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/Transforms/Scalar.h"
50 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
51 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
52 #include "llvm/Transforms/Utils/Cloning.h"
53 #include "llvm/Transforms/Utils/Local.h"
54 #include "llvm/Transforms/Utils/ModuleUtils.h"
55 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
58 #include <system_error>
62 #define DEBUG_TYPE "asan"
64 static const uint64_t kDefaultShadowScale = 3;
65 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
66 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
67 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
68 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
69 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
70 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
71 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
72 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
73 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
74 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
75 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
77 static const size_t kMinStackMallocSize = 1 << 6; // 64B
78 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
79 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
80 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
82 static const char *const kAsanModuleCtorName = "asan.module_ctor";
83 static const char *const kAsanModuleDtorName = "asan.module_dtor";
84 static const uint64_t kAsanCtorAndDtorPriority = 1;
85 static const char *const kAsanReportErrorTemplate = "__asan_report_";
86 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
87 static const char *const kAsanUnregisterGlobalsName =
88 "__asan_unregister_globals";
89 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
90 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
91 static const char *const kAsanInitName = "__asan_init_v5";
92 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
93 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
94 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
95 static const int kMaxAsanStackMallocSizeClass = 10;
96 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
97 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
98 static const char *const kAsanGenPrefix = "__asan_gen_";
99 static const char *const kSanCovGenPrefix = "__sancov_gen_";
100 static const char *const kAsanPoisonStackMemoryName =
101 "__asan_poison_stack_memory";
102 static const char *const kAsanUnpoisonStackMemoryName =
103 "__asan_unpoison_stack_memory";
105 static const char *const kAsanOptionDetectUAR =
106 "__asan_option_detect_stack_use_after_return";
108 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
109 static const size_t kNumberOfAccessSizes = 5;
111 static const unsigned kAllocaRzSize = 32;
112 static const unsigned kAsanAllocaLeftMagic = 0xcacacacaU;
113 static const unsigned kAsanAllocaRightMagic = 0xcbcbcbcbU;
114 static const unsigned kAsanAllocaPartialVal1 = 0xcbcbcb00U;
115 static const unsigned kAsanAllocaPartialVal2 = 0x000000cbU;
117 // Command-line flags.
119 // This flag may need to be replaced with -f[no-]asan-reads.
120 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
121 cl::desc("instrument read instructions"),
122 cl::Hidden, cl::init(true));
123 static cl::opt<bool> ClInstrumentWrites(
124 "asan-instrument-writes", cl::desc("instrument write instructions"),
125 cl::Hidden, cl::init(true));
126 static cl::opt<bool> ClInstrumentAtomics(
127 "asan-instrument-atomics",
128 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
130 static cl::opt<bool> ClAlwaysSlowPath(
131 "asan-always-slow-path",
132 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
134 // This flag limits the number of instructions to be instrumented
135 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
136 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
138 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
139 "asan-max-ins-per-bb", cl::init(10000),
140 cl::desc("maximal number of instructions to instrument in any given BB"),
142 // This flag may need to be replaced with -f[no]asan-stack.
143 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
144 cl::Hidden, cl::init(true));
145 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
146 cl::desc("Check return-after-free"),
147 cl::Hidden, cl::init(true));
148 // This flag may need to be replaced with -f[no]asan-globals.
149 static cl::opt<bool> ClGlobals("asan-globals",
150 cl::desc("Handle global objects"), cl::Hidden,
152 static cl::opt<bool> ClInitializers("asan-initialization-order",
153 cl::desc("Handle C++ initializer order"),
154 cl::Hidden, cl::init(true));
155 static cl::opt<bool> ClInvalidPointerPairs(
156 "asan-detect-invalid-pointer-pair",
157 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
159 static cl::opt<unsigned> ClRealignStack(
160 "asan-realign-stack",
161 cl::desc("Realign stack to the value of this flag (power of two)"),
162 cl::Hidden, cl::init(32));
163 static cl::opt<int> ClInstrumentationWithCallsThreshold(
164 "asan-instrumentation-with-call-threshold",
166 "If the function being instrumented contains more than "
167 "this number of memory accesses, use callbacks instead of "
168 "inline checks (-1 means never use callbacks)."),
169 cl::Hidden, cl::init(7000));
170 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
171 "asan-memory-access-callback-prefix",
172 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
173 cl::init("__asan_"));
174 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
175 cl::desc("instrument dynamic allocas"),
176 cl::Hidden, cl::init(false));
177 static cl::opt<bool> ClSkipPromotableAllocas(
178 "asan-skip-promotable-allocas",
179 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
182 // These flags allow to change the shadow mapping.
183 // The shadow mapping looks like
184 // Shadow = (Mem >> scale) + (1 << offset_log)
185 static cl::opt<int> ClMappingScale("asan-mapping-scale",
186 cl::desc("scale of asan shadow mapping"),
187 cl::Hidden, cl::init(0));
189 // Optimization flags. Not user visible, used mostly for testing
190 // and benchmarking the tool.
191 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
192 cl::Hidden, cl::init(true));
193 static cl::opt<bool> ClOptSameTemp(
194 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
195 cl::Hidden, cl::init(true));
196 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
197 cl::desc("Don't instrument scalar globals"),
198 cl::Hidden, cl::init(true));
199 static cl::opt<bool> ClOptStack(
200 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
201 cl::Hidden, cl::init(false));
203 static cl::opt<bool> ClCheckLifetime(
204 "asan-check-lifetime",
205 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
208 static cl::opt<bool> ClDynamicAllocaStack(
209 "asan-stack-dynamic-alloca",
210 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
213 static cl::opt<uint32_t> ClForceExperiment(
214 "asan-force-experiment",
215 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
219 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
221 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
222 cl::Hidden, cl::init(0));
223 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
224 cl::desc("Debug func"));
225 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
226 cl::Hidden, cl::init(-1));
227 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
228 cl::Hidden, cl::init(-1));
230 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
231 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
232 STATISTIC(NumInstrumentedDynamicAllocas,
233 "Number of instrumented dynamic allocas");
234 STATISTIC(NumOptimizedAccessesToGlobalVar,
235 "Number of optimized accesses to global vars");
236 STATISTIC(NumOptimizedAccessesToStackVar,
237 "Number of optimized accesses to stack vars");
240 /// Frontend-provided metadata for source location.
241 struct LocationMetadata {
246 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
248 bool empty() const { return Filename.empty(); }
250 void parse(MDNode *MDN) {
251 assert(MDN->getNumOperands() == 3);
252 MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
253 Filename = MDFilename->getString();
255 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
257 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
261 /// Frontend-provided metadata for global variables.
262 class GlobalsMetadata {
265 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
266 LocationMetadata SourceLoc;
272 GlobalsMetadata() : inited_(false) {}
274 void init(Module &M) {
277 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
278 if (!Globals) return;
279 for (auto MDN : Globals->operands()) {
280 // Metadata node contains the global and the fields of "Entry".
281 assert(MDN->getNumOperands() == 5);
282 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
283 // The optimizer may optimize away a global entirely.
285 // We can already have an entry for GV if it was merged with another
287 Entry &E = Entries[GV];
288 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
289 E.SourceLoc.parse(Loc);
290 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
291 E.Name = Name->getString();
292 ConstantInt *IsDynInit =
293 mdconst::extract<ConstantInt>(MDN->getOperand(3));
294 E.IsDynInit |= IsDynInit->isOne();
295 ConstantInt *IsBlacklisted =
296 mdconst::extract<ConstantInt>(MDN->getOperand(4));
297 E.IsBlacklisted |= IsBlacklisted->isOne();
301 /// Returns metadata entry for a given global.
302 Entry get(GlobalVariable *G) const {
303 auto Pos = Entries.find(G);
304 return (Pos != Entries.end()) ? Pos->second : Entry();
309 DenseMap<GlobalVariable *, Entry> Entries;
312 /// This struct defines the shadow mapping using the rule:
313 /// shadow = (mem >> Scale) ADD-or-OR Offset.
314 struct ShadowMapping {
320 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) {
321 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
322 bool IsIOS = TargetTriple.isiOS();
323 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
324 bool IsLinux = TargetTriple.isOSLinux();
325 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
326 TargetTriple.getArch() == llvm::Triple::ppc64le;
327 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
328 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
329 TargetTriple.getArch() == llvm::Triple::mipsel;
330 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
331 TargetTriple.getArch() == llvm::Triple::mips64el;
332 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
333 bool IsWindows = TargetTriple.isOSWindows();
335 ShadowMapping Mapping;
337 if (LongSize == 32) {
341 Mapping.Offset = kMIPS32_ShadowOffset32;
343 Mapping.Offset = kFreeBSD_ShadowOffset32;
345 Mapping.Offset = kIOSShadowOffset32;
347 Mapping.Offset = kWindowsShadowOffset32;
349 Mapping.Offset = kDefaultShadowOffset32;
350 } else { // LongSize == 64
352 Mapping.Offset = kPPC64_ShadowOffset64;
354 Mapping.Offset = kFreeBSD_ShadowOffset64;
355 else if (IsLinux && IsX86_64)
356 Mapping.Offset = kSmallX86_64ShadowOffset;
358 Mapping.Offset = kMIPS64_ShadowOffset64;
360 Mapping.Offset = kAArch64_ShadowOffset64;
362 Mapping.Offset = kDefaultShadowOffset64;
365 Mapping.Scale = kDefaultShadowScale;
366 if (ClMappingScale) {
367 Mapping.Scale = ClMappingScale;
370 // OR-ing shadow offset if more efficient (at least on x86) if the offset
371 // is a power of two, but on ppc64 we have to use add since the shadow
372 // offset is not necessary 1/8-th of the address space.
373 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
378 static size_t RedzoneSizeForScale(int MappingScale) {
379 // Redzone used for stack and globals is at least 32 bytes.
380 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
381 return std::max(32U, 1U << MappingScale);
384 /// AddressSanitizer: instrument the code in module to find memory bugs.
385 struct AddressSanitizer : public FunctionPass {
386 AddressSanitizer() : FunctionPass(ID) {
387 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
389 const char *getPassName() const override {
390 return "AddressSanitizerFunctionPass";
392 void getAnalysisUsage(AnalysisUsage &AU) const override {
393 AU.addRequired<DominatorTreeWrapperPass>();
394 AU.addRequired<TargetLibraryInfoWrapperPass>();
396 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
397 Type *Ty = AI->getAllocatedType();
398 uint64_t SizeInBytes =
399 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
402 /// Check if we want (and can) handle this alloca.
403 bool isInterestingAlloca(AllocaInst &AI) const;
404 /// If it is an interesting memory access, return the PointerOperand
405 /// and set IsWrite/Alignment. Otherwise return nullptr.
406 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
408 unsigned *Alignment) const;
409 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
410 bool UseCalls, const DataLayout &DL);
411 void instrumentPointerComparisonOrSubtraction(Instruction *I);
412 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
413 Value *Addr, uint32_t TypeSize, bool IsWrite,
414 Value *SizeArgument, bool UseCalls, uint32_t Exp);
415 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
416 uint32_t TypeSize, bool IsWrite,
417 Value *SizeArgument, bool UseCalls,
419 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
420 Value *ShadowValue, uint32_t TypeSize);
421 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
422 bool IsWrite, size_t AccessSizeIndex,
423 Value *SizeArgument, uint32_t Exp);
424 void instrumentMemIntrinsic(MemIntrinsic *MI);
425 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
426 bool runOnFunction(Function &F) override;
427 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
428 bool doInitialization(Module &M) override;
429 static char ID; // Pass identification, replacement for typeid
431 DominatorTree &getDominatorTree() const { return *DT; }
434 void initializeCallbacks(Module &M);
436 bool LooksLikeCodeInBug11395(Instruction *I);
437 bool GlobalIsLinkerInitialized(GlobalVariable *G);
438 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
439 uint64_t TypeSize) const;
445 ShadowMapping Mapping;
447 Function *AsanCtorFunction;
448 Function *AsanInitFunction;
449 Function *AsanHandleNoReturnFunc;
450 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
451 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
452 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
453 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
454 // This array is indexed by AccessIsWrite and Experiment.
455 Function *AsanErrorCallbackSized[2][2];
456 Function *AsanMemoryAccessCallbackSized[2][2];
457 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
459 GlobalsMetadata GlobalsMD;
461 friend struct FunctionStackPoisoner;
464 class AddressSanitizerModule : public ModulePass {
466 AddressSanitizerModule() : ModulePass(ID) {}
467 bool runOnModule(Module &M) override;
468 static char ID; // Pass identification, replacement for typeid
469 const char *getPassName() const override { return "AddressSanitizerModule"; }
472 void initializeCallbacks(Module &M);
474 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
475 bool ShouldInstrumentGlobal(GlobalVariable *G);
476 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
477 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
478 size_t MinRedzoneSizeForGlobal() const {
479 return RedzoneSizeForScale(Mapping.Scale);
482 GlobalsMetadata GlobalsMD;
486 ShadowMapping Mapping;
487 Function *AsanPoisonGlobals;
488 Function *AsanUnpoisonGlobals;
489 Function *AsanRegisterGlobals;
490 Function *AsanUnregisterGlobals;
493 // Stack poisoning does not play well with exception handling.
494 // When an exception is thrown, we essentially bypass the code
495 // that unpoisones the stack. This is why the run-time library has
496 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
497 // stack in the interceptor. This however does not work inside the
498 // actual function which catches the exception. Most likely because the
499 // compiler hoists the load of the shadow value somewhere too high.
500 // This causes asan to report a non-existing bug on 453.povray.
501 // It sounds like an LLVM bug.
502 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
504 AddressSanitizer &ASan;
509 ShadowMapping Mapping;
511 SmallVector<AllocaInst *, 16> AllocaVec;
512 SmallVector<Instruction *, 8> RetVec;
513 unsigned StackAlignment;
515 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
516 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
517 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
519 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
520 struct AllocaPoisonCall {
521 IntrinsicInst *InsBefore;
526 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
528 // Stores left and right redzone shadow addresses for dynamic alloca
529 // and pointer to alloca instruction itself.
530 // LeftRzAddr is a shadow address for alloca left redzone.
531 // RightRzAddr is a shadow address for alloca right redzone.
532 struct DynamicAllocaCall {
537 explicit DynamicAllocaCall(AllocaInst *AI, Value *LeftRzAddr = nullptr,
538 Value *RightRzAddr = nullptr)
540 LeftRzAddr(LeftRzAddr),
541 RightRzAddr(RightRzAddr),
544 SmallVector<DynamicAllocaCall, 1> DynamicAllocaVec;
546 // Maps Value to an AllocaInst from which the Value is originated.
547 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
548 AllocaForValueMapTy AllocaForValue;
550 bool HasNonEmptyInlineAsm;
551 std::unique_ptr<CallInst> EmptyInlineAsm;
553 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
556 DIB(*F.getParent(), /*AllowUnresolved*/ false),
558 IntptrTy(ASan.IntptrTy),
559 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
560 Mapping(ASan.Mapping),
561 StackAlignment(1 << Mapping.Scale),
562 HasNonEmptyInlineAsm(false),
563 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
565 bool runOnFunction() {
566 if (!ClStack) return false;
567 // Collect alloca, ret, lifetime instructions etc.
568 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
570 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
572 initializeCallbacks(*F.getParent());
582 // Finds all Alloca instructions and puts
583 // poisoned red zones around all of them.
584 // Then unpoison everything back before the function returns.
587 // ----------------------- Visitors.
588 /// \brief Collect all Ret instructions.
589 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
591 // Unpoison dynamic allocas redzones.
592 void unpoisonDynamicAlloca(DynamicAllocaCall &AllocaCall) {
593 if (!AllocaCall.Poison) return;
594 for (auto Ret : RetVec) {
595 IRBuilder<> IRBRet(Ret);
596 PointerType *Int32PtrTy = PointerType::getUnqual(IRBRet.getInt32Ty());
597 Value *Zero = Constant::getNullValue(IRBRet.getInt32Ty());
598 Value *PartialRzAddr = IRBRet.CreateSub(AllocaCall.RightRzAddr,
599 ConstantInt::get(IntptrTy, 4));
601 Zero, IRBRet.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
602 IRBRet.CreateStore(Zero,
603 IRBRet.CreateIntToPtr(PartialRzAddr, Int32PtrTy));
605 Zero, IRBRet.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
609 // Right shift for BigEndian and left shift for LittleEndian.
610 Value *shiftAllocaMagic(Value *Val, IRBuilder<> &IRB, Value *Shift) {
611 auto &DL = F.getParent()->getDataLayout();
612 return DL.isLittleEndian() ? IRB.CreateShl(Val, Shift)
613 : IRB.CreateLShr(Val, Shift);
616 // Compute PartialRzMagic for dynamic alloca call. Since we don't know the
617 // size of requested memory until runtime, we should compute it dynamically.
618 // If PartialSize is 0, PartialRzMagic would contain kAsanAllocaRightMagic,
619 // otherwise it would contain the value that we will use to poison the
620 // partial redzone for alloca call.
621 Value *computePartialRzMagic(Value *PartialSize, IRBuilder<> &IRB);
623 // Deploy and poison redzones around dynamic alloca call. To do this, we
624 // should replace this call with another one with changed parameters and
625 // replace all its uses with new address, so
626 // addr = alloca type, old_size, align
628 // new_size = (old_size + additional_size) * sizeof(type)
629 // tmp = alloca i8, new_size, max(align, 32)
630 // addr = tmp + 32 (first 32 bytes are for the left redzone).
631 // Additional_size is added to make new memory allocation contain not only
632 // requested memory, but also left, partial and right redzones.
633 // After that, we should poison redzones:
634 // (1) Left redzone with kAsanAllocaLeftMagic.
635 // (2) Partial redzone with the value, computed in runtime by
636 // computePartialRzMagic function.
637 // (3) Right redzone with kAsanAllocaRightMagic.
638 void handleDynamicAllocaCall(DynamicAllocaCall &AllocaCall);
640 /// \brief Collect Alloca instructions we want (and can) handle.
641 void visitAllocaInst(AllocaInst &AI) {
642 if (!ASan.isInterestingAlloca(AI)) return;
644 StackAlignment = std::max(StackAlignment, AI.getAlignment());
645 if (isDynamicAlloca(AI))
646 DynamicAllocaVec.push_back(DynamicAllocaCall(&AI));
648 AllocaVec.push_back(&AI);
651 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
653 void visitIntrinsicInst(IntrinsicInst &II) {
654 if (!ClCheckLifetime) return;
655 Intrinsic::ID ID = II.getIntrinsicID();
656 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
658 // Found lifetime intrinsic, add ASan instrumentation if necessary.
659 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
660 // If size argument is undefined, don't do anything.
661 if (Size->isMinusOne()) return;
662 // Check that size doesn't saturate uint64_t and can
663 // be stored in IntptrTy.
664 const uint64_t SizeValue = Size->getValue().getLimitedValue();
665 if (SizeValue == ~0ULL ||
666 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
668 // Find alloca instruction that corresponds to llvm.lifetime argument.
669 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
671 bool DoPoison = (ID == Intrinsic::lifetime_end);
672 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
673 AllocaPoisonCallVec.push_back(APC);
676 void visitCallInst(CallInst &CI) {
677 HasNonEmptyInlineAsm |=
678 CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get());
681 // ---------------------- Helpers.
682 void initializeCallbacks(Module &M);
684 bool doesDominateAllExits(const Instruction *I) const {
685 for (auto Ret : RetVec) {
686 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
691 bool isDynamicAlloca(AllocaInst &AI) const {
692 return AI.isArrayAllocation() || !AI.isStaticAlloca();
694 /// Finds alloca where the value comes from.
695 AllocaInst *findAllocaForValue(Value *V);
696 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
697 Value *ShadowBase, bool DoPoison);
698 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
700 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
702 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
704 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
705 Instruction *ThenTerm, Value *ValueIfFalse);
710 char AddressSanitizer::ID = 0;
711 INITIALIZE_PASS_BEGIN(
712 AddressSanitizer, "asan",
713 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
715 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
717 AddressSanitizer, "asan",
718 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
720 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
721 return new AddressSanitizer();
724 char AddressSanitizerModule::ID = 0;
726 AddressSanitizerModule, "asan-module",
727 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
730 ModulePass *llvm::createAddressSanitizerModulePass() {
731 return new AddressSanitizerModule();
734 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
735 size_t Res = countTrailingZeros(TypeSize / 8);
736 assert(Res < kNumberOfAccessSizes);
740 // \brief Create a constant for Str so that we can pass it to the run-time lib.
741 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
743 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
744 // We use private linkage for module-local strings. If they can be merged
745 // with another one, we set the unnamed_addr attribute.
747 new GlobalVariable(M, StrConst->getType(), true,
748 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
749 if (AllowMerging) GV->setUnnamedAddr(true);
750 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
754 /// \brief Create a global describing a source location.
755 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
756 LocationMetadata MD) {
757 Constant *LocData[] = {
758 createPrivateGlobalForString(M, MD.Filename, true),
759 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
760 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
762 auto LocStruct = ConstantStruct::getAnon(LocData);
763 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
764 GlobalValue::PrivateLinkage, LocStruct,
766 GV->setUnnamedAddr(true);
770 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
771 return G->getName().find(kAsanGenPrefix) == 0 ||
772 G->getName().find(kSanCovGenPrefix) == 0;
775 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
777 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
778 if (Mapping.Offset == 0) return Shadow;
779 // (Shadow >> scale) | offset
780 if (Mapping.OrShadowOffset)
781 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
783 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
786 // Instrument memset/memmove/memcpy
787 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
789 if (isa<MemTransferInst>(MI)) {
791 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
792 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
793 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
794 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
795 } else if (isa<MemSetInst>(MI)) {
798 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
799 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
800 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
802 MI->eraseFromParent();
805 /// Check if we want (and can) handle this alloca.
806 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) const {
807 return (AI.getAllocatedType()->isSized() &&
808 // alloca() may be called with 0 size, ignore it.
809 getAllocaSizeInBytes(&AI) > 0 &&
810 // We are only interested in allocas not promotable to registers.
811 // Promotable allocas are common under -O0.
812 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)));
815 /// If I is an interesting memory access, return the PointerOperand
816 /// and set IsWrite/Alignment. Otherwise return nullptr.
817 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
820 unsigned *Alignment) const {
821 // Skip memory accesses inserted by another instrumentation.
822 if (I->getMetadata("nosanitize")) return nullptr;
824 Value *PtrOperand = nullptr;
825 const DataLayout &DL = I->getModule()->getDataLayout();
826 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
827 if (!ClInstrumentReads) return nullptr;
829 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
830 *Alignment = LI->getAlignment();
831 PtrOperand = LI->getPointerOperand();
832 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
833 if (!ClInstrumentWrites) return nullptr;
835 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
836 *Alignment = SI->getAlignment();
837 PtrOperand = SI->getPointerOperand();
838 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
839 if (!ClInstrumentAtomics) return nullptr;
841 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
843 PtrOperand = RMW->getPointerOperand();
844 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
845 if (!ClInstrumentAtomics) return nullptr;
847 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
849 PtrOperand = XCHG->getPointerOperand();
852 // Treat memory accesses to promotable allocas as non-interesting since they
853 // will not cause memory violations. This greatly speeds up the instrumented
854 // executable at -O0.
855 if (ClSkipPromotableAllocas)
856 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
857 return isInterestingAlloca(*AI) ? AI : nullptr;
862 static bool isPointerOperand(Value *V) {
863 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
866 // This is a rough heuristic; it may cause both false positives and
867 // false negatives. The proper implementation requires cooperation with
869 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
870 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
871 if (!Cmp->isRelational()) return false;
872 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
873 if (BO->getOpcode() != Instruction::Sub) return false;
877 if (!isPointerOperand(I->getOperand(0)) ||
878 !isPointerOperand(I->getOperand(1)))
883 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
884 // If a global variable does not have dynamic initialization we don't
885 // have to instrument it. However, if a global does not have initializer
886 // at all, we assume it has dynamic initializer (in other TU).
887 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
890 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
893 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
894 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
895 for (int i = 0; i < 2; i++) {
896 if (Param[i]->getType()->isPointerTy())
897 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
899 IRB.CreateCall2(F, Param[0], Param[1]);
902 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
903 Instruction *I, bool UseCalls,
904 const DataLayout &DL) {
905 bool IsWrite = false;
906 unsigned Alignment = 0;
907 uint64_t TypeSize = 0;
908 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
911 // Optimization experiments.
912 // The experiments can be used to evaluate potential optimizations that remove
913 // instrumentation (assess false negatives). Instead of completely removing
914 // some instrumentation, you set Exp to a non-zero value (mask of optimization
915 // experiments that want to remove instrumentation of this instruction).
916 // If Exp is non-zero, this pass will emit special calls into runtime
917 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
918 // make runtime terminate the program in a special way (with a different
919 // exit status). Then you run the new compiler on a buggy corpus, collect
920 // the special terminations (ideally, you don't see them at all -- no false
921 // negatives) and make the decision on the optimization.
922 uint32_t Exp = ClForceExperiment;
924 if (ClOpt && ClOptGlobals) {
925 // If initialization order checking is disabled, a simple access to a
926 // dynamically initialized global is always valid.
927 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
928 if (G != NULL && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
929 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
930 NumOptimizedAccessesToGlobalVar++;
935 if (ClOpt && ClOptStack) {
936 // A direct inbounds access to a stack variable is always valid.
937 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
938 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
939 NumOptimizedAccessesToStackVar++;
945 NumInstrumentedWrites++;
947 NumInstrumentedReads++;
949 unsigned Granularity = 1 << Mapping.Scale;
950 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
951 // if the data is properly aligned.
952 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
954 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
955 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
957 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
961 // Validate the result of Module::getOrInsertFunction called for an interface
962 // function of AddressSanitizer. If the instrumented module defines a function
963 // with the same name, their prototypes must match, otherwise
964 // getOrInsertFunction returns a bitcast.
965 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
966 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
967 FuncOrBitcast->dump();
969 "trying to redefine an AddressSanitizer "
970 "interface function");
973 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
974 Value *Addr, bool IsWrite,
975 size_t AccessSizeIndex,
978 IRBuilder<> IRB(InsertBefore);
979 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
980 CallInst *Call = nullptr;
983 Call = IRB.CreateCall2(AsanErrorCallbackSized[IsWrite][0], Addr,
986 Call = IRB.CreateCall3(AsanErrorCallbackSized[IsWrite][1], Addr,
987 SizeArgument, ExpVal);
991 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
993 Call = IRB.CreateCall2(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
997 // We don't do Call->setDoesNotReturn() because the BB already has
998 // UnreachableInst at the end.
999 // This EmptyAsm is required to avoid callback merge.
1000 IRB.CreateCall(EmptyAsm);
1004 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1006 uint32_t TypeSize) {
1007 size_t Granularity = 1 << Mapping.Scale;
1008 // Addr & (Granularity - 1)
1009 Value *LastAccessedByte =
1010 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1011 // (Addr & (Granularity - 1)) + size - 1
1012 if (TypeSize / 8 > 1)
1013 LastAccessedByte = IRB.CreateAdd(
1014 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1015 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1017 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1018 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1019 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1022 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1023 Instruction *InsertBefore, Value *Addr,
1024 uint32_t TypeSize, bool IsWrite,
1025 Value *SizeArgument, bool UseCalls,
1027 IRBuilder<> IRB(InsertBefore);
1028 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1029 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1033 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1036 IRB.CreateCall2(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1037 AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp));
1042 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1043 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1044 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1045 Value *CmpVal = Constant::getNullValue(ShadowTy);
1046 Value *ShadowValue =
1047 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1049 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1050 size_t Granularity = 1 << Mapping.Scale;
1051 TerminatorInst *CrashTerm = nullptr;
1053 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1054 // We use branch weights for the slow path check, to indicate that the slow
1055 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1056 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1057 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1058 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
1059 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1060 IRB.SetInsertPoint(CheckTerm);
1061 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1062 BasicBlock *CrashBlock =
1063 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1064 CrashTerm = new UnreachableInst(*C, CrashBlock);
1065 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1066 ReplaceInstWithInst(CheckTerm, NewTerm);
1068 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1071 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1072 AccessSizeIndex, SizeArgument, Exp);
1073 Crash->setDebugLoc(OrigIns->getDebugLoc());
1076 // Instrument unusual size or unusual alignment.
1077 // We can not do it with a single check, so we do 1-byte check for the first
1078 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1079 // to report the actual access size.
1080 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1081 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1082 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1084 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1085 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1088 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite][0], AddrLong,
1091 IRB.CreateCall3(AsanMemoryAccessCallbackSized[IsWrite][1], AddrLong, Size,
1092 ConstantInt::get(IRB.getInt32Ty(), Exp));
1094 Value *LastByte = IRB.CreateIntToPtr(
1095 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1097 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1098 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1102 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1103 GlobalValue *ModuleName) {
1104 // Set up the arguments to our poison/unpoison functions.
1105 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1107 // Add a call to poison all external globals before the given function starts.
1108 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1109 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1111 // Add calls to unpoison all globals before each return instruction.
1112 for (auto &BB : GlobalInit.getBasicBlockList())
1113 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1114 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1117 void AddressSanitizerModule::createInitializerPoisonCalls(
1118 Module &M, GlobalValue *ModuleName) {
1119 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1121 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1122 for (Use &OP : CA->operands()) {
1123 if (isa<ConstantAggregateZero>(OP)) continue;
1124 ConstantStruct *CS = cast<ConstantStruct>(OP);
1126 // Must have a function or null ptr.
1127 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1128 if (F->getName() == kAsanModuleCtorName) continue;
1129 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1130 // Don't instrument CTORs that will run before asan.module_ctor.
1131 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1132 poisonOneInitializer(*F, ModuleName);
1137 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1138 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1139 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1141 if (GlobalsMD.get(G).IsBlacklisted) return false;
1142 if (!Ty->isSized()) return false;
1143 if (!G->hasInitializer()) return false;
1144 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1145 // Touch only those globals that will not be defined in other modules.
1146 // Don't handle ODR linkage types and COMDATs since other modules may be built
1148 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1149 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1150 G->getLinkage() != GlobalVariable::InternalLinkage)
1152 if (G->hasComdat()) return false;
1153 // Two problems with thread-locals:
1154 // - The address of the main thread's copy can't be computed at link-time.
1155 // - Need to poison all copies, not just the main thread's one.
1156 if (G->isThreadLocal()) return false;
1157 // For now, just ignore this Global if the alignment is large.
1158 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1160 if (G->hasSection()) {
1161 StringRef Section(G->getSection());
1163 if (TargetTriple.isOSBinFormatMachO()) {
1164 StringRef ParsedSegment, ParsedSection;
1165 unsigned TAA = 0, StubSize = 0;
1167 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1168 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1169 if (!ErrorCode.empty()) {
1170 report_fatal_error("Invalid section specifier '" + ParsedSection +
1171 "': " + ErrorCode + ".");
1174 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1175 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1177 if (ParsedSegment == "__OBJC" ||
1178 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1179 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1182 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1183 // Constant CFString instances are compiled in the following way:
1184 // -- the string buffer is emitted into
1185 // __TEXT,__cstring,cstring_literals
1186 // -- the constant NSConstantString structure referencing that buffer
1187 // is placed into __DATA,__cfstring
1188 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1189 // Moreover, it causes the linker to crash on OS X 10.7
1190 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1191 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1194 // The linker merges the contents of cstring_literals and removes the
1196 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1197 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1202 // Callbacks put into the CRT initializer/terminator sections
1203 // should not be instrumented.
1204 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1205 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1206 if (Section.startswith(".CRT")) {
1207 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1211 // Globals from llvm.metadata aren't emitted, do not instrument them.
1212 if (Section == "llvm.metadata") return false;
1218 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1219 IRBuilder<> IRB(*C);
1220 // Declare our poisoning and unpoisoning functions.
1221 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1222 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1223 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1224 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1225 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1226 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1227 // Declare functions that register/unregister globals.
1228 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1229 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1230 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1231 AsanUnregisterGlobals = checkInterfaceFunction(
1232 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1233 IntptrTy, IntptrTy, nullptr));
1234 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1237 // This function replaces all global variables with new variables that have
1238 // trailing redzones. It also creates a function that poisons
1239 // redzones and inserts this function into llvm.global_ctors.
1240 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1243 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1245 for (auto &G : M.globals()) {
1246 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1249 size_t n = GlobalsToChange.size();
1250 if (n == 0) return false;
1252 // A global is described by a structure
1255 // size_t size_with_redzone;
1256 // const char *name;
1257 // const char *module_name;
1258 // size_t has_dynamic_init;
1259 // void *source_location;
1260 // We initialize an array of such structures and pass it to a run-time call.
1261 StructType *GlobalStructTy =
1262 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1263 IntptrTy, IntptrTy, nullptr);
1264 SmallVector<Constant *, 16> Initializers(n);
1266 bool HasDynamicallyInitializedGlobals = false;
1268 // We shouldn't merge same module names, as this string serves as unique
1269 // module ID in runtime.
1270 GlobalVariable *ModuleName = createPrivateGlobalForString(
1271 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1273 auto &DL = M.getDataLayout();
1274 for (size_t i = 0; i < n; i++) {
1275 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1276 GlobalVariable *G = GlobalsToChange[i];
1278 auto MD = GlobalsMD.get(G);
1279 // Create string holding the global name (use global name from metadata
1280 // if it's available, otherwise just write the name of global variable).
1281 GlobalVariable *Name = createPrivateGlobalForString(
1282 M, MD.Name.empty() ? G->getName() : MD.Name,
1283 /*AllowMerging*/ true);
1285 PointerType *PtrTy = cast<PointerType>(G->getType());
1286 Type *Ty = PtrTy->getElementType();
1287 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1288 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1289 // MinRZ <= RZ <= kMaxGlobalRedzone
1290 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1291 uint64_t RZ = std::max(
1292 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1293 uint64_t RightRedzoneSize = RZ;
1294 // Round up to MinRZ
1295 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1296 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1297 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1299 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1300 Constant *NewInitializer =
1301 ConstantStruct::get(NewTy, G->getInitializer(),
1302 Constant::getNullValue(RightRedZoneTy), nullptr);
1304 // Create a new global variable with enough space for a redzone.
1305 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1306 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1307 Linkage = GlobalValue::InternalLinkage;
1308 GlobalVariable *NewGlobal =
1309 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1310 "", G, G->getThreadLocalMode());
1311 NewGlobal->copyAttributesFrom(G);
1312 NewGlobal->setAlignment(MinRZ);
1315 Indices2[0] = IRB.getInt32(0);
1316 Indices2[1] = IRB.getInt32(0);
1318 G->replaceAllUsesWith(
1319 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1320 NewGlobal->takeName(G);
1321 G->eraseFromParent();
1323 Constant *SourceLoc;
1324 if (!MD.SourceLoc.empty()) {
1325 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1326 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1328 SourceLoc = ConstantInt::get(IntptrTy, 0);
1331 Initializers[i] = ConstantStruct::get(
1332 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1333 ConstantInt::get(IntptrTy, SizeInBytes),
1334 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1335 ConstantExpr::getPointerCast(Name, IntptrTy),
1336 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1337 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1339 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1341 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1344 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1345 GlobalVariable *AllGlobals = new GlobalVariable(
1346 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1347 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1349 // Create calls for poisoning before initializers run and unpoisoning after.
1350 if (HasDynamicallyInitializedGlobals)
1351 createInitializerPoisonCalls(M, ModuleName);
1352 IRB.CreateCall2(AsanRegisterGlobals,
1353 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1354 ConstantInt::get(IntptrTy, n));
1356 // We also need to unregister globals at the end, e.g. when a shared library
1358 Function *AsanDtorFunction =
1359 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1360 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1361 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1362 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1363 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1364 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1365 ConstantInt::get(IntptrTy, n));
1366 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1372 bool AddressSanitizerModule::runOnModule(Module &M) {
1373 C = &(M.getContext());
1374 int LongSize = M.getDataLayout().getPointerSizeInBits();
1375 IntptrTy = Type::getIntNTy(*C, LongSize);
1376 TargetTriple = Triple(M.getTargetTriple());
1377 Mapping = getShadowMapping(TargetTriple, LongSize);
1378 initializeCallbacks(M);
1380 bool Changed = false;
1382 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1384 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1386 if (ClGlobals) Changed |= InstrumentGlobals(IRB, M);
1391 void AddressSanitizer::initializeCallbacks(Module &M) {
1392 IRBuilder<> IRB(*C);
1393 // Create __asan_report* callbacks.
1394 // IsWrite, TypeSize and Exp are encoded in the function name.
1395 for (int Exp = 0; Exp < 2; Exp++) {
1396 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1397 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1398 const std::string ExpStr = Exp ? "exp_" : "";
1399 const Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1400 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1401 checkInterfaceFunction(M.getOrInsertFunction(
1402 kAsanReportErrorTemplate + ExpStr + TypeStr + "_n",
1403 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1404 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1405 checkInterfaceFunction(M.getOrInsertFunction(
1406 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N",
1407 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1408 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1409 AccessSizeIndex++) {
1410 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1411 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1412 checkInterfaceFunction(M.getOrInsertFunction(
1413 kAsanReportErrorTemplate + ExpStr + Suffix, IRB.getVoidTy(),
1414 IntptrTy, ExpType, nullptr));
1415 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1416 checkInterfaceFunction(M.getOrInsertFunction(
1417 ClMemoryAccessCallbackPrefix + ExpStr + Suffix, IRB.getVoidTy(),
1418 IntptrTy, ExpType, nullptr));
1423 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1424 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1425 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1426 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1427 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1428 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1429 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1430 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1431 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1433 AsanHandleNoReturnFunc = checkInterfaceFunction(
1434 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1436 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1437 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1438 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1439 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1440 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1441 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1442 StringRef(""), StringRef(""),
1443 /*hasSideEffects=*/true);
1447 bool AddressSanitizer::doInitialization(Module &M) {
1448 // Initialize the private fields. No one has accessed them before.
1452 C = &(M.getContext());
1453 LongSize = M.getDataLayout().getPointerSizeInBits();
1454 IntptrTy = Type::getIntNTy(*C, LongSize);
1455 TargetTriple = Triple(M.getTargetTriple());
1458 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1459 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1460 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1461 // call __asan_init in the module ctor.
1462 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1463 AsanInitFunction = checkInterfaceFunction(
1464 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr));
1465 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1466 IRB.CreateCall(AsanInitFunction);
1468 Mapping = getShadowMapping(TargetTriple, LongSize);
1470 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1474 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1475 // For each NSObject descendant having a +load method, this method is invoked
1476 // by the ObjC runtime before any of the static constructors is called.
1477 // Therefore we need to instrument such methods with a call to __asan_init
1478 // at the beginning in order to initialize our runtime before any access to
1479 // the shadow memory.
1480 // We cannot just ignore these methods, because they may call other
1481 // instrumented functions.
1482 if (F.getName().find(" load]") != std::string::npos) {
1483 IRBuilder<> IRB(F.begin()->begin());
1484 IRB.CreateCall(AsanInitFunction);
1490 bool AddressSanitizer::runOnFunction(Function &F) {
1491 if (&F == AsanCtorFunction) return false;
1492 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1493 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1494 initializeCallbacks(*F.getParent());
1496 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1498 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1499 maybeInsertAsanInitAtFunctionEntry(F);
1501 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1503 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1505 // We want to instrument every address only once per basic block (unless there
1506 // are calls between uses).
1507 SmallSet<Value *, 16> TempsToInstrument;
1508 SmallVector<Instruction *, 16> ToInstrument;
1509 SmallVector<Instruction *, 8> NoReturnCalls;
1510 SmallVector<BasicBlock *, 16> AllBlocks;
1511 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1517 // Fill the set of memory operations to instrument.
1518 for (auto &BB : F) {
1519 AllBlocks.push_back(&BB);
1520 TempsToInstrument.clear();
1521 int NumInsnsPerBB = 0;
1522 for (auto &Inst : BB) {
1523 if (LooksLikeCodeInBug11395(&Inst)) return false;
1524 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1526 if (ClOpt && ClOptSameTemp) {
1527 if (!TempsToInstrument.insert(Addr).second)
1528 continue; // We've seen this temp in the current BB.
1530 } else if (ClInvalidPointerPairs &&
1531 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1532 PointerComparisonsOrSubtracts.push_back(&Inst);
1534 } else if (isa<MemIntrinsic>(Inst)) {
1537 if (isa<AllocaInst>(Inst)) NumAllocas++;
1540 // A call inside BB.
1541 TempsToInstrument.clear();
1542 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1546 ToInstrument.push_back(&Inst);
1548 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1552 bool UseCalls = false;
1553 if (ClInstrumentationWithCallsThreshold >= 0 &&
1554 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1557 const TargetLibraryInfo *TLI =
1558 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1559 const DataLayout &DL = F.getParent()->getDataLayout();
1560 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1561 /*RoundToAlign=*/true);
1564 int NumInstrumented = 0;
1565 for (auto Inst : ToInstrument) {
1566 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1567 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1568 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1569 instrumentMop(ObjSizeVis, Inst, UseCalls,
1570 F.getParent()->getDataLayout());
1572 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1577 FunctionStackPoisoner FSP(F, *this);
1578 bool ChangedStack = FSP.runOnFunction();
1580 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1581 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1582 for (auto CI : NoReturnCalls) {
1583 IRBuilder<> IRB(CI);
1584 IRB.CreateCall(AsanHandleNoReturnFunc);
1587 for (auto Inst : PointerComparisonsOrSubtracts) {
1588 instrumentPointerComparisonOrSubtraction(Inst);
1592 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1594 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1599 // Workaround for bug 11395: we don't want to instrument stack in functions
1600 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1601 // FIXME: remove once the bug 11395 is fixed.
1602 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1603 if (LongSize != 32) return false;
1604 CallInst *CI = dyn_cast<CallInst>(I);
1605 if (!CI || !CI->isInlineAsm()) return false;
1606 if (CI->getNumArgOperands() <= 5) return false;
1607 // We have inline assembly with quite a few arguments.
1611 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1612 IRBuilder<> IRB(*C);
1613 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1614 std::string Suffix = itostr(i);
1615 AsanStackMallocFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1616 kAsanStackMallocNameTemplate + Suffix, IntptrTy, IntptrTy, nullptr));
1617 AsanStackFreeFunc[i] = checkInterfaceFunction(
1618 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1619 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1621 AsanPoisonStackMemoryFunc = checkInterfaceFunction(
1622 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1623 IntptrTy, IntptrTy, nullptr));
1624 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(
1625 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1626 IntptrTy, IntptrTy, nullptr));
1629 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1630 IRBuilder<> &IRB, Value *ShadowBase,
1632 size_t n = ShadowBytes.size();
1634 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1635 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1636 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1637 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1638 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1639 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1641 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1642 if (F.getParent()->getDataLayout().isLittleEndian())
1643 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1645 Val = (Val << 8) | ShadowBytes[i + j];
1648 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1649 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1650 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1651 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1656 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1657 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1658 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1659 assert(LocalStackSize <= kMaxStackMallocSize);
1660 uint64_t MaxSize = kMinStackMallocSize;
1661 for (int i = 0;; i++, MaxSize *= 2)
1662 if (LocalStackSize <= MaxSize) return i;
1663 llvm_unreachable("impossible LocalStackSize");
1666 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1667 // We can not use MemSet intrinsic because it may end up calling the actual
1668 // memset. Size is a multiple of 8.
1669 // Currently this generates 8-byte stores on x86_64; it may be better to
1670 // generate wider stores.
1671 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1672 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1673 assert(!(Size % 8));
1675 // kAsanStackAfterReturnMagic is 0xf5.
1676 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1678 for (int i = 0; i < Size; i += 8) {
1679 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1681 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1682 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1686 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1687 for (const auto &Inst : F.getEntryBlock())
1688 if (!isa<AllocaInst>(Inst)) return Inst.getDebugLoc();
1692 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1694 Instruction *ThenTerm,
1695 Value *ValueIfFalse) {
1696 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1697 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1698 PHI->addIncoming(ValueIfFalse, CondBlock);
1699 BasicBlock *ThenBlock = ThenTerm->getParent();
1700 PHI->addIncoming(ValueIfTrue, ThenBlock);
1704 Value *FunctionStackPoisoner::createAllocaForLayout(
1705 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1708 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1709 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1712 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1713 nullptr, "MyAlloca");
1714 assert(Alloca->isStaticAlloca());
1716 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1717 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1718 Alloca->setAlignment(FrameAlignment);
1719 return IRB.CreatePointerCast(Alloca, IntptrTy);
1722 void FunctionStackPoisoner::poisonStack() {
1723 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1725 if (ClInstrumentAllocas) {
1726 // Handle dynamic allocas.
1727 for (auto &AllocaCall : DynamicAllocaVec) {
1728 handleDynamicAllocaCall(AllocaCall);
1729 unpoisonDynamicAlloca(AllocaCall);
1733 if (AllocaVec.size() == 0) return;
1735 int StackMallocIdx = -1;
1736 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1738 Instruction *InsBefore = AllocaVec[0];
1739 IRBuilder<> IRB(InsBefore);
1740 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1742 SmallVector<ASanStackVariableDescription, 16> SVD;
1743 SVD.reserve(AllocaVec.size());
1744 for (AllocaInst *AI : AllocaVec) {
1745 ASanStackVariableDescription D = {AI->getName().data(),
1746 ASan.getAllocaSizeInBytes(AI),
1747 AI->getAlignment(), AI, 0};
1750 // Minimal header size (left redzone) is 4 pointers,
1751 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1752 size_t MinHeaderSize = ASan.LongSize / 2;
1753 ASanStackFrameLayout L;
1754 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1755 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1756 uint64_t LocalStackSize = L.FrameSize;
1757 bool DoStackMalloc =
1758 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1759 // Don't do dynamic alloca in presence of inline asm: too often it
1760 // makes assumptions on which registers are available.
1761 bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
1763 Value *StaticAlloca =
1764 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1767 Value *LocalStackBase;
1769 if (DoStackMalloc) {
1770 // void *FakeStack = __asan_option_detect_stack_use_after_return
1771 // ? __asan_stack_malloc_N(LocalStackSize)
1773 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1774 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1775 kAsanOptionDetectUAR, IRB.getInt32Ty());
1776 Value *UARIsEnabled =
1777 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1778 Constant::getNullValue(IRB.getInt32Ty()));
1780 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1781 IRBuilder<> IRBIf(Term);
1782 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1783 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1784 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1785 Value *FakeStackValue =
1786 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1787 ConstantInt::get(IntptrTy, LocalStackSize));
1788 IRB.SetInsertPoint(InsBefore);
1789 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1790 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1791 ConstantInt::get(IntptrTy, 0));
1793 Value *NoFakeStack =
1794 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1795 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1796 IRBIf.SetInsertPoint(Term);
1797 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1798 Value *AllocaValue =
1799 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1800 IRB.SetInsertPoint(InsBefore);
1801 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1802 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1804 // void *FakeStack = nullptr;
1805 // void *LocalStackBase = alloca(LocalStackSize);
1806 FakeStack = ConstantInt::get(IntptrTy, 0);
1808 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1811 // Insert poison calls for lifetime intrinsics for alloca.
1812 bool HavePoisonedAllocas = false;
1813 for (const auto &APC : AllocaPoisonCallVec) {
1814 assert(APC.InsBefore);
1816 IRBuilder<> IRB(APC.InsBefore);
1817 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1818 HavePoisonedAllocas |= APC.DoPoison;
1821 // Replace Alloca instructions with base+offset.
1822 for (const auto &Desc : SVD) {
1823 AllocaInst *AI = Desc.AI;
1824 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1825 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1827 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1828 AI->replaceAllUsesWith(NewAllocaPtr);
1831 // The left-most redzone has enough space for at least 4 pointers.
1832 // Write the Magic value to redzone[0].
1833 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1834 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1836 // Write the frame description constant to redzone[1].
1837 Value *BasePlus1 = IRB.CreateIntToPtr(
1838 IRB.CreateAdd(LocalStackBase,
1839 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1841 GlobalVariable *StackDescriptionGlobal =
1842 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1843 /*AllowMerging*/ true);
1844 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1845 IRB.CreateStore(Description, BasePlus1);
1846 // Write the PC to redzone[2].
1847 Value *BasePlus2 = IRB.CreateIntToPtr(
1848 IRB.CreateAdd(LocalStackBase,
1849 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1851 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1853 // Poison the stack redzones at the entry.
1854 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1855 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1857 // (Un)poison the stack before all ret instructions.
1858 for (auto Ret : RetVec) {
1859 IRBuilder<> IRBRet(Ret);
1860 // Mark the current frame as retired.
1861 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1863 if (DoStackMalloc) {
1864 assert(StackMallocIdx >= 0);
1865 // if FakeStack != 0 // LocalStackBase == FakeStack
1866 // // In use-after-return mode, poison the whole stack frame.
1867 // if StackMallocIdx <= 4
1868 // // For small sizes inline the whole thing:
1869 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1870 // **SavedFlagPtr(FakeStack) = 0
1872 // __asan_stack_free_N(FakeStack, LocalStackSize)
1874 // <This is not a fake stack; unpoison the redzones>
1876 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1877 TerminatorInst *ThenTerm, *ElseTerm;
1878 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1880 IRBuilder<> IRBPoison(ThenTerm);
1881 if (StackMallocIdx <= 4) {
1882 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1883 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1884 ClassSize >> Mapping.Scale);
1885 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1887 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1888 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1889 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1890 IRBPoison.CreateStore(
1891 Constant::getNullValue(IRBPoison.getInt8Ty()),
1892 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1894 // For larger frames call __asan_stack_free_*.
1895 IRBPoison.CreateCall2(AsanStackFreeFunc[StackMallocIdx], FakeStack,
1896 ConstantInt::get(IntptrTy, LocalStackSize));
1899 IRBuilder<> IRBElse(ElseTerm);
1900 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1901 } else if (HavePoisonedAllocas) {
1902 // If we poisoned some allocas in llvm.lifetime analysis,
1903 // unpoison whole stack frame now.
1904 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1906 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1910 // We are done. Remove the old unused alloca instructions.
1911 for (auto AI : AllocaVec) AI->eraseFromParent();
1914 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1915 IRBuilder<> &IRB, bool DoPoison) {
1916 // For now just insert the call to ASan runtime.
1917 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1918 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1920 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
1924 // Handling llvm.lifetime intrinsics for a given %alloca:
1925 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1926 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1927 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1928 // could be poisoned by previous llvm.lifetime.end instruction, as the
1929 // variable may go in and out of scope several times, e.g. in loops).
1930 // (3) if we poisoned at least one %alloca in a function,
1931 // unpoison the whole stack frame at function exit.
1933 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1934 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1935 // We're intested only in allocas we can handle.
1936 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
1937 // See if we've already calculated (or started to calculate) alloca for a
1939 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1940 if (I != AllocaForValue.end()) return I->second;
1941 // Store 0 while we're calculating alloca for value V to avoid
1942 // infinite recursion if the value references itself.
1943 AllocaForValue[V] = nullptr;
1944 AllocaInst *Res = nullptr;
1945 if (CastInst *CI = dyn_cast<CastInst>(V))
1946 Res = findAllocaForValue(CI->getOperand(0));
1947 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1948 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1949 Value *IncValue = PN->getIncomingValue(i);
1950 // Allow self-referencing phi-nodes.
1951 if (IncValue == PN) continue;
1952 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1953 // AI for incoming values should exist and should all be equal.
1954 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1959 if (Res) AllocaForValue[V] = Res;
1963 // Compute PartialRzMagic for dynamic alloca call. PartialRzMagic is
1964 // constructed from two separate 32-bit numbers: PartialRzMagic = Val1 | Val2.
1965 // (1) Val1 is resposible for forming base value for PartialRzMagic, containing
1966 // only 00 for fully addressable and 0xcb for fully poisoned bytes for each
1967 // 8-byte chunk of user memory respectively.
1968 // (2) Val2 forms the value for marking first poisoned byte in shadow memory
1969 // with appropriate value (0x01 - 0x07 or 0xcb if Padding % 8 == 0).
1971 // Shift = Padding & ~7; // the number of bits we need to shift to access first
1972 // chunk in shadow memory, containing nonzero bytes.
1974 // Padding = 21 Padding = 16
1975 // Shadow: |00|00|05|cb| Shadow: |00|00|cb|cb|
1978 // Shift = 21 & ~7 = 16 Shift = 16 & ~7 = 16
1980 // Val1 = 0xcbcbcbcb << Shift;
1981 // PartialBits = Padding ? Padding & 7 : 0xcb;
1982 // Val2 = PartialBits << Shift;
1983 // Result = Val1 | Val2;
1984 Value *FunctionStackPoisoner::computePartialRzMagic(Value *PartialSize,
1986 PartialSize = IRB.CreateIntCast(PartialSize, IRB.getInt32Ty(), false);
1987 Value *Shift = IRB.CreateAnd(PartialSize, IRB.getInt32(~7));
1988 unsigned Val1Int = kAsanAllocaPartialVal1;
1989 unsigned Val2Int = kAsanAllocaPartialVal2;
1990 if (!F.getParent()->getDataLayout().isLittleEndian()) {
1991 Val1Int = sys::getSwappedBytes(Val1Int);
1992 Val2Int = sys::getSwappedBytes(Val2Int);
1994 Value *Val1 = shiftAllocaMagic(IRB.getInt32(Val1Int), IRB, Shift);
1995 Value *PartialBits = IRB.CreateAnd(PartialSize, IRB.getInt32(7));
1996 // For BigEndian get 0x000000YZ -> 0xYZ000000.
1997 if (F.getParent()->getDataLayout().isBigEndian())
1998 PartialBits = IRB.CreateShl(PartialBits, IRB.getInt32(24));
1999 Value *Val2 = IRB.getInt32(Val2Int);
2001 IRB.CreateICmpNE(PartialBits, Constant::getNullValue(IRB.getInt32Ty()));
2002 Val2 = IRB.CreateSelect(Cond, shiftAllocaMagic(PartialBits, IRB, Shift),
2003 shiftAllocaMagic(Val2, IRB, Shift));
2004 return IRB.CreateOr(Val1, Val2);
2007 void FunctionStackPoisoner::handleDynamicAllocaCall(
2008 DynamicAllocaCall &AllocaCall) {
2009 AllocaInst *AI = AllocaCall.AI;
2010 if (!doesDominateAllExits(AI)) {
2011 // We do not yet handle complex allocas
2012 AllocaCall.Poison = false;
2016 IRBuilder<> IRB(AI);
2018 PointerType *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
2019 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2020 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2022 Value *Zero = Constant::getNullValue(IntptrTy);
2023 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2024 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2025 Value *NotAllocaRzMask = ConstantInt::get(IntptrTy, ~AllocaRedzoneMask);
2027 // Since we need to extend alloca with additional memory to locate
2028 // redzones, and OldSize is number of allocated blocks with
2029 // ElementSize size, get allocated memory size in bytes by
2030 // OldSize * ElementSize.
2031 unsigned ElementSize =
2032 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2033 Value *OldSize = IRB.CreateMul(AI->getArraySize(),
2034 ConstantInt::get(IntptrTy, ElementSize));
2036 // PartialSize = OldSize % 32
2037 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2039 // Misalign = kAllocaRzSize - PartialSize;
2040 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2042 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2043 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2044 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2046 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2047 // Align is added to locate left redzone, PartialPadding for possible
2048 // partial redzone and kAllocaRzSize for right redzone respectively.
2049 Value *AdditionalChunkSize = IRB.CreateAdd(
2050 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2052 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2054 // Insert new alloca with new NewSize and Align params.
2055 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2056 NewAlloca->setAlignment(Align);
2058 // NewAddress = Address + Align
2059 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2060 ConstantInt::get(IntptrTy, Align));
2062 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2064 // LeftRzAddress = NewAddress - kAllocaRzSize
2065 Value *LeftRzAddress = IRB.CreateSub(NewAddress, AllocaRzSize);
2067 // Poisoning left redzone.
2068 AllocaCall.LeftRzAddr = ASan.memToShadow(LeftRzAddress, IRB);
2069 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaLeftMagic),
2070 IRB.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
2072 // PartialRzAligned = PartialRzAddr & ~AllocaRzMask
2073 Value *PartialRzAddr = IRB.CreateAdd(NewAddress, OldSize);
2074 Value *PartialRzAligned = IRB.CreateAnd(PartialRzAddr, NotAllocaRzMask);
2076 // Poisoning partial redzone.
2077 Value *PartialRzMagic = computePartialRzMagic(PartialSize, IRB);
2078 Value *PartialRzShadowAddr = ASan.memToShadow(PartialRzAligned, IRB);
2079 IRB.CreateStore(PartialRzMagic,
2080 IRB.CreateIntToPtr(PartialRzShadowAddr, Int32PtrTy));
2083 // = (PartialRzAddr + AllocaRzMask) & ~AllocaRzMask
2084 Value *RightRzAddress = IRB.CreateAnd(
2085 IRB.CreateAdd(PartialRzAddr, AllocaRzMask), NotAllocaRzMask);
2087 // Poisoning right redzone.
2088 AllocaCall.RightRzAddr = ASan.memToShadow(RightRzAddress, IRB);
2089 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaRightMagic),
2090 IRB.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
2092 // Replace all uses of AddessReturnedByAlloca with NewAddress.
2093 AI->replaceAllUsesWith(NewAddressPtr);
2095 // We are done. Erase old alloca and store left, partial and right redzones
2096 // shadow addresses for future unpoisoning.
2097 AI->eraseFromParent();
2098 NumInstrumentedDynamicAllocas++;
2101 // isSafeAccess returns true if Addr is always inbounds with respect to its
2102 // base object. For example, it is a field access or an array access with
2103 // constant inbounds index.
2104 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2105 Value *Addr, uint64_t TypeSize) const {
2106 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2107 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2108 uint64_t Size = SizeOffset.first.getZExtValue();
2109 int64_t Offset = SizeOffset.second.getSExtValue();
2110 // Three checks are required to ensure safety:
2111 // . Offset >= 0 (since the offset is given from the base ptr)
2112 // . Size >= Offset (unsigned)
2113 // . Size - Offset >= NeededSize (unsigned)
2114 return Offset >= 0 && Size >= uint64_t(Offset) &&
2115 Size - uint64_t(Offset) >= TypeSize / 8;