1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file is a part of AddressSanitizer, an address sanity checker.
11 // Details of the algorithm:
12 // http://code.google.com/p/address-sanitizer/wiki/AddressSanitizerAlgorithm
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Transforms/Instrumentation.h"
17 #include "llvm/ADT/ArrayRef.h"
18 #include "llvm/ADT/DenseMap.h"
19 #include "llvm/ADT/DenseSet.h"
20 #include "llvm/ADT/DepthFirstIterator.h"
21 #include "llvm/ADT/SmallSet.h"
22 #include "llvm/ADT/SmallString.h"
23 #include "llvm/ADT/SmallVector.h"
24 #include "llvm/ADT/Statistic.h"
25 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/ADT/Triple.h"
27 #include "llvm/IR/CallSite.h"
28 #include "llvm/IR/DIBuilder.h"
29 #include "llvm/IR/DataLayout.h"
30 #include "llvm/IR/Dominators.h"
31 #include "llvm/IR/Function.h"
32 #include "llvm/IR/IRBuilder.h"
33 #include "llvm/IR/InlineAsm.h"
34 #include "llvm/IR/InstVisitor.h"
35 #include "llvm/IR/IntrinsicInst.h"
36 #include "llvm/IR/LLVMContext.h"
37 #include "llvm/IR/MDBuilder.h"
38 #include "llvm/IR/Module.h"
39 #include "llvm/IR/Type.h"
40 #include "llvm/MC/MCSectionMachO.h"
41 #include "llvm/Support/CommandLine.h"
42 #include "llvm/Support/DataTypes.h"
43 #include "llvm/Support/Debug.h"
44 #include "llvm/Support/Endian.h"
45 #include "llvm/Support/SwapByteOrder.h"
46 #include "llvm/Transforms/Scalar.h"
47 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
48 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
49 #include "llvm/Transforms/Utils/Cloning.h"
50 #include "llvm/Transforms/Utils/Local.h"
51 #include "llvm/Transforms/Utils/ModuleUtils.h"
54 #include <system_error>
58 #define DEBUG_TYPE "asan"
60 static const uint64_t kDefaultShadowScale = 3;
61 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
62 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
63 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
64 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
65 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
66 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
67 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 36;
68 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
69 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
70 static const uint64_t kWindowsShadowOffset32 = 1ULL << 30;
72 static const size_t kMinStackMallocSize = 1 << 6; // 64B
73 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
74 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
75 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
77 static const char *const kAsanModuleCtorName = "asan.module_ctor";
78 static const char *const kAsanModuleDtorName = "asan.module_dtor";
79 static const uint64_t kAsanCtorAndDtorPriority = 1;
80 static const char *const kAsanReportErrorTemplate = "__asan_report_";
81 static const char *const kAsanReportLoadN = "__asan_report_load_n";
82 static const char *const kAsanReportStoreN = "__asan_report_store_n";
83 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
84 static const char *const kAsanUnregisterGlobalsName =
85 "__asan_unregister_globals";
86 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
87 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
88 static const char *const kAsanInitName = "__asan_init_v5";
89 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
90 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
91 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
92 static const int kMaxAsanStackMallocSizeClass = 10;
93 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
94 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
95 static const char *const kAsanGenPrefix = "__asan_gen_";
96 static const char *const kSanCovGenPrefix = "__sancov_gen_";
97 static const char *const kAsanPoisonStackMemoryName =
98 "__asan_poison_stack_memory";
99 static const char *const kAsanUnpoisonStackMemoryName =
100 "__asan_unpoison_stack_memory";
102 static const char *const kAsanOptionDetectUAR =
103 "__asan_option_detect_stack_use_after_return";
106 static const int kAsanStackAfterReturnMagic = 0xf5;
109 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
110 static const size_t kNumberOfAccessSizes = 5;
112 static const unsigned kAllocaRzSize = 32;
113 static const unsigned kAsanAllocaLeftMagic = 0xcacacacaU;
114 static const unsigned kAsanAllocaRightMagic = 0xcbcbcbcbU;
115 static const unsigned kAsanAllocaPartialVal1 = 0xcbcbcb00U;
116 static const unsigned kAsanAllocaPartialVal2 = 0x000000cbU;
118 // Command-line flags.
120 // This flag may need to be replaced with -f[no-]asan-reads.
121 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
122 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
123 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
124 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
125 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
126 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
127 cl::Hidden, cl::init(true));
128 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
129 cl::desc("use instrumentation with slow path for all accesses"),
130 cl::Hidden, cl::init(false));
131 // This flag limits the number of instructions to be instrumented
132 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
133 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
135 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
137 cl::desc("maximal number of instructions to instrument in any given BB"),
139 // This flag may need to be replaced with -f[no]asan-stack.
140 static cl::opt<bool> ClStack("asan-stack",
141 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
142 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
143 cl::desc("Check return-after-free"), cl::Hidden, cl::init(true));
144 // This flag may need to be replaced with -f[no]asan-globals.
145 static cl::opt<bool> ClGlobals("asan-globals",
146 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
147 static cl::opt<bool> ClInitializers("asan-initialization-order",
148 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(true));
149 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
150 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
151 cl::Hidden, cl::init(false));
152 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
153 cl::desc("Realign stack to the value of this flag (power of two)"),
154 cl::Hidden, cl::init(32));
155 static cl::opt<int> ClInstrumentationWithCallsThreshold(
156 "asan-instrumentation-with-call-threshold",
157 cl::desc("If the function being instrumented contains more than "
158 "this number of memory accesses, use callbacks instead of "
159 "inline checks (-1 means never use callbacks)."),
160 cl::Hidden, cl::init(7000));
161 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
162 "asan-memory-access-callback-prefix",
163 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
164 cl::init("__asan_"));
165 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
166 cl::desc("instrument dynamic allocas"), cl::Hidden, cl::init(false));
168 // These flags allow to change the shadow mapping.
169 // The shadow mapping looks like
170 // Shadow = (Mem >> scale) + (1 << offset_log)
171 static cl::opt<int> ClMappingScale("asan-mapping-scale",
172 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
174 // Optimization flags. Not user visible, used mostly for testing
175 // and benchmarking the tool.
176 static cl::opt<bool> ClOpt("asan-opt",
177 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
178 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
179 cl::desc("Instrument the same temp just once"), cl::Hidden,
181 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
182 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
184 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
185 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
186 cl::Hidden, cl::init(false));
188 static cl::opt<bool> ClDynamicAllocaStack(
189 "asan-stack-dynamic-alloca",
190 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
194 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
196 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
197 cl::Hidden, cl::init(0));
198 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
199 cl::Hidden, cl::desc("Debug func"));
200 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
201 cl::Hidden, cl::init(-1));
202 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
203 cl::Hidden, cl::init(-1));
205 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
206 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
207 STATISTIC(NumInstrumentedDynamicAllocas,
208 "Number of instrumented dynamic allocas");
209 STATISTIC(NumOptimizedAccessesToGlobalArray,
210 "Number of optimized accesses to global arrays");
211 STATISTIC(NumOptimizedAccessesToGlobalVar,
212 "Number of optimized accesses to global vars");
215 /// Frontend-provided metadata for source location.
216 struct LocationMetadata {
221 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
223 bool empty() const { return Filename.empty(); }
225 void parse(MDNode *MDN) {
226 assert(MDN->getNumOperands() == 3);
227 MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
228 Filename = MDFilename->getString();
230 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
232 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
236 /// Frontend-provided metadata for global variables.
237 class GlobalsMetadata {
241 : SourceLoc(), Name(), IsDynInit(false),
242 IsBlacklisted(false) {}
243 LocationMetadata SourceLoc;
249 GlobalsMetadata() : inited_(false) {}
251 void init(Module& M) {
254 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
257 for (auto MDN : Globals->operands()) {
258 // Metadata node contains the global and the fields of "Entry".
259 assert(MDN->getNumOperands() == 5);
260 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
261 // The optimizer may optimize away a global entirely.
264 // We can already have an entry for GV if it was merged with another
266 Entry &E = Entries[GV];
267 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
268 E.SourceLoc.parse(Loc);
269 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
270 E.Name = Name->getString();
271 ConstantInt *IsDynInit =
272 mdconst::extract<ConstantInt>(MDN->getOperand(3));
273 E.IsDynInit |= IsDynInit->isOne();
274 ConstantInt *IsBlacklisted =
275 mdconst::extract<ConstantInt>(MDN->getOperand(4));
276 E.IsBlacklisted |= IsBlacklisted->isOne();
280 /// Returns metadata entry for a given global.
281 Entry get(GlobalVariable *G) const {
282 auto Pos = Entries.find(G);
283 return (Pos != Entries.end()) ? Pos->second : Entry();
288 DenseMap<GlobalVariable*, Entry> Entries;
291 /// This struct defines the shadow mapping using the rule:
292 /// shadow = (mem >> Scale) ADD-or-OR Offset.
293 struct ShadowMapping {
299 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) {
300 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
301 bool IsIOS = TargetTriple.isiOS();
302 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
303 bool IsLinux = TargetTriple.isOSLinux();
304 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
305 TargetTriple.getArch() == llvm::Triple::ppc64le;
306 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
307 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
308 TargetTriple.getArch() == llvm::Triple::mipsel;
309 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
310 TargetTriple.getArch() == llvm::Triple::mips64el;
311 bool IsWindows = TargetTriple.isOSWindows();
313 ShadowMapping Mapping;
315 if (LongSize == 32) {
319 Mapping.Offset = kMIPS32_ShadowOffset32;
321 Mapping.Offset = kFreeBSD_ShadowOffset32;
323 Mapping.Offset = kIOSShadowOffset32;
325 Mapping.Offset = kWindowsShadowOffset32;
327 Mapping.Offset = kDefaultShadowOffset32;
328 } else { // LongSize == 64
330 Mapping.Offset = kPPC64_ShadowOffset64;
332 Mapping.Offset = kFreeBSD_ShadowOffset64;
333 else if (IsLinux && IsX86_64)
334 Mapping.Offset = kSmallX86_64ShadowOffset;
336 Mapping.Offset = kMIPS64_ShadowOffset64;
338 Mapping.Offset = kDefaultShadowOffset64;
341 Mapping.Scale = kDefaultShadowScale;
342 if (ClMappingScale) {
343 Mapping.Scale = ClMappingScale;
346 // OR-ing shadow offset if more efficient (at least on x86) if the offset
347 // is a power of two, but on ppc64 we have to use add since the shadow
348 // offset is not necessary 1/8-th of the address space.
349 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
354 static size_t RedzoneSizeForScale(int MappingScale) {
355 // Redzone used for stack and globals is at least 32 bytes.
356 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
357 return std::max(32U, 1U << MappingScale);
360 /// AddressSanitizer: instrument the code in module to find memory bugs.
361 struct AddressSanitizer : public FunctionPass {
362 AddressSanitizer() : FunctionPass(ID) {
363 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
365 const char *getPassName() const override {
366 return "AddressSanitizerFunctionPass";
368 void getAnalysisUsage(AnalysisUsage &AU) const override {
369 AU.addRequired<DominatorTreeWrapperPass>();
371 void instrumentMop(Instruction *I, bool UseCalls);
372 void instrumentPointerComparisonOrSubtraction(Instruction *I);
373 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
374 Value *Addr, uint32_t TypeSize, bool IsWrite,
375 Value *SizeArgument, bool UseCalls);
376 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
377 Value *ShadowValue, uint32_t TypeSize);
378 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
379 bool IsWrite, size_t AccessSizeIndex,
380 Value *SizeArgument);
381 void instrumentMemIntrinsic(MemIntrinsic *MI);
382 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
383 bool runOnFunction(Function &F) override;
384 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
385 bool doInitialization(Module &M) override;
386 static char ID; // Pass identification, replacement for typeid
388 DominatorTree &getDominatorTree() const { return *DT; }
391 void initializeCallbacks(Module &M);
393 bool LooksLikeCodeInBug11395(Instruction *I);
394 bool GlobalIsLinkerInitialized(GlobalVariable *G);
397 const DataLayout *DL;
401 ShadowMapping Mapping;
403 Function *AsanCtorFunction;
404 Function *AsanInitFunction;
405 Function *AsanHandleNoReturnFunc;
406 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
407 // This array is indexed by AccessIsWrite and log2(AccessSize).
408 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
409 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
410 // This array is indexed by AccessIsWrite.
411 Function *AsanErrorCallbackSized[2],
412 *AsanMemoryAccessCallbackSized[2];
413 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
415 GlobalsMetadata GlobalsMD;
417 friend struct FunctionStackPoisoner;
420 class AddressSanitizerModule : public ModulePass {
422 AddressSanitizerModule() : ModulePass(ID) {}
423 bool runOnModule(Module &M) override;
424 static char ID; // Pass identification, replacement for typeid
425 const char *getPassName() const override {
426 return "AddressSanitizerModule";
430 void initializeCallbacks(Module &M);
432 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
433 bool ShouldInstrumentGlobal(GlobalVariable *G);
434 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
435 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
436 size_t MinRedzoneSizeForGlobal() const {
437 return RedzoneSizeForScale(Mapping.Scale);
440 GlobalsMetadata GlobalsMD;
443 const DataLayout *DL;
445 ShadowMapping Mapping;
446 Function *AsanPoisonGlobals;
447 Function *AsanUnpoisonGlobals;
448 Function *AsanRegisterGlobals;
449 Function *AsanUnregisterGlobals;
452 // Stack poisoning does not play well with exception handling.
453 // When an exception is thrown, we essentially bypass the code
454 // that unpoisones the stack. This is why the run-time library has
455 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
456 // stack in the interceptor. This however does not work inside the
457 // actual function which catches the exception. Most likely because the
458 // compiler hoists the load of the shadow value somewhere too high.
459 // This causes asan to report a non-existing bug on 453.povray.
460 // It sounds like an LLVM bug.
461 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
463 AddressSanitizer &ASan;
468 ShadowMapping Mapping;
470 SmallVector<AllocaInst*, 16> AllocaVec;
471 SmallVector<Instruction*, 8> RetVec;
472 unsigned StackAlignment;
474 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
475 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
476 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
478 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
479 struct AllocaPoisonCall {
480 IntrinsicInst *InsBefore;
485 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
487 // Stores left and right redzone shadow addresses for dynamic alloca
488 // and pointer to alloca instruction itself.
489 // LeftRzAddr is a shadow address for alloca left redzone.
490 // RightRzAddr is a shadow address for alloca right redzone.
491 struct DynamicAllocaCall {
496 explicit DynamicAllocaCall(AllocaInst *AI,
497 Value *LeftRzAddr = nullptr,
498 Value *RightRzAddr = nullptr)
499 : AI(AI), LeftRzAddr(LeftRzAddr), RightRzAddr(RightRzAddr), Poison(true)
502 SmallVector<DynamicAllocaCall, 1> DynamicAllocaVec;
504 // Maps Value to an AllocaInst from which the Value is originated.
505 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
506 AllocaForValueMapTy AllocaForValue;
508 bool HasNonEmptyInlineAsm;
509 std::unique_ptr<CallInst> EmptyInlineAsm;
511 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
512 : F(F), ASan(ASan), DIB(*F.getParent(), /*AllowUnresolved*/ false),
513 C(ASan.C), IntptrTy(ASan.IntptrTy),
514 IntptrPtrTy(PointerType::get(IntptrTy, 0)), Mapping(ASan.Mapping),
515 StackAlignment(1 << Mapping.Scale), HasNonEmptyInlineAsm(false),
516 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
518 bool runOnFunction() {
519 if (!ClStack) return false;
520 // Collect alloca, ret, lifetime instructions etc.
521 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
524 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
526 initializeCallbacks(*F.getParent());
536 // Finds all Alloca instructions and puts
537 // poisoned red zones around all of them.
538 // Then unpoison everything back before the function returns.
541 // ----------------------- Visitors.
542 /// \brief Collect all Ret instructions.
543 void visitReturnInst(ReturnInst &RI) {
544 RetVec.push_back(&RI);
547 // Unpoison dynamic allocas redzones.
548 void unpoisonDynamicAlloca(DynamicAllocaCall &AllocaCall) {
549 if (!AllocaCall.Poison)
551 for (auto Ret : RetVec) {
552 IRBuilder<> IRBRet(Ret);
553 PointerType *Int32PtrTy = PointerType::getUnqual(IRBRet.getInt32Ty());
554 Value *Zero = Constant::getNullValue(IRBRet.getInt32Ty());
555 Value *PartialRzAddr = IRBRet.CreateSub(AllocaCall.RightRzAddr,
556 ConstantInt::get(IntptrTy, 4));
557 IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(AllocaCall.LeftRzAddr,
559 IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(PartialRzAddr,
561 IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(AllocaCall.RightRzAddr,
566 // Right shift for BigEndian and left shift for LittleEndian.
567 Value *shiftAllocaMagic(Value *Val, IRBuilder<> &IRB, Value *Shift) {
568 return ASan.DL->isLittleEndian() ? IRB.CreateShl(Val, Shift)
569 : IRB.CreateLShr(Val, Shift);
572 // Compute PartialRzMagic for dynamic alloca call. Since we don't know the
573 // size of requested memory until runtime, we should compute it dynamically.
574 // If PartialSize is 0, PartialRzMagic would contain kAsanAllocaRightMagic,
575 // otherwise it would contain the value that we will use to poison the
576 // partial redzone for alloca call.
577 Value *computePartialRzMagic(Value *PartialSize, IRBuilder<> &IRB);
579 // Deploy and poison redzones around dynamic alloca call. To do this, we
580 // should replace this call with another one with changed parameters and
581 // replace all its uses with new address, so
582 // addr = alloca type, old_size, align
584 // new_size = (old_size + additional_size) * sizeof(type)
585 // tmp = alloca i8, new_size, max(align, 32)
586 // addr = tmp + 32 (first 32 bytes are for the left redzone).
587 // Additional_size is added to make new memory allocation contain not only
588 // requested memory, but also left, partial and right redzones.
589 // After that, we should poison redzones:
590 // (1) Left redzone with kAsanAllocaLeftMagic.
591 // (2) Partial redzone with the value, computed in runtime by
592 // computePartialRzMagic function.
593 // (3) Right redzone with kAsanAllocaRightMagic.
594 void handleDynamicAllocaCall(DynamicAllocaCall &AllocaCall);
596 /// \brief Collect Alloca instructions we want (and can) handle.
597 void visitAllocaInst(AllocaInst &AI) {
598 if (!isInterestingAlloca(AI)) return;
600 StackAlignment = std::max(StackAlignment, AI.getAlignment());
601 if (isDynamicAlloca(AI))
602 DynamicAllocaVec.push_back(DynamicAllocaCall(&AI));
604 AllocaVec.push_back(&AI);
607 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
609 void visitIntrinsicInst(IntrinsicInst &II) {
610 if (!ClCheckLifetime) return;
611 Intrinsic::ID ID = II.getIntrinsicID();
612 if (ID != Intrinsic::lifetime_start &&
613 ID != Intrinsic::lifetime_end)
615 // Found lifetime intrinsic, add ASan instrumentation if necessary.
616 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
617 // If size argument is undefined, don't do anything.
618 if (Size->isMinusOne()) return;
619 // Check that size doesn't saturate uint64_t and can
620 // be stored in IntptrTy.
621 const uint64_t SizeValue = Size->getValue().getLimitedValue();
622 if (SizeValue == ~0ULL ||
623 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
625 // Find alloca instruction that corresponds to llvm.lifetime argument.
626 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
628 bool DoPoison = (ID == Intrinsic::lifetime_end);
629 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
630 AllocaPoisonCallVec.push_back(APC);
633 void visitCallInst(CallInst &CI) {
634 HasNonEmptyInlineAsm |=
635 CI.isInlineAsm() && !CI.isIdenticalTo(EmptyInlineAsm.get());
638 // ---------------------- Helpers.
639 void initializeCallbacks(Module &M);
641 bool doesDominateAllExits(const Instruction *I) const {
642 for (auto Ret : RetVec) {
643 if (!ASan.getDominatorTree().dominates(I, Ret))
649 bool isDynamicAlloca(AllocaInst &AI) const {
650 return AI.isArrayAllocation() || !AI.isStaticAlloca();
653 // Check if we want (and can) handle this alloca.
654 bool isInterestingAlloca(AllocaInst &AI) const {
655 return (AI.getAllocatedType()->isSized() &&
656 // alloca() may be called with 0 size, ignore it.
657 getAllocaSizeInBytes(&AI) > 0);
660 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
661 Type *Ty = AI->getAllocatedType();
662 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
665 /// Finds alloca where the value comes from.
666 AllocaInst *findAllocaForValue(Value *V);
667 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
668 Value *ShadowBase, bool DoPoison);
669 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
671 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
673 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
675 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
676 Instruction *ThenTerm, Value *ValueIfFalse);
681 char AddressSanitizer::ID = 0;
682 INITIALIZE_PASS_BEGIN(AddressSanitizer, "asan",
683 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
685 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
686 INITIALIZE_PASS_END(AddressSanitizer, "asan",
687 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
689 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
690 return new AddressSanitizer();
693 char AddressSanitizerModule::ID = 0;
694 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
695 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
696 "ModulePass", false, false)
697 ModulePass *llvm::createAddressSanitizerModulePass() {
698 return new AddressSanitizerModule();
701 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
702 size_t Res = countTrailingZeros(TypeSize / 8);
703 assert(Res < kNumberOfAccessSizes);
707 // \brief Create a constant for Str so that we can pass it to the run-time lib.
708 static GlobalVariable *createPrivateGlobalForString(
709 Module &M, StringRef Str, bool AllowMerging) {
710 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
711 // We use private linkage for module-local strings. If they can be merged
712 // with another one, we set the unnamed_addr attribute.
714 new GlobalVariable(M, StrConst->getType(), true,
715 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
717 GV->setUnnamedAddr(true);
718 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
722 /// \brief Create a global describing a source location.
723 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
724 LocationMetadata MD) {
725 Constant *LocData[] = {
726 createPrivateGlobalForString(M, MD.Filename, true),
727 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
728 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
730 auto LocStruct = ConstantStruct::getAnon(LocData);
731 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
732 GlobalValue::PrivateLinkage, LocStruct,
734 GV->setUnnamedAddr(true);
738 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
739 return G->getName().find(kAsanGenPrefix) == 0 ||
740 G->getName().find(kSanCovGenPrefix) == 0;
743 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
745 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
746 if (Mapping.Offset == 0)
748 // (Shadow >> scale) | offset
749 if (Mapping.OrShadowOffset)
750 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
752 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
755 // Instrument memset/memmove/memcpy
756 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
758 if (isa<MemTransferInst>(MI)) {
760 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
761 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
762 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
763 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
764 } else if (isa<MemSetInst>(MI)) {
767 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
768 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
769 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
771 MI->eraseFromParent();
774 // If I is an interesting memory access, return the PointerOperand
775 // and set IsWrite/Alignment. Otherwise return nullptr.
776 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
777 unsigned *Alignment) {
778 // Skip memory accesses inserted by another instrumentation.
779 if (I->getMetadata("nosanitize"))
781 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
782 if (!ClInstrumentReads) return nullptr;
784 *Alignment = LI->getAlignment();
785 return LI->getPointerOperand();
787 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
788 if (!ClInstrumentWrites) return nullptr;
790 *Alignment = SI->getAlignment();
791 return SI->getPointerOperand();
793 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
794 if (!ClInstrumentAtomics) return nullptr;
797 return RMW->getPointerOperand();
799 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
800 if (!ClInstrumentAtomics) return nullptr;
803 return XCHG->getPointerOperand();
808 static bool isPointerOperand(Value *V) {
809 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
812 // This is a rough heuristic; it may cause both false positives and
813 // false negatives. The proper implementation requires cooperation with
815 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
816 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
817 if (!Cmp->isRelational())
819 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
820 if (BO->getOpcode() != Instruction::Sub)
825 if (!isPointerOperand(I->getOperand(0)) ||
826 !isPointerOperand(I->getOperand(1)))
831 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
832 // If a global variable does not have dynamic initialization we don't
833 // have to instrument it. However, if a global does not have initializer
834 // at all, we assume it has dynamic initializer (in other TU).
835 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
839 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
841 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
842 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
843 for (int i = 0; i < 2; i++) {
844 if (Param[i]->getType()->isPointerTy())
845 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
847 IRB.CreateCall2(F, Param[0], Param[1]);
850 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
851 bool IsWrite = false;
852 unsigned Alignment = 0;
853 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
855 if (ClOpt && ClOptGlobals) {
856 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
857 // If initialization order checking is disabled, a simple access to a
858 // dynamically initialized global is always valid.
859 if (!ClInitializers || GlobalIsLinkerInitialized(G)) {
860 NumOptimizedAccessesToGlobalVar++;
864 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
865 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
866 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
867 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
868 NumOptimizedAccessesToGlobalArray++;
875 Type *OrigPtrTy = Addr->getType();
876 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
878 assert(OrigTy->isSized());
879 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
881 assert((TypeSize % 8) == 0);
884 NumInstrumentedWrites++;
886 NumInstrumentedReads++;
888 unsigned Granularity = 1 << Mapping.Scale;
889 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
890 // if the data is properly aligned.
891 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
893 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
894 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
895 // Instrument unusual size or unusual alignment.
896 // We can not do it with a single check, so we do 1-byte check for the first
897 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
898 // to report the actual access size.
900 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
901 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
903 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
905 Value *LastByte = IRB.CreateIntToPtr(
906 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
908 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
909 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
913 // Validate the result of Module::getOrInsertFunction called for an interface
914 // function of AddressSanitizer. If the instrumented module defines a function
915 // with the same name, their prototypes must match, otherwise
916 // getOrInsertFunction returns a bitcast.
917 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
918 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
919 FuncOrBitcast->dump();
920 report_fatal_error("trying to redefine an AddressSanitizer "
921 "interface function");
924 Instruction *AddressSanitizer::generateCrashCode(
925 Instruction *InsertBefore, Value *Addr,
926 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
927 IRBuilder<> IRB(InsertBefore);
928 CallInst *Call = SizeArgument
929 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
930 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
932 // We don't do Call->setDoesNotReturn() because the BB already has
933 // UnreachableInst at the end.
934 // This EmptyAsm is required to avoid callback merge.
935 IRB.CreateCall(EmptyAsm);
939 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
942 size_t Granularity = 1 << Mapping.Scale;
943 // Addr & (Granularity - 1)
944 Value *LastAccessedByte = IRB.CreateAnd(
945 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
946 // (Addr & (Granularity - 1)) + size - 1
947 if (TypeSize / 8 > 1)
948 LastAccessedByte = IRB.CreateAdd(
949 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
950 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
951 LastAccessedByte = IRB.CreateIntCast(
952 LastAccessedByte, ShadowValue->getType(), false);
953 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
954 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
957 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
958 Instruction *InsertBefore, Value *Addr,
959 uint32_t TypeSize, bool IsWrite,
960 Value *SizeArgument, bool UseCalls) {
961 IRBuilder<> IRB(InsertBefore);
962 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
963 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
966 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
971 Type *ShadowTy = IntegerType::get(
972 *C, std::max(8U, TypeSize >> Mapping.Scale));
973 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
974 Value *ShadowPtr = memToShadow(AddrLong, IRB);
975 Value *CmpVal = Constant::getNullValue(ShadowTy);
976 Value *ShadowValue = IRB.CreateLoad(
977 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
979 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
980 size_t Granularity = 1 << Mapping.Scale;
981 TerminatorInst *CrashTerm = nullptr;
983 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
984 // We use branch weights for the slow path check, to indicate that the slow
985 // path is rarely taken. This seems to be the case for SPEC benchmarks.
986 TerminatorInst *CheckTerm =
987 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false,
988 MDBuilder(*C).createBranchWeights(1, 100000));
989 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
990 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
991 IRB.SetInsertPoint(CheckTerm);
992 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
993 BasicBlock *CrashBlock =
994 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
995 CrashTerm = new UnreachableInst(*C, CrashBlock);
996 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
997 ReplaceInstWithInst(CheckTerm, NewTerm);
999 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
1002 Instruction *Crash = generateCrashCode(
1003 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
1004 Crash->setDebugLoc(OrigIns->getDebugLoc());
1007 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1008 GlobalValue *ModuleName) {
1009 // Set up the arguments to our poison/unpoison functions.
1010 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
1012 // Add a call to poison all external globals before the given function starts.
1013 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1014 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1016 // Add calls to unpoison all globals before each return instruction.
1017 for (auto &BB : GlobalInit.getBasicBlockList())
1018 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1019 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1022 void AddressSanitizerModule::createInitializerPoisonCalls(
1023 Module &M, GlobalValue *ModuleName) {
1024 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1026 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1027 for (Use &OP : CA->operands()) {
1028 if (isa<ConstantAggregateZero>(OP))
1030 ConstantStruct *CS = cast<ConstantStruct>(OP);
1032 // Must have a function or null ptr.
1033 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
1034 if (F->getName() == kAsanModuleCtorName) continue;
1035 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1036 // Don't instrument CTORs that will run before asan.module_ctor.
1037 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1038 poisonOneInitializer(*F, ModuleName);
1043 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1044 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1045 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1047 if (GlobalsMD.get(G).IsBlacklisted) return false;
1048 if (!Ty->isSized()) return false;
1049 if (!G->hasInitializer()) return false;
1050 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1051 // Touch only those globals that will not be defined in other modules.
1052 // Don't handle ODR linkage types and COMDATs since other modules may be built
1054 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1055 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1056 G->getLinkage() != GlobalVariable::InternalLinkage)
1060 // Two problems with thread-locals:
1061 // - The address of the main thread's copy can't be computed at link-time.
1062 // - Need to poison all copies, not just the main thread's one.
1063 if (G->isThreadLocal())
1065 // For now, just ignore this Global if the alignment is large.
1066 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1068 if (G->hasSection()) {
1069 StringRef Section(G->getSection());
1071 if (TargetTriple.isOSBinFormatMachO()) {
1072 StringRef ParsedSegment, ParsedSection;
1073 unsigned TAA = 0, StubSize = 0;
1075 std::string ErrorCode =
1076 MCSectionMachO::ParseSectionSpecifier(Section, ParsedSegment,
1077 ParsedSection, TAA, TAAParsed,
1079 if (!ErrorCode.empty()) {
1080 report_fatal_error("Invalid section specifier '" + ParsedSection +
1081 "': " + ErrorCode + ".");
1084 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1085 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1087 if (ParsedSegment == "__OBJC" ||
1088 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1089 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1092 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1093 // Constant CFString instances are compiled in the following way:
1094 // -- the string buffer is emitted into
1095 // __TEXT,__cstring,cstring_literals
1096 // -- the constant NSConstantString structure referencing that buffer
1097 // is placed into __DATA,__cfstring
1098 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1099 // Moreover, it causes the linker to crash on OS X 10.7
1100 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1101 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1104 // The linker merges the contents of cstring_literals and removes the
1106 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1107 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1112 // Callbacks put into the CRT initializer/terminator sections
1113 // should not be instrumented.
1114 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1115 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1116 if (Section.startswith(".CRT")) {
1117 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1121 // Globals from llvm.metadata aren't emitted, do not instrument them.
1122 if (Section == "llvm.metadata") return false;
1128 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1129 IRBuilder<> IRB(*C);
1130 // Declare our poisoning and unpoisoning functions.
1131 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1132 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1133 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1134 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1135 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1136 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1137 // Declare functions that register/unregister globals.
1138 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1139 kAsanRegisterGlobalsName, IRB.getVoidTy(),
1140 IntptrTy, IntptrTy, nullptr));
1141 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1142 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1143 kAsanUnregisterGlobalsName,
1144 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1145 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1148 // This function replaces all global variables with new variables that have
1149 // trailing redzones. It also creates a function that poisons
1150 // redzones and inserts this function into llvm.global_ctors.
1151 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1154 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1156 for (auto &G : M.globals()) {
1157 if (ShouldInstrumentGlobal(&G))
1158 GlobalsToChange.push_back(&G);
1161 size_t n = GlobalsToChange.size();
1162 if (n == 0) return false;
1164 // A global is described by a structure
1167 // size_t size_with_redzone;
1168 // const char *name;
1169 // const char *module_name;
1170 // size_t has_dynamic_init;
1171 // void *source_location;
1172 // We initialize an array of such structures and pass it to a run-time call.
1173 StructType *GlobalStructTy =
1174 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1175 IntptrTy, IntptrTy, nullptr);
1176 SmallVector<Constant *, 16> Initializers(n);
1178 bool HasDynamicallyInitializedGlobals = false;
1180 // We shouldn't merge same module names, as this string serves as unique
1181 // module ID in runtime.
1182 GlobalVariable *ModuleName = createPrivateGlobalForString(
1183 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1185 for (size_t i = 0; i < n; i++) {
1186 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1187 GlobalVariable *G = GlobalsToChange[i];
1189 auto MD = GlobalsMD.get(G);
1190 // Create string holding the global name (use global name from metadata
1191 // if it's available, otherwise just write the name of global variable).
1192 GlobalVariable *Name = createPrivateGlobalForString(
1193 M, MD.Name.empty() ? G->getName() : MD.Name,
1194 /*AllowMerging*/ true);
1196 PointerType *PtrTy = cast<PointerType>(G->getType());
1197 Type *Ty = PtrTy->getElementType();
1198 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1199 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1200 // MinRZ <= RZ <= kMaxGlobalRedzone
1201 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1202 uint64_t RZ = std::max(MinRZ,
1203 std::min(kMaxGlobalRedzone,
1204 (SizeInBytes / MinRZ / 4) * MinRZ));
1205 uint64_t RightRedzoneSize = RZ;
1206 // Round up to MinRZ
1207 if (SizeInBytes % MinRZ)
1208 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1209 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1210 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1212 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1213 Constant *NewInitializer = ConstantStruct::get(
1214 NewTy, G->getInitializer(),
1215 Constant::getNullValue(RightRedZoneTy), nullptr);
1217 // Create a new global variable with enough space for a redzone.
1218 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1219 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1220 Linkage = GlobalValue::InternalLinkage;
1221 GlobalVariable *NewGlobal = new GlobalVariable(
1222 M, NewTy, G->isConstant(), Linkage,
1223 NewInitializer, "", G, G->getThreadLocalMode());
1224 NewGlobal->copyAttributesFrom(G);
1225 NewGlobal->setAlignment(MinRZ);
1228 Indices2[0] = IRB.getInt32(0);
1229 Indices2[1] = IRB.getInt32(0);
1231 G->replaceAllUsesWith(
1232 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1233 NewGlobal->takeName(G);
1234 G->eraseFromParent();
1236 Constant *SourceLoc;
1237 if (!MD.SourceLoc.empty()) {
1238 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1239 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1241 SourceLoc = ConstantInt::get(IntptrTy, 0);
1244 Initializers[i] = ConstantStruct::get(
1245 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1246 ConstantInt::get(IntptrTy, SizeInBytes),
1247 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1248 ConstantExpr::getPointerCast(Name, IntptrTy),
1249 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1250 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1252 if (ClInitializers && MD.IsDynInit)
1253 HasDynamicallyInitializedGlobals = true;
1255 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1258 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1259 GlobalVariable *AllGlobals = new GlobalVariable(
1260 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1261 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1263 // Create calls for poisoning before initializers run and unpoisoning after.
1264 if (HasDynamicallyInitializedGlobals)
1265 createInitializerPoisonCalls(M, ModuleName);
1266 IRB.CreateCall2(AsanRegisterGlobals,
1267 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1268 ConstantInt::get(IntptrTy, n));
1270 // We also need to unregister globals at the end, e.g. when a shared library
1272 Function *AsanDtorFunction = Function::Create(
1273 FunctionType::get(Type::getVoidTy(*C), false),
1274 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1275 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1276 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1277 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1278 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1279 ConstantInt::get(IntptrTy, n));
1280 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1286 bool AddressSanitizerModule::runOnModule(Module &M) {
1287 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1290 DL = &DLP->getDataLayout();
1291 C = &(M.getContext());
1292 int LongSize = DL->getPointerSizeInBits();
1293 IntptrTy = Type::getIntNTy(*C, LongSize);
1294 TargetTriple = Triple(M.getTargetTriple());
1295 Mapping = getShadowMapping(TargetTriple, LongSize);
1296 initializeCallbacks(M);
1298 bool Changed = false;
1300 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1302 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1305 Changed |= InstrumentGlobals(IRB, M);
1310 void AddressSanitizer::initializeCallbacks(Module &M) {
1311 IRBuilder<> IRB(*C);
1312 // Create __asan_report* callbacks.
1313 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1314 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1315 AccessSizeIndex++) {
1316 // IsWrite and TypeSize are encoded in the function name.
1317 std::string Suffix =
1318 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1319 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1320 checkInterfaceFunction(
1321 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1322 IRB.getVoidTy(), IntptrTy, nullptr));
1323 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1324 checkInterfaceFunction(
1325 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1326 IRB.getVoidTy(), IntptrTy, nullptr));
1329 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1330 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1331 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1332 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1334 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1335 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1336 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1337 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1338 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1339 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1341 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1342 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1343 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1344 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1345 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1346 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1347 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1348 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1349 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1351 AsanHandleNoReturnFunc = checkInterfaceFunction(
1352 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1354 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1355 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1356 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1357 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1358 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1359 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1360 StringRef(""), StringRef(""),
1361 /*hasSideEffects=*/true);
1365 bool AddressSanitizer::doInitialization(Module &M) {
1366 // Initialize the private fields. No one has accessed them before.
1367 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1369 report_fatal_error("data layout missing");
1370 DL = &DLP->getDataLayout();
1374 C = &(M.getContext());
1375 LongSize = DL->getPointerSizeInBits();
1376 IntptrTy = Type::getIntNTy(*C, LongSize);
1377 TargetTriple = Triple(M.getTargetTriple());
1379 AsanCtorFunction = Function::Create(
1380 FunctionType::get(Type::getVoidTy(*C), false),
1381 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1382 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1383 // call __asan_init in the module ctor.
1384 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1385 AsanInitFunction = checkInterfaceFunction(
1386 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr));
1387 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1388 IRB.CreateCall(AsanInitFunction);
1390 Mapping = getShadowMapping(TargetTriple, LongSize);
1392 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1396 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1397 // For each NSObject descendant having a +load method, this method is invoked
1398 // by the ObjC runtime before any of the static constructors is called.
1399 // Therefore we need to instrument such methods with a call to __asan_init
1400 // at the beginning in order to initialize our runtime before any access to
1401 // the shadow memory.
1402 // We cannot just ignore these methods, because they may call other
1403 // instrumented functions.
1404 if (F.getName().find(" load]") != std::string::npos) {
1405 IRBuilder<> IRB(F.begin()->begin());
1406 IRB.CreateCall(AsanInitFunction);
1412 bool AddressSanitizer::runOnFunction(Function &F) {
1413 if (&F == AsanCtorFunction) return false;
1414 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1415 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1416 initializeCallbacks(*F.getParent());
1418 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1420 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1421 maybeInsertAsanInitAtFunctionEntry(F);
1423 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1426 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1429 // We want to instrument every address only once per basic block (unless there
1430 // are calls between uses).
1431 SmallSet<Value*, 16> TempsToInstrument;
1432 SmallVector<Instruction*, 16> ToInstrument;
1433 SmallVector<Instruction*, 8> NoReturnCalls;
1434 SmallVector<BasicBlock*, 16> AllBlocks;
1435 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1440 // Fill the set of memory operations to instrument.
1441 for (auto &BB : F) {
1442 AllBlocks.push_back(&BB);
1443 TempsToInstrument.clear();
1444 int NumInsnsPerBB = 0;
1445 for (auto &Inst : BB) {
1446 if (LooksLikeCodeInBug11395(&Inst)) return false;
1448 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1449 if (ClOpt && ClOptSameTemp) {
1450 if (!TempsToInstrument.insert(Addr).second)
1451 continue; // We've seen this temp in the current BB.
1453 } else if (ClInvalidPointerPairs &&
1454 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1455 PointerComparisonsOrSubtracts.push_back(&Inst);
1457 } else if (isa<MemIntrinsic>(Inst)) {
1460 if (isa<AllocaInst>(Inst))
1464 // A call inside BB.
1465 TempsToInstrument.clear();
1466 if (CS.doesNotReturn())
1467 NoReturnCalls.push_back(CS.getInstruction());
1471 ToInstrument.push_back(&Inst);
1473 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1478 bool UseCalls = false;
1479 if (ClInstrumentationWithCallsThreshold >= 0 &&
1480 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1484 int NumInstrumented = 0;
1485 for (auto Inst : ToInstrument) {
1486 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1487 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1488 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1489 instrumentMop(Inst, UseCalls);
1491 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1496 FunctionStackPoisoner FSP(F, *this);
1497 bool ChangedStack = FSP.runOnFunction();
1499 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1500 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1501 for (auto CI : NoReturnCalls) {
1502 IRBuilder<> IRB(CI);
1503 IRB.CreateCall(AsanHandleNoReturnFunc);
1506 for (auto Inst : PointerComparisonsOrSubtracts) {
1507 instrumentPointerComparisonOrSubtraction(Inst);
1511 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1513 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1518 // Workaround for bug 11395: we don't want to instrument stack in functions
1519 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1520 // FIXME: remove once the bug 11395 is fixed.
1521 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1522 if (LongSize != 32) return false;
1523 CallInst *CI = dyn_cast<CallInst>(I);
1524 if (!CI || !CI->isInlineAsm()) return false;
1525 if (CI->getNumArgOperands() <= 5) return false;
1526 // We have inline assembly with quite a few arguments.
1530 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1531 IRBuilder<> IRB(*C);
1532 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1533 std::string Suffix = itostr(i);
1534 AsanStackMallocFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1535 kAsanStackMallocNameTemplate + Suffix, IntptrTy, IntptrTy, nullptr));
1536 AsanStackFreeFunc[i] = checkInterfaceFunction(
1537 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
1538 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1540 AsanPoisonStackMemoryFunc = checkInterfaceFunction(
1541 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1542 IntptrTy, IntptrTy, nullptr));
1543 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(
1544 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1545 IntptrTy, IntptrTy, nullptr));
1549 FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1550 IRBuilder<> &IRB, Value *ShadowBase,
1552 size_t n = ShadowBytes.size();
1554 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1555 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1556 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1557 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1558 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1559 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1561 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1562 if (ASan.DL->isLittleEndian())
1563 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1565 Val = (Val << 8) | ShadowBytes[i + j];
1568 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1569 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1570 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1571 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1576 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1577 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1578 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1579 assert(LocalStackSize <= kMaxStackMallocSize);
1580 uint64_t MaxSize = kMinStackMallocSize;
1581 for (int i = 0; ; i++, MaxSize *= 2)
1582 if (LocalStackSize <= MaxSize)
1584 llvm_unreachable("impossible LocalStackSize");
1587 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1588 // We can not use MemSet intrinsic because it may end up calling the actual
1589 // memset. Size is a multiple of 8.
1590 // Currently this generates 8-byte stores on x86_64; it may be better to
1591 // generate wider stores.
1592 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1593 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1594 assert(!(Size % 8));
1595 assert(kAsanStackAfterReturnMagic == 0xf5);
1596 for (int i = 0; i < Size; i += 8) {
1597 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1598 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1599 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1603 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1604 for (const auto &Inst : F.getEntryBlock())
1605 if (!isa<AllocaInst>(Inst))
1606 return Inst.getDebugLoc();
1610 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
1612 Instruction *ThenTerm,
1613 Value *ValueIfFalse) {
1614 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
1615 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
1616 PHI->addIncoming(ValueIfFalse, CondBlock);
1617 BasicBlock *ThenBlock = ThenTerm->getParent();
1618 PHI->addIncoming(ValueIfTrue, ThenBlock);
1622 Value *FunctionStackPoisoner::createAllocaForLayout(
1623 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
1626 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
1627 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
1630 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
1631 nullptr, "MyAlloca");
1632 assert(Alloca->isStaticAlloca());
1634 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1635 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1636 Alloca->setAlignment(FrameAlignment);
1637 return IRB.CreatePointerCast(Alloca, IntptrTy);
1640 void FunctionStackPoisoner::poisonStack() {
1641 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1643 if (ClInstrumentAllocas)
1644 // Handle dynamic allocas.
1645 for (auto &AllocaCall : DynamicAllocaVec)
1646 handleDynamicAllocaCall(AllocaCall);
1648 if (AllocaVec.size() == 0) return;
1650 int StackMallocIdx = -1;
1651 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1653 Instruction *InsBefore = AllocaVec[0];
1654 IRBuilder<> IRB(InsBefore);
1655 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1657 SmallVector<ASanStackVariableDescription, 16> SVD;
1658 SVD.reserve(AllocaVec.size());
1659 for (AllocaInst *AI : AllocaVec) {
1660 ASanStackVariableDescription D = { AI->getName().data(),
1661 getAllocaSizeInBytes(AI),
1662 AI->getAlignment(), AI, 0};
1665 // Minimal header size (left redzone) is 4 pointers,
1666 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1667 size_t MinHeaderSize = ASan.LongSize / 2;
1668 ASanStackFrameLayout L;
1669 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1670 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1671 uint64_t LocalStackSize = L.FrameSize;
1672 bool DoStackMalloc =
1673 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1674 // Don't do dynamic alloca in presence of inline asm: too often it
1675 // makes assumptions on which registers are available.
1676 bool DoDynamicAlloca = ClDynamicAllocaStack && !HasNonEmptyInlineAsm;
1678 Value *StaticAlloca =
1679 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
1682 Value *LocalStackBase;
1684 if (DoStackMalloc) {
1685 // void *FakeStack = __asan_option_detect_stack_use_after_return
1686 // ? __asan_stack_malloc_N(LocalStackSize)
1688 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
1689 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1690 kAsanOptionDetectUAR, IRB.getInt32Ty());
1691 Value *UARIsEnabled =
1692 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1693 Constant::getNullValue(IRB.getInt32Ty()));
1695 SplitBlockAndInsertIfThen(UARIsEnabled, InsBefore, false);
1696 IRBuilder<> IRBIf(Term);
1697 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1698 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1699 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1700 Value *FakeStackValue =
1701 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
1702 ConstantInt::get(IntptrTy, LocalStackSize));
1703 IRB.SetInsertPoint(InsBefore);
1704 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1705 FakeStack = createPHI(IRB, UARIsEnabled, FakeStackValue, Term,
1706 ConstantInt::get(IntptrTy, 0));
1708 Value *NoFakeStack =
1709 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
1710 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
1711 IRBIf.SetInsertPoint(Term);
1712 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1713 Value *AllocaValue =
1714 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
1715 IRB.SetInsertPoint(InsBefore);
1716 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1717 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
1719 // void *FakeStack = nullptr;
1720 // void *LocalStackBase = alloca(LocalStackSize);
1721 FakeStack = ConstantInt::get(IntptrTy, 0);
1723 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
1726 // Insert poison calls for lifetime intrinsics for alloca.
1727 bool HavePoisonedAllocas = false;
1728 for (const auto &APC : AllocaPoisonCallVec) {
1729 assert(APC.InsBefore);
1731 IRBuilder<> IRB(APC.InsBefore);
1732 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1733 HavePoisonedAllocas |= APC.DoPoison;
1736 // Replace Alloca instructions with base+offset.
1737 for (const auto &Desc : SVD) {
1738 AllocaInst *AI = Desc.AI;
1739 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1740 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1742 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1743 AI->replaceAllUsesWith(NewAllocaPtr);
1746 // The left-most redzone has enough space for at least 4 pointers.
1747 // Write the Magic value to redzone[0].
1748 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1749 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1751 // Write the frame description constant to redzone[1].
1752 Value *BasePlus1 = IRB.CreateIntToPtr(
1753 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1755 GlobalVariable *StackDescriptionGlobal =
1756 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1757 /*AllowMerging*/true);
1758 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1760 IRB.CreateStore(Description, BasePlus1);
1761 // Write the PC to redzone[2].
1762 Value *BasePlus2 = IRB.CreateIntToPtr(
1763 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1764 2 * ASan.LongSize/8)),
1766 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1768 // Poison the stack redzones at the entry.
1769 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1770 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1772 // (Un)poison the stack before all ret instructions.
1773 for (auto Ret : RetVec) {
1774 IRBuilder<> IRBRet(Ret);
1775 // Mark the current frame as retired.
1776 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1778 if (DoStackMalloc) {
1779 assert(StackMallocIdx >= 0);
1780 // if FakeStack != 0 // LocalStackBase == FakeStack
1781 // // In use-after-return mode, poison the whole stack frame.
1782 // if StackMallocIdx <= 4
1783 // // For small sizes inline the whole thing:
1784 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1785 // **SavedFlagPtr(FakeStack) = 0
1787 // __asan_stack_free_N(FakeStack, LocalStackSize)
1789 // <This is not a fake stack; unpoison the redzones>
1791 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
1792 TerminatorInst *ThenTerm, *ElseTerm;
1793 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1795 IRBuilder<> IRBPoison(ThenTerm);
1796 if (StackMallocIdx <= 4) {
1797 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1798 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1799 ClassSize >> Mapping.Scale);
1800 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1802 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1803 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1804 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1805 IRBPoison.CreateStore(
1806 Constant::getNullValue(IRBPoison.getInt8Ty()),
1807 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1809 // For larger frames call __asan_stack_free_*.
1810 IRBPoison.CreateCall2(AsanStackFreeFunc[StackMallocIdx], FakeStack,
1811 ConstantInt::get(IntptrTy, LocalStackSize));
1814 IRBuilder<> IRBElse(ElseTerm);
1815 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1816 } else if (HavePoisonedAllocas) {
1817 // If we poisoned some allocas in llvm.lifetime analysis,
1818 // unpoison whole stack frame now.
1819 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1821 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1825 if (ClInstrumentAllocas)
1826 // Unpoison dynamic allocas.
1827 for (auto &AllocaCall : DynamicAllocaVec)
1828 unpoisonDynamicAlloca(AllocaCall);
1830 // We are done. Remove the old unused alloca instructions.
1831 for (auto AI : AllocaVec)
1832 AI->eraseFromParent();
1835 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1836 IRBuilder<> &IRB, bool DoPoison) {
1837 // For now just insert the call to ASan runtime.
1838 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1839 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1840 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1841 : AsanUnpoisonStackMemoryFunc,
1845 // Handling llvm.lifetime intrinsics for a given %alloca:
1846 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1847 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1848 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1849 // could be poisoned by previous llvm.lifetime.end instruction, as the
1850 // variable may go in and out of scope several times, e.g. in loops).
1851 // (3) if we poisoned at least one %alloca in a function,
1852 // unpoison the whole stack frame at function exit.
1854 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1855 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1856 // We're intested only in allocas we can handle.
1857 return isInterestingAlloca(*AI) ? AI : nullptr;
1858 // See if we've already calculated (or started to calculate) alloca for a
1860 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1861 if (I != AllocaForValue.end())
1863 // Store 0 while we're calculating alloca for value V to avoid
1864 // infinite recursion if the value references itself.
1865 AllocaForValue[V] = nullptr;
1866 AllocaInst *Res = nullptr;
1867 if (CastInst *CI = dyn_cast<CastInst>(V))
1868 Res = findAllocaForValue(CI->getOperand(0));
1869 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1870 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1871 Value *IncValue = PN->getIncomingValue(i);
1872 // Allow self-referencing phi-nodes.
1873 if (IncValue == PN) continue;
1874 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1875 // AI for incoming values should exist and should all be equal.
1876 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1882 AllocaForValue[V] = Res;
1886 // Compute PartialRzMagic for dynamic alloca call. PartialRzMagic is
1887 // constructed from two separate 32-bit numbers: PartialRzMagic = Val1 | Val2.
1888 // (1) Val1 is resposible for forming base value for PartialRzMagic, containing
1889 // only 00 for fully addressable and 0xcb for fully poisoned bytes for each
1890 // 8-byte chunk of user memory respectively.
1891 // (2) Val2 forms the value for marking first poisoned byte in shadow memory
1892 // with appropriate value (0x01 - 0x07 or 0xcb if Padding % 8 == 0).
1894 // Shift = Padding & ~7; // the number of bits we need to shift to access first
1895 // chunk in shadow memory, containing nonzero bytes.
1897 // Padding = 21 Padding = 16
1898 // Shadow: |00|00|05|cb| Shadow: |00|00|cb|cb|
1901 // Shift = 21 & ~7 = 16 Shift = 16 & ~7 = 16
1903 // Val1 = 0xcbcbcbcb << Shift;
1904 // PartialBits = Padding ? Padding & 7 : 0xcb;
1905 // Val2 = PartialBits << Shift;
1906 // Result = Val1 | Val2;
1907 Value *FunctionStackPoisoner::computePartialRzMagic(Value *PartialSize,
1909 PartialSize = IRB.CreateIntCast(PartialSize, IRB.getInt32Ty(), false);
1910 Value *Shift = IRB.CreateAnd(PartialSize, IRB.getInt32(~7));
1911 unsigned Val1Int = kAsanAllocaPartialVal1;
1912 unsigned Val2Int = kAsanAllocaPartialVal2;
1913 if (!ASan.DL->isLittleEndian()) {
1914 Val1Int = sys::getSwappedBytes(Val1Int);
1915 Val2Int = sys::getSwappedBytes(Val2Int);
1917 Value *Val1 = shiftAllocaMagic(IRB.getInt32(Val1Int), IRB, Shift);
1918 Value *PartialBits = IRB.CreateAnd(PartialSize, IRB.getInt32(7));
1919 // For BigEndian get 0x000000YZ -> 0xYZ000000.
1920 if (ASan.DL->isBigEndian())
1921 PartialBits = IRB.CreateShl(PartialBits, IRB.getInt32(24));
1922 Value *Val2 = IRB.getInt32(Val2Int);
1924 IRB.CreateICmpNE(PartialBits, Constant::getNullValue(IRB.getInt32Ty()));
1925 Val2 = IRB.CreateSelect(Cond, shiftAllocaMagic(PartialBits, IRB, Shift),
1926 shiftAllocaMagic(Val2, IRB, Shift));
1927 return IRB.CreateOr(Val1, Val2);
1930 void FunctionStackPoisoner::handleDynamicAllocaCall(
1931 DynamicAllocaCall &AllocaCall) {
1932 AllocaInst *AI = AllocaCall.AI;
1933 if (!doesDominateAllExits(AI)) {
1934 // We do not yet handle complex allocas
1935 AllocaCall.Poison = false;
1939 IRBuilder<> IRB(AI);
1941 PointerType *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
1942 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
1943 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
1945 Value *Zero = Constant::getNullValue(IntptrTy);
1946 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
1947 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
1948 Value *NotAllocaRzMask = ConstantInt::get(IntptrTy, ~AllocaRedzoneMask);
1950 // Since we need to extend alloca with additional memory to locate
1951 // redzones, and OldSize is number of allocated blocks with
1952 // ElementSize size, get allocated memory size in bytes by
1953 // OldSize * ElementSize.
1954 unsigned ElementSize = ASan.DL->getTypeAllocSize(AI->getAllocatedType());
1955 Value *OldSize = IRB.CreateMul(AI->getArraySize(),
1956 ConstantInt::get(IntptrTy, ElementSize));
1958 // PartialSize = OldSize % 32
1959 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
1961 // Misalign = kAllocaRzSize - PartialSize;
1962 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
1964 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
1965 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
1966 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
1968 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
1969 // Align is added to locate left redzone, PartialPadding for possible
1970 // partial redzone and kAllocaRzSize for right redzone respectively.
1971 Value *AdditionalChunkSize = IRB.CreateAdd(
1972 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
1974 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
1976 // Insert new alloca with new NewSize and Align params.
1977 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
1978 NewAlloca->setAlignment(Align);
1980 // NewAddress = Address + Align
1981 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
1982 ConstantInt::get(IntptrTy, Align));
1984 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
1986 // LeftRzAddress = NewAddress - kAllocaRzSize
1987 Value *LeftRzAddress = IRB.CreateSub(NewAddress, AllocaRzSize);
1989 // Poisoning left redzone.
1990 AllocaCall.LeftRzAddr = ASan.memToShadow(LeftRzAddress, IRB);
1991 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaLeftMagic),
1992 IRB.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
1994 // PartialRzAligned = PartialRzAddr & ~AllocaRzMask
1995 Value *PartialRzAddr = IRB.CreateAdd(NewAddress, OldSize);
1996 Value *PartialRzAligned = IRB.CreateAnd(PartialRzAddr, NotAllocaRzMask);
1998 // Poisoning partial redzone.
1999 Value *PartialRzMagic = computePartialRzMagic(PartialSize, IRB);
2000 Value *PartialRzShadowAddr = ASan.memToShadow(PartialRzAligned, IRB);
2001 IRB.CreateStore(PartialRzMagic,
2002 IRB.CreateIntToPtr(PartialRzShadowAddr, Int32PtrTy));
2005 // = (PartialRzAddr + AllocaRzMask) & ~AllocaRzMask
2006 Value *RightRzAddress = IRB.CreateAnd(
2007 IRB.CreateAdd(PartialRzAddr, AllocaRzMask), NotAllocaRzMask);
2009 // Poisoning right redzone.
2010 AllocaCall.RightRzAddr = ASan.memToShadow(RightRzAddress, IRB);
2011 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaRightMagic),
2012 IRB.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
2014 // Replace all uses of AddessReturnedByAlloca with NewAddress.
2015 AI->replaceAllUsesWith(NewAddressPtr);
2017 // We are done. Erase old alloca and store left, partial and right redzones
2018 // shadow addresses for future unpoisoning.
2019 AI->eraseFromParent();
2020 NumInstrumentedDynamicAllocas++;