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/SetVector.h"
22 #include "llvm/ADT/SmallSet.h"
23 #include "llvm/ADT/SmallString.h"
24 #include "llvm/ADT/SmallVector.h"
25 #include "llvm/ADT/Statistic.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/ADT/Triple.h"
28 #include "llvm/Analysis/MemoryBuiltins.h"
29 #include "llvm/Analysis/TargetLibraryInfo.h"
30 #include "llvm/Analysis/ValueTracking.h"
31 #include "llvm/IR/CallSite.h"
32 #include "llvm/IR/DIBuilder.h"
33 #include "llvm/IR/DataLayout.h"
34 #include "llvm/IR/Dominators.h"
35 #include "llvm/IR/Function.h"
36 #include "llvm/IR/IRBuilder.h"
37 #include "llvm/IR/InlineAsm.h"
38 #include "llvm/IR/InstVisitor.h"
39 #include "llvm/IR/IntrinsicInst.h"
40 #include "llvm/IR/LLVMContext.h"
41 #include "llvm/IR/MDBuilder.h"
42 #include "llvm/IR/Module.h"
43 #include "llvm/IR/Type.h"
44 #include "llvm/MC/MCSectionMachO.h"
45 #include "llvm/Support/CommandLine.h"
46 #include "llvm/Support/DataTypes.h"
47 #include "llvm/Support/Debug.h"
48 #include "llvm/Support/Endian.h"
49 #include "llvm/Support/SwapByteOrder.h"
50 #include "llvm/Support/raw_ostream.h"
51 #include "llvm/Transforms/Scalar.h"
52 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
53 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
54 #include "llvm/Transforms/Utils/Cloning.h"
55 #include "llvm/Transforms/Utils/Local.h"
56 #include "llvm/Transforms/Utils/ModuleUtils.h"
57 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
60 #include <system_error>
64 #define DEBUG_TYPE "asan"
66 static const uint64_t kDefaultShadowScale = 3;
67 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
68 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
69 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
70 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
71 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
72 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
73 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
74 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
75 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
76 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
77 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
78 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
80 static const size_t kMinStackMallocSize = 1 << 6; // 64B
81 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
82 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
83 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
85 static const char *const kAsanModuleCtorName = "asan.module_ctor";
86 static const char *const kAsanModuleDtorName = "asan.module_dtor";
87 static const uint64_t kAsanCtorAndDtorPriority = 1;
88 static const char *const kAsanReportErrorTemplate = "__asan_report_";
89 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
90 static const char *const kAsanUnregisterGlobalsName =
91 "__asan_unregister_globals";
92 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
93 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
94 static const char *const kAsanInitName = "__asan_init";
95 static const char *const kAsanVersionCheckName =
96 "__asan_version_mismatch_check_v6";
97 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
98 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
99 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
100 static const int kMaxAsanStackMallocSizeClass = 10;
101 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
102 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
103 static const char *const kAsanGenPrefix = "__asan_gen_";
104 static const char *const kSanCovGenPrefix = "__sancov_gen_";
105 static const char *const kAsanPoisonStackMemoryName =
106 "__asan_poison_stack_memory";
107 static const char *const kAsanUnpoisonStackMemoryName =
108 "__asan_unpoison_stack_memory";
110 static const char *const kAsanOptionDetectUAR =
111 "__asan_option_detect_stack_use_after_return";
113 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
114 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
116 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
117 static const size_t kNumberOfAccessSizes = 5;
119 static const unsigned kAllocaRzSize = 32;
121 // Command-line flags.
122 static cl::opt<bool> ClEnableKasan(
123 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
124 cl::Hidden, cl::init(false));
125 static cl::opt<bool> ClRecover(
127 cl::desc("Enable recovery mode (continue-after-error)."),
128 cl::Hidden, cl::init(false));
130 // This flag may need to be replaced with -f[no-]asan-reads.
131 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
132 cl::desc("instrument read instructions"),
133 cl::Hidden, cl::init(true));
134 static cl::opt<bool> ClInstrumentWrites(
135 "asan-instrument-writes", cl::desc("instrument write instructions"),
136 cl::Hidden, cl::init(true));
137 static cl::opt<bool> ClInstrumentAtomics(
138 "asan-instrument-atomics",
139 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
141 static cl::opt<bool> ClAlwaysSlowPath(
142 "asan-always-slow-path",
143 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
145 // This flag limits the number of instructions to be instrumented
146 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
147 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
149 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
150 "asan-max-ins-per-bb", cl::init(10000),
151 cl::desc("maximal number of instructions to instrument in any given BB"),
153 // This flag may need to be replaced with -f[no]asan-stack.
154 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
155 cl::Hidden, cl::init(true));
156 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
157 cl::desc("Check return-after-free"),
158 cl::Hidden, cl::init(true));
159 // This flag may need to be replaced with -f[no]asan-globals.
160 static cl::opt<bool> ClGlobals("asan-globals",
161 cl::desc("Handle global objects"), cl::Hidden,
163 static cl::opt<bool> ClInitializers("asan-initialization-order",
164 cl::desc("Handle C++ initializer order"),
165 cl::Hidden, cl::init(true));
166 static cl::opt<bool> ClInvalidPointerPairs(
167 "asan-detect-invalid-pointer-pair",
168 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
170 static cl::opt<unsigned> ClRealignStack(
171 "asan-realign-stack",
172 cl::desc("Realign stack to the value of this flag (power of two)"),
173 cl::Hidden, cl::init(32));
174 static cl::opt<int> ClInstrumentationWithCallsThreshold(
175 "asan-instrumentation-with-call-threshold",
177 "If the function being instrumented contains more than "
178 "this number of memory accesses, use callbacks instead of "
179 "inline checks (-1 means never use callbacks)."),
180 cl::Hidden, cl::init(7000));
181 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
182 "asan-memory-access-callback-prefix",
183 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
184 cl::init("__asan_"));
185 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
186 cl::desc("instrument dynamic allocas"),
187 cl::Hidden, cl::init(true));
188 static cl::opt<bool> ClSkipPromotableAllocas(
189 "asan-skip-promotable-allocas",
190 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
193 // These flags allow to change the shadow mapping.
194 // The shadow mapping looks like
195 // Shadow = (Mem >> scale) + (1 << offset_log)
196 static cl::opt<int> ClMappingScale("asan-mapping-scale",
197 cl::desc("scale of asan shadow mapping"),
198 cl::Hidden, cl::init(0));
200 // Optimization flags. Not user visible, used mostly for testing
201 // and benchmarking the tool.
202 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
203 cl::Hidden, cl::init(true));
204 static cl::opt<bool> ClOptSameTemp(
205 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
206 cl::Hidden, cl::init(true));
207 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
208 cl::desc("Don't instrument scalar globals"),
209 cl::Hidden, cl::init(true));
210 static cl::opt<bool> ClOptStack(
211 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
212 cl::Hidden, cl::init(false));
214 static cl::opt<bool> ClCheckLifetime(
215 "asan-check-lifetime",
216 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
219 static cl::opt<bool> ClDynamicAllocaStack(
220 "asan-stack-dynamic-alloca",
221 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
224 static cl::opt<uint32_t> ClForceExperiment(
225 "asan-force-experiment",
226 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
230 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
232 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
233 cl::Hidden, cl::init(0));
234 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
235 cl::desc("Debug func"));
236 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
237 cl::Hidden, cl::init(-1));
238 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
239 cl::Hidden, cl::init(-1));
241 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
242 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
243 STATISTIC(NumOptimizedAccessesToGlobalVar,
244 "Number of optimized accesses to global vars");
245 STATISTIC(NumOptimizedAccessesToStackVar,
246 "Number of optimized accesses to stack vars");
249 /// Frontend-provided metadata for source location.
250 struct LocationMetadata {
255 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
257 bool empty() const { return Filename.empty(); }
259 void parse(MDNode *MDN) {
260 assert(MDN->getNumOperands() == 3);
261 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
262 Filename = DIFilename->getString();
264 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
266 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
270 /// Frontend-provided metadata for global variables.
271 class GlobalsMetadata {
274 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
275 LocationMetadata SourceLoc;
281 GlobalsMetadata() : inited_(false) {}
283 void init(Module &M) {
286 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
287 if (!Globals) return;
288 for (auto MDN : Globals->operands()) {
289 // Metadata node contains the global and the fields of "Entry".
290 assert(MDN->getNumOperands() == 5);
291 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
292 // The optimizer may optimize away a global entirely.
294 // We can already have an entry for GV if it was merged with another
296 Entry &E = Entries[GV];
297 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
298 E.SourceLoc.parse(Loc);
299 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
300 E.Name = Name->getString();
301 ConstantInt *IsDynInit =
302 mdconst::extract<ConstantInt>(MDN->getOperand(3));
303 E.IsDynInit |= IsDynInit->isOne();
304 ConstantInt *IsBlacklisted =
305 mdconst::extract<ConstantInt>(MDN->getOperand(4));
306 E.IsBlacklisted |= IsBlacklisted->isOne();
310 /// Returns metadata entry for a given global.
311 Entry get(GlobalVariable *G) const {
312 auto Pos = Entries.find(G);
313 return (Pos != Entries.end()) ? Pos->second : Entry();
318 DenseMap<GlobalVariable *, Entry> Entries;
321 /// This struct defines the shadow mapping using the rule:
322 /// shadow = (mem >> Scale) ADD-or-OR Offset.
323 struct ShadowMapping {
329 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
331 bool IsAndroid = TargetTriple.isAndroid();
332 bool IsIOS = TargetTriple.isiOS();
333 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
334 bool IsLinux = TargetTriple.isOSLinux();
335 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
336 TargetTriple.getArch() == llvm::Triple::ppc64le;
337 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
338 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
339 TargetTriple.getArch() == llvm::Triple::mipsel;
340 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
341 TargetTriple.getArch() == llvm::Triple::mips64el;
342 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
343 bool IsWindows = TargetTriple.isOSWindows();
345 ShadowMapping Mapping;
347 if (LongSize == 32) {
348 // Android is always PIE, which means that the beginning of the address
349 // space is always available.
353 Mapping.Offset = kMIPS32_ShadowOffset32;
355 Mapping.Offset = kFreeBSD_ShadowOffset32;
357 Mapping.Offset = kIOSShadowOffset32;
359 Mapping.Offset = kWindowsShadowOffset32;
361 Mapping.Offset = kDefaultShadowOffset32;
362 } else { // LongSize == 64
364 Mapping.Offset = kPPC64_ShadowOffset64;
366 Mapping.Offset = kFreeBSD_ShadowOffset64;
367 else if (IsLinux && IsX86_64) {
369 Mapping.Offset = kLinuxKasan_ShadowOffset64;
371 Mapping.Offset = kSmallX86_64ShadowOffset;
373 Mapping.Offset = kMIPS64_ShadowOffset64;
375 Mapping.Offset = kAArch64_ShadowOffset64;
377 Mapping.Offset = kDefaultShadowOffset64;
380 Mapping.Scale = kDefaultShadowScale;
381 if (ClMappingScale) {
382 Mapping.Scale = ClMappingScale;
385 // OR-ing shadow offset if more efficient (at least on x86) if the offset
386 // is a power of two, but on ppc64 we have to use add since the shadow
387 // offset is not necessary 1/8-th of the address space.
388 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64
389 && !(Mapping.Offset & (Mapping.Offset - 1));
394 static size_t RedzoneSizeForScale(int MappingScale) {
395 // Redzone used for stack and globals is at least 32 bytes.
396 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
397 return std::max(32U, 1U << MappingScale);
400 /// AddressSanitizer: instrument the code in module to find memory bugs.
401 struct AddressSanitizer : public FunctionPass {
402 explicit AddressSanitizer(bool CompileKernel = false, bool Recover = false)
403 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan),
404 Recover(Recover || ClRecover) {
405 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
407 const char *getPassName() const override {
408 return "AddressSanitizerFunctionPass";
410 void getAnalysisUsage(AnalysisUsage &AU) const override {
411 AU.addRequired<DominatorTreeWrapperPass>();
412 AU.addRequired<TargetLibraryInfoWrapperPass>();
414 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
415 Type *Ty = AI->getAllocatedType();
416 uint64_t SizeInBytes =
417 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
420 /// Check if we want (and can) handle this alloca.
421 bool isInterestingAlloca(AllocaInst &AI);
423 // Check if we have dynamic alloca.
424 bool isDynamicAlloca(AllocaInst &AI) const {
425 return AI.isArrayAllocation() || !AI.isStaticAlloca();
428 /// If it is an interesting memory access, return the PointerOperand
429 /// and set IsWrite/Alignment. Otherwise return nullptr.
430 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
431 uint64_t *TypeSize, unsigned *Alignment);
432 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
433 bool UseCalls, const DataLayout &DL);
434 void instrumentPointerComparisonOrSubtraction(Instruction *I);
435 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
436 Value *Addr, uint32_t TypeSize, bool IsWrite,
437 Value *SizeArgument, bool UseCalls, uint32_t Exp);
438 void instrumentUnusualSizeOrAlignment(Instruction *I, Value *Addr,
439 uint32_t TypeSize, bool IsWrite,
440 Value *SizeArgument, bool UseCalls,
442 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
443 Value *ShadowValue, uint32_t TypeSize);
444 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
445 bool IsWrite, size_t AccessSizeIndex,
446 Value *SizeArgument, uint32_t Exp);
447 void instrumentMemIntrinsic(MemIntrinsic *MI);
448 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
449 bool runOnFunction(Function &F) override;
450 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
451 void markEscapedLocalAllocas(Function &F);
452 bool doInitialization(Module &M) override;
453 static char ID; // Pass identification, replacement for typeid
455 DominatorTree &getDominatorTree() const { return *DT; }
458 void initializeCallbacks(Module &M);
460 bool LooksLikeCodeInBug11395(Instruction *I);
461 bool GlobalIsLinkerInitialized(GlobalVariable *G);
462 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
463 uint64_t TypeSize) const;
465 /// Helper to cleanup per-function state.
466 struct FunctionStateRAII {
467 AddressSanitizer *Pass;
468 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
469 assert(Pass->ProcessedAllocas.empty() &&
470 "last pass forgot to clear cache");
472 ~FunctionStateRAII() { Pass->ProcessedAllocas.clear(); }
481 ShadowMapping Mapping;
483 Function *AsanCtorFunction = nullptr;
484 Function *AsanInitFunction = nullptr;
485 Function *AsanHandleNoReturnFunc;
486 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
487 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
488 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
489 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
490 // This array is indexed by AccessIsWrite and Experiment.
491 Function *AsanErrorCallbackSized[2][2];
492 Function *AsanMemoryAccessCallbackSized[2][2];
493 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
495 GlobalsMetadata GlobalsMD;
496 DenseMap<AllocaInst *, bool> ProcessedAllocas;
498 friend struct FunctionStackPoisoner;
501 class AddressSanitizerModule : public ModulePass {
503 explicit AddressSanitizerModule(bool CompileKernel = false,
504 bool Recover = false)
505 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
506 Recover(Recover || ClRecover) {}
507 bool runOnModule(Module &M) override;
508 static char ID; // Pass identification, replacement for typeid
509 const char *getPassName() const override { return "AddressSanitizerModule"; }
512 void initializeCallbacks(Module &M);
514 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
515 bool ShouldInstrumentGlobal(GlobalVariable *G);
516 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
517 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
518 size_t MinRedzoneSizeForGlobal() const {
519 return RedzoneSizeForScale(Mapping.Scale);
522 GlobalsMetadata GlobalsMD;
528 ShadowMapping Mapping;
529 Function *AsanPoisonGlobals;
530 Function *AsanUnpoisonGlobals;
531 Function *AsanRegisterGlobals;
532 Function *AsanUnregisterGlobals;
535 // Stack poisoning does not play well with exception handling.
536 // When an exception is thrown, we essentially bypass the code
537 // that unpoisones the stack. This is why the run-time library has
538 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
539 // stack in the interceptor. This however does not work inside the
540 // actual function which catches the exception. Most likely because the
541 // compiler hoists the load of the shadow value somewhere too high.
542 // This causes asan to report a non-existing bug on 453.povray.
543 // It sounds like an LLVM bug.
544 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
546 AddressSanitizer &ASan;
551 ShadowMapping Mapping;
553 SmallVector<AllocaInst *, 16> AllocaVec;
554 SmallSetVector<AllocaInst *, 16> NonInstrumentedStaticAllocaVec;
555 SmallVector<Instruction *, 8> RetVec;
556 unsigned StackAlignment;
558 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
559 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
560 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
561 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
563 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
564 struct AllocaPoisonCall {
565 IntrinsicInst *InsBefore;
570 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
572 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
573 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
574 AllocaInst *DynamicAllocaLayout = nullptr;
575 IntrinsicInst *LocalEscapeCall = nullptr;
577 // Maps Value to an AllocaInst from which the Value is originated.
578 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
579 AllocaForValueMapTy AllocaForValue;
581 bool HasNonEmptyInlineAsm = false;
582 bool HasReturnsTwiceCall = false;
583 std::unique_ptr<CallInst> EmptyInlineAsm;
585 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
588 DIB(*F.getParent(), /*AllowUnresolved*/ false),
590 IntptrTy(ASan.IntptrTy),
591 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
592 Mapping(ASan.Mapping),
593 StackAlignment(1 << Mapping.Scale),
594 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
596 bool runOnFunction() {
597 if (!ClStack) return false;
598 // Collect alloca, ret, lifetime instructions etc.
599 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
601 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
603 initializeCallbacks(*F.getParent());
613 // Finds all Alloca instructions and puts
614 // poisoned red zones around all of them.
615 // Then unpoison everything back before the function returns.
618 void createDynamicAllocasInitStorage();
620 // ----------------------- Visitors.
621 /// \brief Collect all Ret instructions.
622 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
624 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
626 IRBuilder<> IRB(InstBefore);
627 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
628 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
629 // need to adjust extracted SP to compute the address of the most recent
630 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
632 if (!isa<ReturnInst>(InstBefore)) {
633 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
634 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
637 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
639 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
643 IRB.CreateCall(AsanAllocasUnpoisonFunc,
644 {IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr});
647 // Unpoison dynamic allocas redzones.
648 void unpoisonDynamicAllocas() {
649 for (auto &Ret : RetVec)
650 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
652 for (auto &StackRestoreInst : StackRestoreVec)
653 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
654 StackRestoreInst->getOperand(0));
657 // Deploy and poison redzones around dynamic alloca call. To do this, we
658 // should replace this call with another one with changed parameters and
659 // replace all its uses with new address, so
660 // addr = alloca type, old_size, align
662 // new_size = (old_size + additional_size) * sizeof(type)
663 // tmp = alloca i8, new_size, max(align, 32)
664 // addr = tmp + 32 (first 32 bytes are for the left redzone).
665 // Additional_size is added to make new memory allocation contain not only
666 // requested memory, but also left, partial and right redzones.
667 void handleDynamicAllocaCall(AllocaInst *AI);
669 /// \brief Collect Alloca instructions we want (and can) handle.
670 void visitAllocaInst(AllocaInst &AI) {
671 if (!ASan.isInterestingAlloca(AI)) {
672 if (AI.isStaticAlloca()) NonInstrumentedStaticAllocaVec.insert(&AI);
676 StackAlignment = std::max(StackAlignment, AI.getAlignment());
677 if (ASan.isDynamicAlloca(AI))
678 DynamicAllocaVec.push_back(&AI);
680 AllocaVec.push_back(&AI);
683 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
685 void visitIntrinsicInst(IntrinsicInst &II) {
686 Intrinsic::ID ID = II.getIntrinsicID();
687 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
688 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
689 if (!ClCheckLifetime) return;
690 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
692 // Found lifetime intrinsic, add ASan instrumentation if necessary.
693 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
694 // If size argument is undefined, don't do anything.
695 if (Size->isMinusOne()) return;
696 // Check that size doesn't saturate uint64_t and can
697 // be stored in IntptrTy.
698 const uint64_t SizeValue = Size->getValue().getLimitedValue();
699 if (SizeValue == ~0ULL ||
700 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
702 // Find alloca instruction that corresponds to llvm.lifetime argument.
703 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
705 bool DoPoison = (ID == Intrinsic::lifetime_end);
706 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
707 AllocaPoisonCallVec.push_back(APC);
710 void visitCallSite(CallSite CS) {
711 Instruction *I = CS.getInstruction();
712 if (CallInst *CI = dyn_cast<CallInst>(I)) {
713 HasNonEmptyInlineAsm |=
714 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
715 HasReturnsTwiceCall |= CI->canReturnTwice();
719 // ---------------------- Helpers.
720 void initializeCallbacks(Module &M);
722 bool doesDominateAllExits(const Instruction *I) const {
723 for (auto Ret : RetVec) {
724 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
729 /// Finds alloca where the value comes from.
730 AllocaInst *findAllocaForValue(Value *V);
731 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
732 Value *ShadowBase, bool DoPoison);
733 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
735 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
737 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
739 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
740 Instruction *ThenTerm, Value *ValueIfFalse);
743 } // anonymous namespace
745 char AddressSanitizer::ID = 0;
746 INITIALIZE_PASS_BEGIN(
747 AddressSanitizer, "asan",
748 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
750 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
751 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
753 AddressSanitizer, "asan",
754 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
756 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
758 assert(!CompileKernel || Recover);
759 return new AddressSanitizer(CompileKernel, Recover);
762 char AddressSanitizerModule::ID = 0;
764 AddressSanitizerModule, "asan-module",
765 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
768 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
770 assert(!CompileKernel || Recover);
771 return new AddressSanitizerModule(CompileKernel, Recover);
774 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
775 size_t Res = countTrailingZeros(TypeSize / 8);
776 assert(Res < kNumberOfAccessSizes);
780 // \brief Create a constant for Str so that we can pass it to the run-time lib.
781 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
783 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
784 // We use private linkage for module-local strings. If they can be merged
785 // with another one, we set the unnamed_addr attribute.
787 new GlobalVariable(M, StrConst->getType(), true,
788 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
789 if (AllowMerging) GV->setUnnamedAddr(true);
790 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
794 /// \brief Create a global describing a source location.
795 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
796 LocationMetadata MD) {
797 Constant *LocData[] = {
798 createPrivateGlobalForString(M, MD.Filename, true),
799 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
800 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
802 auto LocStruct = ConstantStruct::getAnon(LocData);
803 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
804 GlobalValue::PrivateLinkage, LocStruct,
806 GV->setUnnamedAddr(true);
810 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
811 return G->getName().find(kAsanGenPrefix) == 0 ||
812 G->getName().find(kSanCovGenPrefix) == 0;
815 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
817 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
818 if (Mapping.Offset == 0) return Shadow;
819 // (Shadow >> scale) | offset
820 if (Mapping.OrShadowOffset)
821 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
823 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
826 // Instrument memset/memmove/memcpy
827 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
829 if (isa<MemTransferInst>(MI)) {
831 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
832 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
833 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
834 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
835 } else if (isa<MemSetInst>(MI)) {
838 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
839 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
840 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
842 MI->eraseFromParent();
845 /// Check if we want (and can) handle this alloca.
846 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) {
847 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
849 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
850 return PreviouslySeenAllocaInfo->getSecond();
853 (AI.getAllocatedType()->isSized() &&
854 // alloca() may be called with 0 size, ignore it.
855 getAllocaSizeInBytes(&AI) > 0 &&
856 // We are only interested in allocas not promotable to registers.
857 // Promotable allocas are common under -O0.
858 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
859 // inalloca allocas are not treated as static, and we don't want
860 // dynamic alloca instrumentation for them as well.
861 !AI.isUsedWithInAlloca());
863 ProcessedAllocas[&AI] = IsInteresting;
864 return IsInteresting;
867 /// If I is an interesting memory access, return the PointerOperand
868 /// and set IsWrite/Alignment. Otherwise return nullptr.
869 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
872 unsigned *Alignment) {
873 // Skip memory accesses inserted by another instrumentation.
874 if (I->getMetadata("nosanitize")) return nullptr;
876 Value *PtrOperand = nullptr;
877 const DataLayout &DL = I->getModule()->getDataLayout();
878 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
879 if (!ClInstrumentReads) return nullptr;
881 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
882 *Alignment = LI->getAlignment();
883 PtrOperand = LI->getPointerOperand();
884 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
885 if (!ClInstrumentWrites) return nullptr;
887 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
888 *Alignment = SI->getAlignment();
889 PtrOperand = SI->getPointerOperand();
890 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
891 if (!ClInstrumentAtomics) return nullptr;
893 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
895 PtrOperand = RMW->getPointerOperand();
896 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
897 if (!ClInstrumentAtomics) return nullptr;
899 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
901 PtrOperand = XCHG->getPointerOperand();
904 // Treat memory accesses to promotable allocas as non-interesting since they
905 // will not cause memory violations. This greatly speeds up the instrumented
906 // executable at -O0.
907 if (ClSkipPromotableAllocas)
908 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
909 return isInterestingAlloca(*AI) ? AI : nullptr;
914 static bool isPointerOperand(Value *V) {
915 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
918 // This is a rough heuristic; it may cause both false positives and
919 // false negatives. The proper implementation requires cooperation with
921 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
922 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
923 if (!Cmp->isRelational()) return false;
924 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
925 if (BO->getOpcode() != Instruction::Sub) return false;
929 return isPointerOperand(I->getOperand(0)) &&
930 isPointerOperand(I->getOperand(1));
933 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
934 // If a global variable does not have dynamic initialization we don't
935 // have to instrument it. However, if a global does not have initializer
936 // at all, we assume it has dynamic initializer (in other TU).
937 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
940 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
943 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
944 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
945 for (int i = 0; i < 2; i++) {
946 if (Param[i]->getType()->isPointerTy())
947 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
949 IRB.CreateCall(F, Param);
952 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
953 Instruction *I, bool UseCalls,
954 const DataLayout &DL) {
955 bool IsWrite = false;
956 unsigned Alignment = 0;
957 uint64_t TypeSize = 0;
958 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
961 // Optimization experiments.
962 // The experiments can be used to evaluate potential optimizations that remove
963 // instrumentation (assess false negatives). Instead of completely removing
964 // some instrumentation, you set Exp to a non-zero value (mask of optimization
965 // experiments that want to remove instrumentation of this instruction).
966 // If Exp is non-zero, this pass will emit special calls into runtime
967 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
968 // make runtime terminate the program in a special way (with a different
969 // exit status). Then you run the new compiler on a buggy corpus, collect
970 // the special terminations (ideally, you don't see them at all -- no false
971 // negatives) and make the decision on the optimization.
972 uint32_t Exp = ClForceExperiment;
974 if (ClOpt && ClOptGlobals) {
975 // If initialization order checking is disabled, a simple access to a
976 // dynamically initialized global is always valid.
977 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
978 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
979 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
980 NumOptimizedAccessesToGlobalVar++;
985 if (ClOpt && ClOptStack) {
986 // A direct inbounds access to a stack variable is always valid.
987 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
988 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
989 NumOptimizedAccessesToStackVar++;
995 NumInstrumentedWrites++;
997 NumInstrumentedReads++;
999 unsigned Granularity = 1 << Mapping.Scale;
1000 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1001 // if the data is properly aligned.
1002 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1004 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1005 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls,
1007 instrumentUnusualSizeOrAlignment(I, Addr, TypeSize, IsWrite, nullptr,
1011 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1012 Value *Addr, bool IsWrite,
1013 size_t AccessSizeIndex,
1014 Value *SizeArgument,
1016 IRBuilder<> IRB(InsertBefore);
1017 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1018 CallInst *Call = nullptr;
1021 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1022 {Addr, SizeArgument});
1024 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1025 {Addr, SizeArgument, ExpVal});
1029 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1031 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1035 // We don't do Call->setDoesNotReturn() because the BB already has
1036 // UnreachableInst at the end.
1037 // This EmptyAsm is required to avoid callback merge.
1038 IRB.CreateCall(EmptyAsm, {});
1042 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1044 uint32_t TypeSize) {
1045 size_t Granularity = 1 << Mapping.Scale;
1046 // Addr & (Granularity - 1)
1047 Value *LastAccessedByte =
1048 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1049 // (Addr & (Granularity - 1)) + size - 1
1050 if (TypeSize / 8 > 1)
1051 LastAccessedByte = IRB.CreateAdd(
1052 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1053 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1055 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1056 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1057 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1060 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1061 Instruction *InsertBefore, Value *Addr,
1062 uint32_t TypeSize, bool IsWrite,
1063 Value *SizeArgument, bool UseCalls,
1065 IRBuilder<> IRB(InsertBefore);
1066 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1067 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1071 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1074 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1075 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1080 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1081 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1082 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1083 Value *CmpVal = Constant::getNullValue(ShadowTy);
1084 Value *ShadowValue =
1085 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1087 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1088 size_t Granularity = 1 << Mapping.Scale;
1089 TerminatorInst *CrashTerm = nullptr;
1091 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1092 // We use branch weights for the slow path check, to indicate that the slow
1093 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1094 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1095 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1096 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1097 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1098 IRB.SetInsertPoint(CheckTerm);
1099 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1101 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1103 BasicBlock *CrashBlock =
1104 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1105 CrashTerm = new UnreachableInst(*C, CrashBlock);
1106 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1107 ReplaceInstWithInst(CheckTerm, NewTerm);
1110 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1113 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1114 AccessSizeIndex, SizeArgument, Exp);
1115 Crash->setDebugLoc(OrigIns->getDebugLoc());
1118 // Instrument unusual size or unusual alignment.
1119 // We can not do it with a single check, so we do 1-byte check for the first
1120 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1121 // to report the actual access size.
1122 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1123 Instruction *I, Value *Addr, uint32_t TypeSize, bool IsWrite,
1124 Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1126 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1127 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1130 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1133 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1134 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1136 Value *LastByte = IRB.CreateIntToPtr(
1137 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1139 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false, Exp);
1140 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false, Exp);
1144 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1145 GlobalValue *ModuleName) {
1146 // Set up the arguments to our poison/unpoison functions.
1147 IRBuilder<> IRB(&GlobalInit.front(),
1148 GlobalInit.front().getFirstInsertionPt());
1150 // Add a call to poison all external globals before the given function starts.
1151 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1152 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1154 // Add calls to unpoison all globals before each return instruction.
1155 for (auto &BB : GlobalInit.getBasicBlockList())
1156 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1157 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1160 void AddressSanitizerModule::createInitializerPoisonCalls(
1161 Module &M, GlobalValue *ModuleName) {
1162 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1164 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1165 for (Use &OP : CA->operands()) {
1166 if (isa<ConstantAggregateZero>(OP)) continue;
1167 ConstantStruct *CS = cast<ConstantStruct>(OP);
1169 // Must have a function or null ptr.
1170 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1171 if (F->getName() == kAsanModuleCtorName) continue;
1172 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1173 // Don't instrument CTORs that will run before asan.module_ctor.
1174 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1175 poisonOneInitializer(*F, ModuleName);
1180 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1181 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1182 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1184 if (GlobalsMD.get(G).IsBlacklisted) return false;
1185 if (!Ty->isSized()) return false;
1186 if (!G->hasInitializer()) return false;
1187 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1188 // Touch only those globals that will not be defined in other modules.
1189 // Don't handle ODR linkage types and COMDATs since other modules may be built
1191 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1192 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1193 G->getLinkage() != GlobalVariable::InternalLinkage)
1195 if (G->hasComdat()) return false;
1196 // Two problems with thread-locals:
1197 // - The address of the main thread's copy can't be computed at link-time.
1198 // - Need to poison all copies, not just the main thread's one.
1199 if (G->isThreadLocal()) return false;
1200 // For now, just ignore this Global if the alignment is large.
1201 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1203 if (G->hasSection()) {
1204 StringRef Section(G->getSection());
1206 // Globals from llvm.metadata aren't emitted, do not instrument them.
1207 if (Section == "llvm.metadata") return false;
1208 // Do not instrument globals from special LLVM sections.
1209 if (Section.find("__llvm") != StringRef::npos) return false;
1211 // Do not instrument function pointers to initialization and termination
1212 // routines: dynamic linker will not properly handle redzones.
1213 if (Section.startswith(".preinit_array") ||
1214 Section.startswith(".init_array") ||
1215 Section.startswith(".fini_array")) {
1219 // Callbacks put into the CRT initializer/terminator sections
1220 // should not be instrumented.
1221 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1222 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1223 if (Section.startswith(".CRT")) {
1224 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1228 if (TargetTriple.isOSBinFormatMachO()) {
1229 StringRef ParsedSegment, ParsedSection;
1230 unsigned TAA = 0, StubSize = 0;
1232 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1233 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1234 assert(ErrorCode.empty() && "Invalid section specifier.");
1236 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1237 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1239 if (ParsedSegment == "__OBJC" ||
1240 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1241 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1244 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1245 // Constant CFString instances are compiled in the following way:
1246 // -- the string buffer is emitted into
1247 // __TEXT,__cstring,cstring_literals
1248 // -- the constant NSConstantString structure referencing that buffer
1249 // is placed into __DATA,__cfstring
1250 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1251 // Moreover, it causes the linker to crash on OS X 10.7
1252 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1253 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1256 // The linker merges the contents of cstring_literals and removes the
1258 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1259 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1268 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1269 IRBuilder<> IRB(*C);
1270 // Declare our poisoning and unpoisoning functions.
1271 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1272 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1273 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1274 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1275 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1276 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1277 // Declare functions that register/unregister globals.
1278 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1279 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1280 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1281 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1282 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1283 IntptrTy, IntptrTy, nullptr));
1284 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1287 // This function replaces all global variables with new variables that have
1288 // trailing redzones. It also creates a function that poisons
1289 // redzones and inserts this function into llvm.global_ctors.
1290 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1293 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1295 for (auto &G : M.globals()) {
1296 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1299 size_t n = GlobalsToChange.size();
1300 if (n == 0) return false;
1302 // A global is described by a structure
1305 // size_t size_with_redzone;
1306 // const char *name;
1307 // const char *module_name;
1308 // size_t has_dynamic_init;
1309 // void *source_location;
1310 // We initialize an array of such structures and pass it to a run-time call.
1311 StructType *GlobalStructTy =
1312 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1313 IntptrTy, IntptrTy, nullptr);
1314 SmallVector<Constant *, 16> Initializers(n);
1316 bool HasDynamicallyInitializedGlobals = false;
1318 // We shouldn't merge same module names, as this string serves as unique
1319 // module ID in runtime.
1320 GlobalVariable *ModuleName = createPrivateGlobalForString(
1321 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1323 auto &DL = M.getDataLayout();
1324 for (size_t i = 0; i < n; i++) {
1325 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1326 GlobalVariable *G = GlobalsToChange[i];
1328 auto MD = GlobalsMD.get(G);
1329 // Create string holding the global name (use global name from metadata
1330 // if it's available, otherwise just write the name of global variable).
1331 GlobalVariable *Name = createPrivateGlobalForString(
1332 M, MD.Name.empty() ? G->getName() : MD.Name,
1333 /*AllowMerging*/ true);
1335 PointerType *PtrTy = cast<PointerType>(G->getType());
1336 Type *Ty = PtrTy->getElementType();
1337 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1338 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1339 // MinRZ <= RZ <= kMaxGlobalRedzone
1340 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1341 uint64_t RZ = std::max(
1342 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1343 uint64_t RightRedzoneSize = RZ;
1344 // Round up to MinRZ
1345 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1346 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1347 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1349 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1350 Constant *NewInitializer =
1351 ConstantStruct::get(NewTy, G->getInitializer(),
1352 Constant::getNullValue(RightRedZoneTy), nullptr);
1354 // Create a new global variable with enough space for a redzone.
1355 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1356 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1357 Linkage = GlobalValue::InternalLinkage;
1358 GlobalVariable *NewGlobal =
1359 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1360 "", G, G->getThreadLocalMode());
1361 NewGlobal->copyAttributesFrom(G);
1362 NewGlobal->setAlignment(MinRZ);
1365 Indices2[0] = IRB.getInt32(0);
1366 Indices2[1] = IRB.getInt32(0);
1368 G->replaceAllUsesWith(
1369 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1370 NewGlobal->takeName(G);
1371 G->eraseFromParent();
1373 Constant *SourceLoc;
1374 if (!MD.SourceLoc.empty()) {
1375 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1376 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1378 SourceLoc = ConstantInt::get(IntptrTy, 0);
1381 Initializers[i] = ConstantStruct::get(
1382 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1383 ConstantInt::get(IntptrTy, SizeInBytes),
1384 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1385 ConstantExpr::getPointerCast(Name, IntptrTy),
1386 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1387 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1389 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1391 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1394 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1395 GlobalVariable *AllGlobals = new GlobalVariable(
1396 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1397 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1399 // Create calls for poisoning before initializers run and unpoisoning after.
1400 if (HasDynamicallyInitializedGlobals)
1401 createInitializerPoisonCalls(M, ModuleName);
1402 IRB.CreateCall(AsanRegisterGlobals,
1403 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1404 ConstantInt::get(IntptrTy, n)});
1406 // We also need to unregister globals at the end, e.g. when a shared library
1408 Function *AsanDtorFunction =
1409 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1410 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1411 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1412 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1413 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1414 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1415 ConstantInt::get(IntptrTy, n)});
1416 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1422 bool AddressSanitizerModule::runOnModule(Module &M) {
1423 C = &(M.getContext());
1424 int LongSize = M.getDataLayout().getPointerSizeInBits();
1425 IntptrTy = Type::getIntNTy(*C, LongSize);
1426 TargetTriple = Triple(M.getTargetTriple());
1427 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1428 initializeCallbacks(M);
1430 bool Changed = false;
1432 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1433 if (ClGlobals && !CompileKernel) {
1434 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1436 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1437 Changed |= InstrumentGlobals(IRB, M);
1443 void AddressSanitizer::initializeCallbacks(Module &M) {
1444 IRBuilder<> IRB(*C);
1445 // Create __asan_report* callbacks.
1446 // IsWrite, TypeSize and Exp are encoded in the function name.
1447 for (int Exp = 0; Exp < 2; Exp++) {
1448 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1449 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1450 const std::string ExpStr = Exp ? "exp_" : "";
1451 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1452 const std::string EndingStr = Recover ? "_noabort" : "";
1453 Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1454 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1455 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1456 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr + EndingStr,
1457 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1458 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1459 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1460 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1461 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1462 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1463 AccessSizeIndex++) {
1464 const std::string Suffix = TypeStr + itostr(1 << AccessSizeIndex);
1465 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1466 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1467 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
1468 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1469 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1470 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1471 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1472 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1477 const std::string MemIntrinCallbackPrefix =
1478 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1479 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1480 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1481 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1482 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1483 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1484 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1485 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1486 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1487 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1489 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1490 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1492 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1493 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1494 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1495 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1496 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1497 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1498 StringRef(""), StringRef(""),
1499 /*hasSideEffects=*/true);
1503 bool AddressSanitizer::doInitialization(Module &M) {
1504 // Initialize the private fields. No one has accessed them before.
1508 C = &(M.getContext());
1509 LongSize = M.getDataLayout().getPointerSizeInBits();
1510 IntptrTy = Type::getIntNTy(*C, LongSize);
1511 TargetTriple = Triple(M.getTargetTriple());
1513 if (!CompileKernel) {
1514 std::tie(AsanCtorFunction, AsanInitFunction) =
1515 createSanitizerCtorAndInitFunctions(
1516 M, kAsanModuleCtorName, kAsanInitName,
1517 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
1518 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1520 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1524 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1525 // For each NSObject descendant having a +load method, this method is invoked
1526 // by the ObjC runtime before any of the static constructors is called.
1527 // Therefore we need to instrument such methods with a call to __asan_init
1528 // at the beginning in order to initialize our runtime before any access to
1529 // the shadow memory.
1530 // We cannot just ignore these methods, because they may call other
1531 // instrumented functions.
1532 if (F.getName().find(" load]") != std::string::npos) {
1533 IRBuilder<> IRB(&F.front(), F.front().begin());
1534 IRB.CreateCall(AsanInitFunction, {});
1540 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
1541 // Find the one possible call to llvm.localescape and pre-mark allocas passed
1542 // to it as uninteresting. This assumes we haven't started processing allocas
1543 // yet. This check is done up front because iterating the use list in
1544 // isInterestingAlloca would be algorithmically slower.
1545 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
1547 // Try to get the declaration of llvm.localescape. If it's not in the module,
1548 // we can exit early.
1549 if (!F.getParent()->getFunction("llvm.localescape")) return;
1551 // Look for a call to llvm.localescape call in the entry block. It can't be in
1553 for (Instruction &I : F.getEntryBlock()) {
1554 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
1555 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
1556 // We found a call. Mark all the allocas passed in as uninteresting.
1557 for (Value *Arg : II->arg_operands()) {
1558 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
1559 assert(AI && AI->isStaticAlloca() &&
1560 "non-static alloca arg to localescape");
1561 ProcessedAllocas[AI] = false;
1568 bool AddressSanitizer::runOnFunction(Function &F) {
1569 if (&F == AsanCtorFunction) return false;
1570 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1571 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1572 initializeCallbacks(*F.getParent());
1574 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1576 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1577 maybeInsertAsanInitAtFunctionEntry(F);
1579 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1581 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1583 FunctionStateRAII CleanupObj(this);
1585 // We can't instrument allocas used with llvm.localescape. Only static allocas
1586 // can be passed to that intrinsic.
1587 markEscapedLocalAllocas(F);
1589 // We want to instrument every address only once per basic block (unless there
1590 // are calls between uses).
1591 SmallSet<Value *, 16> TempsToInstrument;
1592 SmallVector<Instruction *, 16> ToInstrument;
1593 SmallVector<Instruction *, 8> NoReturnCalls;
1594 SmallVector<BasicBlock *, 16> AllBlocks;
1595 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1601 // Fill the set of memory operations to instrument.
1602 for (auto &BB : F) {
1603 AllBlocks.push_back(&BB);
1604 TempsToInstrument.clear();
1605 int NumInsnsPerBB = 0;
1606 for (auto &Inst : BB) {
1607 if (LooksLikeCodeInBug11395(&Inst)) return false;
1608 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1610 if (ClOpt && ClOptSameTemp) {
1611 if (!TempsToInstrument.insert(Addr).second)
1612 continue; // We've seen this temp in the current BB.
1614 } else if (ClInvalidPointerPairs &&
1615 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1616 PointerComparisonsOrSubtracts.push_back(&Inst);
1618 } else if (isa<MemIntrinsic>(Inst)) {
1621 if (isa<AllocaInst>(Inst)) NumAllocas++;
1624 // A call inside BB.
1625 TempsToInstrument.clear();
1626 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1630 ToInstrument.push_back(&Inst);
1632 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1638 (ClInstrumentationWithCallsThreshold >= 0 &&
1639 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
1640 const TargetLibraryInfo *TLI =
1641 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1642 const DataLayout &DL = F.getParent()->getDataLayout();
1643 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1644 /*RoundToAlign=*/true);
1647 int NumInstrumented = 0;
1648 for (auto Inst : ToInstrument) {
1649 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1650 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1651 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1652 instrumentMop(ObjSizeVis, Inst, UseCalls,
1653 F.getParent()->getDataLayout());
1655 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1660 FunctionStackPoisoner FSP(F, *this);
1661 bool ChangedStack = FSP.runOnFunction();
1663 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1664 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1665 for (auto CI : NoReturnCalls) {
1666 IRBuilder<> IRB(CI);
1667 IRB.CreateCall(AsanHandleNoReturnFunc, {});
1670 for (auto Inst : PointerComparisonsOrSubtracts) {
1671 instrumentPointerComparisonOrSubtraction(Inst);
1675 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1677 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1682 // Workaround for bug 11395: we don't want to instrument stack in functions
1683 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1684 // FIXME: remove once the bug 11395 is fixed.
1685 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1686 if (LongSize != 32) return false;
1687 CallInst *CI = dyn_cast<CallInst>(I);
1688 if (!CI || !CI->isInlineAsm()) return false;
1689 if (CI->getNumArgOperands() <= 5) return false;
1690 // We have inline assembly with quite a few arguments.
1694 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1695 IRBuilder<> IRB(*C);
1696 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1697 std::string Suffix = itostr(i);
1698 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
1699 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1700 IntptrTy, nullptr));
1701 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
1702 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1703 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1705 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1706 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1707 IntptrTy, IntptrTy, nullptr));
1708 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
1709 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1710 IntptrTy, IntptrTy, nullptr));
1711 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1712 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1713 AsanAllocasUnpoisonFunc =
1714 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1715 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1718 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1719 IRBuilder<> &IRB, Value *ShadowBase,
1721 size_t n = ShadowBytes.size();
1723 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1724 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1725 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1726 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1727 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1728 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1730 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1731 if (F.getParent()->getDataLayout().isLittleEndian())
1732 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1734 Val = (Val << 8) | ShadowBytes[i + j];
1737 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1738 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1739 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1740 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1745 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1746 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1747 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1748 assert(LocalStackSize <= kMaxStackMallocSize);
1749 uint64_t MaxSize = kMinStackMallocSize;
1750 for (int i = 0;; i++, MaxSize *= 2)
1751 if (LocalStackSize <= MaxSize) return i;
1752 llvm_unreachable("impossible LocalStackSize");
1755 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1756 // We can not use MemSet intrinsic because it may end up calling the actual
1757 // memset. Size is a multiple of 8.
1758 // Currently this generates 8-byte stores on x86_64; it may be better to
1759 // generate wider stores.
1760 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1761 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1762 assert(!(Size % 8));
1764 // kAsanStackAfterReturnMagic is 0xf5.
1765 const uint64_t kAsanStackAfterReturnMagic64 = 0xf5f5f5f5f5f5f5f5ULL;
1767 for (int i = 0; i < Size; i += 8) {
1768 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1770 ConstantInt::get(IRB.getInt64Ty(), kAsanStackAfterReturnMagic64),
1771 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1775 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1777 Instruction *ThenTerm,
1778 Value *ValueIfFalse) {
1779 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1780 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1781 PHI->addIncoming(ValueIfFalse, CondBlock);
1782 BasicBlock *ThenBlock = ThenTerm->getParent();
1783 PHI->addIncoming(ValueIfTrue, ThenBlock);
1787 Value *FunctionStackPoisoner::createAllocaForLayout(
1788 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1791 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1792 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1795 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1796 nullptr, "MyAlloca");
1797 assert(Alloca->isStaticAlloca());
1799 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1800 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1801 Alloca->setAlignment(FrameAlignment);
1802 return IRB.CreatePointerCast(Alloca, IntptrTy);
1805 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
1806 BasicBlock &FirstBB = *F.begin();
1807 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
1808 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
1809 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
1810 DynamicAllocaLayout->setAlignment(32);
1813 void FunctionStackPoisoner::poisonStack() {
1814 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1816 // Insert poison calls for lifetime intrinsics for alloca.
1817 bool HavePoisonedAllocas = false;
1818 for (const auto &APC : AllocaPoisonCallVec) {
1819 assert(APC.InsBefore);
1821 IRBuilder<> IRB(APC.InsBefore);
1822 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1823 HavePoisonedAllocas |= APC.DoPoison;
1826 if (ClInstrumentAllocas && DynamicAllocaVec.size() > 0) {
1827 // Handle dynamic allocas.
1828 createDynamicAllocasInitStorage();
1829 for (auto &AI : DynamicAllocaVec) handleDynamicAllocaCall(AI);
1831 unpoisonDynamicAllocas();
1834 if (AllocaVec.empty()) return;
1836 int StackMallocIdx = -1;
1837 DebugLoc EntryDebugLocation;
1838 if (auto SP = getDISubprogram(&F))
1839 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
1841 Instruction *InsBefore = AllocaVec[0];
1842 IRBuilder<> IRB(InsBefore);
1843 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1845 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
1846 // debug info is broken, because only entry-block allocas are treated as
1847 // regular stack slots.
1848 auto InsBeforeB = InsBefore->getParent();
1849 assert(InsBeforeB == &F.getEntryBlock());
1850 for (BasicBlock::iterator I(InsBefore); I != InsBeforeB->end(); ++I)
1851 if (auto *AI = dyn_cast<AllocaInst>(I))
1852 if (NonInstrumentedStaticAllocaVec.count(AI) > 0)
1853 AI->moveBefore(InsBefore);
1855 // If we have a call to llvm.localescape, keep it in the entry block.
1856 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
1858 SmallVector<ASanStackVariableDescription, 16> SVD;
1859 SVD.reserve(AllocaVec.size());
1860 for (AllocaInst *AI : AllocaVec) {
1861 ASanStackVariableDescription D = {AI->getName().data(),
1862 ASan.getAllocaSizeInBytes(AI),
1863 AI->getAlignment(), AI, 0};
1866 // Minimal header size (left redzone) is 4 pointers,
1867 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1868 size_t MinHeaderSize = ASan.LongSize / 2;
1869 ASanStackFrameLayout L;
1870 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1871 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1872 uint64_t LocalStackSize = L.FrameSize;
1873 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
1874 LocalStackSize <= kMaxStackMallocSize;
1875 bool DoDynamicAlloca = ClDynamicAllocaStack;
1876 // Don't do dynamic alloca or stack malloc if:
1877 // 1) There is inline asm: too often it makes assumptions on which registers
1879 // 2) There is a returns_twice call (typically setjmp), which is
1880 // optimization-hostile, and doesn't play well with introduced indirect
1881 // register-relative calculation of local variable addresses.
1882 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
1883 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
1885 Value *StaticAlloca =
1886 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1889 Value *LocalStackBase;
1891 if (DoStackMalloc) {
1892 // void *FakeStack = __asan_option_detect_stack_use_after_return
1893 // ? __asan_stack_malloc_N(LocalStackSize)
1895 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1896 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1897 kAsanOptionDetectUAR, IRB.getInt32Ty());
1898 Value *UARIsEnabled =
1899 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1900 Constant::getNullValue(IRB.getInt32Ty()));
1902 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1903 IRBuilder<> IRBIf(Term);
1904 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1905 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1906 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1907 Value *FakeStackValue =
1908 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1909 ConstantInt::get(IntptrTy, LocalStackSize));
1910 IRB.SetInsertPoint(InsBefore);
1911 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1912 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1913 ConstantInt::get(IntptrTy, 0));
1915 Value *NoFakeStack =
1916 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1917 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1918 IRBIf.SetInsertPoint(Term);
1919 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1920 Value *AllocaValue =
1921 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1922 IRB.SetInsertPoint(InsBefore);
1923 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1924 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1926 // void *FakeStack = nullptr;
1927 // void *LocalStackBase = alloca(LocalStackSize);
1928 FakeStack = ConstantInt::get(IntptrTy, 0);
1930 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1933 // Replace Alloca instructions with base+offset.
1934 for (const auto &Desc : SVD) {
1935 AllocaInst *AI = Desc.AI;
1936 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1937 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1939 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1940 AI->replaceAllUsesWith(NewAllocaPtr);
1943 // The left-most redzone has enough space for at least 4 pointers.
1944 // Write the Magic value to redzone[0].
1945 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1946 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1948 // Write the frame description constant to redzone[1].
1949 Value *BasePlus1 = IRB.CreateIntToPtr(
1950 IRB.CreateAdd(LocalStackBase,
1951 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1953 GlobalVariable *StackDescriptionGlobal =
1954 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1955 /*AllowMerging*/ true);
1956 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1957 IRB.CreateStore(Description, BasePlus1);
1958 // Write the PC to redzone[2].
1959 Value *BasePlus2 = IRB.CreateIntToPtr(
1960 IRB.CreateAdd(LocalStackBase,
1961 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1963 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1965 // Poison the stack redzones at the entry.
1966 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1967 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1969 // (Un)poison the stack before all ret instructions.
1970 for (auto Ret : RetVec) {
1971 IRBuilder<> IRBRet(Ret);
1972 // Mark the current frame as retired.
1973 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1975 if (DoStackMalloc) {
1976 assert(StackMallocIdx >= 0);
1977 // if FakeStack != 0 // LocalStackBase == FakeStack
1978 // // In use-after-return mode, poison the whole stack frame.
1979 // if StackMallocIdx <= 4
1980 // // For small sizes inline the whole thing:
1981 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1982 // **SavedFlagPtr(FakeStack) = 0
1984 // __asan_stack_free_N(FakeStack, LocalStackSize)
1986 // <This is not a fake stack; unpoison the redzones>
1988 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1989 TerminatorInst *ThenTerm, *ElseTerm;
1990 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1992 IRBuilder<> IRBPoison(ThenTerm);
1993 if (StackMallocIdx <= 4) {
1994 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1995 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1996 ClassSize >> Mapping.Scale);
1997 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1999 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
2000 Value *SavedFlagPtr = IRBPoison.CreateLoad(
2001 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
2002 IRBPoison.CreateStore(
2003 Constant::getNullValue(IRBPoison.getInt8Ty()),
2004 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
2006 // For larger frames call __asan_stack_free_*.
2007 IRBPoison.CreateCall(
2008 AsanStackFreeFunc[StackMallocIdx],
2009 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
2012 IRBuilder<> IRBElse(ElseTerm);
2013 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
2014 } else if (HavePoisonedAllocas) {
2015 // If we poisoned some allocas in llvm.lifetime analysis,
2016 // unpoison whole stack frame now.
2017 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
2019 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
2023 // We are done. Remove the old unused alloca instructions.
2024 for (auto AI : AllocaVec) AI->eraseFromParent();
2027 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2028 IRBuilder<> &IRB, bool DoPoison) {
2029 // For now just insert the call to ASan runtime.
2030 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2031 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2033 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2034 {AddrArg, SizeArg});
2037 // Handling llvm.lifetime intrinsics for a given %alloca:
2038 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2039 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2040 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2041 // could be poisoned by previous llvm.lifetime.end instruction, as the
2042 // variable may go in and out of scope several times, e.g. in loops).
2043 // (3) if we poisoned at least one %alloca in a function,
2044 // unpoison the whole stack frame at function exit.
2046 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2047 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2048 // We're intested only in allocas we can handle.
2049 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2050 // See if we've already calculated (or started to calculate) alloca for a
2052 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2053 if (I != AllocaForValue.end()) return I->second;
2054 // Store 0 while we're calculating alloca for value V to avoid
2055 // infinite recursion if the value references itself.
2056 AllocaForValue[V] = nullptr;
2057 AllocaInst *Res = nullptr;
2058 if (CastInst *CI = dyn_cast<CastInst>(V))
2059 Res = findAllocaForValue(CI->getOperand(0));
2060 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2061 for (Value *IncValue : PN->incoming_values()) {
2062 // Allow self-referencing phi-nodes.
2063 if (IncValue == PN) continue;
2064 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2065 // AI for incoming values should exist and should all be equal.
2066 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2071 if (Res) AllocaForValue[V] = Res;
2075 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2076 IRBuilder<> IRB(AI);
2078 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2079 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2081 Value *Zero = Constant::getNullValue(IntptrTy);
2082 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2083 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2085 // Since we need to extend alloca with additional memory to locate
2086 // redzones, and OldSize is number of allocated blocks with
2087 // ElementSize size, get allocated memory size in bytes by
2088 // OldSize * ElementSize.
2089 const unsigned ElementSize =
2090 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2092 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2093 ConstantInt::get(IntptrTy, ElementSize));
2095 // PartialSize = OldSize % 32
2096 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2098 // Misalign = kAllocaRzSize - PartialSize;
2099 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2101 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2102 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2103 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2105 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2106 // Align is added to locate left redzone, PartialPadding for possible
2107 // partial redzone and kAllocaRzSize for right redzone respectively.
2108 Value *AdditionalChunkSize = IRB.CreateAdd(
2109 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2111 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2113 // Insert new alloca with new NewSize and Align params.
2114 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2115 NewAlloca->setAlignment(Align);
2117 // NewAddress = Address + Align
2118 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2119 ConstantInt::get(IntptrTy, Align));
2121 // Insert __asan_alloca_poison call for new created alloca.
2122 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2124 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2125 // for unpoisoning stuff.
2126 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2128 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2130 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2131 AI->replaceAllUsesWith(NewAddressPtr);
2133 // We are done. Erase old alloca from parent.
2134 AI->eraseFromParent();
2137 // isSafeAccess returns true if Addr is always inbounds with respect to its
2138 // base object. For example, it is a field access or an array access with
2139 // constant inbounds index.
2140 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2141 Value *Addr, uint64_t TypeSize) const {
2142 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2143 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2144 uint64_t Size = SizeOffset.first.getZExtValue();
2145 int64_t Offset = SizeOffset.second.getSExtValue();
2146 // Three checks are required to ensure safety:
2147 // . Offset >= 0 (since the offset is given from the base ptr)
2148 // . Size >= Offset (unsigned)
2149 // . Size - Offset >= NeededSize (unsigned)
2150 return Offset >= 0 && Size >= uint64_t(Offset) &&
2151 Size - uint64_t(Offset) >= TypeSize / 8;