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 kAsanReportLoadN = "__asan_report_load_n";
87 static const char *const kAsanReportStoreN = "__asan_report_store_n";
88 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
89 static const char *const kAsanUnregisterGlobalsName =
90 "__asan_unregister_globals";
91 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
92 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
93 static const char *const kAsanInitName = "__asan_init_v5";
94 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
95 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
96 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
97 static const int kMaxAsanStackMallocSizeClass = 10;
98 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
99 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
100 static const char *const kAsanGenPrefix = "__asan_gen_";
101 static const char *const kSanCovGenPrefix = "__sancov_gen_";
102 static const char *const kAsanPoisonStackMemoryName =
103 "__asan_poison_stack_memory";
104 static const char *const kAsanUnpoisonStackMemoryName =
105 "__asan_unpoison_stack_memory";
107 static const char *const kAsanOptionDetectUAR =
108 "__asan_option_detect_stack_use_after_return";
111 static const int kAsanStackAfterReturnMagic = 0xf5;
114 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
115 static const size_t kNumberOfAccessSizes = 5;
117 static const unsigned kAllocaRzSize = 32;
118 static const unsigned kAsanAllocaLeftMagic = 0xcacacacaU;
119 static const unsigned kAsanAllocaRightMagic = 0xcbcbcbcbU;
120 static const unsigned kAsanAllocaPartialVal1 = 0xcbcbcb00U;
121 static const unsigned kAsanAllocaPartialVal2 = 0x000000cbU;
123 // Command-line flags.
125 // This flag may need to be replaced with -f[no-]asan-reads.
126 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
127 cl::desc("instrument read instructions"),
128 cl::Hidden, cl::init(true));
129 static cl::opt<bool> ClInstrumentWrites(
130 "asan-instrument-writes", cl::desc("instrument write instructions"),
131 cl::Hidden, cl::init(true));
132 static cl::opt<bool> ClInstrumentAtomics(
133 "asan-instrument-atomics",
134 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
136 static cl::opt<bool> ClAlwaysSlowPath(
137 "asan-always-slow-path",
138 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
140 // This flag limits the number of instructions to be instrumented
141 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
142 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
144 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
145 "asan-max-ins-per-bb", cl::init(10000),
146 cl::desc("maximal number of instructions to instrument in any given BB"),
148 // This flag may need to be replaced with -f[no]asan-stack.
149 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
150 cl::Hidden, cl::init(true));
151 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
152 cl::desc("Check return-after-free"),
153 cl::Hidden, cl::init(true));
154 // This flag may need to be replaced with -f[no]asan-globals.
155 static cl::opt<bool> ClGlobals("asan-globals",
156 cl::desc("Handle global objects"), cl::Hidden,
158 static cl::opt<bool> ClInitializers("asan-initialization-order",
159 cl::desc("Handle C++ initializer order"),
160 cl::Hidden, cl::init(true));
161 static cl::opt<bool> ClInvalidPointerPairs(
162 "asan-detect-invalid-pointer-pair",
163 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
165 static cl::opt<unsigned> ClRealignStack(
166 "asan-realign-stack",
167 cl::desc("Realign stack to the value of this flag (power of two)"),
168 cl::Hidden, cl::init(32));
169 static cl::opt<int> ClInstrumentationWithCallsThreshold(
170 "asan-instrumentation-with-call-threshold",
172 "If the function being instrumented contains more than "
173 "this number of memory accesses, use callbacks instead of "
174 "inline checks (-1 means never use callbacks)."),
175 cl::Hidden, cl::init(7000));
176 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
177 "asan-memory-access-callback-prefix",
178 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
179 cl::init("__asan_"));
180 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
181 cl::desc("instrument dynamic allocas"),
182 cl::Hidden, cl::init(false));
183 static cl::opt<bool> ClSkipPromotableAllocas(
184 "asan-skip-promotable-allocas",
185 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
188 // These flags allow to change the shadow mapping.
189 // The shadow mapping looks like
190 // Shadow = (Mem >> scale) + (1 << offset_log)
191 static cl::opt<int> ClMappingScale("asan-mapping-scale",
192 cl::desc("scale of asan shadow mapping"),
193 cl::Hidden, cl::init(0));
195 // Optimization flags. Not user visible, used mostly for testing
196 // and benchmarking the tool.
197 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
198 cl::Hidden, cl::init(true));
199 static cl::opt<bool> ClOptSameTemp(
200 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
201 cl::Hidden, cl::init(true));
202 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
203 cl::desc("Don't instrument scalar globals"),
204 cl::Hidden, cl::init(true));
205 static cl::opt<bool> ClOptStack(
206 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
207 cl::Hidden, cl::init(false));
209 static cl::opt<bool> ClCheckLifetime(
210 "asan-check-lifetime",
211 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), cl::Hidden,
214 static cl::opt<bool> ClDynamicAllocaStack(
215 "asan-stack-dynamic-alloca",
216 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
220 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
222 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
223 cl::Hidden, cl::init(0));
224 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
225 cl::desc("Debug func"));
226 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
227 cl::Hidden, cl::init(-1));
228 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
229 cl::Hidden, cl::init(-1));
231 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
232 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
233 STATISTIC(NumInstrumentedDynamicAllocas,
234 "Number of instrumented dynamic allocas");
235 STATISTIC(NumOptimizedAccessesToGlobalVar,
236 "Number of optimized accesses to global vars");
237 STATISTIC(NumOptimizedAccessesToStackVar,
238 "Number of optimized accesses to stack vars");
241 /// Frontend-provided metadata for source location.
242 struct LocationMetadata {
247 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
249 bool empty() const { return Filename.empty(); }
251 void parse(MDNode *MDN) {
252 assert(MDN->getNumOperands() == 3);
253 MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
254 Filename = MDFilename->getString();
256 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
258 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
262 /// Frontend-provided metadata for global variables.
263 class GlobalsMetadata {
266 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
267 LocationMetadata SourceLoc;
273 GlobalsMetadata() : inited_(false) {}
275 void init(Module &M) {
278 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
279 if (!Globals) return;
280 for (auto MDN : Globals->operands()) {
281 // Metadata node contains the global and the fields of "Entry".
282 assert(MDN->getNumOperands() == 5);
283 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
284 // The optimizer may optimize away a global entirely.
286 // We can already have an entry for GV if it was merged with another
288 Entry &E = Entries[GV];
289 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
290 E.SourceLoc.parse(Loc);
291 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
292 E.Name = Name->getString();
293 ConstantInt *IsDynInit =
294 mdconst::extract<ConstantInt>(MDN->getOperand(3));
295 E.IsDynInit |= IsDynInit->isOne();
296 ConstantInt *IsBlacklisted =
297 mdconst::extract<ConstantInt>(MDN->getOperand(4));
298 E.IsBlacklisted |= IsBlacklisted->isOne();
302 /// Returns metadata entry for a given global.
303 Entry get(GlobalVariable *G) const {
304 auto Pos = Entries.find(G);
305 return (Pos != Entries.end()) ? Pos->second : Entry();
310 DenseMap<GlobalVariable *, Entry> Entries;
313 /// This struct defines the shadow mapping using the rule:
314 /// shadow = (mem >> Scale) ADD-or-OR Offset.
315 struct ShadowMapping {
321 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) {
322 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
323 bool IsIOS = TargetTriple.isiOS();
324 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
325 bool IsLinux = TargetTriple.isOSLinux();
326 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
327 TargetTriple.getArch() == llvm::Triple::ppc64le;
328 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
329 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
330 TargetTriple.getArch() == llvm::Triple::mipsel;
331 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
332 TargetTriple.getArch() == llvm::Triple::mips64el;
333 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
334 bool IsWindows = TargetTriple.isOSWindows();
336 ShadowMapping Mapping;
338 if (LongSize == 32) {
342 Mapping.Offset = kMIPS32_ShadowOffset32;
344 Mapping.Offset = kFreeBSD_ShadowOffset32;
346 Mapping.Offset = kIOSShadowOffset32;
348 Mapping.Offset = kWindowsShadowOffset32;
350 Mapping.Offset = kDefaultShadowOffset32;
351 } else { // LongSize == 64
353 Mapping.Offset = kPPC64_ShadowOffset64;
355 Mapping.Offset = kFreeBSD_ShadowOffset64;
356 else if (IsLinux && IsX86_64)
357 Mapping.Offset = kSmallX86_64ShadowOffset;
359 Mapping.Offset = kMIPS64_ShadowOffset64;
361 Mapping.Offset = kAArch64_ShadowOffset64;
363 Mapping.Offset = kDefaultShadowOffset64;
366 Mapping.Scale = kDefaultShadowScale;
367 if (ClMappingScale) {
368 Mapping.Scale = ClMappingScale;
371 // OR-ing shadow offset if more efficient (at least on x86) if the offset
372 // is a power of two, but on ppc64 we have to use add since the shadow
373 // offset is not necessary 1/8-th of the address space.
374 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
379 static size_t RedzoneSizeForScale(int MappingScale) {
380 // Redzone used for stack and globals is at least 32 bytes.
381 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
382 return std::max(32U, 1U << MappingScale);
385 /// AddressSanitizer: instrument the code in module to find memory bugs.
386 struct AddressSanitizer : public FunctionPass {
387 AddressSanitizer() : FunctionPass(ID) {
388 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
390 const char *getPassName() const override {
391 return "AddressSanitizerFunctionPass";
393 void getAnalysisUsage(AnalysisUsage &AU) const override {
394 AU.addRequired<DominatorTreeWrapperPass>();
395 AU.addRequired<TargetLibraryInfoWrapperPass>();
397 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
398 Type *Ty = AI->getAllocatedType();
399 uint64_t SizeInBytes =
400 AI->getModule()->getDataLayout().getTypeAllocSize(Ty);
403 /// Check if we want (and can) handle this alloca.
404 bool isInterestingAlloca(AllocaInst &AI) const;
405 /// If it is an interesting memory access, return the PointerOperand
406 /// and set IsWrite/Alignment. Otherwise return nullptr.
407 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
409 unsigned *Alignment) const;
410 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
411 bool UseCalls, const DataLayout &DL);
412 void instrumentPointerComparisonOrSubtraction(Instruction *I);
413 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
414 Value *Addr, uint32_t TypeSize, bool IsWrite,
415 Value *SizeArgument, bool UseCalls);
416 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
417 Value *ShadowValue, uint32_t TypeSize);
418 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
419 bool IsWrite, size_t AccessSizeIndex,
420 Value *SizeArgument);
421 void instrumentMemIntrinsic(MemIntrinsic *MI);
422 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
423 bool runOnFunction(Function &F) override;
424 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
425 bool doInitialization(Module &M) override;
426 static char ID; // Pass identification, replacement for typeid
428 DominatorTree &getDominatorTree() const { return *DT; }
431 void initializeCallbacks(Module &M);
433 bool LooksLikeCodeInBug11395(Instruction *I);
434 bool GlobalIsLinkerInitialized(GlobalVariable *G);
435 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
436 uint64_t TypeSize) const;
442 ShadowMapping Mapping;
444 Function *AsanCtorFunction;
445 Function *AsanInitFunction;
446 Function *AsanHandleNoReturnFunc;
447 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
448 // This array is indexed by AccessIsWrite and log2(AccessSize).
449 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
450 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
451 // This array is indexed by AccessIsWrite.
452 Function *AsanErrorCallbackSized[2], *AsanMemoryAccessCallbackSized[2];
453 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
455 GlobalsMetadata GlobalsMD;
457 friend struct FunctionStackPoisoner;
460 class AddressSanitizerModule : public ModulePass {
462 AddressSanitizerModule() : ModulePass(ID) {}
463 bool runOnModule(Module &M) override;
464 static char ID; // Pass identification, replacement for typeid
465 const char *getPassName() const override { return "AddressSanitizerModule"; }
468 void initializeCallbacks(Module &M);
470 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
471 bool ShouldInstrumentGlobal(GlobalVariable *G);
472 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
473 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
474 size_t MinRedzoneSizeForGlobal() const {
475 return RedzoneSizeForScale(Mapping.Scale);
478 GlobalsMetadata GlobalsMD;
482 ShadowMapping Mapping;
483 Function *AsanPoisonGlobals;
484 Function *AsanUnpoisonGlobals;
485 Function *AsanRegisterGlobals;
486 Function *AsanUnregisterGlobals;
489 // Stack poisoning does not play well with exception handling.
490 // When an exception is thrown, we essentially bypass the code
491 // that unpoisones the stack. This is why the run-time library has
492 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
493 // stack in the interceptor. This however does not work inside the
494 // actual function which catches the exception. Most likely because the
495 // compiler hoists the load of the shadow value somewhere too high.
496 // This causes asan to report a non-existing bug on 453.povray.
497 // It sounds like an LLVM bug.
498 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
500 AddressSanitizer &ASan;
505 ShadowMapping Mapping;
507 SmallVector<AllocaInst *, 16> AllocaVec;
508 SmallVector<Instruction *, 8> RetVec;
509 unsigned StackAlignment;
511 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
512 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
513 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
515 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
516 struct AllocaPoisonCall {
517 IntrinsicInst *InsBefore;
522 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
524 // Stores left and right redzone shadow addresses for dynamic alloca
525 // and pointer to alloca instruction itself.
526 // LeftRzAddr is a shadow address for alloca left redzone.
527 // RightRzAddr is a shadow address for alloca right redzone.
528 struct DynamicAllocaCall {
533 explicit DynamicAllocaCall(AllocaInst *AI, Value *LeftRzAddr = nullptr,
534 Value *RightRzAddr = nullptr)
536 LeftRzAddr(LeftRzAddr),
537 RightRzAddr(RightRzAddr),
540 SmallVector<DynamicAllocaCall, 1> DynamicAllocaVec;
542 // Maps Value to an AllocaInst from which the Value is originated.
543 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
544 AllocaForValueMapTy AllocaForValue;
546 bool HasNonEmptyInlineAsm;
547 std::unique_ptr<CallInst> EmptyInlineAsm;
549 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
552 DIB(*F.getParent(), /*AllowUnresolved*/ false),
554 IntptrTy(ASan.IntptrTy),
555 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
556 Mapping(ASan.Mapping),
557 StackAlignment(1 << Mapping.Scale),
558 HasNonEmptyInlineAsm(false),
559 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
561 bool runOnFunction() {
562 if (!ClStack) return false;
563 // Collect alloca, ret, lifetime instructions etc.
564 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
566 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
568 initializeCallbacks(*F.getParent());
578 // Finds all Alloca instructions and puts
579 // poisoned red zones around all of them.
580 // Then unpoison everything back before the function returns.
583 // ----------------------- Visitors.
584 /// \brief Collect all Ret instructions.
585 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
587 // Unpoison dynamic allocas redzones.
588 void unpoisonDynamicAlloca(DynamicAllocaCall &AllocaCall) {
589 if (!AllocaCall.Poison) return;
590 for (auto Ret : RetVec) {
591 IRBuilder<> IRBRet(Ret);
592 PointerType *Int32PtrTy = PointerType::getUnqual(IRBRet.getInt32Ty());
593 Value *Zero = Constant::getNullValue(IRBRet.getInt32Ty());
594 Value *PartialRzAddr = IRBRet.CreateSub(AllocaCall.RightRzAddr,
595 ConstantInt::get(IntptrTy, 4));
597 Zero, IRBRet.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
598 IRBRet.CreateStore(Zero,
599 IRBRet.CreateIntToPtr(PartialRzAddr, Int32PtrTy));
601 Zero, IRBRet.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
605 // Right shift for BigEndian and left shift for LittleEndian.
606 Value *shiftAllocaMagic(Value *Val, IRBuilder<> &IRB, Value *Shift) {
607 auto &DL = F.getParent()->getDataLayout();
608 return DL.isLittleEndian() ? IRB.CreateShl(Val, Shift)
609 : IRB.CreateLShr(Val, Shift);
612 // Compute PartialRzMagic for dynamic alloca call. Since we don't know the
613 // size of requested memory until runtime, we should compute it dynamically.
614 // If PartialSize is 0, PartialRzMagic would contain kAsanAllocaRightMagic,
615 // otherwise it would contain the value that we will use to poison the
616 // partial redzone for alloca call.
617 Value *computePartialRzMagic(Value *PartialSize, IRBuilder<> &IRB);
619 // Deploy and poison redzones around dynamic alloca call. To do this, we
620 // should replace this call with another one with changed parameters and
621 // replace all its uses with new address, so
622 // addr = alloca type, old_size, align
624 // new_size = (old_size + additional_size) * sizeof(type)
625 // tmp = alloca i8, new_size, max(align, 32)
626 // addr = tmp + 32 (first 32 bytes are for the left redzone).
627 // Additional_size is added to make new memory allocation contain not only
628 // requested memory, but also left, partial and right redzones.
629 // After that, we should poison redzones:
630 // (1) Left redzone with kAsanAllocaLeftMagic.
631 // (2) Partial redzone with the value, computed in runtime by
632 // computePartialRzMagic function.
633 // (3) Right redzone with kAsanAllocaRightMagic.
634 void handleDynamicAllocaCall(DynamicAllocaCall &AllocaCall);
636 /// \brief Collect Alloca instructions we want (and can) handle.
637 void visitAllocaInst(AllocaInst &AI) {
638 if (!ASan.isInterestingAlloca(AI)) return;
640 StackAlignment = std::max(StackAlignment, AI.getAlignment());
641 if (isDynamicAlloca(AI))
642 DynamicAllocaVec.push_back(DynamicAllocaCall(&AI));
644 AllocaVec.push_back(&AI);
647 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
649 void visitIntrinsicInst(IntrinsicInst &II) {
650 if (!ClCheckLifetime) return;
651 Intrinsic::ID ID = II.getIntrinsicID();
652 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
654 // Found lifetime intrinsic, add ASan instrumentation if necessary.
655 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
656 // If size argument is undefined, don't do anything.
657 if (Size->isMinusOne()) return;
658 // Check that size doesn't saturate uint64_t and can
659 // be stored in IntptrTy.
660 const uint64_t SizeValue = Size->getValue().getLimitedValue();
661 if (SizeValue == ~0ULL ||
662 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
664 // Find alloca instruction that corresponds to llvm.lifetime argument.
665 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
667 bool DoPoison = (ID == Intrinsic::lifetime_end);
668 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
669 AllocaPoisonCallVec.push_back(APC);
672 void visitCallInst(CallInst &CI) {
673 HasNonEmptyInlineAsm |=
674 CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get());
677 // ---------------------- Helpers.
678 void initializeCallbacks(Module &M);
680 bool doesDominateAllExits(const Instruction *I) const {
681 for (auto Ret : RetVec) {
682 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
687 bool isDynamicAlloca(AllocaInst &AI) const {
688 return AI.isArrayAllocation() || !AI.isStaticAlloca();
690 /// Finds alloca where the value comes from.
691 AllocaInst *findAllocaForValue(Value *V);
692 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
693 Value *ShadowBase, bool DoPoison);
694 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
696 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
698 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
700 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
701 Instruction *ThenTerm, Value *ValueIfFalse);
706 char AddressSanitizer::ID = 0;
707 INITIALIZE_PASS_BEGIN(
708 AddressSanitizer, "asan",
709 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
711 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
713 AddressSanitizer, "asan",
714 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
716 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
717 return new AddressSanitizer();
720 char AddressSanitizerModule::ID = 0;
722 AddressSanitizerModule, "asan-module",
723 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
726 ModulePass *llvm::createAddressSanitizerModulePass() {
727 return new AddressSanitizerModule();
730 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
731 size_t Res = countTrailingZeros(TypeSize / 8);
732 assert(Res < kNumberOfAccessSizes);
736 // \brief Create a constant for Str so that we can pass it to the run-time lib.
737 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
739 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
740 // We use private linkage for module-local strings. If they can be merged
741 // with another one, we set the unnamed_addr attribute.
743 new GlobalVariable(M, StrConst->getType(), true,
744 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
745 if (AllowMerging) GV->setUnnamedAddr(true);
746 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
750 /// \brief Create a global describing a source location.
751 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
752 LocationMetadata MD) {
753 Constant *LocData[] = {
754 createPrivateGlobalForString(M, MD.Filename, true),
755 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
756 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
758 auto LocStruct = ConstantStruct::getAnon(LocData);
759 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
760 GlobalValue::PrivateLinkage, LocStruct,
762 GV->setUnnamedAddr(true);
766 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
767 return G->getName().find(kAsanGenPrefix) == 0 ||
768 G->getName().find(kSanCovGenPrefix) == 0;
771 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
773 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
774 if (Mapping.Offset == 0) return Shadow;
775 // (Shadow >> scale) | offset
776 if (Mapping.OrShadowOffset)
777 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
779 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
782 // Instrument memset/memmove/memcpy
783 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
785 if (isa<MemTransferInst>(MI)) {
787 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
788 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
789 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
790 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
791 } else if (isa<MemSetInst>(MI)) {
794 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
795 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
796 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
798 MI->eraseFromParent();
801 /// Check if we want (and can) handle this alloca.
802 bool AddressSanitizer::isInterestingAlloca(AllocaInst &AI) const {
803 return (AI.getAllocatedType()->isSized() &&
804 // alloca() may be called with 0 size, ignore it.
805 getAllocaSizeInBytes(&AI) > 0 &&
806 // We are only interested in allocas not promotable to registers.
807 // Promotable allocas are common under -O0.
808 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)));
811 /// If I is an interesting memory access, return the PointerOperand
812 /// and set IsWrite/Alignment. Otherwise return nullptr.
813 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
816 unsigned *Alignment) const {
817 // Skip memory accesses inserted by another instrumentation.
818 if (I->getMetadata("nosanitize")) return nullptr;
820 Value *PtrOperand = nullptr;
821 const DataLayout &DL = I->getModule()->getDataLayout();
822 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
823 if (!ClInstrumentReads) return nullptr;
825 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
826 *Alignment = LI->getAlignment();
827 PtrOperand = LI->getPointerOperand();
828 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
829 if (!ClInstrumentWrites) return nullptr;
831 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
832 *Alignment = SI->getAlignment();
833 PtrOperand = SI->getPointerOperand();
834 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
835 if (!ClInstrumentAtomics) return nullptr;
837 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
839 PtrOperand = RMW->getPointerOperand();
840 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
841 if (!ClInstrumentAtomics) return nullptr;
843 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
845 PtrOperand = XCHG->getPointerOperand();
848 // Treat memory accesses to promotable allocas as non-interesting since they
849 // will not cause memory violations. This greatly speeds up the instrumented
850 // executable at -O0.
851 if (ClSkipPromotableAllocas)
852 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
853 return isInterestingAlloca(*AI) ? AI : nullptr;
858 static bool isPointerOperand(Value *V) {
859 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
862 // This is a rough heuristic; it may cause both false positives and
863 // false negatives. The proper implementation requires cooperation with
865 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
866 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
867 if (!Cmp->isRelational()) return false;
868 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
869 if (BO->getOpcode() != Instruction::Sub) return false;
873 if (!isPointerOperand(I->getOperand(0)) ||
874 !isPointerOperand(I->getOperand(1)))
879 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
880 // If a global variable does not have dynamic initialization we don't
881 // have to instrument it. However, if a global does not have initializer
882 // at all, we assume it has dynamic initializer (in other TU).
883 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
886 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
889 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
890 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
891 for (int i = 0; i < 2; i++) {
892 if (Param[i]->getType()->isPointerTy())
893 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
895 IRB.CreateCall2(F, Param[0], Param[1]);
898 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
899 Instruction *I, bool UseCalls,
900 const DataLayout &DL) {
901 bool IsWrite = false;
902 unsigned Alignment = 0;
903 uint64_t TypeSize = 0;
904 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment);
907 if (ClOpt && ClOptGlobals) {
908 // If initialization order checking is disabled, a simple access to a
909 // dynamically initialized global is always valid.
910 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
911 if (G != NULL && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
912 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
913 NumOptimizedAccessesToGlobalVar++;
918 if (ClOpt && ClOptStack) {
919 // A direct inbounds access to a stack variable is always valid.
920 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
921 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
922 NumOptimizedAccessesToStackVar++;
928 NumInstrumentedWrites++;
930 NumInstrumentedReads++;
932 unsigned Granularity = 1 << Mapping.Scale;
933 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
934 // if the data is properly aligned.
935 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
937 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
938 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
939 // Instrument unusual size or unusual alignment.
940 // We can not do it with a single check, so we do 1-byte check for the first
941 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
942 // to report the actual access size.
944 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
945 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
947 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
949 Value *LastByte = IRB.CreateIntToPtr(
950 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
952 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
953 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
957 // Validate the result of Module::getOrInsertFunction called for an interface
958 // function of AddressSanitizer. If the instrumented module defines a function
959 // with the same name, their prototypes must match, otherwise
960 // getOrInsertFunction returns a bitcast.
961 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
962 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
963 FuncOrBitcast->dump();
965 "trying to redefine an AddressSanitizer "
966 "interface function");
969 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
970 Value *Addr, bool IsWrite,
971 size_t AccessSizeIndex,
972 Value *SizeArgument) {
973 IRBuilder<> IRB(InsertBefore);
976 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
977 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
979 // We don't do Call->setDoesNotReturn() because the BB already has
980 // UnreachableInst at the end.
981 // This EmptyAsm is required to avoid callback merge.
982 IRB.CreateCall(EmptyAsm);
986 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
989 size_t Granularity = 1 << Mapping.Scale;
990 // Addr & (Granularity - 1)
991 Value *LastAccessedByte =
992 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
993 // (Addr & (Granularity - 1)) + size - 1
994 if (TypeSize / 8 > 1)
995 LastAccessedByte = IRB.CreateAdd(
996 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
997 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
999 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1000 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1001 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1004 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1005 Instruction *InsertBefore, Value *Addr,
1006 uint32_t TypeSize, bool IsWrite,
1007 Value *SizeArgument, bool UseCalls) {
1008 IRBuilder<> IRB(InsertBefore);
1009 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1010 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1013 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
1019 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1020 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1021 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1022 Value *CmpVal = Constant::getNullValue(ShadowTy);
1023 Value *ShadowValue =
1024 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1026 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1027 size_t Granularity = 1 << Mapping.Scale;
1028 TerminatorInst *CrashTerm = nullptr;
1030 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1031 // We use branch weights for the slow path check, to indicate that the slow
1032 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1033 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1034 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1035 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
1036 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1037 IRB.SetInsertPoint(CheckTerm);
1038 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1039 BasicBlock *CrashBlock =
1040 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1041 CrashTerm = new UnreachableInst(*C, CrashBlock);
1042 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1043 ReplaceInstWithInst(CheckTerm, NewTerm);
1045 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1048 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1049 AccessSizeIndex, SizeArgument);
1050 Crash->setDebugLoc(OrigIns->getDebugLoc());
1053 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1054 GlobalValue *ModuleName) {
1055 // Set up the arguments to our poison/unpoison functions.
1056 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1058 // Add a call to poison all external globals before the given function starts.
1059 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1060 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1062 // Add calls to unpoison all globals before each return instruction.
1063 for (auto &BB : GlobalInit.getBasicBlockList())
1064 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1065 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1068 void AddressSanitizerModule::createInitializerPoisonCalls(
1069 Module &M, GlobalValue *ModuleName) {
1070 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1072 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1073 for (Use &OP : CA->operands()) {
1074 if (isa<ConstantAggregateZero>(OP)) continue;
1075 ConstantStruct *CS = cast<ConstantStruct>(OP);
1077 // Must have a function or null ptr.
1078 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1079 if (F->getName() == kAsanModuleCtorName) continue;
1080 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1081 // Don't instrument CTORs that will run before asan.module_ctor.
1082 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1083 poisonOneInitializer(*F, ModuleName);
1088 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1089 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1090 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1092 if (GlobalsMD.get(G).IsBlacklisted) return false;
1093 if (!Ty->isSized()) return false;
1094 if (!G->hasInitializer()) return false;
1095 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1096 // Touch only those globals that will not be defined in other modules.
1097 // Don't handle ODR linkage types and COMDATs since other modules may be built
1099 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1100 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1101 G->getLinkage() != GlobalVariable::InternalLinkage)
1103 if (G->hasComdat()) return false;
1104 // Two problems with thread-locals:
1105 // - The address of the main thread's copy can't be computed at link-time.
1106 // - Need to poison all copies, not just the main thread's one.
1107 if (G->isThreadLocal()) return false;
1108 // For now, just ignore this Global if the alignment is large.
1109 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1111 if (G->hasSection()) {
1112 StringRef Section(G->getSection());
1114 if (TargetTriple.isOSBinFormatMachO()) {
1115 StringRef ParsedSegment, ParsedSection;
1116 unsigned TAA = 0, StubSize = 0;
1118 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1119 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1120 if (!ErrorCode.empty()) {
1121 report_fatal_error("Invalid section specifier '" + ParsedSection +
1122 "': " + ErrorCode + ".");
1125 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1126 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1128 if (ParsedSegment == "__OBJC" ||
1129 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1130 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1133 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1134 // Constant CFString instances are compiled in the following way:
1135 // -- the string buffer is emitted into
1136 // __TEXT,__cstring,cstring_literals
1137 // -- the constant NSConstantString structure referencing that buffer
1138 // is placed into __DATA,__cfstring
1139 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1140 // Moreover, it causes the linker to crash on OS X 10.7
1141 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1142 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1145 // The linker merges the contents of cstring_literals and removes the
1147 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1148 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1153 // Callbacks put into the CRT initializer/terminator sections
1154 // should not be instrumented.
1155 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1156 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1157 if (Section.startswith(".CRT")) {
1158 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1162 // Globals from llvm.metadata aren't emitted, do not instrument them.
1163 if (Section == "llvm.metadata") return false;
1169 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1170 IRBuilder<> IRB(*C);
1171 // Declare our poisoning and unpoisoning functions.
1172 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1173 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1174 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1175 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1176 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1177 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1178 // Declare functions that register/unregister globals.
1179 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1180 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1181 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1182 AsanUnregisterGlobals = checkInterfaceFunction(
1183 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1184 IntptrTy, IntptrTy, nullptr));
1185 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1188 // This function replaces all global variables with new variables that have
1189 // trailing redzones. It also creates a function that poisons
1190 // redzones and inserts this function into llvm.global_ctors.
1191 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1194 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1196 for (auto &G : M.globals()) {
1197 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1200 size_t n = GlobalsToChange.size();
1201 if (n == 0) return false;
1203 // A global is described by a structure
1206 // size_t size_with_redzone;
1207 // const char *name;
1208 // const char *module_name;
1209 // size_t has_dynamic_init;
1210 // void *source_location;
1211 // We initialize an array of such structures and pass it to a run-time call.
1212 StructType *GlobalStructTy =
1213 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1214 IntptrTy, IntptrTy, nullptr);
1215 SmallVector<Constant *, 16> Initializers(n);
1217 bool HasDynamicallyInitializedGlobals = false;
1219 // We shouldn't merge same module names, as this string serves as unique
1220 // module ID in runtime.
1221 GlobalVariable *ModuleName = createPrivateGlobalForString(
1222 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1224 auto &DL = M.getDataLayout();
1225 for (size_t i = 0; i < n; i++) {
1226 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1227 GlobalVariable *G = GlobalsToChange[i];
1229 auto MD = GlobalsMD.get(G);
1230 // Create string holding the global name (use global name from metadata
1231 // if it's available, otherwise just write the name of global variable).
1232 GlobalVariable *Name = createPrivateGlobalForString(
1233 M, MD.Name.empty() ? G->getName() : MD.Name,
1234 /*AllowMerging*/ true);
1236 PointerType *PtrTy = cast<PointerType>(G->getType());
1237 Type *Ty = PtrTy->getElementType();
1238 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1239 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1240 // MinRZ <= RZ <= kMaxGlobalRedzone
1241 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1242 uint64_t RZ = std::max(
1243 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1244 uint64_t RightRedzoneSize = RZ;
1245 // Round up to MinRZ
1246 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1247 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1248 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1250 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1251 Constant *NewInitializer =
1252 ConstantStruct::get(NewTy, G->getInitializer(),
1253 Constant::getNullValue(RightRedZoneTy), nullptr);
1255 // Create a new global variable with enough space for a redzone.
1256 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1257 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1258 Linkage = GlobalValue::InternalLinkage;
1259 GlobalVariable *NewGlobal =
1260 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1261 "", G, G->getThreadLocalMode());
1262 NewGlobal->copyAttributesFrom(G);
1263 NewGlobal->setAlignment(MinRZ);
1266 Indices2[0] = IRB.getInt32(0);
1267 Indices2[1] = IRB.getInt32(0);
1269 G->replaceAllUsesWith(
1270 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1271 NewGlobal->takeName(G);
1272 G->eraseFromParent();
1274 Constant *SourceLoc;
1275 if (!MD.SourceLoc.empty()) {
1276 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1277 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1279 SourceLoc = ConstantInt::get(IntptrTy, 0);
1282 Initializers[i] = ConstantStruct::get(
1283 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1284 ConstantInt::get(IntptrTy, SizeInBytes),
1285 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1286 ConstantExpr::getPointerCast(Name, IntptrTy),
1287 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1288 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1290 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1292 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1295 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1296 GlobalVariable *AllGlobals = new GlobalVariable(
1297 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1298 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1300 // Create calls for poisoning before initializers run and unpoisoning after.
1301 if (HasDynamicallyInitializedGlobals)
1302 createInitializerPoisonCalls(M, ModuleName);
1303 IRB.CreateCall2(AsanRegisterGlobals,
1304 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1305 ConstantInt::get(IntptrTy, n));
1307 // We also need to unregister globals at the end, e.g. when a shared library
1309 Function *AsanDtorFunction =
1310 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1311 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1312 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1313 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1314 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1315 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1316 ConstantInt::get(IntptrTy, n));
1317 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1323 bool AddressSanitizerModule::runOnModule(Module &M) {
1324 C = &(M.getContext());
1325 int LongSize = M.getDataLayout().getPointerSizeInBits();
1326 IntptrTy = Type::getIntNTy(*C, LongSize);
1327 TargetTriple = Triple(M.getTargetTriple());
1328 Mapping = getShadowMapping(TargetTriple, LongSize);
1329 initializeCallbacks(M);
1331 bool Changed = false;
1333 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1335 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1337 if (ClGlobals) Changed |= InstrumentGlobals(IRB, M);
1342 void AddressSanitizer::initializeCallbacks(Module &M) {
1343 IRBuilder<> IRB(*C);
1344 // Create __asan_report* callbacks.
1345 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1346 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1347 AccessSizeIndex++) {
1348 // IsWrite and TypeSize are encoded in the function name.
1349 std::string Suffix =
1350 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1351 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1352 checkInterfaceFunction(
1353 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1354 IRB.getVoidTy(), IntptrTy, nullptr));
1355 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1356 checkInterfaceFunction(
1357 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1358 IRB.getVoidTy(), IntptrTy, nullptr));
1361 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1362 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1363 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1364 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1366 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1367 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1368 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1369 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1370 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1371 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1373 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1374 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1375 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1376 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1377 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1378 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1379 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1380 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1381 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1383 AsanHandleNoReturnFunc = checkInterfaceFunction(
1384 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1386 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1387 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1388 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1389 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1390 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1391 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1392 StringRef(""), StringRef(""),
1393 /*hasSideEffects=*/true);
1397 bool AddressSanitizer::doInitialization(Module &M) {
1398 // Initialize the private fields. No one has accessed them before.
1402 C = &(M.getContext());
1403 LongSize = M.getDataLayout().getPointerSizeInBits();
1404 IntptrTy = Type::getIntNTy(*C, LongSize);
1405 TargetTriple = Triple(M.getTargetTriple());
1408 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1409 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1410 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1411 // call __asan_init in the module ctor.
1412 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1413 AsanInitFunction = checkInterfaceFunction(
1414 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr));
1415 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1416 IRB.CreateCall(AsanInitFunction);
1418 Mapping = getShadowMapping(TargetTriple, LongSize);
1420 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1424 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1425 // For each NSObject descendant having a +load method, this method is invoked
1426 // by the ObjC runtime before any of the static constructors is called.
1427 // Therefore we need to instrument such methods with a call to __asan_init
1428 // at the beginning in order to initialize our runtime before any access to
1429 // the shadow memory.
1430 // We cannot just ignore these methods, because they may call other
1431 // instrumented functions.
1432 if (F.getName().find(" load]") != std::string::npos) {
1433 IRBuilder<> IRB(F.begin()->begin());
1434 IRB.CreateCall(AsanInitFunction);
1440 bool AddressSanitizer::runOnFunction(Function &F) {
1441 if (&F == AsanCtorFunction) return false;
1442 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1443 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1444 initializeCallbacks(*F.getParent());
1446 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1448 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1449 maybeInsertAsanInitAtFunctionEntry(F);
1451 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return false;
1453 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) return false;
1455 // We want to instrument every address only once per basic block (unless there
1456 // are calls between uses).
1457 SmallSet<Value *, 16> TempsToInstrument;
1458 SmallVector<Instruction *, 16> ToInstrument;
1459 SmallVector<Instruction *, 8> NoReturnCalls;
1460 SmallVector<BasicBlock *, 16> AllBlocks;
1461 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
1467 // Fill the set of memory operations to instrument.
1468 for (auto &BB : F) {
1469 AllBlocks.push_back(&BB);
1470 TempsToInstrument.clear();
1471 int NumInsnsPerBB = 0;
1472 for (auto &Inst : BB) {
1473 if (LooksLikeCodeInBug11395(&Inst)) return false;
1474 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
1476 if (ClOpt && ClOptSameTemp) {
1477 if (!TempsToInstrument.insert(Addr).second)
1478 continue; // We've seen this temp in the current BB.
1480 } else if (ClInvalidPointerPairs &&
1481 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1482 PointerComparisonsOrSubtracts.push_back(&Inst);
1484 } else if (isa<MemIntrinsic>(Inst)) {
1487 if (isa<AllocaInst>(Inst)) NumAllocas++;
1490 // A call inside BB.
1491 TempsToInstrument.clear();
1492 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
1496 ToInstrument.push_back(&Inst);
1498 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
1502 bool UseCalls = false;
1503 if (ClInstrumentationWithCallsThreshold >= 0 &&
1504 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1507 const TargetLibraryInfo *TLI =
1508 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
1509 const DataLayout &DL = F.getParent()->getDataLayout();
1510 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
1511 /*RoundToAlign=*/true);
1514 int NumInstrumented = 0;
1515 for (auto Inst : ToInstrument) {
1516 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1517 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1518 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
1519 instrumentMop(ObjSizeVis, Inst, UseCalls,
1520 F.getParent()->getDataLayout());
1522 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1527 FunctionStackPoisoner FSP(F, *this);
1528 bool ChangedStack = FSP.runOnFunction();
1530 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1531 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1532 for (auto CI : NoReturnCalls) {
1533 IRBuilder<> IRB(CI);
1534 IRB.CreateCall(AsanHandleNoReturnFunc);
1537 for (auto Inst : PointerComparisonsOrSubtracts) {
1538 instrumentPointerComparisonOrSubtraction(Inst);
1542 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1544 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1549 // Workaround for bug 11395: we don't want to instrument stack in functions
1550 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1551 // FIXME: remove once the bug 11395 is fixed.
1552 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1553 if (LongSize != 32) return false;
1554 CallInst *CI = dyn_cast<CallInst>(I);
1555 if (!CI || !CI->isInlineAsm()) return false;
1556 if (CI->getNumArgOperands() <= 5) return false;
1557 // We have inline assembly with quite a few arguments.
1561 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1562 IRBuilder<> IRB(*C);
1563 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1564 std::string Suffix = itostr(i);
1565 AsanStackMallocFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1566 kAsanStackMallocNameTemplate + Suffix, IntptrTy, IntptrTy, nullptr));
1567 AsanStackFreeFunc[i] = checkInterfaceFunction(
1568 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1569 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1571 AsanPoisonStackMemoryFunc = checkInterfaceFunction(
1572 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1573 IntptrTy, IntptrTy, nullptr));
1574 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(
1575 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1576 IntptrTy, IntptrTy, nullptr));
1579 void FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1580 IRBuilder<> &IRB, Value *ShadowBase,
1582 size_t n = ShadowBytes.size();
1584 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1585 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1586 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1587 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1588 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1589 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1591 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1592 if (F.getParent()->getDataLayout().isLittleEndian())
1593 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1595 Val = (Val << 8) | ShadowBytes[i + j];
1598 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1599 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1600 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1601 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1606 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1607 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1608 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1609 assert(LocalStackSize <= kMaxStackMallocSize);
1610 uint64_t MaxSize = kMinStackMallocSize;
1611 for (int i = 0;; i++, MaxSize *= 2)
1612 if (LocalStackSize <= MaxSize) return i;
1613 llvm_unreachable("impossible LocalStackSize");
1616 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1617 // We can not use MemSet intrinsic because it may end up calling the actual
1618 // memset. Size is a multiple of 8.
1619 // Currently this generates 8-byte stores on x86_64; it may be better to
1620 // generate wider stores.
1621 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1622 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1623 assert(!(Size % 8));
1624 assert(kAsanStackAfterReturnMagic == 0xf5);
1625 for (int i = 0; i < Size; i += 8) {
1626 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1627 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1628 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1632 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1633 for (const auto &Inst : F.getEntryBlock())
1634 if (!isa<AllocaInst>(Inst)) return Inst.getDebugLoc();
1638 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1640 Instruction *ThenTerm,
1641 Value *ValueIfFalse) {
1642 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1643 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1644 PHI->addIncoming(ValueIfFalse, CondBlock);
1645 BasicBlock *ThenBlock = ThenTerm->getParent();
1646 PHI->addIncoming(ValueIfTrue, ThenBlock);
1650 Value *FunctionStackPoisoner::createAllocaForLayout(
1651 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1654 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1655 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1658 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1659 nullptr, "MyAlloca");
1660 assert(Alloca->isStaticAlloca());
1662 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1663 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1664 Alloca->setAlignment(FrameAlignment);
1665 return IRB.CreatePointerCast(Alloca, IntptrTy);
1668 void FunctionStackPoisoner::poisonStack() {
1669 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1671 if (ClInstrumentAllocas) {
1672 // Handle dynamic allocas.
1673 for (auto &AllocaCall : DynamicAllocaVec) {
1674 handleDynamicAllocaCall(AllocaCall);
1675 unpoisonDynamicAlloca(AllocaCall);
1679 if (AllocaVec.size() == 0) return;
1681 int StackMallocIdx = -1;
1682 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1684 Instruction *InsBefore = AllocaVec[0];
1685 IRBuilder<> IRB(InsBefore);
1686 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1688 SmallVector<ASanStackVariableDescription, 16> SVD;
1689 SVD.reserve(AllocaVec.size());
1690 for (AllocaInst *AI : AllocaVec) {
1691 ASanStackVariableDescription D = {AI->getName().data(),
1692 ASan.getAllocaSizeInBytes(AI),
1693 AI->getAlignment(), AI, 0};
1696 // Minimal header size (left redzone) is 4 pointers,
1697 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1698 size_t MinHeaderSize = ASan.LongSize / 2;
1699 ASanStackFrameLayout L;
1700 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1701 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1702 uint64_t LocalStackSize = L.FrameSize;
1703 bool DoStackMalloc =
1704 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1705 // Don't do dynamic alloca in presence of inline asm: too often it
1706 // makes assumptions on which registers are available.
1707 bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
1709 Value *StaticAlloca =
1710 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1713 Value *LocalStackBase;
1715 if (DoStackMalloc) {
1716 // void *FakeStack = __asan_option_detect_stack_use_after_return
1717 // ? __asan_stack_malloc_N(LocalStackSize)
1719 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1720 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1721 kAsanOptionDetectUAR, IRB.getInt32Ty());
1722 Value *UARIsEnabled =
1723 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1724 Constant::getNullValue(IRB.getInt32Ty()));
1726 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1727 IRBuilder<> IRBIf(Term);
1728 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1729 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1730 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1731 Value *FakeStackValue =
1732 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1733 ConstantInt::get(IntptrTy, LocalStackSize));
1734 IRB.SetInsertPoint(InsBefore);
1735 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1736 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1737 ConstantInt::get(IntptrTy, 0));
1739 Value *NoFakeStack =
1740 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1741 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1742 IRBIf.SetInsertPoint(Term);
1743 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1744 Value *AllocaValue =
1745 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1746 IRB.SetInsertPoint(InsBefore);
1747 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1748 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1750 // void *FakeStack = nullptr;
1751 // void *LocalStackBase = alloca(LocalStackSize);
1752 FakeStack = ConstantInt::get(IntptrTy, 0);
1754 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1757 // Insert poison calls for lifetime intrinsics for alloca.
1758 bool HavePoisonedAllocas = false;
1759 for (const auto &APC : AllocaPoisonCallVec) {
1760 assert(APC.InsBefore);
1762 IRBuilder<> IRB(APC.InsBefore);
1763 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1764 HavePoisonedAllocas |= APC.DoPoison;
1767 // Replace Alloca instructions with base+offset.
1768 for (const auto &Desc : SVD) {
1769 AllocaInst *AI = Desc.AI;
1770 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1771 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1773 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
1774 AI->replaceAllUsesWith(NewAllocaPtr);
1777 // The left-most redzone has enough space for at least 4 pointers.
1778 // Write the Magic value to redzone[0].
1779 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1780 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1782 // Write the frame description constant to redzone[1].
1783 Value *BasePlus1 = IRB.CreateIntToPtr(
1784 IRB.CreateAdd(LocalStackBase,
1785 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
1787 GlobalVariable *StackDescriptionGlobal =
1788 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1789 /*AllowMerging*/ true);
1790 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1791 IRB.CreateStore(Description, BasePlus1);
1792 // Write the PC to redzone[2].
1793 Value *BasePlus2 = IRB.CreateIntToPtr(
1794 IRB.CreateAdd(LocalStackBase,
1795 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
1797 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1799 // Poison the stack redzones at the entry.
1800 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1801 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1803 // (Un)poison the stack before all ret instructions.
1804 for (auto Ret : RetVec) {
1805 IRBuilder<> IRBRet(Ret);
1806 // Mark the current frame as retired.
1807 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1809 if (DoStackMalloc) {
1810 assert(StackMallocIdx >= 0);
1811 // if FakeStack != 0 // LocalStackBase == FakeStack
1812 // // In use-after-return mode, poison the whole stack frame.
1813 // if StackMallocIdx <= 4
1814 // // For small sizes inline the whole thing:
1815 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1816 // **SavedFlagPtr(FakeStack) = 0
1818 // __asan_stack_free_N(FakeStack, LocalStackSize)
1820 // <This is not a fake stack; unpoison the redzones>
1822 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1823 TerminatorInst *ThenTerm, *ElseTerm;
1824 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1826 IRBuilder<> IRBPoison(ThenTerm);
1827 if (StackMallocIdx <= 4) {
1828 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1829 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1830 ClassSize >> Mapping.Scale);
1831 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1833 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1834 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1835 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1836 IRBPoison.CreateStore(
1837 Constant::getNullValue(IRBPoison.getInt8Ty()),
1838 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1840 // For larger frames call __asan_stack_free_*.
1841 IRBPoison.CreateCall2(AsanStackFreeFunc[StackMallocIdx], FakeStack,
1842 ConstantInt::get(IntptrTy, LocalStackSize));
1845 IRBuilder<> IRBElse(ElseTerm);
1846 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1847 } else if (HavePoisonedAllocas) {
1848 // If we poisoned some allocas in llvm.lifetime analysis,
1849 // unpoison whole stack frame now.
1850 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1852 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1856 // We are done. Remove the old unused alloca instructions.
1857 for (auto AI : AllocaVec) AI->eraseFromParent();
1860 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1861 IRBuilder<> &IRB, bool DoPoison) {
1862 // For now just insert the call to ASan runtime.
1863 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1864 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1866 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
1870 // Handling llvm.lifetime intrinsics for a given %alloca:
1871 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1872 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1873 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1874 // could be poisoned by previous llvm.lifetime.end instruction, as the
1875 // variable may go in and out of scope several times, e.g. in loops).
1876 // (3) if we poisoned at least one %alloca in a function,
1877 // unpoison the whole stack frame at function exit.
1879 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1880 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1881 // We're intested only in allocas we can handle.
1882 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
1883 // See if we've already calculated (or started to calculate) alloca for a
1885 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1886 if (I != AllocaForValue.end()) return I->second;
1887 // Store 0 while we're calculating alloca for value V to avoid
1888 // infinite recursion if the value references itself.
1889 AllocaForValue[V] = nullptr;
1890 AllocaInst *Res = nullptr;
1891 if (CastInst *CI = dyn_cast<CastInst>(V))
1892 Res = findAllocaForValue(CI->getOperand(0));
1893 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1894 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1895 Value *IncValue = PN->getIncomingValue(i);
1896 // Allow self-referencing phi-nodes.
1897 if (IncValue == PN) continue;
1898 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1899 // AI for incoming values should exist and should all be equal.
1900 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1905 if (Res) AllocaForValue[V] = Res;
1909 // Compute PartialRzMagic for dynamic alloca call. PartialRzMagic is
1910 // constructed from two separate 32-bit numbers: PartialRzMagic = Val1 | Val2.
1911 // (1) Val1 is resposible for forming base value for PartialRzMagic, containing
1912 // only 00 for fully addressable and 0xcb for fully poisoned bytes for each
1913 // 8-byte chunk of user memory respectively.
1914 // (2) Val2 forms the value for marking first poisoned byte in shadow memory
1915 // with appropriate value (0x01 - 0x07 or 0xcb if Padding % 8 == 0).
1917 // Shift = Padding & ~7; // the number of bits we need to shift to access first
1918 // chunk in shadow memory, containing nonzero bytes.
1920 // Padding = 21 Padding = 16
1921 // Shadow: |00|00|05|cb| Shadow: |00|00|cb|cb|
1924 // Shift = 21 & ~7 = 16 Shift = 16 & ~7 = 16
1926 // Val1 = 0xcbcbcbcb << Shift;
1927 // PartialBits = Padding ? Padding & 7 : 0xcb;
1928 // Val2 = PartialBits << Shift;
1929 // Result = Val1 | Val2;
1930 Value *FunctionStackPoisoner::computePartialRzMagic(Value *PartialSize,
1932 PartialSize = IRB.CreateIntCast(PartialSize, IRB.getInt32Ty(), false);
1933 Value *Shift = IRB.CreateAnd(PartialSize, IRB.getInt32(~7));
1934 unsigned Val1Int = kAsanAllocaPartialVal1;
1935 unsigned Val2Int = kAsanAllocaPartialVal2;
1936 if (!F.getParent()->getDataLayout().isLittleEndian()) {
1937 Val1Int = sys::getSwappedBytes(Val1Int);
1938 Val2Int = sys::getSwappedBytes(Val2Int);
1940 Value *Val1 = shiftAllocaMagic(IRB.getInt32(Val1Int), IRB, Shift);
1941 Value *PartialBits = IRB.CreateAnd(PartialSize, IRB.getInt32(7));
1942 // For BigEndian get 0x000000YZ -> 0xYZ000000.
1943 if (F.getParent()->getDataLayout().isBigEndian())
1944 PartialBits = IRB.CreateShl(PartialBits, IRB.getInt32(24));
1945 Value *Val2 = IRB.getInt32(Val2Int);
1947 IRB.CreateICmpNE(PartialBits, Constant::getNullValue(IRB.getInt32Ty()));
1948 Val2 = IRB.CreateSelect(Cond, shiftAllocaMagic(PartialBits, IRB, Shift),
1949 shiftAllocaMagic(Val2, IRB, Shift));
1950 return IRB.CreateOr(Val1, Val2);
1953 void FunctionStackPoisoner::handleDynamicAllocaCall(
1954 DynamicAllocaCall &AllocaCall) {
1955 AllocaInst *AI = AllocaCall.AI;
1956 if (!doesDominateAllExits(AI)) {
1957 // We do not yet handle complex allocas
1958 AllocaCall.Poison = false;
1962 IRBuilder<> IRB(AI);
1964 PointerType *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
1965 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
1966 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
1968 Value *Zero = Constant::getNullValue(IntptrTy);
1969 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
1970 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
1971 Value *NotAllocaRzMask = ConstantInt::get(IntptrTy, ~AllocaRedzoneMask);
1973 // Since we need to extend alloca with additional memory to locate
1974 // redzones, and OldSize is number of allocated blocks with
1975 // ElementSize size, get allocated memory size in bytes by
1976 // OldSize * ElementSize.
1977 unsigned ElementSize =
1978 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
1979 Value *OldSize = IRB.CreateMul(AI->getArraySize(),
1980 ConstantInt::get(IntptrTy, ElementSize));
1982 // PartialSize = OldSize % 32
1983 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
1985 // Misalign = kAllocaRzSize - PartialSize;
1986 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
1988 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
1989 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
1990 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
1992 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
1993 // Align is added to locate left redzone, PartialPadding for possible
1994 // partial redzone and kAllocaRzSize for right redzone respectively.
1995 Value *AdditionalChunkSize = IRB.CreateAdd(
1996 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
1998 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2000 // Insert new alloca with new NewSize and Align params.
2001 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2002 NewAlloca->setAlignment(Align);
2004 // NewAddress = Address + Align
2005 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2006 ConstantInt::get(IntptrTy, Align));
2008 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2010 // LeftRzAddress = NewAddress - kAllocaRzSize
2011 Value *LeftRzAddress = IRB.CreateSub(NewAddress, AllocaRzSize);
2013 // Poisoning left redzone.
2014 AllocaCall.LeftRzAddr = ASan.memToShadow(LeftRzAddress, IRB);
2015 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaLeftMagic),
2016 IRB.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
2018 // PartialRzAligned = PartialRzAddr & ~AllocaRzMask
2019 Value *PartialRzAddr = IRB.CreateAdd(NewAddress, OldSize);
2020 Value *PartialRzAligned = IRB.CreateAnd(PartialRzAddr, NotAllocaRzMask);
2022 // Poisoning partial redzone.
2023 Value *PartialRzMagic = computePartialRzMagic(PartialSize, IRB);
2024 Value *PartialRzShadowAddr = ASan.memToShadow(PartialRzAligned, IRB);
2025 IRB.CreateStore(PartialRzMagic,
2026 IRB.CreateIntToPtr(PartialRzShadowAddr, Int32PtrTy));
2029 // = (PartialRzAddr + AllocaRzMask) & ~AllocaRzMask
2030 Value *RightRzAddress = IRB.CreateAnd(
2031 IRB.CreateAdd(PartialRzAddr, AllocaRzMask), NotAllocaRzMask);
2033 // Poisoning right redzone.
2034 AllocaCall.RightRzAddr = ASan.memToShadow(RightRzAddress, IRB);
2035 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaRightMagic),
2036 IRB.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
2038 // Replace all uses of AddessReturnedByAlloca with NewAddress.
2039 AI->replaceAllUsesWith(NewAddressPtr);
2041 // We are done. Erase old alloca and store left, partial and right redzones
2042 // shadow addresses for future unpoisoning.
2043 AI->eraseFromParent();
2044 NumInstrumentedDynamicAllocas++;
2047 // isSafeAccess returns true if Addr is always inbounds with respect to its
2048 // base object. For example, it is a field access or an array access with
2049 // constant inbounds index.
2050 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2051 Value *Addr, uint64_t TypeSize) const {
2052 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2053 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2054 int64_t Size = SizeOffset.first.getSExtValue();
2055 int64_t Offset = SizeOffset.second.getSExtValue();
2056 // Three checks are required to ensure safety:
2057 // . Offset >= 0 (since the offset is given from the base ptr)
2058 // . Size >= Offset (unsigned)
2059 // . Size - Offset >= NeededSize (unsigned)
2060 return Offset >= 0 && Size >= Offset &&
2061 uint64_t(Size - Offset) >= TypeSize / 8;