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;
71 static const size_t kMinStackMallocSize = 1 << 6; // 64B
72 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
73 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
74 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
76 static const char *const kAsanModuleCtorName = "asan.module_ctor";
77 static const char *const kAsanModuleDtorName = "asan.module_dtor";
78 static const uint64_t kAsanCtorAndDtorPriority = 1;
79 static const char *const kAsanReportErrorTemplate = "__asan_report_";
80 static const char *const kAsanReportLoadN = "__asan_report_load_n";
81 static const char *const kAsanReportStoreN = "__asan_report_store_n";
82 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
83 static const char *const kAsanUnregisterGlobalsName =
84 "__asan_unregister_globals";
85 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
86 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
87 static const char *const kAsanInitName = "__asan_init_v4";
88 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
89 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
90 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
91 static const int kMaxAsanStackMallocSizeClass = 10;
92 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
93 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
94 static const char *const kAsanGenPrefix = "__asan_gen_";
95 static const char *const kSanCovGenPrefix = "__sancov_gen_";
96 static const char *const kAsanPoisonStackMemoryName =
97 "__asan_poison_stack_memory";
98 static const char *const kAsanUnpoisonStackMemoryName =
99 "__asan_unpoison_stack_memory";
101 static const char *const kAsanOptionDetectUAR =
102 "__asan_option_detect_stack_use_after_return";
105 static const int kAsanStackAfterReturnMagic = 0xf5;
108 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
109 static const size_t kNumberOfAccessSizes = 5;
111 static const unsigned kAllocaRzSize = 32;
112 static const unsigned kAsanAllocaLeftMagic = 0xcacacacaU;
113 static const unsigned kAsanAllocaRightMagic = 0xcbcbcbcbU;
114 static const unsigned kAsanAllocaPartialVal1 = 0xcbcbcb00U;
115 static const unsigned kAsanAllocaPartialVal2 = 0x000000cbU;
117 // Command-line flags.
119 // This flag may need to be replaced with -f[no-]asan-reads.
120 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
121 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
122 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
123 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
124 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
125 cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
126 cl::Hidden, cl::init(true));
127 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
128 cl::desc("use instrumentation with slow path for all accesses"),
129 cl::Hidden, cl::init(false));
130 // This flag limits the number of instructions to be instrumented
131 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
132 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
134 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
136 cl::desc("maximal number of instructions to instrument in any given BB"),
138 // This flag may need to be replaced with -f[no]asan-stack.
139 static cl::opt<bool> ClStack("asan-stack",
140 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
141 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
142 cl::desc("Check return-after-free"), cl::Hidden, cl::init(true));
143 // This flag may need to be replaced with -f[no]asan-globals.
144 static cl::opt<bool> ClGlobals("asan-globals",
145 cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
146 static cl::opt<bool> ClInitializers("asan-initialization-order",
147 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(true));
148 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
149 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
150 cl::Hidden, cl::init(false));
151 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
152 cl::desc("Realign stack to the value of this flag (power of two)"),
153 cl::Hidden, cl::init(32));
154 static cl::opt<int> ClInstrumentationWithCallsThreshold(
155 "asan-instrumentation-with-call-threshold",
156 cl::desc("If the function being instrumented contains more than "
157 "this number of memory accesses, use callbacks instead of "
158 "inline checks (-1 means never use callbacks)."),
159 cl::Hidden, cl::init(7000));
160 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
161 "asan-memory-access-callback-prefix",
162 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
163 cl::init("__asan_"));
164 static cl::opt<bool> ClInstrumentAllocas("asan-instrument-allocas",
165 cl::desc("instrument dynamic allocas"), cl::Hidden, cl::init(false));
167 // These flags allow to change the shadow mapping.
168 // The shadow mapping looks like
169 // Shadow = (Mem >> scale) + (1 << offset_log)
170 static cl::opt<int> ClMappingScale("asan-mapping-scale",
171 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
173 // Optimization flags. Not user visible, used mostly for testing
174 // and benchmarking the tool.
175 static cl::opt<bool> ClOpt("asan-opt",
176 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
177 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
178 cl::desc("Instrument the same temp just once"), cl::Hidden,
180 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
181 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
183 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
184 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
185 cl::Hidden, cl::init(false));
188 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
190 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
191 cl::Hidden, cl::init(0));
192 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
193 cl::Hidden, cl::desc("Debug func"));
194 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
195 cl::Hidden, cl::init(-1));
196 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
197 cl::Hidden, cl::init(-1));
199 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
200 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
201 STATISTIC(NumInstrumentedDynamicAllocas,
202 "Number of instrumented dynamic allocas");
203 STATISTIC(NumOptimizedAccessesToGlobalArray,
204 "Number of optimized accesses to global arrays");
205 STATISTIC(NumOptimizedAccessesToGlobalVar,
206 "Number of optimized accesses to global vars");
209 /// Frontend-provided metadata for source location.
210 struct LocationMetadata {
215 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
217 bool empty() const { return Filename.empty(); }
219 void parse(MDNode *MDN) {
220 assert(MDN->getNumOperands() == 3);
221 MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
222 Filename = MDFilename->getString();
223 LineNo = cast<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
224 ColumnNo = cast<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
228 /// Frontend-provided metadata for global variables.
229 class GlobalsMetadata {
233 : SourceLoc(), Name(), IsDynInit(false),
234 IsBlacklisted(false) {}
235 LocationMetadata SourceLoc;
241 GlobalsMetadata() : inited_(false) {}
243 void init(Module& M) {
246 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
249 for (auto MDN : Globals->operands()) {
250 // Metadata node contains the global and the fields of "Entry".
251 assert(MDN->getNumOperands() == 5);
252 Value *V = MDN->getOperand(0);
253 // The optimizer may optimize away a global entirely.
256 GlobalVariable *GV = cast<GlobalVariable>(V);
257 // We can already have an entry for GV if it was merged with another
259 Entry &E = Entries[GV];
260 if (Value *Loc = MDN->getOperand(1))
261 E.SourceLoc.parse(cast<MDNode>(Loc));
262 if (Value *Name = MDN->getOperand(2)) {
263 MDString *MDName = cast<MDString>(Name);
264 E.Name = MDName->getString();
266 ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(3));
267 E.IsDynInit |= IsDynInit->isOne();
268 ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(4));
269 E.IsBlacklisted |= IsBlacklisted->isOne();
273 /// Returns metadata entry for a given global.
274 Entry get(GlobalVariable *G) const {
275 auto Pos = Entries.find(G);
276 return (Pos != Entries.end()) ? Pos->second : Entry();
281 DenseMap<GlobalVariable*, Entry> Entries;
284 /// This struct defines the shadow mapping using the rule:
285 /// shadow = (mem >> Scale) ADD-or-OR Offset.
286 struct ShadowMapping {
292 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) {
293 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
294 bool IsIOS = TargetTriple.isiOS();
295 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
296 bool IsLinux = TargetTriple.isOSLinux();
297 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
298 TargetTriple.getArch() == llvm::Triple::ppc64le;
299 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
300 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
301 TargetTriple.getArch() == llvm::Triple::mipsel;
302 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
303 TargetTriple.getArch() == llvm::Triple::mips64el;
305 ShadowMapping Mapping;
307 if (LongSize == 32) {
311 Mapping.Offset = kMIPS32_ShadowOffset32;
313 Mapping.Offset = kFreeBSD_ShadowOffset32;
315 Mapping.Offset = kIOSShadowOffset32;
317 Mapping.Offset = kDefaultShadowOffset32;
318 } else { // LongSize == 64
320 Mapping.Offset = kPPC64_ShadowOffset64;
322 Mapping.Offset = kFreeBSD_ShadowOffset64;
323 else if (IsLinux && IsX86_64)
324 Mapping.Offset = kSmallX86_64ShadowOffset;
326 Mapping.Offset = kMIPS64_ShadowOffset64;
328 Mapping.Offset = kDefaultShadowOffset64;
331 Mapping.Scale = kDefaultShadowScale;
332 if (ClMappingScale) {
333 Mapping.Scale = ClMappingScale;
336 // OR-ing shadow offset if more efficient (at least on x86) if the offset
337 // is a power of two, but on ppc64 we have to use add since the shadow
338 // offset is not necessary 1/8-th of the address space.
339 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
344 static size_t RedzoneSizeForScale(int MappingScale) {
345 // Redzone used for stack and globals is at least 32 bytes.
346 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
347 return std::max(32U, 1U << MappingScale);
350 /// AddressSanitizer: instrument the code in module to find memory bugs.
351 struct AddressSanitizer : public FunctionPass {
352 AddressSanitizer() : FunctionPass(ID) {
353 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
355 const char *getPassName() const override {
356 return "AddressSanitizerFunctionPass";
358 void getAnalysisUsage(AnalysisUsage &AU) const override {
359 AU.addRequired<DominatorTreeWrapperPass>();
361 void instrumentMop(Instruction *I, bool UseCalls);
362 void instrumentPointerComparisonOrSubtraction(Instruction *I);
363 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
364 Value *Addr, uint32_t TypeSize, bool IsWrite,
365 Value *SizeArgument, bool UseCalls);
366 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
367 Value *ShadowValue, uint32_t TypeSize);
368 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
369 bool IsWrite, size_t AccessSizeIndex,
370 Value *SizeArgument);
371 void instrumentMemIntrinsic(MemIntrinsic *MI);
372 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
373 bool runOnFunction(Function &F) override;
374 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
375 bool doInitialization(Module &M) override;
376 static char ID; // Pass identification, replacement for typeid
378 DominatorTree &getDominatorTree() const { return *DT; }
381 void initializeCallbacks(Module &M);
383 bool LooksLikeCodeInBug11395(Instruction *I);
384 bool GlobalIsLinkerInitialized(GlobalVariable *G);
387 const DataLayout *DL;
391 ShadowMapping Mapping;
393 Function *AsanCtorFunction;
394 Function *AsanInitFunction;
395 Function *AsanHandleNoReturnFunc;
396 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
397 // This array is indexed by AccessIsWrite and log2(AccessSize).
398 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
399 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
400 // This array is indexed by AccessIsWrite.
401 Function *AsanErrorCallbackSized[2],
402 *AsanMemoryAccessCallbackSized[2];
403 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
405 GlobalsMetadata GlobalsMD;
407 friend struct FunctionStackPoisoner;
410 class AddressSanitizerModule : public ModulePass {
412 AddressSanitizerModule() : ModulePass(ID) {}
413 bool runOnModule(Module &M) override;
414 static char ID; // Pass identification, replacement for typeid
415 const char *getPassName() const override {
416 return "AddressSanitizerModule";
420 void initializeCallbacks(Module &M);
422 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
423 bool ShouldInstrumentGlobal(GlobalVariable *G);
424 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
425 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
426 size_t MinRedzoneSizeForGlobal() const {
427 return RedzoneSizeForScale(Mapping.Scale);
430 GlobalsMetadata GlobalsMD;
433 const DataLayout *DL;
435 ShadowMapping Mapping;
436 Function *AsanPoisonGlobals;
437 Function *AsanUnpoisonGlobals;
438 Function *AsanRegisterGlobals;
439 Function *AsanUnregisterGlobals;
442 // Stack poisoning does not play well with exception handling.
443 // When an exception is thrown, we essentially bypass the code
444 // that unpoisones the stack. This is why the run-time library has
445 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
446 // stack in the interceptor. This however does not work inside the
447 // actual function which catches the exception. Most likely because the
448 // compiler hoists the load of the shadow value somewhere too high.
449 // This causes asan to report a non-existing bug on 453.povray.
450 // It sounds like an LLVM bug.
451 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
453 AddressSanitizer &ASan;
458 ShadowMapping Mapping;
460 SmallVector<AllocaInst*, 16> AllocaVec;
461 SmallVector<Instruction*, 8> RetVec;
462 unsigned StackAlignment;
464 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
465 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
466 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
468 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
469 struct AllocaPoisonCall {
470 IntrinsicInst *InsBefore;
475 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
477 // Stores left and right redzone shadow addresses for dynamic alloca
478 // and pointer to alloca instruction itself.
479 // LeftRzAddr is a shadow address for alloca left redzone.
480 // RightRzAddr is a shadow address for alloca right redzone.
481 struct DynamicAllocaCall {
486 explicit DynamicAllocaCall(AllocaInst *AI,
487 Value *LeftRzAddr = nullptr,
488 Value *RightRzAddr = nullptr)
489 : AI(AI), LeftRzAddr(LeftRzAddr), RightRzAddr(RightRzAddr), Poison(true)
492 SmallVector<DynamicAllocaCall, 1> DynamicAllocaVec;
494 // Maps Value to an AllocaInst from which the Value is originated.
495 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
496 AllocaForValueMapTy AllocaForValue;
498 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
499 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
500 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
501 Mapping(ASan.Mapping),
502 StackAlignment(1 << Mapping.Scale) {}
504 bool runOnFunction() {
505 if (!ClStack) return false;
506 // Collect alloca, ret, lifetime instructions etc.
507 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
510 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
512 initializeCallbacks(*F.getParent());
522 // Finds all Alloca instructions and puts
523 // poisoned red zones around all of them.
524 // Then unpoison everything back before the function returns.
527 // ----------------------- Visitors.
528 /// \brief Collect all Ret instructions.
529 void visitReturnInst(ReturnInst &RI) {
530 RetVec.push_back(&RI);
533 // Unpoison dynamic allocas redzones.
534 void unpoisonDynamicAlloca(DynamicAllocaCall &AllocaCall) {
535 if (!AllocaCall.Poison)
537 for (auto Ret : RetVec) {
538 IRBuilder<> IRBRet(Ret);
539 PointerType *Int32PtrTy = PointerType::getUnqual(IRBRet.getInt32Ty());
540 Value *Zero = Constant::getNullValue(IRBRet.getInt32Ty());
541 Value *PartialRzAddr = IRBRet.CreateSub(AllocaCall.RightRzAddr,
542 ConstantInt::get(IntptrTy, 4));
543 IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(AllocaCall.LeftRzAddr,
545 IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(PartialRzAddr,
547 IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(AllocaCall.RightRzAddr,
552 // Right shift for BigEndian and left shift for LittleEndian.
553 Value *shiftAllocaMagic(Value *Val, IRBuilder<> &IRB, Value *Shift) {
554 return ASan.DL->isLittleEndian() ? IRB.CreateShl(Val, Shift)
555 : IRB.CreateLShr(Val, Shift);
558 // Compute PartialRzMagic for dynamic alloca call. Since we don't know the
559 // size of requested memory until runtime, we should compute it dynamically.
560 // If PartialSize is 0, PartialRzMagic would contain kAsanAllocaRightMagic,
561 // otherwise it would contain the value that we will use to poison the
562 // partial redzone for alloca call.
563 Value *computePartialRzMagic(Value *PartialSize, IRBuilder<> &IRB);
565 // Deploy and poison redzones around dynamic alloca call. To do this, we
566 // should replace this call with another one with changed parameters and
567 // replace all its uses with new address, so
568 // addr = alloca type, old_size, align
570 // new_size = (old_size + additional_size) * sizeof(type)
571 // tmp = alloca i8, new_size, max(align, 32)
572 // addr = tmp + 32 (first 32 bytes are for the left redzone).
573 // Additional_size is added to make new memory allocation contain not only
574 // requested memory, but also left, partial and right redzones.
575 // After that, we should poison redzones:
576 // (1) Left redzone with kAsanAllocaLeftMagic.
577 // (2) Partial redzone with the value, computed in runtime by
578 // computePartialRzMagic function.
579 // (3) Right redzone with kAsanAllocaRightMagic.
580 void handleDynamicAllocaCall(DynamicAllocaCall &AllocaCall);
582 /// \brief Collect Alloca instructions we want (and can) handle.
583 void visitAllocaInst(AllocaInst &AI) {
584 if (!isInterestingAlloca(AI)) return;
586 StackAlignment = std::max(StackAlignment, AI.getAlignment());
587 if (isDynamicAlloca(AI))
588 DynamicAllocaVec.push_back(DynamicAllocaCall(&AI));
590 AllocaVec.push_back(&AI);
593 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
595 void visitIntrinsicInst(IntrinsicInst &II) {
596 if (!ClCheckLifetime) return;
597 Intrinsic::ID ID = II.getIntrinsicID();
598 if (ID != Intrinsic::lifetime_start &&
599 ID != Intrinsic::lifetime_end)
601 // Found lifetime intrinsic, add ASan instrumentation if necessary.
602 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
603 // If size argument is undefined, don't do anything.
604 if (Size->isMinusOne()) return;
605 // Check that size doesn't saturate uint64_t and can
606 // be stored in IntptrTy.
607 const uint64_t SizeValue = Size->getValue().getLimitedValue();
608 if (SizeValue == ~0ULL ||
609 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
611 // Find alloca instruction that corresponds to llvm.lifetime argument.
612 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
614 bool DoPoison = (ID == Intrinsic::lifetime_end);
615 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
616 AllocaPoisonCallVec.push_back(APC);
619 // ---------------------- Helpers.
620 void initializeCallbacks(Module &M);
622 bool doesDominateAllExits(const Instruction *I) const {
623 for (auto Ret : RetVec) {
624 if (!ASan.getDominatorTree().dominates(I, Ret))
630 bool isDynamicAlloca(AllocaInst &AI) const {
631 return AI.isArrayAllocation() || !AI.isStaticAlloca();
634 // Check if we want (and can) handle this alloca.
635 bool isInterestingAlloca(AllocaInst &AI) const {
636 return (AI.getAllocatedType()->isSized() &&
637 // alloca() may be called with 0 size, ignore it.
638 getAllocaSizeInBytes(&AI) > 0);
641 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
642 Type *Ty = AI->getAllocatedType();
643 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
646 /// Finds alloca where the value comes from.
647 AllocaInst *findAllocaForValue(Value *V);
648 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
649 Value *ShadowBase, bool DoPoison);
650 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
652 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
658 char AddressSanitizer::ID = 0;
659 INITIALIZE_PASS_BEGIN(AddressSanitizer, "asan",
660 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
662 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
663 INITIALIZE_PASS_END(AddressSanitizer, "asan",
664 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
666 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
667 return new AddressSanitizer();
670 char AddressSanitizerModule::ID = 0;
671 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
672 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
673 "ModulePass", false, false)
674 ModulePass *llvm::createAddressSanitizerModulePass() {
675 return new AddressSanitizerModule();
678 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
679 size_t Res = countTrailingZeros(TypeSize / 8);
680 assert(Res < kNumberOfAccessSizes);
684 // \brief Create a constant for Str so that we can pass it to the run-time lib.
685 static GlobalVariable *createPrivateGlobalForString(
686 Module &M, StringRef Str, bool AllowMerging) {
687 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
688 // We use private linkage for module-local strings. If they can be merged
689 // with another one, we set the unnamed_addr attribute.
691 new GlobalVariable(M, StrConst->getType(), true,
692 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
694 GV->setUnnamedAddr(true);
695 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
699 /// \brief Create a global describing a source location.
700 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
701 LocationMetadata MD) {
702 Constant *LocData[] = {
703 createPrivateGlobalForString(M, MD.Filename, true),
704 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
705 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
707 auto LocStruct = ConstantStruct::getAnon(LocData);
708 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
709 GlobalValue::PrivateLinkage, LocStruct,
711 GV->setUnnamedAddr(true);
715 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
716 return G->getName().find(kAsanGenPrefix) == 0 ||
717 G->getName().find(kSanCovGenPrefix) == 0;
720 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
722 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
723 if (Mapping.Offset == 0)
725 // (Shadow >> scale) | offset
726 if (Mapping.OrShadowOffset)
727 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
729 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
732 // Instrument memset/memmove/memcpy
733 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
735 if (isa<MemTransferInst>(MI)) {
737 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
738 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
739 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
740 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
741 } else if (isa<MemSetInst>(MI)) {
744 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
745 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
746 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
748 MI->eraseFromParent();
751 // If I is an interesting memory access, return the PointerOperand
752 // and set IsWrite/Alignment. Otherwise return nullptr.
753 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
754 unsigned *Alignment) {
755 // Skip memory accesses inserted by another instrumentation.
756 if (I->getMetadata("nosanitize"))
758 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
759 if (!ClInstrumentReads) return nullptr;
761 *Alignment = LI->getAlignment();
762 return LI->getPointerOperand();
764 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
765 if (!ClInstrumentWrites) return nullptr;
767 *Alignment = SI->getAlignment();
768 return SI->getPointerOperand();
770 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
771 if (!ClInstrumentAtomics) return nullptr;
774 return RMW->getPointerOperand();
776 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
777 if (!ClInstrumentAtomics) return nullptr;
780 return XCHG->getPointerOperand();
785 static bool isPointerOperand(Value *V) {
786 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
789 // This is a rough heuristic; it may cause both false positives and
790 // false negatives. The proper implementation requires cooperation with
792 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
793 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
794 if (!Cmp->isRelational())
796 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
797 if (BO->getOpcode() != Instruction::Sub)
802 if (!isPointerOperand(I->getOperand(0)) ||
803 !isPointerOperand(I->getOperand(1)))
808 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
809 // If a global variable does not have dynamic initialization we don't
810 // have to instrument it. However, if a global does not have initializer
811 // at all, we assume it has dynamic initializer (in other TU).
812 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
816 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
818 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
819 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
820 for (int i = 0; i < 2; i++) {
821 if (Param[i]->getType()->isPointerTy())
822 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
824 IRB.CreateCall2(F, Param[0], Param[1]);
827 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
828 bool IsWrite = false;
829 unsigned Alignment = 0;
830 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
832 if (ClOpt && ClOptGlobals) {
833 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
834 // If initialization order checking is disabled, a simple access to a
835 // dynamically initialized global is always valid.
836 if (!ClInitializers || GlobalIsLinkerInitialized(G)) {
837 NumOptimizedAccessesToGlobalVar++;
841 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
842 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
843 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
844 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
845 NumOptimizedAccessesToGlobalArray++;
852 Type *OrigPtrTy = Addr->getType();
853 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
855 assert(OrigTy->isSized());
856 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
858 assert((TypeSize % 8) == 0);
861 NumInstrumentedWrites++;
863 NumInstrumentedReads++;
865 unsigned Granularity = 1 << Mapping.Scale;
866 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
867 // if the data is properly aligned.
868 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
870 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
871 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
872 // Instrument unusual size or unusual alignment.
873 // We can not do it with a single check, so we do 1-byte check for the first
874 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
875 // to report the actual access size.
877 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
878 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
880 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
882 Value *LastByte = IRB.CreateIntToPtr(
883 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
885 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
886 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
890 // Validate the result of Module::getOrInsertFunction called for an interface
891 // function of AddressSanitizer. If the instrumented module defines a function
892 // with the same name, their prototypes must match, otherwise
893 // getOrInsertFunction returns a bitcast.
894 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
895 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
896 FuncOrBitcast->dump();
897 report_fatal_error("trying to redefine an AddressSanitizer "
898 "interface function");
901 Instruction *AddressSanitizer::generateCrashCode(
902 Instruction *InsertBefore, Value *Addr,
903 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
904 IRBuilder<> IRB(InsertBefore);
905 CallInst *Call = SizeArgument
906 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
907 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
909 // We don't do Call->setDoesNotReturn() because the BB already has
910 // UnreachableInst at the end.
911 // This EmptyAsm is required to avoid callback merge.
912 IRB.CreateCall(EmptyAsm);
916 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
919 size_t Granularity = 1 << Mapping.Scale;
920 // Addr & (Granularity - 1)
921 Value *LastAccessedByte = IRB.CreateAnd(
922 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
923 // (Addr & (Granularity - 1)) + size - 1
924 if (TypeSize / 8 > 1)
925 LastAccessedByte = IRB.CreateAdd(
926 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
927 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
928 LastAccessedByte = IRB.CreateIntCast(
929 LastAccessedByte, ShadowValue->getType(), false);
930 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
931 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
934 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
935 Instruction *InsertBefore, Value *Addr,
936 uint32_t TypeSize, bool IsWrite,
937 Value *SizeArgument, bool UseCalls) {
938 IRBuilder<> IRB(InsertBefore);
939 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
940 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
943 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
948 Type *ShadowTy = IntegerType::get(
949 *C, std::max(8U, TypeSize >> Mapping.Scale));
950 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
951 Value *ShadowPtr = memToShadow(AddrLong, IRB);
952 Value *CmpVal = Constant::getNullValue(ShadowTy);
953 Value *ShadowValue = IRB.CreateLoad(
954 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
956 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
957 size_t Granularity = 1 << Mapping.Scale;
958 TerminatorInst *CrashTerm = nullptr;
960 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
961 // We use branch weights for the slow path check, to indicate that the slow
962 // path is rarely taken. This seems to be the case for SPEC benchmarks.
963 TerminatorInst *CheckTerm =
964 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false,
965 MDBuilder(*C).createBranchWeights(1, 100000));
966 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
967 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
968 IRB.SetInsertPoint(CheckTerm);
969 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
970 BasicBlock *CrashBlock =
971 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
972 CrashTerm = new UnreachableInst(*C, CrashBlock);
973 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
974 ReplaceInstWithInst(CheckTerm, NewTerm);
976 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
979 Instruction *Crash = generateCrashCode(
980 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
981 Crash->setDebugLoc(OrigIns->getDebugLoc());
984 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
985 GlobalValue *ModuleName) {
986 // Set up the arguments to our poison/unpoison functions.
987 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
989 // Add a call to poison all external globals before the given function starts.
990 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
991 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
993 // Add calls to unpoison all globals before each return instruction.
994 for (auto &BB : GlobalInit.getBasicBlockList())
995 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
996 CallInst::Create(AsanUnpoisonGlobals, "", RI);
999 void AddressSanitizerModule::createInitializerPoisonCalls(
1000 Module &M, GlobalValue *ModuleName) {
1001 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1003 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1004 for (Use &OP : CA->operands()) {
1005 if (isa<ConstantAggregateZero>(OP))
1007 ConstantStruct *CS = cast<ConstantStruct>(OP);
1009 // Must have a function or null ptr.
1010 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
1011 if (F->getName() == kAsanModuleCtorName) continue;
1012 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1013 // Don't instrument CTORs that will run before asan.module_ctor.
1014 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1015 poisonOneInitializer(*F, ModuleName);
1020 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1021 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1022 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1024 if (GlobalsMD.get(G).IsBlacklisted) return false;
1025 if (!Ty->isSized()) return false;
1026 if (!G->hasInitializer()) return false;
1027 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1028 // Touch only those globals that will not be defined in other modules.
1029 // Don't handle ODR linkage types and COMDATs since other modules may be built
1031 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1032 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1033 G->getLinkage() != GlobalVariable::InternalLinkage)
1037 // Two problems with thread-locals:
1038 // - The address of the main thread's copy can't be computed at link-time.
1039 // - Need to poison all copies, not just the main thread's one.
1040 if (G->isThreadLocal())
1042 // For now, just ignore this Global if the alignment is large.
1043 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1045 if (G->hasSection()) {
1046 StringRef Section(G->getSection());
1048 if (TargetTriple.isOSBinFormatMachO()) {
1049 StringRef ParsedSegment, ParsedSection;
1050 unsigned TAA = 0, StubSize = 0;
1052 std::string ErrorCode =
1053 MCSectionMachO::ParseSectionSpecifier(Section, ParsedSegment,
1054 ParsedSection, TAA, TAAParsed,
1056 if (!ErrorCode.empty()) {
1057 report_fatal_error("Invalid section specifier '" + ParsedSection +
1058 "': " + ErrorCode + ".");
1061 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1062 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1064 if (ParsedSegment == "__OBJC" ||
1065 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1066 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1069 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1070 // Constant CFString instances are compiled in the following way:
1071 // -- the string buffer is emitted into
1072 // __TEXT,__cstring,cstring_literals
1073 // -- the constant NSConstantString structure referencing that buffer
1074 // is placed into __DATA,__cfstring
1075 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1076 // Moreover, it causes the linker to crash on OS X 10.7
1077 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1078 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1081 // The linker merges the contents of cstring_literals and removes the
1083 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1084 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1089 // Callbacks put into the CRT initializer/terminator sections
1090 // should not be instrumented.
1091 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1092 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1093 if (Section.startswith(".CRT")) {
1094 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1098 // Globals from llvm.metadata aren't emitted, do not instrument them.
1099 if (Section == "llvm.metadata") return false;
1105 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1106 IRBuilder<> IRB(*C);
1107 // Declare our poisoning and unpoisoning functions.
1108 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1109 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1110 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1111 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1112 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1113 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1114 // Declare functions that register/unregister globals.
1115 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1116 kAsanRegisterGlobalsName, IRB.getVoidTy(),
1117 IntptrTy, IntptrTy, nullptr));
1118 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1119 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1120 kAsanUnregisterGlobalsName,
1121 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1122 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1125 // This function replaces all global variables with new variables that have
1126 // trailing redzones. It also creates a function that poisons
1127 // redzones and inserts this function into llvm.global_ctors.
1128 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1131 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1133 for (auto &G : M.globals()) {
1134 if (ShouldInstrumentGlobal(&G))
1135 GlobalsToChange.push_back(&G);
1138 size_t n = GlobalsToChange.size();
1139 if (n == 0) return false;
1141 // A global is described by a structure
1144 // size_t size_with_redzone;
1145 // const char *name;
1146 // const char *module_name;
1147 // size_t has_dynamic_init;
1148 // void *source_location;
1149 // We initialize an array of such structures and pass it to a run-time call.
1150 StructType *GlobalStructTy =
1151 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1152 IntptrTy, IntptrTy, nullptr);
1153 SmallVector<Constant *, 16> Initializers(n);
1155 bool HasDynamicallyInitializedGlobals = false;
1157 // We shouldn't merge same module names, as this string serves as unique
1158 // module ID in runtime.
1159 GlobalVariable *ModuleName = createPrivateGlobalForString(
1160 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1162 for (size_t i = 0; i < n; i++) {
1163 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1164 GlobalVariable *G = GlobalsToChange[i];
1166 auto MD = GlobalsMD.get(G);
1167 // Create string holding the global name (use global name from metadata
1168 // if it's available, otherwise just write the name of global variable).
1169 GlobalVariable *Name = createPrivateGlobalForString(
1170 M, MD.Name.empty() ? G->getName() : MD.Name,
1171 /*AllowMerging*/ true);
1173 PointerType *PtrTy = cast<PointerType>(G->getType());
1174 Type *Ty = PtrTy->getElementType();
1175 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1176 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1177 // MinRZ <= RZ <= kMaxGlobalRedzone
1178 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1179 uint64_t RZ = std::max(MinRZ,
1180 std::min(kMaxGlobalRedzone,
1181 (SizeInBytes / MinRZ / 4) * MinRZ));
1182 uint64_t RightRedzoneSize = RZ;
1183 // Round up to MinRZ
1184 if (SizeInBytes % MinRZ)
1185 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1186 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1187 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1189 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1190 Constant *NewInitializer = ConstantStruct::get(
1191 NewTy, G->getInitializer(),
1192 Constant::getNullValue(RightRedZoneTy), nullptr);
1194 // Create a new global variable with enough space for a redzone.
1195 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1196 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1197 Linkage = GlobalValue::InternalLinkage;
1198 GlobalVariable *NewGlobal = new GlobalVariable(
1199 M, NewTy, G->isConstant(), Linkage,
1200 NewInitializer, "", G, G->getThreadLocalMode());
1201 NewGlobal->copyAttributesFrom(G);
1202 NewGlobal->setAlignment(MinRZ);
1205 Indices2[0] = IRB.getInt32(0);
1206 Indices2[1] = IRB.getInt32(0);
1208 G->replaceAllUsesWith(
1209 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1210 NewGlobal->takeName(G);
1211 G->eraseFromParent();
1213 Constant *SourceLoc;
1214 if (!MD.SourceLoc.empty()) {
1215 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1216 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1218 SourceLoc = ConstantInt::get(IntptrTy, 0);
1221 Initializers[i] = ConstantStruct::get(
1222 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1223 ConstantInt::get(IntptrTy, SizeInBytes),
1224 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1225 ConstantExpr::getPointerCast(Name, IntptrTy),
1226 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1227 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1229 if (ClInitializers && MD.IsDynInit)
1230 HasDynamicallyInitializedGlobals = true;
1232 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1235 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1236 GlobalVariable *AllGlobals = new GlobalVariable(
1237 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1238 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1240 // Create calls for poisoning before initializers run and unpoisoning after.
1241 if (HasDynamicallyInitializedGlobals)
1242 createInitializerPoisonCalls(M, ModuleName);
1243 IRB.CreateCall2(AsanRegisterGlobals,
1244 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1245 ConstantInt::get(IntptrTy, n));
1247 // We also need to unregister globals at the end, e.g. when a shared library
1249 Function *AsanDtorFunction = Function::Create(
1250 FunctionType::get(Type::getVoidTy(*C), false),
1251 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1252 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1253 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1254 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1255 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1256 ConstantInt::get(IntptrTy, n));
1257 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1263 bool AddressSanitizerModule::runOnModule(Module &M) {
1264 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1267 DL = &DLP->getDataLayout();
1268 C = &(M.getContext());
1269 int LongSize = DL->getPointerSizeInBits();
1270 IntptrTy = Type::getIntNTy(*C, LongSize);
1271 TargetTriple = Triple(M.getTargetTriple());
1272 Mapping = getShadowMapping(TargetTriple, LongSize);
1273 initializeCallbacks(M);
1275 bool Changed = false;
1277 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1279 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1282 Changed |= InstrumentGlobals(IRB, M);
1287 void AddressSanitizer::initializeCallbacks(Module &M) {
1288 IRBuilder<> IRB(*C);
1289 // Create __asan_report* callbacks.
1290 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1291 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1292 AccessSizeIndex++) {
1293 // IsWrite and TypeSize are encoded in the function name.
1294 std::string Suffix =
1295 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1296 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1297 checkInterfaceFunction(
1298 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1299 IRB.getVoidTy(), IntptrTy, nullptr));
1300 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1301 checkInterfaceFunction(
1302 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1303 IRB.getVoidTy(), IntptrTy, nullptr));
1306 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1307 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1308 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1309 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1311 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1312 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1313 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1314 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1315 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1316 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1318 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1319 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1320 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1321 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1322 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1323 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1324 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1325 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1326 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1328 AsanHandleNoReturnFunc = checkInterfaceFunction(
1329 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1331 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1332 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1333 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1334 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1335 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1336 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1337 StringRef(""), StringRef(""),
1338 /*hasSideEffects=*/true);
1342 bool AddressSanitizer::doInitialization(Module &M) {
1343 // Initialize the private fields. No one has accessed them before.
1344 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1346 report_fatal_error("data layout missing");
1347 DL = &DLP->getDataLayout();
1351 C = &(M.getContext());
1352 LongSize = DL->getPointerSizeInBits();
1353 IntptrTy = Type::getIntNTy(*C, LongSize);
1354 TargetTriple = Triple(M.getTargetTriple());
1356 AsanCtorFunction = Function::Create(
1357 FunctionType::get(Type::getVoidTy(*C), false),
1358 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1359 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1360 // call __asan_init in the module ctor.
1361 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1362 AsanInitFunction = checkInterfaceFunction(
1363 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr));
1364 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1365 IRB.CreateCall(AsanInitFunction);
1367 Mapping = getShadowMapping(TargetTriple, LongSize);
1369 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1373 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1374 // For each NSObject descendant having a +load method, this method is invoked
1375 // by the ObjC runtime before any of the static constructors is called.
1376 // Therefore we need to instrument such methods with a call to __asan_init
1377 // at the beginning in order to initialize our runtime before any access to
1378 // the shadow memory.
1379 // We cannot just ignore these methods, because they may call other
1380 // instrumented functions.
1381 if (F.getName().find(" load]") != std::string::npos) {
1382 IRBuilder<> IRB(F.begin()->begin());
1383 IRB.CreateCall(AsanInitFunction);
1389 bool AddressSanitizer::runOnFunction(Function &F) {
1390 if (&F == AsanCtorFunction) return false;
1391 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1392 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1393 initializeCallbacks(*F.getParent());
1395 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1397 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1398 maybeInsertAsanInitAtFunctionEntry(F);
1400 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1403 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1406 // We want to instrument every address only once per basic block (unless there
1407 // are calls between uses).
1408 SmallSet<Value*, 16> TempsToInstrument;
1409 SmallVector<Instruction*, 16> ToInstrument;
1410 SmallVector<Instruction*, 8> NoReturnCalls;
1411 SmallVector<BasicBlock*, 16> AllBlocks;
1412 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1417 // Fill the set of memory operations to instrument.
1418 for (auto &BB : F) {
1419 AllBlocks.push_back(&BB);
1420 TempsToInstrument.clear();
1421 int NumInsnsPerBB = 0;
1422 for (auto &Inst : BB) {
1423 if (LooksLikeCodeInBug11395(&Inst)) return false;
1425 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1426 if (ClOpt && ClOptSameTemp) {
1427 if (!TempsToInstrument.insert(Addr).second)
1428 continue; // We've seen this temp in the current BB.
1430 } else if (ClInvalidPointerPairs &&
1431 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1432 PointerComparisonsOrSubtracts.push_back(&Inst);
1434 } else if (isa<MemIntrinsic>(Inst)) {
1437 if (isa<AllocaInst>(Inst))
1441 // A call inside BB.
1442 TempsToInstrument.clear();
1443 if (CS.doesNotReturn())
1444 NoReturnCalls.push_back(CS.getInstruction());
1448 ToInstrument.push_back(&Inst);
1450 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1455 bool UseCalls = false;
1456 if (ClInstrumentationWithCallsThreshold >= 0 &&
1457 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1461 int NumInstrumented = 0;
1462 for (auto Inst : ToInstrument) {
1463 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1464 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1465 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1466 instrumentMop(Inst, UseCalls);
1468 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1473 FunctionStackPoisoner FSP(F, *this);
1474 bool ChangedStack = FSP.runOnFunction();
1476 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1477 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1478 for (auto CI : NoReturnCalls) {
1479 IRBuilder<> IRB(CI);
1480 IRB.CreateCall(AsanHandleNoReturnFunc);
1483 for (auto Inst : PointerComparisonsOrSubtracts) {
1484 instrumentPointerComparisonOrSubtraction(Inst);
1488 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1490 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1495 // Workaround for bug 11395: we don't want to instrument stack in functions
1496 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1497 // FIXME: remove once the bug 11395 is fixed.
1498 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1499 if (LongSize != 32) return false;
1500 CallInst *CI = dyn_cast<CallInst>(I);
1501 if (!CI || !CI->isInlineAsm()) return false;
1502 if (CI->getNumArgOperands() <= 5) return false;
1503 // We have inline assembly with quite a few arguments.
1507 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1508 IRBuilder<> IRB(*C);
1509 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1510 std::string Suffix = itostr(i);
1511 AsanStackMallocFunc[i] = checkInterfaceFunction(
1512 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1513 IntptrTy, IntptrTy, nullptr));
1514 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1515 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1516 IntptrTy, IntptrTy, nullptr));
1518 AsanPoisonStackMemoryFunc = checkInterfaceFunction(
1519 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1520 IntptrTy, IntptrTy, nullptr));
1521 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(
1522 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1523 IntptrTy, IntptrTy, nullptr));
1527 FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1528 IRBuilder<> &IRB, Value *ShadowBase,
1530 size_t n = ShadowBytes.size();
1532 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1533 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1534 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1535 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1536 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1537 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1539 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1540 if (ASan.DL->isLittleEndian())
1541 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1543 Val = (Val << 8) | ShadowBytes[i + j];
1546 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1547 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1548 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1549 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1554 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1555 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1556 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1557 assert(LocalStackSize <= kMaxStackMallocSize);
1558 uint64_t MaxSize = kMinStackMallocSize;
1559 for (int i = 0; ; i++, MaxSize *= 2)
1560 if (LocalStackSize <= MaxSize)
1562 llvm_unreachable("impossible LocalStackSize");
1565 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1566 // We can not use MemSet intrinsic because it may end up calling the actual
1567 // memset. Size is a multiple of 8.
1568 // Currently this generates 8-byte stores on x86_64; it may be better to
1569 // generate wider stores.
1570 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1571 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1572 assert(!(Size % 8));
1573 assert(kAsanStackAfterReturnMagic == 0xf5);
1574 for (int i = 0; i < Size; i += 8) {
1575 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1576 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1577 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1581 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1582 for (const auto &Inst : F.getEntryBlock())
1583 if (!isa<AllocaInst>(Inst))
1584 return Inst.getDebugLoc();
1588 void FunctionStackPoisoner::poisonStack() {
1589 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1591 if (ClInstrumentAllocas)
1592 // Handle dynamic allocas.
1593 for (auto &AllocaCall : DynamicAllocaVec)
1594 handleDynamicAllocaCall(AllocaCall);
1596 if (AllocaVec.size() == 0) return;
1598 int StackMallocIdx = -1;
1599 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1601 Instruction *InsBefore = AllocaVec[0];
1602 IRBuilder<> IRB(InsBefore);
1603 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1605 SmallVector<ASanStackVariableDescription, 16> SVD;
1606 SVD.reserve(AllocaVec.size());
1607 for (AllocaInst *AI : AllocaVec) {
1608 ASanStackVariableDescription D = { AI->getName().data(),
1609 getAllocaSizeInBytes(AI),
1610 AI->getAlignment(), AI, 0};
1613 // Minimal header size (left redzone) is 4 pointers,
1614 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1615 size_t MinHeaderSize = ASan.LongSize / 2;
1616 ASanStackFrameLayout L;
1617 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1618 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1619 uint64_t LocalStackSize = L.FrameSize;
1620 bool DoStackMalloc =
1621 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1623 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1624 AllocaInst *MyAlloca =
1625 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1626 MyAlloca->setDebugLoc(EntryDebugLocation);
1627 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1628 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1629 MyAlloca->setAlignment(FrameAlignment);
1630 assert(MyAlloca->isStaticAlloca());
1631 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1632 Value *LocalStackBase = OrigStackBase;
1634 if (DoStackMalloc) {
1635 // LocalStackBase = OrigStackBase
1636 // if (__asan_option_detect_stack_use_after_return)
1637 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1638 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1639 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1640 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1641 kAsanOptionDetectUAR, IRB.getInt32Ty());
1642 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1643 Constant::getNullValue(IRB.getInt32Ty()));
1644 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1645 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1646 IRBuilder<> IRBIf(Term);
1647 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1648 LocalStackBase = IRBIf.CreateCall2(
1649 AsanStackMallocFunc[StackMallocIdx],
1650 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1651 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1652 IRB.SetInsertPoint(InsBefore);
1653 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1654 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1655 Phi->addIncoming(OrigStackBase, CmpBlock);
1656 Phi->addIncoming(LocalStackBase, SetBlock);
1657 LocalStackBase = Phi;
1660 // Insert poison calls for lifetime intrinsics for alloca.
1661 bool HavePoisonedAllocas = false;
1662 for (const auto &APC : AllocaPoisonCallVec) {
1663 assert(APC.InsBefore);
1665 IRBuilder<> IRB(APC.InsBefore);
1666 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1667 HavePoisonedAllocas |= APC.DoPoison;
1670 // Replace Alloca instructions with base+offset.
1671 for (const auto &Desc : SVD) {
1672 AllocaInst *AI = Desc.AI;
1673 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1674 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1676 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1677 AI->replaceAllUsesWith(NewAllocaPtr);
1680 // The left-most redzone has enough space for at least 4 pointers.
1681 // Write the Magic value to redzone[0].
1682 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1683 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1685 // Write the frame description constant to redzone[1].
1686 Value *BasePlus1 = IRB.CreateIntToPtr(
1687 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1689 GlobalVariable *StackDescriptionGlobal =
1690 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1691 /*AllowMerging*/true);
1692 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1694 IRB.CreateStore(Description, BasePlus1);
1695 // Write the PC to redzone[2].
1696 Value *BasePlus2 = IRB.CreateIntToPtr(
1697 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1698 2 * ASan.LongSize/8)),
1700 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1702 // Poison the stack redzones at the entry.
1703 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1704 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1706 // (Un)poison the stack before all ret instructions.
1707 for (auto Ret : RetVec) {
1708 IRBuilder<> IRBRet(Ret);
1709 // Mark the current frame as retired.
1710 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1712 if (DoStackMalloc) {
1713 assert(StackMallocIdx >= 0);
1714 // if LocalStackBase != OrigStackBase:
1715 // // In use-after-return mode, poison the whole stack frame.
1716 // if StackMallocIdx <= 4
1717 // // For small sizes inline the whole thing:
1718 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1719 // **SavedFlagPtr(LocalStackBase) = 0
1721 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1723 // <This is not a fake stack; unpoison the redzones>
1724 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1725 TerminatorInst *ThenTerm, *ElseTerm;
1726 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1728 IRBuilder<> IRBPoison(ThenTerm);
1729 if (StackMallocIdx <= 4) {
1730 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1731 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1732 ClassSize >> Mapping.Scale);
1733 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1735 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1736 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1737 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1738 IRBPoison.CreateStore(
1739 Constant::getNullValue(IRBPoison.getInt8Ty()),
1740 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1742 // For larger frames call __asan_stack_free_*.
1743 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1744 ConstantInt::get(IntptrTy, LocalStackSize),
1748 IRBuilder<> IRBElse(ElseTerm);
1749 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1750 } else if (HavePoisonedAllocas) {
1751 // If we poisoned some allocas in llvm.lifetime analysis,
1752 // unpoison whole stack frame now.
1753 assert(LocalStackBase == OrigStackBase);
1754 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1756 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1760 if (ClInstrumentAllocas)
1761 // Unpoison dynamic allocas.
1762 for (auto &AllocaCall : DynamicAllocaVec)
1763 unpoisonDynamicAlloca(AllocaCall);
1765 // We are done. Remove the old unused alloca instructions.
1766 for (auto AI : AllocaVec)
1767 AI->eraseFromParent();
1770 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1771 IRBuilder<> &IRB, bool DoPoison) {
1772 // For now just insert the call to ASan runtime.
1773 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1774 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1775 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1776 : AsanUnpoisonStackMemoryFunc,
1780 // Handling llvm.lifetime intrinsics for a given %alloca:
1781 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1782 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1783 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1784 // could be poisoned by previous llvm.lifetime.end instruction, as the
1785 // variable may go in and out of scope several times, e.g. in loops).
1786 // (3) if we poisoned at least one %alloca in a function,
1787 // unpoison the whole stack frame at function exit.
1789 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1790 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1791 // We're intested only in allocas we can handle.
1792 return isInterestingAlloca(*AI) ? AI : nullptr;
1793 // See if we've already calculated (or started to calculate) alloca for a
1795 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1796 if (I != AllocaForValue.end())
1798 // Store 0 while we're calculating alloca for value V to avoid
1799 // infinite recursion if the value references itself.
1800 AllocaForValue[V] = nullptr;
1801 AllocaInst *Res = nullptr;
1802 if (CastInst *CI = dyn_cast<CastInst>(V))
1803 Res = findAllocaForValue(CI->getOperand(0));
1804 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1805 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1806 Value *IncValue = PN->getIncomingValue(i);
1807 // Allow self-referencing phi-nodes.
1808 if (IncValue == PN) continue;
1809 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1810 // AI for incoming values should exist and should all be equal.
1811 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1817 AllocaForValue[V] = Res;
1821 // Compute PartialRzMagic for dynamic alloca call. PartialRzMagic is
1822 // constructed from two separate 32-bit numbers: PartialRzMagic = Val1 | Val2.
1823 // (1) Val1 is resposible for forming base value for PartialRzMagic, containing
1824 // only 00 for fully addressable and 0xcb for fully poisoned bytes for each
1825 // 8-byte chunk of user memory respectively.
1826 // (2) Val2 forms the value for marking first poisoned byte in shadow memory
1827 // with appropriate value (0x01 - 0x07 or 0xcb if Padding % 8 == 0).
1829 // Shift = Padding & ~7; // the number of bits we need to shift to access first
1830 // chunk in shadow memory, containing nonzero bytes.
1832 // Padding = 21 Padding = 16
1833 // Shadow: |00|00|05|cb| Shadow: |00|00|cb|cb|
1836 // Shift = 21 & ~7 = 16 Shift = 16 & ~7 = 16
1838 // Val1 = 0xcbcbcbcb << Shift;
1839 // PartialBits = Padding ? Padding & 7 : 0xcb;
1840 // Val2 = PartialBits << Shift;
1841 // Result = Val1 | Val2;
1842 Value *FunctionStackPoisoner::computePartialRzMagic(Value *PartialSize,
1844 PartialSize = IRB.CreateIntCast(PartialSize, IRB.getInt32Ty(), false);
1845 Value *Shift = IRB.CreateAnd(PartialSize, IRB.getInt32(~7));
1846 unsigned Val1Int = kAsanAllocaPartialVal1;
1847 unsigned Val2Int = kAsanAllocaPartialVal2;
1848 if (!ASan.DL->isLittleEndian()) {
1849 Val1Int = sys::getSwappedBytes(Val1Int);
1850 Val2Int = sys::getSwappedBytes(Val2Int);
1852 Value *Val1 = shiftAllocaMagic(IRB.getInt32(Val1Int), IRB, Shift);
1853 Value *PartialBits = IRB.CreateAnd(PartialSize, IRB.getInt32(7));
1854 // For BigEndian get 0x000000YZ -> 0xYZ000000.
1855 if (ASan.DL->isBigEndian())
1856 PartialBits = IRB.CreateShl(PartialBits, IRB.getInt32(24));
1857 Value *Val2 = IRB.getInt32(Val2Int);
1859 IRB.CreateICmpNE(PartialBits, Constant::getNullValue(IRB.getInt32Ty()));
1860 Val2 = IRB.CreateSelect(Cond, shiftAllocaMagic(PartialBits, IRB, Shift),
1861 shiftAllocaMagic(Val2, IRB, Shift));
1862 return IRB.CreateOr(Val1, Val2);
1865 void FunctionStackPoisoner::handleDynamicAllocaCall(
1866 DynamicAllocaCall &AllocaCall) {
1867 AllocaInst *AI = AllocaCall.AI;
1868 if (!doesDominateAllExits(AI)) {
1869 // We do not yet handle complex allocas
1870 AllocaCall.Poison = false;
1874 IRBuilder<> IRB(AI);
1876 PointerType *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
1877 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
1878 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
1880 Value *Zero = Constant::getNullValue(IntptrTy);
1881 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
1882 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
1883 Value *NotAllocaRzMask = ConstantInt::get(IntptrTy, ~AllocaRedzoneMask);
1885 // Since we need to extend alloca with additional memory to locate
1886 // redzones, and OldSize is number of allocated blocks with
1887 // ElementSize size, get allocated memory size in bytes by
1888 // OldSize * ElementSize.
1889 unsigned ElementSize = ASan.DL->getTypeAllocSize(AI->getAllocatedType());
1890 Value *OldSize = IRB.CreateMul(AI->getArraySize(),
1891 ConstantInt::get(IntptrTy, ElementSize));
1893 // PartialSize = OldSize % 32
1894 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
1896 // Misalign = kAllocaRzSize - PartialSize;
1897 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
1899 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
1900 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
1901 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
1903 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
1904 // Align is added to locate left redzone, PartialPadding for possible
1905 // partial redzone and kAllocaRzSize for right redzone respectively.
1906 Value *AdditionalChunkSize = IRB.CreateAdd(
1907 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
1909 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
1911 // Insert new alloca with new NewSize and Align params.
1912 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
1913 NewAlloca->setAlignment(Align);
1915 // NewAddress = Address + Align
1916 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
1917 ConstantInt::get(IntptrTy, Align));
1919 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
1921 // LeftRzAddress = NewAddress - kAllocaRzSize
1922 Value *LeftRzAddress = IRB.CreateSub(NewAddress, AllocaRzSize);
1924 // Poisoning left redzone.
1925 AllocaCall.LeftRzAddr = ASan.memToShadow(LeftRzAddress, IRB);
1926 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaLeftMagic),
1927 IRB.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
1929 // PartialRzAligned = PartialRzAddr & ~AllocaRzMask
1930 Value *PartialRzAddr = IRB.CreateAdd(NewAddress, OldSize);
1931 Value *PartialRzAligned = IRB.CreateAnd(PartialRzAddr, NotAllocaRzMask);
1933 // Poisoning partial redzone.
1934 Value *PartialRzMagic = computePartialRzMagic(PartialSize, IRB);
1935 Value *PartialRzShadowAddr = ASan.memToShadow(PartialRzAligned, IRB);
1936 IRB.CreateStore(PartialRzMagic,
1937 IRB.CreateIntToPtr(PartialRzShadowAddr, Int32PtrTy));
1940 // = (PartialRzAddr + AllocaRzMask) & ~AllocaRzMask
1941 Value *RightRzAddress = IRB.CreateAnd(
1942 IRB.CreateAdd(PartialRzAddr, AllocaRzMask), NotAllocaRzMask);
1944 // Poisoning right redzone.
1945 AllocaCall.RightRzAddr = ASan.memToShadow(RightRzAddress, IRB);
1946 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaRightMagic),
1947 IRB.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
1949 // Replace all uses of AddessReturnedByAlloca with NewAddress.
1950 AI->replaceAllUsesWith(NewAddressPtr);
1952 // We are done. Erase old alloca and store left, partial and right redzones
1953 // shadow addresses for future unpoisoning.
1954 AI->eraseFromParent();
1955 NumInstrumentedDynamicAllocas++;