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();
224 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
226 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
230 /// Frontend-provided metadata for global variables.
231 class GlobalsMetadata {
235 : SourceLoc(), Name(), IsDynInit(false),
236 IsBlacklisted(false) {}
237 LocationMetadata SourceLoc;
243 GlobalsMetadata() : inited_(false) {}
245 void init(Module& M) {
248 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
251 for (auto MDN : Globals->operands()) {
252 // Metadata node contains the global and the fields of "Entry".
253 assert(MDN->getNumOperands() == 5);
254 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
255 // The optimizer may optimize away a global entirely.
258 // We can already have an entry for GV if it was merged with another
260 Entry &E = Entries[GV];
261 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
262 E.SourceLoc.parse(Loc);
263 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
264 E.Name = Name->getString();
265 ConstantInt *IsDynInit =
266 mdconst::extract<ConstantInt>(MDN->getOperand(3));
267 E.IsDynInit |= IsDynInit->isOne();
268 ConstantInt *IsBlacklisted =
269 mdconst::extract<ConstantInt>(MDN->getOperand(4));
270 E.IsBlacklisted |= IsBlacklisted->isOne();
274 /// Returns metadata entry for a given global.
275 Entry get(GlobalVariable *G) const {
276 auto Pos = Entries.find(G);
277 return (Pos != Entries.end()) ? Pos->second : Entry();
282 DenseMap<GlobalVariable*, Entry> Entries;
285 /// This struct defines the shadow mapping using the rule:
286 /// shadow = (mem >> Scale) ADD-or-OR Offset.
287 struct ShadowMapping {
293 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize) {
294 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
295 bool IsIOS = TargetTriple.isiOS();
296 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
297 bool IsLinux = TargetTriple.isOSLinux();
298 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
299 TargetTriple.getArch() == llvm::Triple::ppc64le;
300 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
301 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
302 TargetTriple.getArch() == llvm::Triple::mipsel;
303 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
304 TargetTriple.getArch() == llvm::Triple::mips64el;
306 ShadowMapping Mapping;
308 if (LongSize == 32) {
312 Mapping.Offset = kMIPS32_ShadowOffset32;
314 Mapping.Offset = kFreeBSD_ShadowOffset32;
316 Mapping.Offset = kIOSShadowOffset32;
318 Mapping.Offset = kDefaultShadowOffset32;
319 } else { // LongSize == 64
321 Mapping.Offset = kPPC64_ShadowOffset64;
323 Mapping.Offset = kFreeBSD_ShadowOffset64;
324 else if (IsLinux && IsX86_64)
325 Mapping.Offset = kSmallX86_64ShadowOffset;
327 Mapping.Offset = kMIPS64_ShadowOffset64;
329 Mapping.Offset = kDefaultShadowOffset64;
332 Mapping.Scale = kDefaultShadowScale;
333 if (ClMappingScale) {
334 Mapping.Scale = ClMappingScale;
337 // OR-ing shadow offset if more efficient (at least on x86) if the offset
338 // is a power of two, but on ppc64 we have to use add since the shadow
339 // offset is not necessary 1/8-th of the address space.
340 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
345 static size_t RedzoneSizeForScale(int MappingScale) {
346 // Redzone used for stack and globals is at least 32 bytes.
347 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
348 return std::max(32U, 1U << MappingScale);
351 /// AddressSanitizer: instrument the code in module to find memory bugs.
352 struct AddressSanitizer : public FunctionPass {
353 AddressSanitizer() : FunctionPass(ID) {
354 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
356 const char *getPassName() const override {
357 return "AddressSanitizerFunctionPass";
359 void getAnalysisUsage(AnalysisUsage &AU) const override {
360 AU.addRequired<DominatorTreeWrapperPass>();
362 void instrumentMop(Instruction *I, bool UseCalls);
363 void instrumentPointerComparisonOrSubtraction(Instruction *I);
364 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
365 Value *Addr, uint32_t TypeSize, bool IsWrite,
366 Value *SizeArgument, bool UseCalls);
367 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
368 Value *ShadowValue, uint32_t TypeSize);
369 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
370 bool IsWrite, size_t AccessSizeIndex,
371 Value *SizeArgument);
372 void instrumentMemIntrinsic(MemIntrinsic *MI);
373 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
374 bool runOnFunction(Function &F) override;
375 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
376 bool doInitialization(Module &M) override;
377 static char ID; // Pass identification, replacement for typeid
379 DominatorTree &getDominatorTree() const { return *DT; }
382 void initializeCallbacks(Module &M);
384 bool LooksLikeCodeInBug11395(Instruction *I);
385 bool GlobalIsLinkerInitialized(GlobalVariable *G);
388 const DataLayout *DL;
392 ShadowMapping Mapping;
394 Function *AsanCtorFunction;
395 Function *AsanInitFunction;
396 Function *AsanHandleNoReturnFunc;
397 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
398 // This array is indexed by AccessIsWrite and log2(AccessSize).
399 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
400 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
401 // This array is indexed by AccessIsWrite.
402 Function *AsanErrorCallbackSized[2],
403 *AsanMemoryAccessCallbackSized[2];
404 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
406 GlobalsMetadata GlobalsMD;
408 friend struct FunctionStackPoisoner;
411 class AddressSanitizerModule : public ModulePass {
413 AddressSanitizerModule() : ModulePass(ID) {}
414 bool runOnModule(Module &M) override;
415 static char ID; // Pass identification, replacement for typeid
416 const char *getPassName() const override {
417 return "AddressSanitizerModule";
421 void initializeCallbacks(Module &M);
423 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
424 bool ShouldInstrumentGlobal(GlobalVariable *G);
425 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
426 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
427 size_t MinRedzoneSizeForGlobal() const {
428 return RedzoneSizeForScale(Mapping.Scale);
431 GlobalsMetadata GlobalsMD;
434 const DataLayout *DL;
436 ShadowMapping Mapping;
437 Function *AsanPoisonGlobals;
438 Function *AsanUnpoisonGlobals;
439 Function *AsanRegisterGlobals;
440 Function *AsanUnregisterGlobals;
443 // Stack poisoning does not play well with exception handling.
444 // When an exception is thrown, we essentially bypass the code
445 // that unpoisones the stack. This is why the run-time library has
446 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
447 // stack in the interceptor. This however does not work inside the
448 // actual function which catches the exception. Most likely because the
449 // compiler hoists the load of the shadow value somewhere too high.
450 // This causes asan to report a non-existing bug on 453.povray.
451 // It sounds like an LLVM bug.
452 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
454 AddressSanitizer &ASan;
459 ShadowMapping Mapping;
461 SmallVector<AllocaInst*, 16> AllocaVec;
462 SmallVector<Instruction*, 8> RetVec;
463 unsigned StackAlignment;
465 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
466 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
467 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
469 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
470 struct AllocaPoisonCall {
471 IntrinsicInst *InsBefore;
476 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
478 // Stores left and right redzone shadow addresses for dynamic alloca
479 // and pointer to alloca instruction itself.
480 // LeftRzAddr is a shadow address for alloca left redzone.
481 // RightRzAddr is a shadow address for alloca right redzone.
482 struct DynamicAllocaCall {
487 explicit DynamicAllocaCall(AllocaInst *AI,
488 Value *LeftRzAddr = nullptr,
489 Value *RightRzAddr = nullptr)
490 : AI(AI), LeftRzAddr(LeftRzAddr), RightRzAddr(RightRzAddr), Poison(true)
493 SmallVector<DynamicAllocaCall, 1> DynamicAllocaVec;
495 // Maps Value to an AllocaInst from which the Value is originated.
496 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
497 AllocaForValueMapTy AllocaForValue;
499 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
500 : F(F), ASan(ASan), DIB(*F.getParent(), /*AllowUnresolved*/ false),
501 C(ASan.C), IntptrTy(ASan.IntptrTy),
502 IntptrPtrTy(PointerType::get(IntptrTy, 0)), Mapping(ASan.Mapping),
503 StackAlignment(1 << Mapping.Scale) {}
505 bool runOnFunction() {
506 if (!ClStack) return false;
507 // Collect alloca, ret, lifetime instructions etc.
508 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
511 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
513 initializeCallbacks(*F.getParent());
523 // Finds all Alloca instructions and puts
524 // poisoned red zones around all of them.
525 // Then unpoison everything back before the function returns.
528 // ----------------------- Visitors.
529 /// \brief Collect all Ret instructions.
530 void visitReturnInst(ReturnInst &RI) {
531 RetVec.push_back(&RI);
534 // Unpoison dynamic allocas redzones.
535 void unpoisonDynamicAlloca(DynamicAllocaCall &AllocaCall) {
536 if (!AllocaCall.Poison)
538 for (auto Ret : RetVec) {
539 IRBuilder<> IRBRet(Ret);
540 PointerType *Int32PtrTy = PointerType::getUnqual(IRBRet.getInt32Ty());
541 Value *Zero = Constant::getNullValue(IRBRet.getInt32Ty());
542 Value *PartialRzAddr = IRBRet.CreateSub(AllocaCall.RightRzAddr,
543 ConstantInt::get(IntptrTy, 4));
544 IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(AllocaCall.LeftRzAddr,
546 IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(PartialRzAddr,
548 IRBRet.CreateStore(Zero, IRBRet.CreateIntToPtr(AllocaCall.RightRzAddr,
553 // Right shift for BigEndian and left shift for LittleEndian.
554 Value *shiftAllocaMagic(Value *Val, IRBuilder<> &IRB, Value *Shift) {
555 return ASan.DL->isLittleEndian() ? IRB.CreateShl(Val, Shift)
556 : IRB.CreateLShr(Val, Shift);
559 // Compute PartialRzMagic for dynamic alloca call. Since we don't know the
560 // size of requested memory until runtime, we should compute it dynamically.
561 // If PartialSize is 0, PartialRzMagic would contain kAsanAllocaRightMagic,
562 // otherwise it would contain the value that we will use to poison the
563 // partial redzone for alloca call.
564 Value *computePartialRzMagic(Value *PartialSize, IRBuilder<> &IRB);
566 // Deploy and poison redzones around dynamic alloca call. To do this, we
567 // should replace this call with another one with changed parameters and
568 // replace all its uses with new address, so
569 // addr = alloca type, old_size, align
571 // new_size = (old_size + additional_size) * sizeof(type)
572 // tmp = alloca i8, new_size, max(align, 32)
573 // addr = tmp + 32 (first 32 bytes are for the left redzone).
574 // Additional_size is added to make new memory allocation contain not only
575 // requested memory, but also left, partial and right redzones.
576 // After that, we should poison redzones:
577 // (1) Left redzone with kAsanAllocaLeftMagic.
578 // (2) Partial redzone with the value, computed in runtime by
579 // computePartialRzMagic function.
580 // (3) Right redzone with kAsanAllocaRightMagic.
581 void handleDynamicAllocaCall(DynamicAllocaCall &AllocaCall);
583 /// \brief Collect Alloca instructions we want (and can) handle.
584 void visitAllocaInst(AllocaInst &AI) {
585 if (!isInterestingAlloca(AI)) return;
587 StackAlignment = std::max(StackAlignment, AI.getAlignment());
588 if (isDynamicAlloca(AI))
589 DynamicAllocaVec.push_back(DynamicAllocaCall(&AI));
591 AllocaVec.push_back(&AI);
594 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
596 void visitIntrinsicInst(IntrinsicInst &II) {
597 if (!ClCheckLifetime) return;
598 Intrinsic::ID ID = II.getIntrinsicID();
599 if (ID != Intrinsic::lifetime_start &&
600 ID != Intrinsic::lifetime_end)
602 // Found lifetime intrinsic, add ASan instrumentation if necessary.
603 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
604 // If size argument is undefined, don't do anything.
605 if (Size->isMinusOne()) return;
606 // Check that size doesn't saturate uint64_t and can
607 // be stored in IntptrTy.
608 const uint64_t SizeValue = Size->getValue().getLimitedValue();
609 if (SizeValue == ~0ULL ||
610 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
612 // Find alloca instruction that corresponds to llvm.lifetime argument.
613 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
615 bool DoPoison = (ID == Intrinsic::lifetime_end);
616 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
617 AllocaPoisonCallVec.push_back(APC);
620 // ---------------------- Helpers.
621 void initializeCallbacks(Module &M);
623 bool doesDominateAllExits(const Instruction *I) const {
624 for (auto Ret : RetVec) {
625 if (!ASan.getDominatorTree().dominates(I, Ret))
631 bool isDynamicAlloca(AllocaInst &AI) const {
632 return AI.isArrayAllocation() || !AI.isStaticAlloca();
635 // Check if we want (and can) handle this alloca.
636 bool isInterestingAlloca(AllocaInst &AI) const {
637 return (AI.getAllocatedType()->isSized() &&
638 // alloca() may be called with 0 size, ignore it.
639 getAllocaSizeInBytes(&AI) > 0);
642 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
643 Type *Ty = AI->getAllocatedType();
644 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
647 /// Finds alloca where the value comes from.
648 AllocaInst *findAllocaForValue(Value *V);
649 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
650 Value *ShadowBase, bool DoPoison);
651 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
653 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
659 char AddressSanitizer::ID = 0;
660 INITIALIZE_PASS_BEGIN(AddressSanitizer, "asan",
661 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
663 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
664 INITIALIZE_PASS_END(AddressSanitizer, "asan",
665 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
667 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
668 return new AddressSanitizer();
671 char AddressSanitizerModule::ID = 0;
672 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
673 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
674 "ModulePass", false, false)
675 ModulePass *llvm::createAddressSanitizerModulePass() {
676 return new AddressSanitizerModule();
679 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
680 size_t Res = countTrailingZeros(TypeSize / 8);
681 assert(Res < kNumberOfAccessSizes);
685 // \brief Create a constant for Str so that we can pass it to the run-time lib.
686 static GlobalVariable *createPrivateGlobalForString(
687 Module &M, StringRef Str, bool AllowMerging) {
688 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
689 // We use private linkage for module-local strings. If they can be merged
690 // with another one, we set the unnamed_addr attribute.
692 new GlobalVariable(M, StrConst->getType(), true,
693 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
695 GV->setUnnamedAddr(true);
696 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
700 /// \brief Create a global describing a source location.
701 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
702 LocationMetadata MD) {
703 Constant *LocData[] = {
704 createPrivateGlobalForString(M, MD.Filename, true),
705 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
706 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
708 auto LocStruct = ConstantStruct::getAnon(LocData);
709 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
710 GlobalValue::PrivateLinkage, LocStruct,
712 GV->setUnnamedAddr(true);
716 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
717 return G->getName().find(kAsanGenPrefix) == 0 ||
718 G->getName().find(kSanCovGenPrefix) == 0;
721 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
723 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
724 if (Mapping.Offset == 0)
726 // (Shadow >> scale) | offset
727 if (Mapping.OrShadowOffset)
728 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
730 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
733 // Instrument memset/memmove/memcpy
734 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
736 if (isa<MemTransferInst>(MI)) {
738 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
739 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
740 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
741 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
742 } else if (isa<MemSetInst>(MI)) {
745 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
746 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
747 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
749 MI->eraseFromParent();
752 // If I is an interesting memory access, return the PointerOperand
753 // and set IsWrite/Alignment. Otherwise return nullptr.
754 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
755 unsigned *Alignment) {
756 // Skip memory accesses inserted by another instrumentation.
757 if (I->getMetadata("nosanitize"))
759 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
760 if (!ClInstrumentReads) return nullptr;
762 *Alignment = LI->getAlignment();
763 return LI->getPointerOperand();
765 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
766 if (!ClInstrumentWrites) return nullptr;
768 *Alignment = SI->getAlignment();
769 return SI->getPointerOperand();
771 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
772 if (!ClInstrumentAtomics) return nullptr;
775 return RMW->getPointerOperand();
777 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
778 if (!ClInstrumentAtomics) return nullptr;
781 return XCHG->getPointerOperand();
786 static bool isPointerOperand(Value *V) {
787 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
790 // This is a rough heuristic; it may cause both false positives and
791 // false negatives. The proper implementation requires cooperation with
793 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
794 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
795 if (!Cmp->isRelational())
797 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
798 if (BO->getOpcode() != Instruction::Sub)
803 if (!isPointerOperand(I->getOperand(0)) ||
804 !isPointerOperand(I->getOperand(1)))
809 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
810 // If a global variable does not have dynamic initialization we don't
811 // have to instrument it. However, if a global does not have initializer
812 // at all, we assume it has dynamic initializer (in other TU).
813 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
817 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
819 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
820 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
821 for (int i = 0; i < 2; i++) {
822 if (Param[i]->getType()->isPointerTy())
823 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
825 IRB.CreateCall2(F, Param[0], Param[1]);
828 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
829 bool IsWrite = false;
830 unsigned Alignment = 0;
831 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
833 if (ClOpt && ClOptGlobals) {
834 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
835 // If initialization order checking is disabled, a simple access to a
836 // dynamically initialized global is always valid.
837 if (!ClInitializers || GlobalIsLinkerInitialized(G)) {
838 NumOptimizedAccessesToGlobalVar++;
842 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
843 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
844 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
845 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
846 NumOptimizedAccessesToGlobalArray++;
853 Type *OrigPtrTy = Addr->getType();
854 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
856 assert(OrigTy->isSized());
857 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
859 assert((TypeSize % 8) == 0);
862 NumInstrumentedWrites++;
864 NumInstrumentedReads++;
866 unsigned Granularity = 1 << Mapping.Scale;
867 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
868 // if the data is properly aligned.
869 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
871 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
872 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
873 // Instrument unusual size or unusual alignment.
874 // We can not do it with a single check, so we do 1-byte check for the first
875 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
876 // to report the actual access size.
878 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
879 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
881 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
883 Value *LastByte = IRB.CreateIntToPtr(
884 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
886 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
887 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
891 // Validate the result of Module::getOrInsertFunction called for an interface
892 // function of AddressSanitizer. If the instrumented module defines a function
893 // with the same name, their prototypes must match, otherwise
894 // getOrInsertFunction returns a bitcast.
895 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
896 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
897 FuncOrBitcast->dump();
898 report_fatal_error("trying to redefine an AddressSanitizer "
899 "interface function");
902 Instruction *AddressSanitizer::generateCrashCode(
903 Instruction *InsertBefore, Value *Addr,
904 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
905 IRBuilder<> IRB(InsertBefore);
906 CallInst *Call = SizeArgument
907 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
908 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
910 // We don't do Call->setDoesNotReturn() because the BB already has
911 // UnreachableInst at the end.
912 // This EmptyAsm is required to avoid callback merge.
913 IRB.CreateCall(EmptyAsm);
917 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
920 size_t Granularity = 1 << Mapping.Scale;
921 // Addr & (Granularity - 1)
922 Value *LastAccessedByte = IRB.CreateAnd(
923 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
924 // (Addr & (Granularity - 1)) + size - 1
925 if (TypeSize / 8 > 1)
926 LastAccessedByte = IRB.CreateAdd(
927 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
928 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
929 LastAccessedByte = IRB.CreateIntCast(
930 LastAccessedByte, ShadowValue->getType(), false);
931 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
932 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
935 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
936 Instruction *InsertBefore, Value *Addr,
937 uint32_t TypeSize, bool IsWrite,
938 Value *SizeArgument, bool UseCalls) {
939 IRBuilder<> IRB(InsertBefore);
940 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
941 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
944 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
949 Type *ShadowTy = IntegerType::get(
950 *C, std::max(8U, TypeSize >> Mapping.Scale));
951 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
952 Value *ShadowPtr = memToShadow(AddrLong, IRB);
953 Value *CmpVal = Constant::getNullValue(ShadowTy);
954 Value *ShadowValue = IRB.CreateLoad(
955 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
957 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
958 size_t Granularity = 1 << Mapping.Scale;
959 TerminatorInst *CrashTerm = nullptr;
961 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
962 // We use branch weights for the slow path check, to indicate that the slow
963 // path is rarely taken. This seems to be the case for SPEC benchmarks.
964 TerminatorInst *CheckTerm =
965 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false,
966 MDBuilder(*C).createBranchWeights(1, 100000));
967 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
968 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
969 IRB.SetInsertPoint(CheckTerm);
970 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
971 BasicBlock *CrashBlock =
972 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
973 CrashTerm = new UnreachableInst(*C, CrashBlock);
974 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
975 ReplaceInstWithInst(CheckTerm, NewTerm);
977 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
980 Instruction *Crash = generateCrashCode(
981 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
982 Crash->setDebugLoc(OrigIns->getDebugLoc());
985 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
986 GlobalValue *ModuleName) {
987 // Set up the arguments to our poison/unpoison functions.
988 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
990 // Add a call to poison all external globals before the given function starts.
991 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
992 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
994 // Add calls to unpoison all globals before each return instruction.
995 for (auto &BB : GlobalInit.getBasicBlockList())
996 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
997 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1000 void AddressSanitizerModule::createInitializerPoisonCalls(
1001 Module &M, GlobalValue *ModuleName) {
1002 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1004 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1005 for (Use &OP : CA->operands()) {
1006 if (isa<ConstantAggregateZero>(OP))
1008 ConstantStruct *CS = cast<ConstantStruct>(OP);
1010 // Must have a function or null ptr.
1011 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
1012 if (F->getName() == kAsanModuleCtorName) continue;
1013 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1014 // Don't instrument CTORs that will run before asan.module_ctor.
1015 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1016 poisonOneInitializer(*F, ModuleName);
1021 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1022 Type *Ty = cast<PointerType>(G->getType())->getElementType();
1023 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1025 if (GlobalsMD.get(G).IsBlacklisted) return false;
1026 if (!Ty->isSized()) return false;
1027 if (!G->hasInitializer()) return false;
1028 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
1029 // Touch only those globals that will not be defined in other modules.
1030 // Don't handle ODR linkage types and COMDATs since other modules may be built
1032 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1033 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1034 G->getLinkage() != GlobalVariable::InternalLinkage)
1038 // Two problems with thread-locals:
1039 // - The address of the main thread's copy can't be computed at link-time.
1040 // - Need to poison all copies, not just the main thread's one.
1041 if (G->isThreadLocal())
1043 // For now, just ignore this Global if the alignment is large.
1044 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1046 if (G->hasSection()) {
1047 StringRef Section(G->getSection());
1049 if (TargetTriple.isOSBinFormatMachO()) {
1050 StringRef ParsedSegment, ParsedSection;
1051 unsigned TAA = 0, StubSize = 0;
1053 std::string ErrorCode =
1054 MCSectionMachO::ParseSectionSpecifier(Section, ParsedSegment,
1055 ParsedSection, TAA, TAAParsed,
1057 if (!ErrorCode.empty()) {
1058 report_fatal_error("Invalid section specifier '" + ParsedSection +
1059 "': " + ErrorCode + ".");
1062 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1063 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1065 if (ParsedSegment == "__OBJC" ||
1066 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1067 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1070 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1071 // Constant CFString instances are compiled in the following way:
1072 // -- the string buffer is emitted into
1073 // __TEXT,__cstring,cstring_literals
1074 // -- the constant NSConstantString structure referencing that buffer
1075 // is placed into __DATA,__cfstring
1076 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1077 // Moreover, it causes the linker to crash on OS X 10.7
1078 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1079 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1082 // The linker merges the contents of cstring_literals and removes the
1084 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1085 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1090 // Callbacks put into the CRT initializer/terminator sections
1091 // should not be instrumented.
1092 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1093 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1094 if (Section.startswith(".CRT")) {
1095 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1099 // Globals from llvm.metadata aren't emitted, do not instrument them.
1100 if (Section == "llvm.metadata") return false;
1106 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1107 IRBuilder<> IRB(*C);
1108 // Declare our poisoning and unpoisoning functions.
1109 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1110 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1111 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1112 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1113 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1114 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1115 // Declare functions that register/unregister globals.
1116 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1117 kAsanRegisterGlobalsName, IRB.getVoidTy(),
1118 IntptrTy, IntptrTy, nullptr));
1119 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1120 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1121 kAsanUnregisterGlobalsName,
1122 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1123 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1126 // This function replaces all global variables with new variables that have
1127 // trailing redzones. It also creates a function that poisons
1128 // redzones and inserts this function into llvm.global_ctors.
1129 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1132 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1134 for (auto &G : M.globals()) {
1135 if (ShouldInstrumentGlobal(&G))
1136 GlobalsToChange.push_back(&G);
1139 size_t n = GlobalsToChange.size();
1140 if (n == 0) return false;
1142 // A global is described by a structure
1145 // size_t size_with_redzone;
1146 // const char *name;
1147 // const char *module_name;
1148 // size_t has_dynamic_init;
1149 // void *source_location;
1150 // We initialize an array of such structures and pass it to a run-time call.
1151 StructType *GlobalStructTy =
1152 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1153 IntptrTy, IntptrTy, nullptr);
1154 SmallVector<Constant *, 16> Initializers(n);
1156 bool HasDynamicallyInitializedGlobals = false;
1158 // We shouldn't merge same module names, as this string serves as unique
1159 // module ID in runtime.
1160 GlobalVariable *ModuleName = createPrivateGlobalForString(
1161 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1163 for (size_t i = 0; i < n; i++) {
1164 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1165 GlobalVariable *G = GlobalsToChange[i];
1167 auto MD = GlobalsMD.get(G);
1168 // Create string holding the global name (use global name from metadata
1169 // if it's available, otherwise just write the name of global variable).
1170 GlobalVariable *Name = createPrivateGlobalForString(
1171 M, MD.Name.empty() ? G->getName() : MD.Name,
1172 /*AllowMerging*/ true);
1174 PointerType *PtrTy = cast<PointerType>(G->getType());
1175 Type *Ty = PtrTy->getElementType();
1176 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1177 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1178 // MinRZ <= RZ <= kMaxGlobalRedzone
1179 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1180 uint64_t RZ = std::max(MinRZ,
1181 std::min(kMaxGlobalRedzone,
1182 (SizeInBytes / MinRZ / 4) * MinRZ));
1183 uint64_t RightRedzoneSize = RZ;
1184 // Round up to MinRZ
1185 if (SizeInBytes % MinRZ)
1186 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1187 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1188 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1190 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1191 Constant *NewInitializer = ConstantStruct::get(
1192 NewTy, G->getInitializer(),
1193 Constant::getNullValue(RightRedZoneTy), nullptr);
1195 // Create a new global variable with enough space for a redzone.
1196 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1197 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1198 Linkage = GlobalValue::InternalLinkage;
1199 GlobalVariable *NewGlobal = new GlobalVariable(
1200 M, NewTy, G->isConstant(), Linkage,
1201 NewInitializer, "", G, G->getThreadLocalMode());
1202 NewGlobal->copyAttributesFrom(G);
1203 NewGlobal->setAlignment(MinRZ);
1206 Indices2[0] = IRB.getInt32(0);
1207 Indices2[1] = IRB.getInt32(0);
1209 G->replaceAllUsesWith(
1210 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1211 NewGlobal->takeName(G);
1212 G->eraseFromParent();
1214 Constant *SourceLoc;
1215 if (!MD.SourceLoc.empty()) {
1216 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1217 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1219 SourceLoc = ConstantInt::get(IntptrTy, 0);
1222 Initializers[i] = ConstantStruct::get(
1223 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1224 ConstantInt::get(IntptrTy, SizeInBytes),
1225 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1226 ConstantExpr::getPointerCast(Name, IntptrTy),
1227 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1228 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, nullptr);
1230 if (ClInitializers && MD.IsDynInit)
1231 HasDynamicallyInitializedGlobals = true;
1233 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1236 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1237 GlobalVariable *AllGlobals = new GlobalVariable(
1238 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1239 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1241 // Create calls for poisoning before initializers run and unpoisoning after.
1242 if (HasDynamicallyInitializedGlobals)
1243 createInitializerPoisonCalls(M, ModuleName);
1244 IRB.CreateCall2(AsanRegisterGlobals,
1245 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1246 ConstantInt::get(IntptrTy, n));
1248 // We also need to unregister globals at the end, e.g. when a shared library
1250 Function *AsanDtorFunction = Function::Create(
1251 FunctionType::get(Type::getVoidTy(*C), false),
1252 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1253 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1254 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1255 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1256 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1257 ConstantInt::get(IntptrTy, n));
1258 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1264 bool AddressSanitizerModule::runOnModule(Module &M) {
1265 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1268 DL = &DLP->getDataLayout();
1269 C = &(M.getContext());
1270 int LongSize = DL->getPointerSizeInBits();
1271 IntptrTy = Type::getIntNTy(*C, LongSize);
1272 TargetTriple = Triple(M.getTargetTriple());
1273 Mapping = getShadowMapping(TargetTriple, LongSize);
1274 initializeCallbacks(M);
1276 bool Changed = false;
1278 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1280 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1283 Changed |= InstrumentGlobals(IRB, M);
1288 void AddressSanitizer::initializeCallbacks(Module &M) {
1289 IRBuilder<> IRB(*C);
1290 // Create __asan_report* callbacks.
1291 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1292 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1293 AccessSizeIndex++) {
1294 // IsWrite and TypeSize are encoded in the function name.
1295 std::string Suffix =
1296 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1297 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1298 checkInterfaceFunction(
1299 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1300 IRB.getVoidTy(), IntptrTy, nullptr));
1301 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1302 checkInterfaceFunction(
1303 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1304 IRB.getVoidTy(), IntptrTy, nullptr));
1307 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1308 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1309 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1310 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1312 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1313 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1314 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1315 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1316 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1317 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1319 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1320 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1321 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1322 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1323 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1324 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1325 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1326 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1327 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1329 AsanHandleNoReturnFunc = checkInterfaceFunction(
1330 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1332 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1333 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1334 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1335 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1336 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1337 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1338 StringRef(""), StringRef(""),
1339 /*hasSideEffects=*/true);
1343 bool AddressSanitizer::doInitialization(Module &M) {
1344 // Initialize the private fields. No one has accessed them before.
1345 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1347 report_fatal_error("data layout missing");
1348 DL = &DLP->getDataLayout();
1352 C = &(M.getContext());
1353 LongSize = DL->getPointerSizeInBits();
1354 IntptrTy = Type::getIntNTy(*C, LongSize);
1355 TargetTriple = Triple(M.getTargetTriple());
1357 AsanCtorFunction = Function::Create(
1358 FunctionType::get(Type::getVoidTy(*C), false),
1359 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1360 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1361 // call __asan_init in the module ctor.
1362 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1363 AsanInitFunction = checkInterfaceFunction(
1364 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), nullptr));
1365 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1366 IRB.CreateCall(AsanInitFunction);
1368 Mapping = getShadowMapping(TargetTriple, LongSize);
1370 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1374 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1375 // For each NSObject descendant having a +load method, this method is invoked
1376 // by the ObjC runtime before any of the static constructors is called.
1377 // Therefore we need to instrument such methods with a call to __asan_init
1378 // at the beginning in order to initialize our runtime before any access to
1379 // the shadow memory.
1380 // We cannot just ignore these methods, because they may call other
1381 // instrumented functions.
1382 if (F.getName().find(" load]") != std::string::npos) {
1383 IRBuilder<> IRB(F.begin()->begin());
1384 IRB.CreateCall(AsanInitFunction);
1390 bool AddressSanitizer::runOnFunction(Function &F) {
1391 if (&F == AsanCtorFunction) return false;
1392 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1393 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1394 initializeCallbacks(*F.getParent());
1396 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
1398 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1399 maybeInsertAsanInitAtFunctionEntry(F);
1401 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1404 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1407 // We want to instrument every address only once per basic block (unless there
1408 // are calls between uses).
1409 SmallSet<Value*, 16> TempsToInstrument;
1410 SmallVector<Instruction*, 16> ToInstrument;
1411 SmallVector<Instruction*, 8> NoReturnCalls;
1412 SmallVector<BasicBlock*, 16> AllBlocks;
1413 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1418 // Fill the set of memory operations to instrument.
1419 for (auto &BB : F) {
1420 AllBlocks.push_back(&BB);
1421 TempsToInstrument.clear();
1422 int NumInsnsPerBB = 0;
1423 for (auto &Inst : BB) {
1424 if (LooksLikeCodeInBug11395(&Inst)) return false;
1426 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1427 if (ClOpt && ClOptSameTemp) {
1428 if (!TempsToInstrument.insert(Addr).second)
1429 continue; // We've seen this temp in the current BB.
1431 } else if (ClInvalidPointerPairs &&
1432 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1433 PointerComparisonsOrSubtracts.push_back(&Inst);
1435 } else if (isa<MemIntrinsic>(Inst)) {
1438 if (isa<AllocaInst>(Inst))
1442 // A call inside BB.
1443 TempsToInstrument.clear();
1444 if (CS.doesNotReturn())
1445 NoReturnCalls.push_back(CS.getInstruction());
1449 ToInstrument.push_back(&Inst);
1451 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1456 bool UseCalls = false;
1457 if (ClInstrumentationWithCallsThreshold >= 0 &&
1458 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1462 int NumInstrumented = 0;
1463 for (auto Inst : ToInstrument) {
1464 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1465 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1466 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1467 instrumentMop(Inst, UseCalls);
1469 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1474 FunctionStackPoisoner FSP(F, *this);
1475 bool ChangedStack = FSP.runOnFunction();
1477 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1478 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1479 for (auto CI : NoReturnCalls) {
1480 IRBuilder<> IRB(CI);
1481 IRB.CreateCall(AsanHandleNoReturnFunc);
1484 for (auto Inst : PointerComparisonsOrSubtracts) {
1485 instrumentPointerComparisonOrSubtraction(Inst);
1489 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1491 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1496 // Workaround for bug 11395: we don't want to instrument stack in functions
1497 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1498 // FIXME: remove once the bug 11395 is fixed.
1499 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1500 if (LongSize != 32) return false;
1501 CallInst *CI = dyn_cast<CallInst>(I);
1502 if (!CI || !CI->isInlineAsm()) return false;
1503 if (CI->getNumArgOperands() <= 5) return false;
1504 // We have inline assembly with quite a few arguments.
1508 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1509 IRBuilder<> IRB(*C);
1510 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1511 std::string Suffix = itostr(i);
1512 AsanStackMallocFunc[i] = checkInterfaceFunction(
1513 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1514 IntptrTy, IntptrTy, nullptr));
1515 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1516 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1517 IntptrTy, IntptrTy, nullptr));
1519 AsanPoisonStackMemoryFunc = checkInterfaceFunction(
1520 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
1521 IntptrTy, IntptrTy, nullptr));
1522 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(
1523 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
1524 IntptrTy, IntptrTy, nullptr));
1528 FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1529 IRBuilder<> &IRB, Value *ShadowBase,
1531 size_t n = ShadowBytes.size();
1533 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1534 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1535 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1536 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1537 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1538 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1540 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1541 if (ASan.DL->isLittleEndian())
1542 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1544 Val = (Val << 8) | ShadowBytes[i + j];
1547 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1548 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1549 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1550 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1555 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1556 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1557 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1558 assert(LocalStackSize <= kMaxStackMallocSize);
1559 uint64_t MaxSize = kMinStackMallocSize;
1560 for (int i = 0; ; i++, MaxSize *= 2)
1561 if (LocalStackSize <= MaxSize)
1563 llvm_unreachable("impossible LocalStackSize");
1566 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1567 // We can not use MemSet intrinsic because it may end up calling the actual
1568 // memset. Size is a multiple of 8.
1569 // Currently this generates 8-byte stores on x86_64; it may be better to
1570 // generate wider stores.
1571 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1572 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1573 assert(!(Size % 8));
1574 assert(kAsanStackAfterReturnMagic == 0xf5);
1575 for (int i = 0; i < Size; i += 8) {
1576 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1577 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1578 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1582 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1583 for (const auto &Inst : F.getEntryBlock())
1584 if (!isa<AllocaInst>(Inst))
1585 return Inst.getDebugLoc();
1589 void FunctionStackPoisoner::poisonStack() {
1590 assert(AllocaVec.size() > 0 || DynamicAllocaVec.size() > 0);
1592 if (ClInstrumentAllocas)
1593 // Handle dynamic allocas.
1594 for (auto &AllocaCall : DynamicAllocaVec)
1595 handleDynamicAllocaCall(AllocaCall);
1597 if (AllocaVec.size() == 0) return;
1599 int StackMallocIdx = -1;
1600 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1602 Instruction *InsBefore = AllocaVec[0];
1603 IRBuilder<> IRB(InsBefore);
1604 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1606 SmallVector<ASanStackVariableDescription, 16> SVD;
1607 SVD.reserve(AllocaVec.size());
1608 for (AllocaInst *AI : AllocaVec) {
1609 ASanStackVariableDescription D = { AI->getName().data(),
1610 getAllocaSizeInBytes(AI),
1611 AI->getAlignment(), AI, 0};
1614 // Minimal header size (left redzone) is 4 pointers,
1615 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1616 size_t MinHeaderSize = ASan.LongSize / 2;
1617 ASanStackFrameLayout L;
1618 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1619 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1620 uint64_t LocalStackSize = L.FrameSize;
1621 bool DoStackMalloc =
1622 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1624 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1625 AllocaInst *MyAlloca =
1626 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1627 MyAlloca->setDebugLoc(EntryDebugLocation);
1628 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1629 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1630 MyAlloca->setAlignment(FrameAlignment);
1631 assert(MyAlloca->isStaticAlloca());
1632 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1633 Value *LocalStackBase = OrigStackBase;
1635 if (DoStackMalloc) {
1636 // LocalStackBase = OrigStackBase
1637 // if (__asan_option_detect_stack_use_after_return)
1638 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1639 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1640 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1641 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1642 kAsanOptionDetectUAR, IRB.getInt32Ty());
1643 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1644 Constant::getNullValue(IRB.getInt32Ty()));
1645 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1646 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1647 IRBuilder<> IRBIf(Term);
1648 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1649 LocalStackBase = IRBIf.CreateCall2(
1650 AsanStackMallocFunc[StackMallocIdx],
1651 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1652 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1653 IRB.SetInsertPoint(InsBefore);
1654 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1655 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1656 Phi->addIncoming(OrigStackBase, CmpBlock);
1657 Phi->addIncoming(LocalStackBase, SetBlock);
1658 LocalStackBase = Phi;
1661 // Insert poison calls for lifetime intrinsics for alloca.
1662 bool HavePoisonedAllocas = false;
1663 for (const auto &APC : AllocaPoisonCallVec) {
1664 assert(APC.InsBefore);
1666 IRBuilder<> IRB(APC.InsBefore);
1667 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1668 HavePoisonedAllocas |= APC.DoPoison;
1671 // Replace Alloca instructions with base+offset.
1672 for (const auto &Desc : SVD) {
1673 AllocaInst *AI = Desc.AI;
1674 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1675 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1677 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1678 AI->replaceAllUsesWith(NewAllocaPtr);
1681 // The left-most redzone has enough space for at least 4 pointers.
1682 // Write the Magic value to redzone[0].
1683 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1684 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1686 // Write the frame description constant to redzone[1].
1687 Value *BasePlus1 = IRB.CreateIntToPtr(
1688 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1690 GlobalVariable *StackDescriptionGlobal =
1691 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1692 /*AllowMerging*/true);
1693 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1695 IRB.CreateStore(Description, BasePlus1);
1696 // Write the PC to redzone[2].
1697 Value *BasePlus2 = IRB.CreateIntToPtr(
1698 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1699 2 * ASan.LongSize/8)),
1701 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1703 // Poison the stack redzones at the entry.
1704 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1705 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1707 // (Un)poison the stack before all ret instructions.
1708 for (auto Ret : RetVec) {
1709 IRBuilder<> IRBRet(Ret);
1710 // Mark the current frame as retired.
1711 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1713 if (DoStackMalloc) {
1714 assert(StackMallocIdx >= 0);
1715 // if LocalStackBase != OrigStackBase:
1716 // // In use-after-return mode, poison the whole stack frame.
1717 // if StackMallocIdx <= 4
1718 // // For small sizes inline the whole thing:
1719 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1720 // **SavedFlagPtr(LocalStackBase) = 0
1722 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1724 // <This is not a fake stack; unpoison the redzones>
1725 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1726 TerminatorInst *ThenTerm, *ElseTerm;
1727 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1729 IRBuilder<> IRBPoison(ThenTerm);
1730 if (StackMallocIdx <= 4) {
1731 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1732 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1733 ClassSize >> Mapping.Scale);
1734 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1736 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1737 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1738 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1739 IRBPoison.CreateStore(
1740 Constant::getNullValue(IRBPoison.getInt8Ty()),
1741 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1743 // For larger frames call __asan_stack_free_*.
1744 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1745 ConstantInt::get(IntptrTy, LocalStackSize),
1749 IRBuilder<> IRBElse(ElseTerm);
1750 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1751 } else if (HavePoisonedAllocas) {
1752 // If we poisoned some allocas in llvm.lifetime analysis,
1753 // unpoison whole stack frame now.
1754 assert(LocalStackBase == OrigStackBase);
1755 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1757 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1761 if (ClInstrumentAllocas)
1762 // Unpoison dynamic allocas.
1763 for (auto &AllocaCall : DynamicAllocaVec)
1764 unpoisonDynamicAlloca(AllocaCall);
1766 // We are done. Remove the old unused alloca instructions.
1767 for (auto AI : AllocaVec)
1768 AI->eraseFromParent();
1771 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1772 IRBuilder<> &IRB, bool DoPoison) {
1773 // For now just insert the call to ASan runtime.
1774 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1775 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1776 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1777 : AsanUnpoisonStackMemoryFunc,
1781 // Handling llvm.lifetime intrinsics for a given %alloca:
1782 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1783 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1784 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1785 // could be poisoned by previous llvm.lifetime.end instruction, as the
1786 // variable may go in and out of scope several times, e.g. in loops).
1787 // (3) if we poisoned at least one %alloca in a function,
1788 // unpoison the whole stack frame at function exit.
1790 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1791 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1792 // We're intested only in allocas we can handle.
1793 return isInterestingAlloca(*AI) ? AI : nullptr;
1794 // See if we've already calculated (or started to calculate) alloca for a
1796 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1797 if (I != AllocaForValue.end())
1799 // Store 0 while we're calculating alloca for value V to avoid
1800 // infinite recursion if the value references itself.
1801 AllocaForValue[V] = nullptr;
1802 AllocaInst *Res = nullptr;
1803 if (CastInst *CI = dyn_cast<CastInst>(V))
1804 Res = findAllocaForValue(CI->getOperand(0));
1805 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1806 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1807 Value *IncValue = PN->getIncomingValue(i);
1808 // Allow self-referencing phi-nodes.
1809 if (IncValue == PN) continue;
1810 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1811 // AI for incoming values should exist and should all be equal.
1812 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1818 AllocaForValue[V] = Res;
1822 // Compute PartialRzMagic for dynamic alloca call. PartialRzMagic is
1823 // constructed from two separate 32-bit numbers: PartialRzMagic = Val1 | Val2.
1824 // (1) Val1 is resposible for forming base value for PartialRzMagic, containing
1825 // only 00 for fully addressable and 0xcb for fully poisoned bytes for each
1826 // 8-byte chunk of user memory respectively.
1827 // (2) Val2 forms the value for marking first poisoned byte in shadow memory
1828 // with appropriate value (0x01 - 0x07 or 0xcb if Padding % 8 == 0).
1830 // Shift = Padding & ~7; // the number of bits we need to shift to access first
1831 // chunk in shadow memory, containing nonzero bytes.
1833 // Padding = 21 Padding = 16
1834 // Shadow: |00|00|05|cb| Shadow: |00|00|cb|cb|
1837 // Shift = 21 & ~7 = 16 Shift = 16 & ~7 = 16
1839 // Val1 = 0xcbcbcbcb << Shift;
1840 // PartialBits = Padding ? Padding & 7 : 0xcb;
1841 // Val2 = PartialBits << Shift;
1842 // Result = Val1 | Val2;
1843 Value *FunctionStackPoisoner::computePartialRzMagic(Value *PartialSize,
1845 PartialSize = IRB.CreateIntCast(PartialSize, IRB.getInt32Ty(), false);
1846 Value *Shift = IRB.CreateAnd(PartialSize, IRB.getInt32(~7));
1847 unsigned Val1Int = kAsanAllocaPartialVal1;
1848 unsigned Val2Int = kAsanAllocaPartialVal2;
1849 if (!ASan.DL->isLittleEndian()) {
1850 Val1Int = sys::getSwappedBytes(Val1Int);
1851 Val2Int = sys::getSwappedBytes(Val2Int);
1853 Value *Val1 = shiftAllocaMagic(IRB.getInt32(Val1Int), IRB, Shift);
1854 Value *PartialBits = IRB.CreateAnd(PartialSize, IRB.getInt32(7));
1855 // For BigEndian get 0x000000YZ -> 0xYZ000000.
1856 if (ASan.DL->isBigEndian())
1857 PartialBits = IRB.CreateShl(PartialBits, IRB.getInt32(24));
1858 Value *Val2 = IRB.getInt32(Val2Int);
1860 IRB.CreateICmpNE(PartialBits, Constant::getNullValue(IRB.getInt32Ty()));
1861 Val2 = IRB.CreateSelect(Cond, shiftAllocaMagic(PartialBits, IRB, Shift),
1862 shiftAllocaMagic(Val2, IRB, Shift));
1863 return IRB.CreateOr(Val1, Val2);
1866 void FunctionStackPoisoner::handleDynamicAllocaCall(
1867 DynamicAllocaCall &AllocaCall) {
1868 AllocaInst *AI = AllocaCall.AI;
1869 if (!doesDominateAllExits(AI)) {
1870 // We do not yet handle complex allocas
1871 AllocaCall.Poison = false;
1875 IRBuilder<> IRB(AI);
1877 PointerType *Int32PtrTy = PointerType::getUnqual(IRB.getInt32Ty());
1878 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
1879 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
1881 Value *Zero = Constant::getNullValue(IntptrTy);
1882 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
1883 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
1884 Value *NotAllocaRzMask = ConstantInt::get(IntptrTy, ~AllocaRedzoneMask);
1886 // Since we need to extend alloca with additional memory to locate
1887 // redzones, and OldSize is number of allocated blocks with
1888 // ElementSize size, get allocated memory size in bytes by
1889 // OldSize * ElementSize.
1890 unsigned ElementSize = ASan.DL->getTypeAllocSize(AI->getAllocatedType());
1891 Value *OldSize = IRB.CreateMul(AI->getArraySize(),
1892 ConstantInt::get(IntptrTy, ElementSize));
1894 // PartialSize = OldSize % 32
1895 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
1897 // Misalign = kAllocaRzSize - PartialSize;
1898 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
1900 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
1901 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
1902 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
1904 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
1905 // Align is added to locate left redzone, PartialPadding for possible
1906 // partial redzone and kAllocaRzSize for right redzone respectively.
1907 Value *AdditionalChunkSize = IRB.CreateAdd(
1908 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
1910 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
1912 // Insert new alloca with new NewSize and Align params.
1913 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
1914 NewAlloca->setAlignment(Align);
1916 // NewAddress = Address + Align
1917 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
1918 ConstantInt::get(IntptrTy, Align));
1920 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
1922 // LeftRzAddress = NewAddress - kAllocaRzSize
1923 Value *LeftRzAddress = IRB.CreateSub(NewAddress, AllocaRzSize);
1925 // Poisoning left redzone.
1926 AllocaCall.LeftRzAddr = ASan.memToShadow(LeftRzAddress, IRB);
1927 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaLeftMagic),
1928 IRB.CreateIntToPtr(AllocaCall.LeftRzAddr, Int32PtrTy));
1930 // PartialRzAligned = PartialRzAddr & ~AllocaRzMask
1931 Value *PartialRzAddr = IRB.CreateAdd(NewAddress, OldSize);
1932 Value *PartialRzAligned = IRB.CreateAnd(PartialRzAddr, NotAllocaRzMask);
1934 // Poisoning partial redzone.
1935 Value *PartialRzMagic = computePartialRzMagic(PartialSize, IRB);
1936 Value *PartialRzShadowAddr = ASan.memToShadow(PartialRzAligned, IRB);
1937 IRB.CreateStore(PartialRzMagic,
1938 IRB.CreateIntToPtr(PartialRzShadowAddr, Int32PtrTy));
1941 // = (PartialRzAddr + AllocaRzMask) & ~AllocaRzMask
1942 Value *RightRzAddress = IRB.CreateAnd(
1943 IRB.CreateAdd(PartialRzAddr, AllocaRzMask), NotAllocaRzMask);
1945 // Poisoning right redzone.
1946 AllocaCall.RightRzAddr = ASan.memToShadow(RightRzAddress, IRB);
1947 IRB.CreateStore(ConstantInt::get(IRB.getInt32Ty(), kAsanAllocaRightMagic),
1948 IRB.CreateIntToPtr(AllocaCall.RightRzAddr, Int32PtrTy));
1950 // Replace all uses of AddessReturnedByAlloca with NewAddress.
1951 AI->replaceAllUsesWith(NewAddressPtr);
1953 // We are done. Erase old alloca and store left, partial and right redzones
1954 // shadow addresses for future unpoisoning.
1955 AI->eraseFromParent();
1956 NumInstrumentedDynamicAllocas++;