getDataLayout().getPointerSizeInBits();
1385 IntptrTy = Type::getIntNTy(*C, LongSize);
1386 TargetTriple = Triple(M.getTargetTriple());
1387 Mapping = getShadowMapping(TargetTriple, LongSize);
1388 initializeCallbacks(M);
1390 bool Changed = false;
1392 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1394 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1396 if (ClGlobals) Changed |= InstrumentGlobals(IRB, M);
1401 void AddressSanitizer::initializeCallbacks(Module &M) {
1402 IRBuilder<> IRB(*C);
1403 // Create __asan_report* callbacks.
1404 // IsWrite, TypeSize and Exp are encoded in the function name.
1405 for (int Exp = 0; Exp < 2; Exp++) {
1406 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1407 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1408 const std::string ExpStr = Exp ? "exp_" : "";
1409 const Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1410 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1411 checkInterfaceFunction(M.getOrInsertFunction(
1412 kAsanReportErrorTemplate + ExpStr + TypeStr + "_n",
1413 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1414 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1415 checkInterfaceFunction(M.getOrInsertFunction(
1416 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N",
1417 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1418 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1419 AccessSizeIndex++) {
1420 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1421 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1422 checkInterfaceFunction(M.getOrInsertFunction(
1423 kAsanReportErrorTemplate + ExpStr + Suffix, IRB.getVoidTy(),
1424 IntptrTy, ExpType, nullptr));
1425 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1426 checkInterfaceFunction(M.getOrInsertFunction(
1427 ClMemoryAccessCallbackPrefix + ExpStr + Suffix, IRB.getVoidTy(),
1428 IntptrTy, ExpType, nullptr));
1433 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1434 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1435 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1436 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1437 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1438 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1439 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1440 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1441 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1443 AsanHandleNoReturnFunc = checkInterfaceFunction(
1444 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1446 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1447 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1448 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1449 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1450 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1451 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1452 StringRef(""), StringRef(""),
1453 /*hasSideEffects=*/true);
1457 bool AddressSanitizer::doInitialization(Module &M) {
1458 // Initialize the private fields. No one has accessed them before.
1462 C = &(M.getContext());
1463 LongSize = M.getDataLayout().getPointerSizeInBits();
1464 IntptrTy = Type::getIntNTy(*C, LongSize);
1465 TargetTriple = Triple(M.getTargetTriple());
1468 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1469 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1470 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1471 // call __asan_init in the module ctor.
1472 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1473 AsanInitFunction = checkInterfaceFunction(
1474 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr));
1475 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1476 IRB.CreateCall(AsanInitFunction);
1478 Mapping = getShadowMapping(TargetTriple, LongSize);
1480 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1484 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1485 // For each NSObject descendant having a +load method, this method is invoked
1486 // by the ObjC runtime before any of the static constructors is called.
1487 // Therefore we need to instrument such methods with a call to __asan_init
1488 // at the beginning in order to initialize our runtime before any access to
1489 // the shadow memory.
1490 // We cannot just ignore these methods, because they may call other
1491 // instrumented functions.
1492 if (F.getName().find(" load]") != std::string::npos) {
1493 IRBuilder<> IRB(F.begin()->begin());
1494 IRB.CreateCall(AsanInitFunction);
1500 bool AddressSanitizer::runOnFunction(Function &F) {
1501 if (&F == AsanCtorFunction) return false;
1502 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1503 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1504 initializeCallbacks(*F.getParent());
1506 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1508 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1509 maybeInsertAsanInitAtFunctionEntry(F);
1511 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1513 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1515 // We want to instrument every address only once per basic block (unless there
1516 // are calls between uses).
1517 SmallSet<Value *, 16> TempsToInstrument;
1518 SmallVector<Instruction *, 16> ToInstrument;
1519 SmallVector<Instruction *, 8> NoReturnCalls;
1520 SmallVector<BasicBlock *, 16> AllBlocks;
1521 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1527 // Fill the set of memory operations to instrument.
1528 for (auto &BB : F) {
1529 AllBlocks.push_back(&BB);
1530 TempsToInstrument.clear();
1531 int NumInsnsPerBB = 0;
1532 for (auto &Inst : BB) {
1533 if (LooksLikeCodeInBug11395(&Inst)) return false;
1534 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1536 if (ClOpt && ClOptSameTemp) {
1537 if (!TempsToInstrument.insert(Addr).second)
1538 continue; // We've seen this temp in the current BB.
1540 } else if (ClInvalidPointerPairs &&
1541 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1542 PointerComparisonsOrSubtracts.push_back(&Inst);
1544 } else if (isa<MemIntrinsic>(Inst)) {
1547 if (isa<AllocaInst>(Inst)) NumAllocas++;
1550 // A call inside BB.
1551 TempsToInstrument.clear();
1552 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1556 ToInstrument.push_back(&Inst);
1558 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1562 bool UseCalls = false;
1563 if (ClInstrumentationWithCallsThreshold >= 0 &&
1564 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1567 const TargetLibraryInfo *TLI =
1568 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1569 const DataLayout &DL = F.getParent()->getDataLayout();
1570 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1571 /*RoundToAlign=*/true);
1574 int NumInstrumented = 0;
1575 for (auto Inst : ToInstrument) {
1576 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1577 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1578 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1579 instrumentMop(ObjSizeVis, Inst, UseCalls,
1580 F.getParent()->getDataLayout());
1582 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1587 FunctionStackPoisoner FSP(F, *this);
1588 bool ChangedStack = FSP.runOnFunction();
1590 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1591 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1592 for (auto CI : NoReturnCalls) {
1593 IRBuilder<> IRB(CI);
1594 IRB.CreateCall(AsanHandleNoReturnFunc);
1597 for (auto Inst : PointerComparisonsOrSubtracts) {
1598 instrumentPointerComparisonOrSubtraction(Inst);
1602 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1604 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1609 // Workaround for bug 11395: we don't want to instrument stack in functions
1610 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1611 // FIXME: remove once the bug 11395 is fixed.
1612 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1613 if (LongSize != 32) return false;
1614 CallInst *CI = dyn_cast<CallInst>(I);
1615 if (!CI || !CI->isInlineAsm()) return false;
1616 if (CI->getNumArgOperands() <= 5) return false;
1617 // We have inline assembly with quite a few arguments.
1621 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1622 IRBuilder<> IRB(*C);
1623 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1624 std::string Suffix = itostr(i);
1625 AsanStackMallocFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1626 kAsanStackMallocNameTemplate + Suffix, IntptrTy, IntptrTy, nullptr));
1627 AsanStackFreeFunc[i] = checkInterfaceFunction(
1628 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1629 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1631 AsanPoisonStackMemoryFunc = checkInterfaceFunction(
1632 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1633 IntptrTy, IntptrTy, nullptr));
1634 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(
1635 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1636 IntptrTy, IntptrTy, nullptr));
1639 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1640 IRBuilder<> &IRB, Value *ShadowBase,
1642 size_t n = ShadowBytes.size();
1644 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1645 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1646 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1647 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1648 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1649 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1651 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1652 if (F.getParent()->getDataLayout().isLittleEndian())
1653 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1655 Val = (Val << 8) | ShadowBytes[i + j];
1658 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1659 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1660 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1661 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1666 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1667 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1668 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1669 assert(LocalStackSize <= kMaxStackMallocSize);
1670 uint64_t MaxSize = kMinStackMallocSize;
1671 for (int i = 0;; i++, MaxSize *= 2)
1672 if (LocalStackSize <= MaxSize) return i;
1673 llvm_unreachable("impossible LocalStackSize");
1676 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1677 // We can not use MemSet intrinsic because it may end up calling the actual
1678 // memset. Size is a multiple of 8.
1679 // Currently this generates 8-byte stores on x86_64; it may be better to
1680 // generate wider stores.
1681 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1682 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1683 assert(!(Size % 8));
1685 // kAsanStackAfterReturnMagic is 0xf5.
1686 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1688 for (int i = 0; i < Size; i += 8) {
1689 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1691 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1692 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1696 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1697 for (const auto &Inst : F.getEntryBlock())
1698 if (!isa<AllocaInst>(Inst)) return Inst.getDebugLoc();
1702 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1704 Instruction *ThenTerm,
1705 Value *ValueIfFalse) {
1706 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1707 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1708 PHI->addIncoming(ValueIfFalse, CondBlock);
1709 BasicBlock *ThenBlock = ThenTerm->getParent();
1710 PHI->addIncoming(ValueIfTrue, ThenBlock);
1714 Value *FunctionStackPoisoner::createAllocaForLayout(
1715 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1718 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1719 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1722 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1723 nullptr, "MyAlloca");
1724 assert(Alloca->isStaticAlloca());
1726 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1727 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1728 Alloca->setAlignment(FrameAlignment);
1729 return IRB.CreatePointerCast(Alloca, IntptrTy);
1732 void FunctionStackPoisoner::poisonStack() {
1733 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1735 if (ClInstrumentAllocas) {
1736 // Handle dynamic allocas.
1737 for (auto &AllocaCall : DynamicAllocaVec) {
1738 handleDynamicAllocaCall(AllocaCall);
1739 unpoisonDynamicAlloca(AllocaCall);
1743 if (AllocaVec.size() == 0) return;
1745 int StackMallocIdx = -1;
1746 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1748 Instruction *InsBefore = AllocaVec[0];
1749 IRBuilder<> IRB(InsBefore);
1750 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1752 SmallVector<ASanStackVariableDescription, 16> SVD;
1753 SVD.reserve(AllocaVec.size());
1754 for (AllocaInst *AI : AllocaVec) {
1755 ASanStackVariableDescription D = {AI->getName().data(),
1756 ASan.getAllocaSizeInBytes(AI),
1757 AI->getAlignment(), AI, 0};
1760 // Minimal header size (left redzone) is 4 pointers,
1761 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1762 size_t MinHeaderSize = ASan.LongSize / 2;
1763 ASanStackFrameLayout L;
1764 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1765 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1766 uint64_t LocalStackSize = L.FrameSize;
1767 bool DoStackMalloc =
1768 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1769 // Don't do dynamic alloca in presence of inline asm: too often it
1770 // makes assumptions on which registers are available.
1771 bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
1773 Value *StaticAlloca =
1774 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1777 Value *LocalStackBase;
1779 if (DoStackMalloc) {
1780 // void *FakeStack = __asan_option_detect_stack_use_after_return
1781 // ? __asan_stack_malloc_N(LocalStackSize)
1783 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1784 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1785 kAsanOptionDetectUAR, IRB.getInt32Ty());
1786 Value *UARIsEnabled =
1787 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1788 Constant::getNullValue(IRB.getInt32Ty()));
1790 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1791 IRBuilder<> IRBIf(Term);
1792 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1793 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1794 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1795 Value *FakeStackValue =
1796 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1797 ConstantInt::get(IntptrTy, LocalStackSize));
1798 IRB.SetInsertPoint(InsBefore);
1799 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1800 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1801 ConstantInt::get(IntptrTy, 0));
1803 Value *NoFakeStack =
1804 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1805 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1806 IRBIf.SetInsertPoint(Term);
1807 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1808 Value *AllocaValue =
1809 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1810 IRB.SetInsertPoint(InsBefore);
1811 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1812 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1814 // void *FakeStack = nullptr;
1815 // void *LocalStackBase = alloca(LocalStackSize);
1816 FakeStack = ConstantInt::get(IntptrTy, 0);
1818 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1821 // Insert poison calls for lifetime intrinsics for alloca.
1822 bool HavePoisonedAllocas = false;
1823 for (const auto &APC : AllocaPoisonCallVec) {
1824 assert(APC.InsBefore);
1826 IRBuilder<> IRB(APC.InsBefore);
1827 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1828 HavePoisonedAllocas |= APC.DoPoison;
1831 // Replace Alloca instructions with base+offset.
1832 for (const auto &Desc : SVD) {
1833 AllocaInst *AI = Desc.AI;
1834 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1835 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1837 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1838 AI->replaceAllUsesWith(NewAllocaPtr);
1841 // The left-most redzone has enough space for at least 4 pointers.
1842 // Write the Magic value to redzone[0].
1843 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1844 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1846 // Write the frame description constant to redzone[1].
1847 Value *BasePlus1 = IRB.CreateIntToPtr(
1848 IRB.CreateAdd(LocalStackBase,
1849 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1851 GlobalVariable *StackDescriptionGlobal =
1852 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1853 /*AllowMerging*/ true);
1854 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1855 IRB.CreateStore(Description, BasePlus1);
1856 // Write the PC to redzone[2].
1857 Value *BasePlus2 = IRB.CreateIntToPtr(
1858 IRB.CreateAdd(LocalStackBase,
1859 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1861 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1863 // Poison the stack redzones at the entry.
1864 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1865 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1867 // (Un)poison the stack before all ret instructions.
1868 for (auto Ret : RetVec) {
1869 IRBuilder<> IRBRet(Ret);
1870 // Mark the current frame as retired.
1871 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1873 if (DoStackMalloc) {
1874 assert(StackMallocIdx >= 0);
1875 // if FakeStack != 0 // LocalStackBase == FakeStack
1876 // // In use-after-return mode, poison the whole stack frame.
1877 // if StackMallocIdx <= 4
1878 // // For small sizes inline the whole thing:
1879 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1880 // **SavedFlagPtr(FakeStack) = 0
1882 // __asan_stack_free_N(FakeStack, LocalStackSize)
1884 // <This is not a fake stack; unpoison the redzones>
1886 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1887 TerminatorInst *ThenTerm, *ElseTerm;
1888 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1890 IRBuilder<> IRBPoison(ThenTerm);
1891 if (StackMallocIdx <= 4) {
1892 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1893 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1894 ClassSize >> Mapping.Scale);
1895 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1897 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1898 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1899 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1900 IRBPoison.CreateStore(
1901 Constant::getNullValue(IRBPoison.getInt8Ty()),
1902 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1904 // For larger frames call __asan_stack_free_*.
1905 IRBPoison.CreateCall2(AsanStackFreeFunc[StackMallocIdx], FakeStack,
1906 ConstantInt::get(IntptrTy, LocalStackSize));
1909 IRBuilder<> IRBElse(ElseTerm);
1910 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1911 } else if (HavePoisonedAllocas) {
1912 // If we poisoned some allocas in llvm.lifetime analysis,
1913 // unpoison whole stack frame now.
1914 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1916 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1920 // We are done. Remove the old unused alloca instructions.
1921 for (auto AI : AllocaVec) AI->eraseFromParent();
1924 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1925 IRBuilder<> &IRB, bool DoPoison) {
1926 // For now just insert the call to ASan runtime.
1927 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1928 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1930 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
1934 // Handling llvm.lifetime intrinsics for a given %alloca:
1935 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1936 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1937 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1938 // could be poisoned by previous llvm.lifetime.end instruction, as the
1939 // variable may go in and out of scope several times, e.g. in loops).
1940 // (3) if we poisoned at least one %alloca in a function,
1941 // unpoison the whole stack frame at function exit.
1943 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1944 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1945 // We're intested only in allocas we can handle.
1946 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
1947 // See if we've already calculated (or started to calculate) alloca for a
1949 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1950 if (I != AllocaForValue.end()) return I->second;
1951 // Store 0 while we're calculating alloca for value V to avoid
1952 // infinite recursion if the value references itself.
1953 AllocaForValue[V] = nullptr;
1954 AllocaInst *Res = nullptr;
1955 if (CastInst *CI = dyn_cast<CastInst>(V))
1956 Res = findAllocaForValue(CI->getOperand(0));
1957 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1958 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1959 Value *IncValue = PN->getIncomingValue(i);
1960 // Allow self-referencing phi-nodes.
1961 if (IncValue == PN) continue;
1962 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1963 // AI for incoming values should exist and should all be equal.
1964 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1969 if (Res) AllocaForValue[V] = Res;
1973 // Compute PartialRzMagic for dynamic alloca call. PartialRzMagic is
1974 // constructed from two separate 32-bit numbers: PartialRzMagic = Val1 | Val2.
1975 // (1) Val1 is resposible for forming base value for PartialRzMagic, containing
1976 // only 00 for fully addressable and 0xcb for fully poisoned bytes for each
1977 // 8-byte chunk of user memory respectively.
1978 // (2) Val2 forms the value for marking first poisoned byte in shadow memory
1979 // with appropriate value (0x01 - 0x07 or 0xcb if Padding % 8 == 0).
1981 // Shift = Padding & ~7; // the number of bits we need to shift to access first
1982 // chunk in shadow memory, containing nonzero bytes.
1984 // Padding = 21 Padding = 16
1985 // Shadow: |00|00|05|cb| Shadow: |00|00|cb|cb|
1988 // Shift = 21 & ~7 = 16 Shift = 16 & ~7 = 16
1990 // Val1 = 0xcbcbcbcb << Shift;
1991 // PartialBits = Padding ? Padding & 7 : 0xcb;
1992 // Val2 = PartialBits << Shift;
1993 // Result = Val1 | Val2;
1994 Value *FunctionStackPoisoner::computePartialRzMagic(Value *PartialSize,
1996 PartialSize = IRB.CreateIntCast(PartialSize, IRB.getInt32Ty(), false);
1997 Value *Shift = IRB.CreateAnd(PartialSize, IRB.getInt32(~7));
1998 unsigned Val1Int = kAsanAllocaPartialVal1;
1999 unsigned Val2Int = kAsanAllocaPartialVal2;
2000 if (!F.getParent()->getDataLayout().isLittleEndian()) {
2001 Val1Int = sys::getSwappedBytes(Val1Int);
2002 Val2Int = sys::getSwappedBytes(Val2Int);
2004 Value *Val1 = shiftAllocaMagic(IRB.getInt32(Val1Int), IRB, Shift);
2005 Value *PartialBits = IRB.CreateAnd(PartialSize, IRB.getInt32(7));
2006 // For BigEndian get 0x000000YZ -> 0xYZ000000.
2007 if (F.getParent()->getDataLayout().isBigEndian())
2008 PartialBits = IRB.CreateShl(PartialBits, IRB.getInt32(24));
2009 Value *Val2 = IRB.getInt32(Val2Int);
2011 IRB.CreateICmpNE(PartialBits, Constant::getNullValue(IRB.getInt32Ty()));
2012 Val2 = IRB.CreateSelect(Cond, shiftAllocaMagic(PartialBits, IRB, Shift),
2013 shiftAllocaMagic(Val2, IRB, Shift));
2014 return IRB.CreateOr(Val1, Val2);
2017 void FunctionStackPoisoner::handleDynamicAllocaCall(
2018 DynamicAllocaCall &AllocaCall) {
2019 AllocaInst *AI = AllocaCall.AI;
2020 if (!doesDominateAllExits(AI)) {
2021 // We do not yet handle complex allocas
2022 AllocaCall.Poison = false;
2026 IRBuilder<> IRB(AI);
2028 PointerType *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
2029 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2030 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2032 Value *Zero = Constant::getNullValue(IntptrTy);
2033 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2034 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2035 Value *NotAllocaRzMask = ConstantInt::get(IntptrTy, ~AllocaRedzoneMask);
2037 // Since we need to extend alloca with additional memory to locate
2038 // redzones, and OldSize is number of allocated blocks with
2039 // ElementSize size, get allocated memory size in bytes by
2040 // OldSize * ElementSize.
2041 unsigned ElementSize =
2042 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2043 Value *OldSize = IRB.CreateMul(AI->getArraySize(),
2044 ConstantInt::get(IntptrTy, ElementSize));
2046 // PartialSize = OldSize % 32
2047 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2049 // Misalign = kAllocaRzSize - PartialSize;
2050 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2052 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2053 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2054 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2056 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2057 // Align is added to locate left redzone, PartialPadding for possible
2058 // partial redzone and kAllocaRzSize for right redzone respectively.
2059 Value *AdditionalChunkSize = IRB.CreateAdd(
2060 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2062 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2064 // Insert new alloca with new NewSize and Align params.
2065 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2066 NewAlloca->setAlignment(Align);
2068 // NewAddress = Address + Align
2069 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2070 ConstantInt::get(IntptrTy, Align));
2072 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2074 // LeftRzAddress = NewAddress - kAllocaRzSize
2075 Value *LeftRzAddress = IRB.CreateSub(NewAddress, AllocaRzSize);
2077 // Poisoning left redzone.
2078 AllocaCall.LeftRzAddr = ASan.memToShadow(LeftRzAddress, IRB);
2079 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaLeftMagic),
2080 IRB.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
2082 // PartialRzAligned = PartialRzAddr & ~AllocaRzMask
2083 Value *PartialRzAddr = IRB.CreateAdd(NewAddress, OldSize);
2084 Value *PartialRzAligned = IRB.CreateAnd(PartialRzAddr, NotAllocaRzMask);
2086 // Poisoning partial redzone.
2087 Value *PartialRzMagic = computePartialRzMagic(PartialSize, IRB);
2088 Value *PartialRzShadowAddr = ASan.memToShadow(PartialRzAligned, IRB);
2089 IRB.CreateStore(PartialRzMagic,
2090 IRB.CreateIntToPtr(PartialRzShadowAddr, Int32PtrTy));
2093 // = (PartialRzAddr + AllocaRzMask) & ~AllocaRzMask
2094 Value *RightRzAddress = IRB.CreateAnd(
2095 IRB.CreateAdd(PartialRzAddr, AllocaRzMask), NotAllocaRzMask);
2097 // Poisoning right redzone.
2098 AllocaCall.RightRzAddr = ASan.memToShadow(RightRzAddress, IRB);
2099 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaRightMagic),
2100 IRB.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
2102 // Replace all uses of AddessReturnedByAlloca with NewAddress.
2103 AI->replaceAllUsesWith(NewAddressPtr);
2105 // We are done. Erase old alloca and store left, partial and right redzones
2106 // shadow addresses for future unpoisoning.
2107 AI->eraseFromParent();
2108 NumInstrumentedDynamicAllocas++;
2111 // isSafeAccess returns true if Addr is always inbounds with respect to its
2112 // base object. For example, it is a field access or an array access with
2113 // constant inbounds index.
2114 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2115 Value *Addr, uint64_t TypeSize) const {
2116 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2117 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2118 uint64_t Size = SizeOffset.first.getZExtValue();
2119 int64_t Offset = SizeOffset.second.getSExtValue();
2120 // Three checks are required to ensure safety:
2121 // . Offset >= 0 (since the offset is given from the base ptr)
2122 // . Size >= Offset (unsigned)
2123 // . Size - Offset >= NeededSize (unsigned)
2124 return Offset >= 0 && Size >= uint64_t(Offset) &&
2125 Size - uint64_t(Offset) >= TypeSize / 8;