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/ADT/ArrayRef.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/DepthFirstIterator.h"
19 #include "llvm/ADT/SetVector.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/ADT/SmallVector.h"
22 #include "llvm/ADT/Statistic.h"
23 #include "llvm/ADT/StringExtras.h"
24 #include "llvm/ADT/Triple.h"
25 #include "llvm/Analysis/MemoryBuiltins.h"
26 #include "llvm/Analysis/TargetLibraryInfo.h"
27 #include "llvm/Analysis/ValueTracking.h"
28 #include "llvm/IR/CallSite.h"
29 #include "llvm/IR/DIBuilder.h"
30 #include "llvm/IR/DataLayout.h"
31 #include "llvm/IR/Dominators.h"
32 #include "llvm/IR/Function.h"
33 #include "llvm/IR/IRBuilder.h"
34 #include "llvm/IR/InlineAsm.h"
35 #include "llvm/IR/InstVisitor.h"
36 #include "llvm/IR/IntrinsicInst.h"
37 #include "llvm/IR/LLVMContext.h"
38 #include "llvm/IR/MDBuilder.h"
39 #include "llvm/IR/Module.h"
40 #include "llvm/IR/Type.h"
41 #include "llvm/MC/MCSectionMachO.h"
42 #include "llvm/Support/CommandLine.h"
43 #include "llvm/Support/DataTypes.h"
44 #include "llvm/Support/Debug.h"
45 #include "llvm/Support/Endian.h"
46 #include "llvm/Support/SwapByteOrder.h"
47 #include "llvm/Support/raw_ostream.h"
48 #include "llvm/Transforms/Instrumentation.h"
49 #include "llvm/Transforms/Scalar.h"
50 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
51 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
52 #include "llvm/Transforms/Utils/Cloning.h"
53 #include "llvm/Transforms/Utils/Local.h"
54 #include "llvm/Transforms/Utils/ModuleUtils.h"
55 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
61 #include <system_error>
65 #define DEBUG_TYPE "asan"
67 static const uint64_t kDefaultShadowScale = 3;
68 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
69 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
70 static const uint64_t kDynamicShadowSentinel = ~(uint64_t)0;
71 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
72 static const uint64_t kIOSSimShadowOffset32 = 1ULL << 30;
73 static const uint64_t kIOSSimShadowOffset64 = kDefaultShadowOffset64;
74 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
75 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
76 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
77 static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
78 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
79 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
80 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
81 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
82 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
83 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
84 // The shadow memory space is dynamically allocated.
85 static const uint64_t kWindowsShadowOffset64 = kDynamicShadowSentinel;
87 static const size_t kMinStackMallocSize = 1 << 6; // 64B
88 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
89 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
90 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
92 static const char *const kAsanModuleCtorName = "asan.module_ctor";
93 static const char *const kAsanModuleDtorName = "asan.module_dtor";
94 static const uint64_t kAsanCtorAndDtorPriority = 1;
95 static const char *const kAsanReportErrorTemplate = "__asan_report_";
96 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
97 static const char *const kAsanUnregisterGlobalsName =
98 "__asan_unregister_globals";
99 static const char *const kAsanRegisterImageGlobalsName =
100 "__asan_register_image_globals";
101 static const char *const kAsanUnregisterImageGlobalsName =
102 "__asan_unregister_image_globals";
103 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
104 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
105 static const char *const kAsanInitName = "__asan_init";
106 static const char *const kAsanVersionCheckName =
107 "__asan_version_mismatch_check_v8";
108 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
109 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
110 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
111 static const int kMaxAsanStackMallocSizeClass = 10;
112 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
113 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
114 static const char *const kAsanGenPrefix = "__asan_gen_";
115 static const char *const kODRGenPrefix = "__odr_asan_gen_";
116 static const char *const kSanCovGenPrefix = "__sancov_gen_";
117 static const char *const kAsanSetShadowPrefix = "__asan_set_shadow_";
118 static const char *const kAsanPoisonStackMemoryName =
119 "__asan_poison_stack_memory";
120 static const char *const kAsanUnpoisonStackMemoryName =
121 "__asan_unpoison_stack_memory";
122 static const char *const kAsanGlobalsRegisteredFlagName =
123 "__asan_globals_registered";
125 static const char *const kAsanOptionDetectUseAfterReturn =
126 "__asan_option_detect_stack_use_after_return";
128 static const char *const kAsanShadowMemoryDynamicAddress =
129 "__asan_shadow_memory_dynamic_address";
131 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
132 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
134 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
135 static const size_t kNumberOfAccessSizes = 5;
137 static const unsigned kAllocaRzSize = 32;
139 // Command-line flags.
140 static cl::opt<bool> ClEnableKasan(
141 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
142 cl::Hidden, cl::init(false));
143 static cl::opt<bool> ClRecover(
145 cl::desc("Enable recovery mode (continue-after-error)."),
146 cl::Hidden, cl::init(false));
148 // This flag may need to be replaced with -f[no-]asan-reads.
149 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
150 cl::desc("instrument read instructions"),
151 cl::Hidden, cl::init(true));
152 static cl::opt<bool> ClInstrumentWrites(
153 "asan-instrument-writes", cl::desc("instrument write instructions"),
154 cl::Hidden, cl::init(true));
155 static cl::opt<bool> ClInstrumentAtomics(
156 "asan-instrument-atomics",
157 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
159 static cl::opt<bool> ClAlwaysSlowPath(
160 "asan-always-slow-path",
161 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
163 static cl::opt<bool> ClForceDynamicShadow(
164 "asan-force-dynamic-shadow",
165 cl::desc("Load shadow address into a local variable for each function"),
166 cl::Hidden, cl::init(false));
168 // This flag limits the number of instructions to be instrumented
169 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
170 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
172 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
173 "asan-max-ins-per-bb", cl::init(10000),
174 cl::desc("maximal number of instructions to instrument in any given BB"),
176 // This flag may need to be replaced with -f[no]asan-stack.
177 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
178 cl::Hidden, cl::init(true));
179 static cl::opt<uint32_t> ClMaxInlinePoisoningSize(
180 "asan-max-inline-poisoning-size",
182 "Inline shadow poisoning for blocks up to the given size in bytes."),
183 cl::Hidden, cl::init(64));
184 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
185 cl::desc("Check stack-use-after-return"),
186 cl::Hidden, cl::init(true));
187 static cl::opt<bool> ClUseAfterScope("asan-use-after-scope",
188 cl::desc("Check stack-use-after-scope"),
189 cl::Hidden, cl::init(false));
190 // This flag may need to be replaced with -f[no]asan-globals.
191 static cl::opt<bool> ClGlobals("asan-globals",
192 cl::desc("Handle global objects"), cl::Hidden,
194 static cl::opt<bool> ClInitializers("asan-initialization-order",
195 cl::desc("Handle C++ initializer order"),
196 cl::Hidden, cl::init(true));
197 static cl::opt<bool> ClInvalidPointerPairs(
198 "asan-detect-invalid-pointer-pair",
199 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
201 static cl::opt<unsigned> ClRealignStack(
202 "asan-realign-stack",
203 cl::desc("Realign stack to the value of this flag (power of two)"),
204 cl::Hidden, cl::init(32));
205 static cl::opt<int> ClInstrumentationWithCallsThreshold(
206 "asan-instrumentation-with-call-threshold",
208 "If the function being instrumented contains more than "
209 "this number of memory accesses, use callbacks instead of "
210 "inline checks (-1 means never use callbacks)."),
211 cl::Hidden, cl::init(7000));
212 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
213 "asan-memory-access-callback-prefix",
214 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
215 cl::init("__asan_"));
217 ClInstrumentDynamicAllocas("asan-instrument-dynamic-allocas",
218 cl::desc("instrument dynamic allocas"),
219 cl::Hidden, cl::init(true));
220 static cl::opt<bool> ClSkipPromotableAllocas(
221 "asan-skip-promotable-allocas",
222 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
225 // These flags allow to change the shadow mapping.
226 // The shadow mapping looks like
227 // Shadow = (Mem >> scale) + offset
228 static cl::opt<int> ClMappingScale("asan-mapping-scale",
229 cl::desc("scale of asan shadow mapping"),
230 cl::Hidden, cl::init(0));
231 static cl::opt<unsigned long long> ClMappingOffset(
232 "asan-mapping-offset",
233 cl::desc("offset of asan shadow mapping [EXPERIMENTAL]"), cl::Hidden,
236 // Optimization flags. Not user visible, used mostly for testing
237 // and benchmarking the tool.
238 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
239 cl::Hidden, cl::init(true));
240 static cl::opt<bool> ClOptSameTemp(
241 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
242 cl::Hidden, cl::init(true));
243 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
244 cl::desc("Don't instrument scalar globals"),
245 cl::Hidden, cl::init(true));
246 static cl::opt<bool> ClOptStack(
247 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
248 cl::Hidden, cl::init(false));
250 static cl::opt<bool> ClDynamicAllocaStack(
251 "asan-stack-dynamic-alloca",
252 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
255 static cl::opt<uint32_t> ClForceExperiment(
256 "asan-force-experiment",
257 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
261 ClUsePrivateAliasForGlobals("asan-use-private-alias",
262 cl::desc("Use private aliases for global"
264 cl::Hidden, cl::init(false));
267 ClUseMachOGlobalsSection("asan-globals-live-support",
268 cl::desc("Use linker features to support dead "
269 "code stripping of globals "
271 cl::Hidden, cl::init(true));
274 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
276 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
277 cl::Hidden, cl::init(0));
278 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
279 cl::desc("Debug func"));
280 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
281 cl::Hidden, cl::init(-1));
282 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug max inst"),
283 cl::Hidden, cl::init(-1));
285 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
286 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
287 STATISTIC(NumOptimizedAccessesToGlobalVar,
288 "Number of optimized accesses to global vars");
289 STATISTIC(NumOptimizedAccessesToStackVar,
290 "Number of optimized accesses to stack vars");
293 /// Frontend-provided metadata for source location.
294 struct LocationMetadata {
299 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
301 bool empty() const { return Filename.empty(); }
303 void parse(MDNode *MDN) {
304 assert(MDN->getNumOperands() == 3);
305 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
306 Filename = DIFilename->getString();
308 mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
310 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
314 /// Frontend-provided metadata for global variables.
315 class GlobalsMetadata {
318 Entry() : SourceLoc(), Name(), IsDynInit(false), IsBlacklisted(false) {}
319 LocationMetadata SourceLoc;
325 GlobalsMetadata() : inited_(false) {}
332 void init(Module &M) {
335 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
336 if (!Globals) return;
337 for (auto MDN : Globals->operands()) {
338 // Metadata node contains the global and the fields of "Entry".
339 assert(MDN->getNumOperands() == 5);
340 auto *GV = mdconst::extract_or_null<GlobalVariable>(MDN->getOperand(0));
341 // The optimizer may optimize away a global entirely.
343 // We can already have an entry for GV if it was merged with another
345 Entry &E = Entries[GV];
346 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
347 E.SourceLoc.parse(Loc);
348 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
349 E.Name = Name->getString();
350 ConstantInt *IsDynInit =
351 mdconst::extract<ConstantInt>(MDN->getOperand(3));
352 E.IsDynInit |= IsDynInit->isOne();
353 ConstantInt *IsBlacklisted =
354 mdconst::extract<ConstantInt>(MDN->getOperand(4));
355 E.IsBlacklisted |= IsBlacklisted->isOne();
359 /// Returns metadata entry for a given global.
360 Entry get(GlobalVariable *G) const {
361 auto Pos = Entries.find(G);
362 return (Pos != Entries.end()) ? Pos->second : Entry();
367 DenseMap<GlobalVariable *, Entry> Entries;
370 /// This struct defines the shadow mapping using the rule:
371 /// shadow = (mem >> Scale) ADD-or-OR Offset.
372 struct ShadowMapping {
378 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
380 bool IsAndroid = TargetTriple.isAndroid();
381 bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
382 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
383 bool IsLinux = TargetTriple.isOSLinux();
384 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
385 TargetTriple.getArch() == llvm::Triple::ppc64le;
386 bool IsSystemZ = TargetTriple.getArch() == llvm::Triple::systemz;
387 bool IsX86 = TargetTriple.getArch() == llvm::Triple::x86;
388 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
389 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
390 TargetTriple.getArch() == llvm::Triple::mipsel;
391 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
392 TargetTriple.getArch() == llvm::Triple::mips64el;
393 bool IsAArch64 = TargetTriple.getArch() == llvm::Triple::aarch64;
394 bool IsWindows = TargetTriple.isOSWindows();
396 ShadowMapping Mapping;
398 if (LongSize == 32) {
399 // Android is always PIE, which means that the beginning of the address
400 // space is always available.
404 Mapping.Offset = kMIPS32_ShadowOffset32;
406 Mapping.Offset = kFreeBSD_ShadowOffset32;
408 // If we're targeting iOS and x86, the binary is built for iOS simulator.
409 Mapping.Offset = IsX86 ? kIOSSimShadowOffset32 : kIOSShadowOffset32;
411 Mapping.Offset = kWindowsShadowOffset32;
413 Mapping.Offset = kDefaultShadowOffset32;
414 } else { // LongSize == 64
416 Mapping.Offset = kPPC64_ShadowOffset64;
418 Mapping.Offset = kSystemZ_ShadowOffset64;
420 Mapping.Offset = kFreeBSD_ShadowOffset64;
421 else if (IsLinux && IsX86_64) {
423 Mapping.Offset = kLinuxKasan_ShadowOffset64;
425 Mapping.Offset = kSmallX86_64ShadowOffset;
426 } else if (IsWindows && IsX86_64) {
427 Mapping.Offset = kWindowsShadowOffset64;
429 Mapping.Offset = kMIPS64_ShadowOffset64;
431 // If we're targeting iOS and x86, the binary is built for iOS simulator.
432 // We are using dynamic shadow offset on the 64-bit devices.
434 IsX86_64 ? kIOSSimShadowOffset64 : kDynamicShadowSentinel;
436 Mapping.Offset = kAArch64_ShadowOffset64;
438 Mapping.Offset = kDefaultShadowOffset64;
441 if (ClForceDynamicShadow) {
442 Mapping.Offset = kDynamicShadowSentinel;
445 Mapping.Scale = kDefaultShadowScale;
446 if (ClMappingScale.getNumOccurrences() > 0) {
447 Mapping.Scale = ClMappingScale;
450 if (ClMappingOffset.getNumOccurrences() > 0) {
451 Mapping.Offset = ClMappingOffset;
454 // OR-ing shadow offset if more efficient (at least on x86) if the offset
455 // is a power of two, but on ppc64 we have to use add since the shadow
456 // offset is not necessary 1/8-th of the address space. On SystemZ,
457 // we could OR the constant in a single instruction, but it's more
458 // efficient to load it once and use indexed addressing.
459 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ
460 && !(Mapping.Offset & (Mapping.Offset - 1))
461 && Mapping.Offset != kDynamicShadowSentinel;
466 static size_t RedzoneSizeForScale(int MappingScale) {
467 // Redzone used for stack and globals is at least 32 bytes.
468 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
469 return std::max(32U, 1U << MappingScale);
472 /// AddressSanitizer: instrument the code in module to find memory bugs.
473 struct AddressSanitizer : public FunctionPass {
474 explicit AddressSanitizer(bool CompileKernel = false, bool Recover = false,
475 bool UseAfterScope = false)
476 : FunctionPass(ID), CompileKernel(CompileKernel || ClEnableKasan),
477 Recover(Recover || ClRecover),
478 UseAfterScope(UseAfterScope || ClUseAfterScope),
479 LocalDynamicShadow(nullptr) {
480 initializeAddressSanitizerPass(*PassRegistry::getPassRegistry());
482 StringRef getPassName() const override {
483 return "AddressSanitizerFunctionPass";
485 void getAnalysisUsage(AnalysisUsage &AU) const override {
486 AU.addRequired<DominatorTreeWrapperPass>();
487 AU.addRequired<TargetLibraryInfoWrapperPass>();
489 uint64_t getAllocaSizeInBytes(const AllocaInst &AI) const {
490 uint64_t ArraySize = 1;
491 if (AI.isArrayAllocation()) {
492 const ConstantInt *CI = dyn_cast<ConstantInt>(AI.getArraySize());
493 assert(CI && "non-constant array size");
494 ArraySize = CI->getZExtValue();
496 Type *Ty = AI.getAllocatedType();
497 uint64_t SizeInBytes =
498 AI.getModule()->getDataLayout().getTypeAllocSize(Ty);
499 return SizeInBytes * ArraySize;
501 /// Check if we want (and can) handle this alloca.
502 bool isInterestingAlloca(const AllocaInst &AI);
504 /// If it is an interesting memory access, return the PointerOperand
505 /// and set IsWrite/Alignment. Otherwise return nullptr.
506 /// MaybeMask is an output parameter for the mask Value, if we're looking at a
507 /// masked load/store.
508 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
509 uint64_t *TypeSize, unsigned *Alignment,
510 Value **MaybeMask = nullptr);
511 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
512 bool UseCalls, const DataLayout &DL);
513 void instrumentPointerComparisonOrSubtraction(Instruction *I);
514 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
515 Value *Addr, uint32_t TypeSize, bool IsWrite,
516 Value *SizeArgument, bool UseCalls, uint32_t Exp);
517 void instrumentUnusualSizeOrAlignment(Instruction *I,
518 Instruction *InsertBefore, Value *Addr,
519 uint32_t TypeSize, bool IsWrite,
520 Value *SizeArgument, bool UseCalls,
522 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
523 Value *ShadowValue, uint32_t TypeSize);
524 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
525 bool IsWrite, size_t AccessSizeIndex,
526 Value *SizeArgument, uint32_t Exp);
527 void instrumentMemIntrinsic(MemIntrinsic *MI);
528 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
529 bool runOnFunction(Function &F) override;
530 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
531 void maybeInsertDynamicShadowAtFunctionEntry(Function &F);
532 void markEscapedLocalAllocas(Function &F);
533 bool doInitialization(Module &M) override;
534 bool doFinalization(Module &M) override;
535 static char ID; // Pass identification, replacement for typeid
537 DominatorTree &getDominatorTree() const { return *DT; }
540 void initializeCallbacks(Module &M);
542 bool LooksLikeCodeInBug11395(Instruction *I);
543 bool GlobalIsLinkerInitialized(GlobalVariable *G);
544 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
545 uint64_t TypeSize) const;
547 /// Helper to cleanup per-function state.
548 struct FunctionStateRAII {
549 AddressSanitizer *Pass;
550 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
551 assert(Pass->ProcessedAllocas.empty() &&
552 "last pass forgot to clear cache");
553 assert(!Pass->LocalDynamicShadow);
555 ~FunctionStateRAII() {
556 Pass->LocalDynamicShadow = nullptr;
557 Pass->ProcessedAllocas.clear();
568 ShadowMapping Mapping;
570 Function *AsanCtorFunction = nullptr;
571 Function *AsanInitFunction = nullptr;
572 Function *AsanHandleNoReturnFunc;
573 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
574 // This array is indexed by AccessIsWrite, Experiment and log2(AccessSize).
575 Function *AsanErrorCallback[2][2][kNumberOfAccessSizes];
576 Function *AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
577 // This array is indexed by AccessIsWrite and Experiment.
578 Function *AsanErrorCallbackSized[2][2];
579 Function *AsanMemoryAccessCallbackSized[2][2];
580 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
582 Value *LocalDynamicShadow;
583 GlobalsMetadata GlobalsMD;
584 DenseMap<const AllocaInst *, bool> ProcessedAllocas;
586 friend struct FunctionStackPoisoner;
589 class AddressSanitizerModule : public ModulePass {
591 explicit AddressSanitizerModule(bool CompileKernel = false,
592 bool Recover = false)
593 : ModulePass(ID), CompileKernel(CompileKernel || ClEnableKasan),
594 Recover(Recover || ClRecover) {}
595 bool runOnModule(Module &M) override;
596 static char ID; // Pass identification, replacement for typeid
597 StringRef getPassName() const override { return "AddressSanitizerModule"; }
600 void initializeCallbacks(Module &M);
602 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
603 void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
604 ArrayRef<GlobalVariable *> ExtendedGlobals,
605 ArrayRef<Constant *> MetadataInitializers);
606 void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
607 ArrayRef<GlobalVariable *> ExtendedGlobals,
608 ArrayRef<Constant *> MetadataInitializers);
610 InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M,
611 ArrayRef<GlobalVariable *> ExtendedGlobals,
612 ArrayRef<Constant *> MetadataInitializers);
614 GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
615 StringRef OriginalName);
616 void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata);
617 IRBuilder<> CreateAsanModuleDtor(Module &M);
619 bool ShouldInstrumentGlobal(GlobalVariable *G);
620 bool ShouldUseMachOGlobalsSection() const;
621 StringRef getGlobalMetadataSection() const;
622 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
623 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
624 size_t MinRedzoneSizeForGlobal() const {
625 return RedzoneSizeForScale(Mapping.Scale);
628 GlobalsMetadata GlobalsMD;
634 ShadowMapping Mapping;
635 Function *AsanPoisonGlobals;
636 Function *AsanUnpoisonGlobals;
637 Function *AsanRegisterGlobals;
638 Function *AsanUnregisterGlobals;
639 Function *AsanRegisterImageGlobals;
640 Function *AsanUnregisterImageGlobals;
643 // Stack poisoning does not play well with exception handling.
644 // When an exception is thrown, we essentially bypass the code
645 // that unpoisones the stack. This is why the run-time library has
646 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
647 // stack in the interceptor. This however does not work inside the
648 // actual function which catches the exception. Most likely because the
649 // compiler hoists the load of the shadow value somewhere too high.
650 // This causes asan to report a non-existing bug on 453.povray.
651 // It sounds like an LLVM bug.
652 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
654 AddressSanitizer &ASan;
659 ShadowMapping Mapping;
661 SmallVector<AllocaInst *, 16> AllocaVec;
662 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
663 SmallVector<Instruction *, 8> RetVec;
664 unsigned StackAlignment;
666 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
667 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
668 Function *AsanSetShadowFunc[0x100] = {};
669 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
670 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
672 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
673 struct AllocaPoisonCall {
674 IntrinsicInst *InsBefore;
679 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
680 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
682 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
683 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
684 AllocaInst *DynamicAllocaLayout = nullptr;
685 IntrinsicInst *LocalEscapeCall = nullptr;
687 // Maps Value to an AllocaInst from which the Value is originated.
688 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
689 AllocaForValueMapTy AllocaForValue;
691 bool HasNonEmptyInlineAsm = false;
692 bool HasReturnsTwiceCall = false;
693 std::unique_ptr<CallInst> EmptyInlineAsm;
695 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
698 DIB(*F.getParent(), /*AllowUnresolved*/ false),
700 IntptrTy(ASan.IntptrTy),
701 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
702 Mapping(ASan.Mapping),
703 StackAlignment(1 << Mapping.Scale),
704 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
706 bool runOnFunction() {
707 if (!ClStack) return false;
708 // Collect alloca, ret, lifetime instructions etc.
709 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
711 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
713 initializeCallbacks(*F.getParent());
715 processDynamicAllocas();
716 processStaticAllocas();
724 // Finds all Alloca instructions and puts
725 // poisoned red zones around all of them.
726 // Then unpoison everything back before the function returns.
727 void processStaticAllocas();
728 void processDynamicAllocas();
730 void createDynamicAllocasInitStorage();
732 // ----------------------- Visitors.
733 /// \brief Collect all Ret instructions.
734 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
736 /// \brief Collect all Resume instructions.
737 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
739 /// \brief Collect all CatchReturnInst instructions.
740 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
742 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
744 IRBuilder<> IRB(InstBefore);
745 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
746 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
747 // need to adjust extracted SP to compute the address of the most recent
748 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
750 if (!isa<ReturnInst>(InstBefore)) {
751 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
752 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
755 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
757 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
761 IRB.CreateCall(AsanAllocasUnpoisonFunc,
762 {IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr});
765 // Unpoison dynamic allocas redzones.
766 void unpoisonDynamicAllocas() {
767 for (auto &Ret : RetVec)
768 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
770 for (auto &StackRestoreInst : StackRestoreVec)
771 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
772 StackRestoreInst->getOperand(0));
775 // Deploy and poison redzones around dynamic alloca call. To do this, we
776 // should replace this call with another one with changed parameters and
777 // replace all its uses with new address, so
778 // addr = alloca type, old_size, align
780 // new_size = (old_size + additional_size) * sizeof(type)
781 // tmp = alloca i8, new_size, max(align, 32)
782 // addr = tmp + 32 (first 32 bytes are for the left redzone).
783 // Additional_size is added to make new memory allocation contain not only
784 // requested memory, but also left, partial and right redzones.
785 void handleDynamicAllocaCall(AllocaInst *AI);
787 /// \brief Collect Alloca instructions we want (and can) handle.
788 void visitAllocaInst(AllocaInst &AI) {
789 if (!ASan.isInterestingAlloca(AI)) {
790 if (AI.isStaticAlloca()) {
791 // Skip over allocas that are present *before* the first instrumented
792 // alloca, we don't want to move those around.
793 if (AllocaVec.empty())
796 StaticAllocasToMoveUp.push_back(&AI);
801 StackAlignment = std::max(StackAlignment, AI.getAlignment());
802 if (!AI.isStaticAlloca())
803 DynamicAllocaVec.push_back(&AI);
805 AllocaVec.push_back(&AI);
808 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
810 void visitIntrinsicInst(IntrinsicInst &II) {
811 Intrinsic::ID ID = II.getIntrinsicID();
812 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
813 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
814 if (!ASan.UseAfterScope)
816 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
818 // Found lifetime intrinsic, add ASan instrumentation if necessary.
819 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
820 // If size argument is undefined, don't do anything.
821 if (Size->isMinusOne()) return;
822 // Check that size doesn't saturate uint64_t and can
823 // be stored in IntptrTy.
824 const uint64_t SizeValue = Size->getValue().getLimitedValue();
825 if (SizeValue == ~0ULL ||
826 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
828 // Find alloca instruction that corresponds to llvm.lifetime argument.
829 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
830 if (!AI || !ASan.isInterestingAlloca(*AI))
832 bool DoPoison = (ID == Intrinsic::lifetime_end);
833 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
834 if (AI->isStaticAlloca())
835 StaticAllocaPoisonCallVec.push_back(APC);
836 else if (ClInstrumentDynamicAllocas)
837 DynamicAllocaPoisonCallVec.push_back(APC);
840 void visitCallSite(CallSite CS) {
841 Instruction *I = CS.getInstruction();
842 if (CallInst *CI = dyn_cast<CallInst>(I)) {
843 HasNonEmptyInlineAsm |=
844 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
845 HasReturnsTwiceCall |= CI->canReturnTwice();
849 // ---------------------- Helpers.
850 void initializeCallbacks(Module &M);
852 bool doesDominateAllExits(const Instruction *I) const {
853 for (auto Ret : RetVec) {
854 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
859 /// Finds alloca where the value comes from.
860 AllocaInst *findAllocaForValue(Value *V);
862 // Copies bytes from ShadowBytes into shadow memory for indexes where
863 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
864 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
865 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
866 IRBuilder<> &IRB, Value *ShadowBase);
867 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
868 size_t Begin, size_t End, IRBuilder<> &IRB,
870 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
871 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
872 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
874 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
876 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
878 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
879 Instruction *ThenTerm, Value *ValueIfFalse);
882 } // anonymous namespace
884 char AddressSanitizer::ID = 0;
885 INITIALIZE_PASS_BEGIN(
886 AddressSanitizer, "asan",
887 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
889 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
890 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
892 AddressSanitizer, "asan",
893 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
895 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
897 bool UseAfterScope) {
898 assert(!CompileKernel || Recover);
899 return new AddressSanitizer(CompileKernel, Recover, UseAfterScope);
902 char AddressSanitizerModule::ID = 0;
904 AddressSanitizerModule, "asan-module",
905 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
908 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
910 assert(!CompileKernel || Recover);
911 return new AddressSanitizerModule(CompileKernel, Recover);
914 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
915 size_t Res = countTrailingZeros(TypeSize / 8);
916 assert(Res < kNumberOfAccessSizes);
920 // \brief Create a constant for Str so that we can pass it to the run-time lib.
921 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
923 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
924 // We use private linkage for module-local strings. If they can be merged
925 // with another one, we set the unnamed_addr attribute.
927 new GlobalVariable(M, StrConst->getType(), true,
928 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
929 if (AllowMerging) GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
930 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
934 /// \brief Create a global describing a source location.
935 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
936 LocationMetadata MD) {
937 Constant *LocData[] = {
938 createPrivateGlobalForString(M, MD.Filename, true),
939 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
940 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
942 auto LocStruct = ConstantStruct::getAnon(LocData);
943 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
944 GlobalValue::PrivateLinkage, LocStruct,
946 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
950 /// \brief Check if \p G has been created by a trusted compiler pass.
951 static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
952 // Do not instrument asan globals.
953 if (G->getName().startswith(kAsanGenPrefix) ||
954 G->getName().startswith(kSanCovGenPrefix) ||
955 G->getName().startswith(kODRGenPrefix))
958 // Do not instrument gcov counter arrays.
959 if (G->getName() == "__llvm_gcov_ctr")
965 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
967 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
968 if (Mapping.Offset == 0) return Shadow;
969 // (Shadow >> scale) | offset
971 if (LocalDynamicShadow)
972 ShadowBase = LocalDynamicShadow;
974 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
975 if (Mapping.OrShadowOffset)
976 return IRB.CreateOr(Shadow, ShadowBase);
978 return IRB.CreateAdd(Shadow, ShadowBase);
981 // Instrument memset/memmove/memcpy
982 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
984 if (isa<MemTransferInst>(MI)) {
986 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
987 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
988 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
989 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
990 } else if (isa<MemSetInst>(MI)) {
993 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
994 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
995 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
997 MI->eraseFromParent();
1000 /// Check if we want (and can) handle this alloca.
1001 bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
1002 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
1004 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
1005 return PreviouslySeenAllocaInfo->getSecond();
1007 bool IsInteresting =
1008 (AI.getAllocatedType()->isSized() &&
1009 // alloca() may be called with 0 size, ignore it.
1010 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
1011 // We are only interested in allocas not promotable to registers.
1012 // Promotable allocas are common under -O0.
1013 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
1014 // inalloca allocas are not treated as static, and we don't want
1015 // dynamic alloca instrumentation for them as well.
1016 !AI.isUsedWithInAlloca());
1018 ProcessedAllocas[&AI] = IsInteresting;
1019 return IsInteresting;
1022 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
1025 unsigned *Alignment,
1026 Value **MaybeMask) {
1027 // Skip memory accesses inserted by another instrumentation.
1028 if (I->getMetadata("nosanitize")) return nullptr;
1030 // Do not instrument the load fetching the dynamic shadow address.
1031 if (LocalDynamicShadow == I)
1034 Value *PtrOperand = nullptr;
1035 const DataLayout &DL = I->getModule()->getDataLayout();
1036 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1037 if (!ClInstrumentReads) return nullptr;
1039 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
1040 *Alignment = LI->getAlignment();
1041 PtrOperand = LI->getPointerOperand();
1042 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1043 if (!ClInstrumentWrites) return nullptr;
1045 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
1046 *Alignment = SI->getAlignment();
1047 PtrOperand = SI->getPointerOperand();
1048 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1049 if (!ClInstrumentAtomics) return nullptr;
1051 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
1053 PtrOperand = RMW->getPointerOperand();
1054 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1055 if (!ClInstrumentAtomics) return nullptr;
1057 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
1059 PtrOperand = XCHG->getPointerOperand();
1060 } else if (auto CI = dyn_cast<CallInst>(I)) {
1061 auto *F = dyn_cast<Function>(CI->getCalledValue());
1062 if (F && (F->getName().startswith("llvm.masked.load.") ||
1063 F->getName().startswith("llvm.masked.store."))) {
1064 unsigned OpOffset = 0;
1065 if (F->getName().startswith("llvm.masked.store.")) {
1066 if (!ClInstrumentWrites)
1068 // Masked store has an initial operand for the value.
1072 if (!ClInstrumentReads)
1077 auto BasePtr = CI->getOperand(0 + OpOffset);
1078 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1079 *TypeSize = DL.getTypeStoreSizeInBits(Ty);
1080 if (auto AlignmentConstant =
1081 dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1082 *Alignment = (unsigned)AlignmentConstant->getZExtValue();
1084 *Alignment = 1; // No alignment guarantees. We probably got Undef
1086 *MaybeMask = CI->getOperand(2 + OpOffset);
1087 PtrOperand = BasePtr;
1091 // Do not instrument acesses from different address spaces; we cannot deal
1094 Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
1095 if (PtrTy->getPointerAddressSpace() != 0)
1099 // Treat memory accesses to promotable allocas as non-interesting since they
1100 // will not cause memory violations. This greatly speeds up the instrumented
1101 // executable at -O0.
1102 if (ClSkipPromotableAllocas)
1103 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
1104 return isInterestingAlloca(*AI) ? AI : nullptr;
1109 static bool isPointerOperand(Value *V) {
1110 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1113 // This is a rough heuristic; it may cause both false positives and
1114 // false negatives. The proper implementation requires cooperation with
1116 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
1117 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1118 if (!Cmp->isRelational()) return false;
1119 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1120 if (BO->getOpcode() != Instruction::Sub) return false;
1124 return isPointerOperand(I->getOperand(0)) &&
1125 isPointerOperand(I->getOperand(1));
1128 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1129 // If a global variable does not have dynamic initialization we don't
1130 // have to instrument it. However, if a global does not have initializer
1131 // at all, we assume it has dynamic initializer (in other TU).
1132 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1135 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1138 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1139 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1140 for (Value *&i : Param) {
1141 if (i->getType()->isPointerTy())
1142 i = IRB.CreatePointerCast(i, IntptrTy);
1144 IRB.CreateCall(F, Param);
1147 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1148 Instruction *InsertBefore, Value *Addr,
1149 unsigned Alignment, unsigned Granularity,
1150 uint32_t TypeSize, bool IsWrite,
1151 Value *SizeArgument, bool UseCalls,
1153 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1154 // if the data is properly aligned.
1155 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1157 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1158 return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
1159 nullptr, UseCalls, Exp);
1160 Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
1161 IsWrite, nullptr, UseCalls, Exp);
1164 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1165 const DataLayout &DL, Type *IntptrTy,
1166 Value *Mask, Instruction *I,
1167 Value *Addr, unsigned Alignment,
1168 unsigned Granularity, uint32_t TypeSize,
1169 bool IsWrite, Value *SizeArgument,
1170 bool UseCalls, uint32_t Exp) {
1171 auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
1172 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1173 unsigned Num = VTy->getVectorNumElements();
1174 auto Zero = ConstantInt::get(IntptrTy, 0);
1175 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1176 Value *InstrumentedAddress = nullptr;
1177 Instruction *InsertBefore = I;
1178 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
1179 // dyn_cast as we might get UndefValue
1180 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
1181 if (Masked->isNullValue())
1182 // Mask is constant false, so no instrumentation needed.
1184 // If we have a true or undef value, fall through to doInstrumentAddress
1185 // with InsertBefore == I
1189 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
1190 TerminatorInst *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
1191 InsertBefore = ThenTerm;
1194 IRBuilder<> IRB(InsertBefore);
1195 InstrumentedAddress =
1196 IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1197 doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
1198 Granularity, ElemTypeSize, IsWrite, SizeArgument,
1203 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1204 Instruction *I, bool UseCalls,
1205 const DataLayout &DL) {
1206 bool IsWrite = false;
1207 unsigned Alignment = 0;
1208 uint64_t TypeSize = 0;
1209 Value *MaybeMask = nullptr;
1211 isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
1214 // Optimization experiments.
1215 // The experiments can be used to evaluate potential optimizations that remove
1216 // instrumentation (assess false negatives). Instead of completely removing
1217 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1218 // experiments that want to remove instrumentation of this instruction).
1219 // If Exp is non-zero, this pass will emit special calls into runtime
1220 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1221 // make runtime terminate the program in a special way (with a different
1222 // exit status). Then you run the new compiler on a buggy corpus, collect
1223 // the special terminations (ideally, you don't see them at all -- no false
1224 // negatives) and make the decision on the optimization.
1225 uint32_t Exp = ClForceExperiment;
1227 if (ClOpt && ClOptGlobals) {
1228 // If initialization order checking is disabled, a simple access to a
1229 // dynamically initialized global is always valid.
1230 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
1231 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1232 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1233 NumOptimizedAccessesToGlobalVar++;
1238 if (ClOpt && ClOptStack) {
1239 // A direct inbounds access to a stack variable is always valid.
1240 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
1241 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1242 NumOptimizedAccessesToStackVar++;
1248 NumInstrumentedWrites++;
1250 NumInstrumentedReads++;
1252 unsigned Granularity = 1 << Mapping.Scale;
1254 instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
1255 Alignment, Granularity, TypeSize, IsWrite,
1256 nullptr, UseCalls, Exp);
1258 doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
1259 IsWrite, nullptr, UseCalls, Exp);
1263 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1264 Value *Addr, bool IsWrite,
1265 size_t AccessSizeIndex,
1266 Value *SizeArgument,
1268 IRBuilder<> IRB(InsertBefore);
1269 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1270 CallInst *Call = nullptr;
1273 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1274 {Addr, SizeArgument});
1276 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1277 {Addr, SizeArgument, ExpVal});
1281 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1283 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1287 // We don't do Call->setDoesNotReturn() because the BB already has
1288 // UnreachableInst at the end.
1289 // This EmptyAsm is required to avoid callback merge.
1290 IRB.CreateCall(EmptyAsm, {});
1294 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1296 uint32_t TypeSize) {
1297 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1298 // Addr & (Granularity - 1)
1299 Value *LastAccessedByte =
1300 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1301 // (Addr & (Granularity - 1)) + size - 1
1302 if (TypeSize / 8 > 1)
1303 LastAccessedByte = IRB.CreateAdd(
1304 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1305 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1307 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1308 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1309 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1312 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1313 Instruction *InsertBefore, Value *Addr,
1314 uint32_t TypeSize, bool IsWrite,
1315 Value *SizeArgument, bool UseCalls,
1317 IRBuilder<> IRB(InsertBefore);
1318 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1319 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1323 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1326 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1327 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1332 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1333 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1334 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1335 Value *CmpVal = Constant::getNullValue(ShadowTy);
1336 Value *ShadowValue =
1337 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1339 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1340 size_t Granularity = 1ULL << Mapping.Scale;
1341 TerminatorInst *CrashTerm = nullptr;
1343 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1344 // We use branch weights for the slow path check, to indicate that the slow
1345 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1346 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1347 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1348 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1349 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1350 IRB.SetInsertPoint(CheckTerm);
1351 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1353 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1355 BasicBlock *CrashBlock =
1356 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1357 CrashTerm = new UnreachableInst(*C, CrashBlock);
1358 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1359 ReplaceInstWithInst(CheckTerm, NewTerm);
1362 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1365 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1366 AccessSizeIndex, SizeArgument, Exp);
1367 Crash->setDebugLoc(OrigIns->getDebugLoc());
1370 // Instrument unusual size or unusual alignment.
1371 // We can not do it with a single check, so we do 1-byte check for the first
1372 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1373 // to report the actual access size.
1374 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1375 Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
1376 bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1377 IRBuilder<> IRB(InsertBefore);
1378 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1379 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1382 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1385 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1386 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1388 Value *LastByte = IRB.CreateIntToPtr(
1389 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1391 instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
1392 instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
1396 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1397 GlobalValue *ModuleName) {
1398 // Set up the arguments to our poison/unpoison functions.
1399 IRBuilder<> IRB(&GlobalInit.front(),
1400 GlobalInit.front().getFirstInsertionPt());
1402 // Add a call to poison all external globals before the given function starts.
1403 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1404 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1406 // Add calls to unpoison all globals before each return instruction.
1407 for (auto &BB : GlobalInit.getBasicBlockList())
1408 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1409 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1412 void AddressSanitizerModule::createInitializerPoisonCalls(
1413 Module &M, GlobalValue *ModuleName) {
1414 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1416 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1417 for (Use &OP : CA->operands()) {
1418 if (isa<ConstantAggregateZero>(OP)) continue;
1419 ConstantStruct *CS = cast<ConstantStruct>(OP);
1421 // Must have a function or null ptr.
1422 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1423 if (F->getName() == kAsanModuleCtorName) continue;
1424 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1425 // Don't instrument CTORs that will run before asan.module_ctor.
1426 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1427 poisonOneInitializer(*F, ModuleName);
1432 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1433 Type *Ty = G->getValueType();
1434 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1436 if (GlobalsMD.get(G).IsBlacklisted) return false;
1437 if (!Ty->isSized()) return false;
1438 if (!G->hasInitializer()) return false;
1439 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1440 // Touch only those globals that will not be defined in other modules.
1441 // Don't handle ODR linkage types and COMDATs since other modules may be built
1443 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1444 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1445 G->getLinkage() != GlobalVariable::InternalLinkage)
1447 if (G->hasComdat()) return false;
1448 // Two problems with thread-locals:
1449 // - The address of the main thread's copy can't be computed at link-time.
1450 // - Need to poison all copies, not just the main thread's one.
1451 if (G->isThreadLocal()) return false;
1452 // For now, just ignore this Global if the alignment is large.
1453 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1455 if (G->hasSection()) {
1456 StringRef Section = G->getSection();
1458 // Globals from llvm.metadata aren't emitted, do not instrument them.
1459 if (Section == "llvm.metadata") return false;
1460 // Do not instrument globals from special LLVM sections.
1461 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1463 // Do not instrument function pointers to initialization and termination
1464 // routines: dynamic linker will not properly handle redzones.
1465 if (Section.startswith(".preinit_array") ||
1466 Section.startswith(".init_array") ||
1467 Section.startswith(".fini_array")) {
1471 // Callbacks put into the CRT initializer/terminator sections
1472 // should not be instrumented.
1473 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1474 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1475 if (Section.startswith(".CRT")) {
1476 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1480 if (TargetTriple.isOSBinFormatMachO()) {
1481 StringRef ParsedSegment, ParsedSection;
1482 unsigned TAA = 0, StubSize = 0;
1484 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1485 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1486 assert(ErrorCode.empty() && "Invalid section specifier.");
1488 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1489 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1491 if (ParsedSegment == "__OBJC" ||
1492 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1493 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1496 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1497 // Constant CFString instances are compiled in the following way:
1498 // -- the string buffer is emitted into
1499 // __TEXT,__cstring,cstring_literals
1500 // -- the constant NSConstantString structure referencing that buffer
1501 // is placed into __DATA,__cfstring
1502 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1503 // Moreover, it causes the linker to crash on OS X 10.7
1504 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1505 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1508 // The linker merges the contents of cstring_literals and removes the
1510 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1511 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1520 // On Mach-O platforms, we emit global metadata in a separate section of the
1521 // binary in order to allow the linker to properly dead strip. This is only
1522 // supported on recent versions of ld64.
1523 bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const {
1524 if (!ClUseMachOGlobalsSection)
1527 if (!TargetTriple.isOSBinFormatMachO())
1530 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
1532 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
1534 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
1540 StringRef AddressSanitizerModule::getGlobalMetadataSection() const {
1541 switch (TargetTriple.getObjectFormat()) {
1542 case Triple::COFF: return ".ASAN$GL";
1543 case Triple::ELF: return "asan_globals";
1544 case Triple::MachO: return "__DATA,__asan_globals,regular";
1547 llvm_unreachable("unsupported object format");
1550 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1551 IRBuilder<> IRB(*C);
1553 // Declare our poisoning and unpoisoning functions.
1554 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1555 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1556 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1557 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1558 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1559 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1561 // Declare functions that register/unregister globals.
1562 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1563 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1564 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1565 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1566 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1567 IntptrTy, IntptrTy, nullptr));
1568 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1570 // Declare the functions that find globals in a shared object and then invoke
1571 // the (un)register function on them.
1572 AsanRegisterImageGlobals =
1573 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1574 kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1575 AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage);
1577 AsanUnregisterImageGlobals =
1578 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1579 kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1580 AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
1583 // Put the metadata and the instrumented global in the same group. This ensures
1584 // that the metadata is discarded if the instrumented global is discarded.
1585 void AddressSanitizerModule::SetComdatForGlobalMetadata(
1586 GlobalVariable *G, GlobalVariable *Metadata) {
1587 Module &M = *G->getParent();
1588 Comdat *C = G->getComdat();
1590 if (!G->hasName()) {
1591 // If G is unnamed, it must be internal. Give it an artificial name
1592 // so we can put it in a comdat.
1593 assert(G->hasLocalLinkage());
1594 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
1596 C = M.getOrInsertComdat(G->getName());
1597 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
1598 if (TargetTriple.isOSBinFormatCOFF())
1599 C->setSelectionKind(Comdat::NoDuplicates);
1603 assert(G->hasComdat());
1604 Metadata->setComdat(G->getComdat());
1607 // Create a separate metadata global and put it in the appropriate ASan
1608 // global registration section.
1610 AddressSanitizerModule::CreateMetadataGlobal(Module &M, Constant *Initializer,
1611 StringRef OriginalName) {
1612 GlobalVariable *Metadata =
1613 new GlobalVariable(M, Initializer->getType(), false,
1614 GlobalVariable::InternalLinkage, Initializer,
1615 Twine("__asan_global_") +
1616 GlobalValue::getRealLinkageName(OriginalName));
1617 Metadata->setSection(getGlobalMetadataSection());
1621 IRBuilder<> AddressSanitizerModule::CreateAsanModuleDtor(Module &M) {
1622 Function *AsanDtorFunction =
1623 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1624 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1625 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1626 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1628 return IRBuilder<>(ReturnInst::Create(*C, AsanDtorBB));
1631 void AddressSanitizerModule::InstrumentGlobalsCOFF(
1632 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1633 ArrayRef<Constant *> MetadataInitializers) {
1634 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1635 auto &DL = M.getDataLayout();
1637 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1638 Constant *Initializer = MetadataInitializers[i];
1639 GlobalVariable *G = ExtendedGlobals[i];
1640 GlobalVariable *Metadata =
1641 CreateMetadataGlobal(M, Initializer, G->getName());
1643 // The MSVC linker always inserts padding when linking incrementally. We
1644 // cope with that by aligning each struct to its size, which must be a power
1646 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
1647 assert(isPowerOf2_32(SizeOfGlobalStruct) &&
1648 "global metadata will not be padded appropriately");
1649 Metadata->setAlignment(SizeOfGlobalStruct);
1651 SetComdatForGlobalMetadata(G, Metadata);
1655 void AddressSanitizerModule::InstrumentGlobalsMachO(
1656 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1657 ArrayRef<Constant *> MetadataInitializers) {
1658 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1660 // On recent Mach-O platforms, use a structure which binds the liveness of
1661 // the global variable to the metadata struct. Keep the list of "Liveness" GV
1662 // created to be added to llvm.compiler.used
1663 StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr);
1664 SmallVector<GlobalValue *, 16> LivenessGlobals(ExtendedGlobals.size());
1666 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
1667 Constant *Initializer = MetadataInitializers[i];
1668 GlobalVariable *G = ExtendedGlobals[i];
1669 GlobalVariable *Metadata =
1670 CreateMetadataGlobal(M, Initializer, G->getName());
1672 // On recent Mach-O platforms, we emit the global metadata in a way that
1673 // allows the linker to properly strip dead globals.
1674 auto LivenessBinder = ConstantStruct::get(
1675 LivenessTy, Initializer->getAggregateElement(0u),
1676 ConstantExpr::getPointerCast(Metadata, IntptrTy), nullptr);
1677 GlobalVariable *Liveness = new GlobalVariable(
1678 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
1679 Twine("__asan_binder_") + G->getName());
1680 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
1681 LivenessGlobals[i] = Liveness;
1684 // Update llvm.compiler.used, adding the new liveness globals. This is
1685 // needed so that during LTO these variables stay alive. The alternative
1686 // would be to have the linker handling the LTO symbols, but libLTO
1687 // current API does not expose access to the section for each symbol.
1688 if (!LivenessGlobals.empty())
1689 appendToCompilerUsed(M, LivenessGlobals);
1691 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1692 // to look up the loaded image that contains it. Second, we can store in it
1693 // whether registration has already occurred, to prevent duplicate
1696 // common linkage ensures that there is only one global per shared library.
1697 GlobalVariable *RegisteredFlag = new GlobalVariable(
1698 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1699 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1700 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
1702 IRB.CreateCall(AsanRegisterImageGlobals,
1703 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1705 // We also need to unregister globals at the end, e.g., when a shared library
1707 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1708 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
1709 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1712 void AddressSanitizerModule::InstrumentGlobalsWithMetadataArray(
1713 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
1714 ArrayRef<Constant *> MetadataInitializers) {
1715 assert(ExtendedGlobals.size() == MetadataInitializers.size());
1716 unsigned N = ExtendedGlobals.size();
1719 // On platforms that don't have a custom metadata section, we emit an array
1720 // of global metadata structures.
1721 ArrayType *ArrayOfGlobalStructTy =
1722 ArrayType::get(MetadataInitializers[0]->getType(), N);
1723 auto AllGlobals = new GlobalVariable(
1724 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1725 ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
1727 IRB.CreateCall(AsanRegisterGlobals,
1728 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1729 ConstantInt::get(IntptrTy, N)});
1731 // We also need to unregister globals at the end, e.g., when a shared library
1733 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
1734 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1735 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1736 ConstantInt::get(IntptrTy, N)});
1739 // This function replaces all global variables with new variables that have
1740 // trailing redzones. It also creates a function that poisons
1741 // redzones and inserts this function into llvm.global_ctors.
1742 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1745 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1747 for (auto &G : M.globals()) {
1748 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1751 size_t n = GlobalsToChange.size();
1752 if (n == 0) return false;
1754 auto &DL = M.getDataLayout();
1756 // A global is described by a structure
1759 // size_t size_with_redzone;
1760 // const char *name;
1761 // const char *module_name;
1762 // size_t has_dynamic_init;
1763 // void *source_location;
1764 // size_t odr_indicator;
1765 // We initialize an array of such structures and pass it to a run-time call.
1766 StructType *GlobalStructTy =
1767 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1768 IntptrTy, IntptrTy, IntptrTy, nullptr);
1769 SmallVector<GlobalVariable *, 16> NewGlobals(n);
1770 SmallVector<Constant *, 16> Initializers(n);
1772 bool HasDynamicallyInitializedGlobals = false;
1774 // We shouldn't merge same module names, as this string serves as unique
1775 // module ID in runtime.
1776 GlobalVariable *ModuleName = createPrivateGlobalForString(
1777 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1779 for (size_t i = 0; i < n; i++) {
1780 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1781 GlobalVariable *G = GlobalsToChange[i];
1783 auto MD = GlobalsMD.get(G);
1784 StringRef NameForGlobal = G->getName();
1785 // Create string holding the global name (use global name from metadata
1786 // if it's available, otherwise just write the name of global variable).
1787 GlobalVariable *Name = createPrivateGlobalForString(
1788 M, MD.Name.empty() ? NameForGlobal : MD.Name,
1789 /*AllowMerging*/ true);
1791 Type *Ty = G->getValueType();
1792 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1793 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1794 // MinRZ <= RZ <= kMaxGlobalRedzone
1795 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1796 uint64_t RZ = std::max(
1797 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1798 uint64_t RightRedzoneSize = RZ;
1799 // Round up to MinRZ
1800 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1801 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1802 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1804 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1805 Constant *NewInitializer =
1806 ConstantStruct::get(NewTy, G->getInitializer(),
1807 Constant::getNullValue(RightRedZoneTy), nullptr);
1809 // Create a new global variable with enough space for a redzone.
1810 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1811 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1812 Linkage = GlobalValue::InternalLinkage;
1813 GlobalVariable *NewGlobal =
1814 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1815 "", G, G->getThreadLocalMode());
1816 NewGlobal->copyAttributesFrom(G);
1817 NewGlobal->setAlignment(MinRZ);
1819 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
1820 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
1822 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
1823 if (Seq && Seq->isCString())
1824 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
1827 // Transfer the debug info. The payload starts at offset zero so we can
1828 // copy the debug info over as is.
1829 SmallVector<DIGlobalVariableExpression *, 1> GVs;
1830 G->getDebugInfo(GVs);
1831 for (auto *GV : GVs)
1832 NewGlobal->addDebugInfo(GV);
1835 Indices2[0] = IRB.getInt32(0);
1836 Indices2[1] = IRB.getInt32(0);
1838 G->replaceAllUsesWith(
1839 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1840 NewGlobal->takeName(G);
1841 G->eraseFromParent();
1842 NewGlobals[i] = NewGlobal;
1844 Constant *SourceLoc;
1845 if (!MD.SourceLoc.empty()) {
1846 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1847 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1849 SourceLoc = ConstantInt::get(IntptrTy, 0);
1852 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
1853 GlobalValue *InstrumentedGlobal = NewGlobal;
1855 bool CanUsePrivateAliases =
1856 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO();
1857 if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) {
1858 // Create local alias for NewGlobal to avoid crash on ODR between
1859 // instrumented and non-instrumented libraries.
1860 auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage,
1861 NameForGlobal + M.getName(), NewGlobal);
1863 // With local aliases, we need to provide another externally visible
1864 // symbol __odr_asan_XXX to detect ODR violation.
1865 auto *ODRIndicatorSym =
1866 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
1867 Constant::getNullValue(IRB.getInt8Ty()),
1868 kODRGenPrefix + NameForGlobal, nullptr,
1869 NewGlobal->getThreadLocalMode());
1871 // Set meaningful attributes for indicator symbol.
1872 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
1873 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
1874 ODRIndicatorSym->setAlignment(1);
1875 ODRIndicator = ODRIndicatorSym;
1876 InstrumentedGlobal = GA;
1879 Constant *Initializer = ConstantStruct::get(
1881 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
1882 ConstantInt::get(IntptrTy, SizeInBytes),
1883 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1884 ConstantExpr::getPointerCast(Name, IntptrTy),
1885 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1886 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
1887 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy), nullptr);
1889 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1891 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1893 Initializers[i] = Initializer;
1896 if (TargetTriple.isOSBinFormatCOFF()) {
1897 InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
1898 } else if (ShouldUseMachOGlobalsSection()) {
1899 InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
1901 InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
1904 // Create calls for poisoning before initializers run and unpoisoning after.
1905 if (HasDynamicallyInitializedGlobals)
1906 createInitializerPoisonCalls(M, ModuleName);
1912 bool AddressSanitizerModule::runOnModule(Module &M) {
1913 C = &(M.getContext());
1914 int LongSize = M.getDataLayout().getPointerSizeInBits();
1915 IntptrTy = Type::getIntNTy(*C, LongSize);
1916 TargetTriple = Triple(M.getTargetTriple());
1917 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1918 initializeCallbacks(M);
1920 bool Changed = false;
1922 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1923 if (ClGlobals && !CompileKernel) {
1924 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1926 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1927 Changed |= InstrumentGlobals(IRB, M);
1933 void AddressSanitizer::initializeCallbacks(Module &M) {
1934 IRBuilder<> IRB(*C);
1935 // Create __asan_report* callbacks.
1936 // IsWrite, TypeSize and Exp are encoded in the function name.
1937 for (int Exp = 0; Exp < 2; Exp++) {
1938 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1939 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1940 const std::string ExpStr = Exp ? "exp_" : "";
1941 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1942 const std::string EndingStr = Recover ? "_noabort" : "";
1943 Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1944 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1945 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1946 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr + EndingStr,
1947 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1948 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1949 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1950 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1951 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1952 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1953 AccessSizeIndex++) {
1954 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
1955 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1956 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1957 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
1958 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1959 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1960 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1961 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1962 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1967 const std::string MemIntrinCallbackPrefix =
1968 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1969 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1970 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1971 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1972 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1973 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1974 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1975 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1976 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1977 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1979 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1980 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1982 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1983 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1984 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1985 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1986 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1987 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1988 StringRef(""), StringRef(""),
1989 /*hasSideEffects=*/true);
1993 bool AddressSanitizer::doInitialization(Module &M) {
1994 // Initialize the private fields. No one has accessed them before.
1998 C = &(M.getContext());
1999 LongSize = M.getDataLayout().getPointerSizeInBits();
2000 IntptrTy = Type::getIntNTy(*C, LongSize);
2001 TargetTriple = Triple(M.getTargetTriple());
2003 if (!CompileKernel) {
2004 std::tie(AsanCtorFunction, AsanInitFunction) =
2005 createSanitizerCtorAndInitFunctions(
2006 M, kAsanModuleCtorName, kAsanInitName,
2007 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
2008 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
2010 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
2014 bool AddressSanitizer::doFinalization(Module &M) {
2019 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
2020 // For each NSObject descendant having a +load method, this method is invoked
2021 // by the ObjC runtime before any of the static constructors is called.
2022 // Therefore we need to instrument such methods with a call to __asan_init
2023 // at the beginning in order to initialize our runtime before any access to
2024 // the shadow memory.
2025 // We cannot just ignore these methods, because they may call other
2026 // instrumented functions.
2027 if (F.getName().find(" load]") != std::string::npos) {
2028 IRBuilder<> IRB(&F.front(), F.front().begin());
2029 IRB.CreateCall(AsanInitFunction, {});
2035 void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
2036 // Generate code only when dynamic addressing is needed.
2037 if (Mapping.Offset != kDynamicShadowSentinel)
2040 IRBuilder<> IRB(&F.front().front());
2041 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
2042 kAsanShadowMemoryDynamicAddress, IntptrTy);
2043 LocalDynamicShadow = IRB.CreateLoad(GlobalDynamicAddress);
2046 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
2047 // Find the one possible call to llvm.localescape and pre-mark allocas passed
2048 // to it as uninteresting. This assumes we haven't started processing allocas
2049 // yet. This check is done up front because iterating the use list in
2050 // isInterestingAlloca would be algorithmically slower.
2051 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
2053 // Try to get the declaration of llvm.localescape. If it's not in the module,
2054 // we can exit early.
2055 if (!F.getParent()->getFunction("llvm.localescape")) return;
2057 // Look for a call to llvm.localescape call in the entry block. It can't be in
2059 for (Instruction &I : F.getEntryBlock()) {
2060 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2061 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2062 // We found a call. Mark all the allocas passed in as uninteresting.
2063 for (Value *Arg : II->arg_operands()) {
2064 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2065 assert(AI && AI->isStaticAlloca() &&
2066 "non-static alloca arg to localescape");
2067 ProcessedAllocas[AI] = false;
2074 bool AddressSanitizer::runOnFunction(Function &F) {
2075 if (&F == AsanCtorFunction) return false;
2076 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2077 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2078 if (F.getName().startswith("__asan_")) return false;
2080 bool FunctionModified = false;
2082 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2083 // This function needs to be called even if the function body is not
2085 if (maybeInsertAsanInitAtFunctionEntry(F))
2086 FunctionModified = true;
2088 // Leave if the function doesn't need instrumentation.
2089 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2091 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
2093 initializeCallbacks(*F.getParent());
2094 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2096 FunctionStateRAII CleanupObj(this);
2098 maybeInsertDynamicShadowAtFunctionEntry(F);
2100 // We can't instrument allocas used with llvm.localescape. Only static allocas
2101 // can be passed to that intrinsic.
2102 markEscapedLocalAllocas(F);
2104 // We want to instrument every address only once per basic block (unless there
2105 // are calls between uses).
2106 SmallSet<Value *, 16> TempsToInstrument;
2107 SmallVector<Instruction *, 16> ToInstrument;
2108 SmallVector<Instruction *, 8> NoReturnCalls;
2109 SmallVector<BasicBlock *, 16> AllBlocks;
2110 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2115 const TargetLibraryInfo *TLI =
2116 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
2118 // Fill the set of memory operations to instrument.
2119 for (auto &BB : F) {
2120 AllBlocks.push_back(&BB);
2121 TempsToInstrument.clear();
2122 int NumInsnsPerBB = 0;
2123 for (auto &Inst : BB) {
2124 if (LooksLikeCodeInBug11395(&Inst)) return false;
2125 Value *MaybeMask = nullptr;
2126 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
2127 &Alignment, &MaybeMask)) {
2128 if (ClOpt && ClOptSameTemp) {
2129 // If we have a mask, skip instrumentation if we've already
2130 // instrumented the full object. But don't add to TempsToInstrument
2131 // because we might get another load/store with a different mask.
2133 if (TempsToInstrument.count(Addr))
2134 continue; // We've seen this (whole) temp in the current BB.
2136 if (!TempsToInstrument.insert(Addr).second)
2137 continue; // We've seen this temp in the current BB.
2140 } else if (ClInvalidPointerPairs &&
2141 isInterestingPointerComparisonOrSubtraction(&Inst)) {
2142 PointerComparisonsOrSubtracts.push_back(&Inst);
2144 } else if (isa<MemIntrinsic>(Inst)) {
2147 if (isa<AllocaInst>(Inst)) NumAllocas++;
2150 // A call inside BB.
2151 TempsToInstrument.clear();
2152 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
2154 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2155 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2158 ToInstrument.push_back(&Inst);
2160 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2166 (ClInstrumentationWithCallsThreshold >= 0 &&
2167 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
2168 const DataLayout &DL = F.getParent()->getDataLayout();
2169 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
2170 /*RoundToAlign=*/true);
2173 int NumInstrumented = 0;
2174 for (auto Inst : ToInstrument) {
2175 if (ClDebugMin < 0 || ClDebugMax < 0 ||
2176 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
2177 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
2178 instrumentMop(ObjSizeVis, Inst, UseCalls,
2179 F.getParent()->getDataLayout());
2181 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
2186 FunctionStackPoisoner FSP(F, *this);
2187 bool ChangedStack = FSP.runOnFunction();
2189 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
2190 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
2191 for (auto CI : NoReturnCalls) {
2192 IRBuilder<> IRB(CI);
2193 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2196 for (auto Inst : PointerComparisonsOrSubtracts) {
2197 instrumentPointerComparisonOrSubtraction(Inst);
2201 if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
2202 FunctionModified = true;
2204 DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
2207 return FunctionModified;
2210 // Workaround for bug 11395: we don't want to instrument stack in functions
2211 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2212 // FIXME: remove once the bug 11395 is fixed.
2213 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2214 if (LongSize != 32) return false;
2215 CallInst *CI = dyn_cast<CallInst>(I);
2216 if (!CI || !CI->isInlineAsm()) return false;
2217 if (CI->getNumArgOperands() <= 5) return false;
2218 // We have inline assembly with quite a few arguments.
2222 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2223 IRBuilder<> IRB(*C);
2224 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
2225 std::string Suffix = itostr(i);
2226 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
2227 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
2228 IntptrTy, nullptr));
2229 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
2230 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2231 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2233 if (ASan.UseAfterScope) {
2234 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2235 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
2236 IntptrTy, IntptrTy, nullptr));
2237 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2238 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
2239 IntptrTy, IntptrTy, nullptr));
2242 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2243 std::ostringstream Name;
2244 Name << kAsanSetShadowPrefix;
2245 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2246 AsanSetShadowFunc[Val] =
2247 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2248 Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2251 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2252 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2253 AsanAllocasUnpoisonFunc =
2254 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2255 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2258 void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2259 ArrayRef<uint8_t> ShadowBytes,
2260 size_t Begin, size_t End,
2262 Value *ShadowBase) {
2266 const size_t LargestStoreSizeInBytes =
2267 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2269 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2271 // Poison given range in shadow using larges store size with out leading and
2272 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2273 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2274 // middle of a store.
2275 for (size_t i = Begin; i < End;) {
2276 if (!ShadowMask[i]) {
2277 assert(!ShadowBytes[i]);
2282 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2283 // Fit store size into the range.
2284 while (StoreSizeInBytes > End - i)
2285 StoreSizeInBytes /= 2;
2287 // Minimize store size by trimming trailing zeros.
2288 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2289 while (j <= StoreSizeInBytes / 2)
2290 StoreSizeInBytes /= 2;
2294 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2296 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
2298 Val = (Val << 8) | ShadowBytes[i + j];
2301 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
2302 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
2303 IRB.CreateAlignedStore(
2304 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
2306 i += StoreSizeInBytes;
2310 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2311 ArrayRef<uint8_t> ShadowBytes,
2312 IRBuilder<> &IRB, Value *ShadowBase) {
2313 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
2316 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2317 ArrayRef<uint8_t> ShadowBytes,
2318 size_t Begin, size_t End,
2319 IRBuilder<> &IRB, Value *ShadowBase) {
2320 assert(ShadowMask.size() == ShadowBytes.size());
2321 size_t Done = Begin;
2322 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
2323 if (!ShadowMask[i]) {
2324 assert(!ShadowBytes[i]);
2327 uint8_t Val = ShadowBytes[i];
2328 if (!AsanSetShadowFunc[Val])
2331 // Skip same values.
2332 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
2335 if (j - i >= ClMaxInlinePoisoningSize) {
2336 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
2337 IRB.CreateCall(AsanSetShadowFunc[Val],
2338 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
2339 ConstantInt::get(IntptrTy, j - i)});
2344 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
2347 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
2348 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
2349 static int StackMallocSizeClass(uint64_t LocalStackSize) {
2350 assert(LocalStackSize <= kMaxStackMallocSize);
2351 uint64_t MaxSize = kMinStackMallocSize;
2352 for (int i = 0;; i++, MaxSize *= 2)
2353 if (LocalStackSize <= MaxSize) return i;
2354 llvm_unreachable("impossible LocalStackSize");
2357 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
2359 Instruction *ThenTerm,
2360 Value *ValueIfFalse) {
2361 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
2362 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
2363 PHI->addIncoming(ValueIfFalse, CondBlock);
2364 BasicBlock *ThenBlock = ThenTerm->getParent();
2365 PHI->addIncoming(ValueIfTrue, ThenBlock);
2369 Value *FunctionStackPoisoner::createAllocaForLayout(
2370 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
2373 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
2374 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
2377 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
2378 nullptr, "MyAlloca");
2379 assert(Alloca->isStaticAlloca());
2381 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
2382 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
2383 Alloca->setAlignment(FrameAlignment);
2384 return IRB.CreatePointerCast(Alloca, IntptrTy);
2387 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
2388 BasicBlock &FirstBB = *F.begin();
2389 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
2390 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
2391 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
2392 DynamicAllocaLayout->setAlignment(32);
2395 void FunctionStackPoisoner::processDynamicAllocas() {
2396 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
2397 assert(DynamicAllocaPoisonCallVec.empty());
2401 // Insert poison calls for lifetime intrinsics for dynamic allocas.
2402 for (const auto &APC : DynamicAllocaPoisonCallVec) {
2403 assert(APC.InsBefore);
2405 assert(ASan.isInterestingAlloca(*APC.AI));
2406 assert(!APC.AI->isStaticAlloca());
2408 IRBuilder<> IRB(APC.InsBefore);
2409 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
2410 // Dynamic allocas will be unpoisoned unconditionally below in
2411 // unpoisonDynamicAllocas.
2412 // Flag that we need unpoison static allocas.
2415 // Handle dynamic allocas.
2416 createDynamicAllocasInitStorage();
2417 for (auto &AI : DynamicAllocaVec)
2418 handleDynamicAllocaCall(AI);
2419 unpoisonDynamicAllocas();
2422 void FunctionStackPoisoner::processStaticAllocas() {
2423 if (AllocaVec.empty()) {
2424 assert(StaticAllocaPoisonCallVec.empty());
2428 int StackMallocIdx = -1;
2429 DebugLoc EntryDebugLocation;
2430 if (auto SP = F.getSubprogram())
2431 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
2433 Instruction *InsBefore = AllocaVec[0];
2434 IRBuilder<> IRB(InsBefore);
2435 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2437 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
2438 // debug info is broken, because only entry-block allocas are treated as
2439 // regular stack slots.
2440 auto InsBeforeB = InsBefore->getParent();
2441 assert(InsBeforeB == &F.getEntryBlock());
2442 for (auto *AI : StaticAllocasToMoveUp)
2443 if (AI->getParent() == InsBeforeB)
2444 AI->moveBefore(InsBefore);
2446 // If we have a call to llvm.localescape, keep it in the entry block.
2447 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
2449 SmallVector<ASanStackVariableDescription, 16> SVD;
2450 SVD.reserve(AllocaVec.size());
2451 for (AllocaInst *AI : AllocaVec) {
2452 ASanStackVariableDescription D = {AI->getName().data(),
2453 ASan.getAllocaSizeInBytes(*AI),
2462 // Minimal header size (left redzone) is 4 pointers,
2463 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
2464 size_t MinHeaderSize = ASan.LongSize / 2;
2465 const ASanStackFrameLayout &L =
2466 ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
2468 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
2469 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
2470 for (auto &Desc : SVD)
2471 AllocaToSVDMap[Desc.AI] = &Desc;
2473 // Update SVD with information from lifetime intrinsics.
2474 for (const auto &APC : StaticAllocaPoisonCallVec) {
2475 assert(APC.InsBefore);
2477 assert(ASan.isInterestingAlloca(*APC.AI));
2478 assert(APC.AI->isStaticAlloca());
2480 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2481 Desc.LifetimeSize = Desc.Size;
2482 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
2483 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
2484 if (LifetimeLoc->getFile() == FnLoc->getFile())
2485 if (unsigned Line = LifetimeLoc->getLine())
2486 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
2491 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
2492 DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
2493 uint64_t LocalStackSize = L.FrameSize;
2494 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
2495 LocalStackSize <= kMaxStackMallocSize;
2496 bool DoDynamicAlloca = ClDynamicAllocaStack;
2497 // Don't do dynamic alloca or stack malloc if:
2498 // 1) There is inline asm: too often it makes assumptions on which registers
2500 // 2) There is a returns_twice call (typically setjmp), which is
2501 // optimization-hostile, and doesn't play well with introduced indirect
2502 // register-relative calculation of local variable addresses.
2503 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2504 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2506 Value *StaticAlloca =
2507 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
2510 Value *LocalStackBase;
2512 if (DoStackMalloc) {
2513 // void *FakeStack = __asan_option_detect_stack_use_after_return
2514 // ? __asan_stack_malloc_N(LocalStackSize)
2516 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
2517 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
2518 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
2519 Value *UseAfterReturnIsEnabled =
2520 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUseAfterReturn),
2521 Constant::getNullValue(IRB.getInt32Ty()));
2523 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
2524 IRBuilder<> IRBIf(Term);
2525 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2526 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
2527 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
2528 Value *FakeStackValue =
2529 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
2530 ConstantInt::get(IntptrTy, LocalStackSize));
2531 IRB.SetInsertPoint(InsBefore);
2532 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2533 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
2534 ConstantInt::get(IntptrTy, 0));
2536 Value *NoFakeStack =
2537 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
2538 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
2539 IRBIf.SetInsertPoint(Term);
2540 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2541 Value *AllocaValue =
2542 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
2543 IRB.SetInsertPoint(InsBefore);
2544 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2545 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
2547 // void *FakeStack = nullptr;
2548 // void *LocalStackBase = alloca(LocalStackSize);
2549 FakeStack = ConstantInt::get(IntptrTy, 0);
2551 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
2554 // Replace Alloca instructions with base+offset.
2555 for (const auto &Desc : SVD) {
2556 AllocaInst *AI = Desc.AI;
2557 Value *NewAllocaPtr = IRB.CreateIntToPtr(
2558 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
2560 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
2561 AI->replaceAllUsesWith(NewAllocaPtr);
2564 // The left-most redzone has enough space for at least 4 pointers.
2565 // Write the Magic value to redzone[0].
2566 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
2567 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
2569 // Write the frame description constant to redzone[1].
2570 Value *BasePlus1 = IRB.CreateIntToPtr(
2571 IRB.CreateAdd(LocalStackBase,
2572 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
2574 GlobalVariable *StackDescriptionGlobal =
2575 createPrivateGlobalForString(*F.getParent(), DescriptionString,
2576 /*AllowMerging*/ true);
2577 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
2578 IRB.CreateStore(Description, BasePlus1);
2579 // Write the PC to redzone[2].
2580 Value *BasePlus2 = IRB.CreateIntToPtr(
2581 IRB.CreateAdd(LocalStackBase,
2582 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
2584 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
2586 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
2588 // Poison the stack red zones at the entry.
2589 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
2590 // As mask we must use most poisoned case: red zones and after scope.
2591 // As bytes we can use either the same or just red zones only.
2592 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
2594 if (!StaticAllocaPoisonCallVec.empty()) {
2595 const auto &ShadowInScope = GetShadowBytes(SVD, L);
2597 // Poison static allocas near lifetime intrinsics.
2598 for (const auto &APC : StaticAllocaPoisonCallVec) {
2599 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2600 assert(Desc.Offset % L.Granularity == 0);
2601 size_t Begin = Desc.Offset / L.Granularity;
2602 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
2604 IRBuilder<> IRB(APC.InsBefore);
2605 copyToShadow(ShadowAfterScope,
2606 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
2611 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
2612 SmallVector<uint8_t, 64> ShadowAfterReturn;
2614 // (Un)poison the stack before all ret instructions.
2615 for (auto Ret : RetVec) {
2616 IRBuilder<> IRBRet(Ret);
2617 // Mark the current frame as retired.
2618 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
2620 if (DoStackMalloc) {
2621 assert(StackMallocIdx >= 0);
2622 // if FakeStack != 0 // LocalStackBase == FakeStack
2623 // // In use-after-return mode, poison the whole stack frame.
2624 // if StackMallocIdx <= 4
2625 // // For small sizes inline the whole thing:
2626 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
2627 // **SavedFlagPtr(FakeStack) = 0
2629 // __asan_stack_free_N(FakeStack, LocalStackSize)
2631 // <This is not a fake stack; unpoison the redzones>
2633 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
2634 TerminatorInst *ThenTerm, *ElseTerm;
2635 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
2637 IRBuilder<> IRBPoison(ThenTerm);
2638 if (StackMallocIdx <= 4) {
2639 int ClassSize = kMinStackMallocSize << StackMallocIdx;
2640 ShadowAfterReturn.resize(ClassSize / L.Granularity,
2641 kAsanStackUseAfterReturnMagic);
2642 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
2644 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
2646 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
2647 Value *SavedFlagPtr = IRBPoison.CreateLoad(
2648 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
2649 IRBPoison.CreateStore(
2650 Constant::getNullValue(IRBPoison.getInt8Ty()),
2651 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
2653 // For larger frames call __asan_stack_free_*.
2654 IRBPoison.CreateCall(
2655 AsanStackFreeFunc[StackMallocIdx],
2656 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
2659 IRBuilder<> IRBElse(ElseTerm);
2660 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
2662 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
2666 // We are done. Remove the old unused alloca instructions.
2667 for (auto AI : AllocaVec) AI->eraseFromParent();
2670 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2671 IRBuilder<> &IRB, bool DoPoison) {
2672 // For now just insert the call to ASan runtime.
2673 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2674 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2676 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2677 {AddrArg, SizeArg});
2680 // Handling llvm.lifetime intrinsics for a given %alloca:
2681 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2682 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2683 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2684 // could be poisoned by previous llvm.lifetime.end instruction, as the
2685 // variable may go in and out of scope several times, e.g. in loops).
2686 // (3) if we poisoned at least one %alloca in a function,
2687 // unpoison the whole stack frame at function exit.
2689 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2690 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2691 // We're interested only in allocas we can handle.
2692 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2693 // See if we've already calculated (or started to calculate) alloca for a
2695 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2696 if (I != AllocaForValue.end()) return I->second;
2697 // Store 0 while we're calculating alloca for value V to avoid
2698 // infinite recursion if the value references itself.
2699 AllocaForValue[V] = nullptr;
2700 AllocaInst *Res = nullptr;
2701 if (CastInst *CI = dyn_cast<CastInst>(V))
2702 Res = findAllocaForValue(CI->getOperand(0));
2703 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2704 for (Value *IncValue : PN->incoming_values()) {
2705 // Allow self-referencing phi-nodes.
2706 if (IncValue == PN) continue;
2707 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2708 // AI for incoming values should exist and should all be equal.
2709 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2713 } else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
2714 Res = findAllocaForValue(EP->getPointerOperand());
2716 DEBUG(dbgs() << "Alloca search canceled on unknown instruction: " << *V << "\n");
2718 if (Res) AllocaForValue[V] = Res;
2722 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2723 IRBuilder<> IRB(AI);
2725 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2726 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2728 Value *Zero = Constant::getNullValue(IntptrTy);
2729 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2730 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2732 // Since we need to extend alloca with additional memory to locate
2733 // redzones, and OldSize is number of allocated blocks with
2734 // ElementSize size, get allocated memory size in bytes by
2735 // OldSize * ElementSize.
2736 const unsigned ElementSize =
2737 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2739 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2740 ConstantInt::get(IntptrTy, ElementSize));
2742 // PartialSize = OldSize % 32
2743 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2745 // Misalign = kAllocaRzSize - PartialSize;
2746 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2748 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2749 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2750 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2752 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2753 // Align is added to locate left redzone, PartialPadding for possible
2754 // partial redzone and kAllocaRzSize for right redzone respectively.
2755 Value *AdditionalChunkSize = IRB.CreateAdd(
2756 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2758 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2760 // Insert new alloca with new NewSize and Align params.
2761 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2762 NewAlloca->setAlignment(Align);
2764 // NewAddress = Address + Align
2765 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2766 ConstantInt::get(IntptrTy, Align));
2768 // Insert __asan_alloca_poison call for new created alloca.
2769 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2771 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2772 // for unpoisoning stuff.
2773 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2775 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2777 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2778 AI->replaceAllUsesWith(NewAddressPtr);
2780 // We are done. Erase old alloca from parent.
2781 AI->eraseFromParent();
2784 // isSafeAccess returns true if Addr is always inbounds with respect to its
2785 // base object. For example, it is a field access or an array access with
2786 // constant inbounds index.
2787 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2788 Value *Addr, uint64_t TypeSize) const {
2789 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2790 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2791 uint64_t Size = SizeOffset.first.getZExtValue();
2792 int64_t Offset = SizeOffset.second.getSExtValue();
2793 // Three checks are required to ensure safety:
2794 // . Offset >= 0 (since the offset is given from the base ptr)
2795 // . Size >= Offset (unsigned)
2796 // . Size - Offset >= NeededSize (unsigned)
2797 return Offset >= 0 && Size >= uint64_t(Offset) &&
2798 Size - uint64_t(Offset) >= TypeSize / 8;