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 bool ShouldInstrumentGlobal(GlobalVariable *G);
604 bool ShouldUseMachOGlobalsSection() const;
605 StringRef getGlobalMetadataSection() const;
606 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
607 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
608 size_t MinRedzoneSizeForGlobal() const {
609 return RedzoneSizeForScale(Mapping.Scale);
612 GlobalsMetadata GlobalsMD;
618 ShadowMapping Mapping;
619 Function *AsanPoisonGlobals;
620 Function *AsanUnpoisonGlobals;
621 Function *AsanRegisterGlobals;
622 Function *AsanUnregisterGlobals;
623 Function *AsanRegisterImageGlobals;
624 Function *AsanUnregisterImageGlobals;
627 // Stack poisoning does not play well with exception handling.
628 // When an exception is thrown, we essentially bypass the code
629 // that unpoisones the stack. This is why the run-time library has
630 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
631 // stack in the interceptor. This however does not work inside the
632 // actual function which catches the exception. Most likely because the
633 // compiler hoists the load of the shadow value somewhere too high.
634 // This causes asan to report a non-existing bug on 453.povray.
635 // It sounds like an LLVM bug.
636 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
638 AddressSanitizer &ASan;
643 ShadowMapping Mapping;
645 SmallVector<AllocaInst *, 16> AllocaVec;
646 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
647 SmallVector<Instruction *, 8> RetVec;
648 unsigned StackAlignment;
650 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
651 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
652 Function *AsanSetShadowFunc[0x100] = {};
653 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
654 Function *AsanAllocaPoisonFunc, *AsanAllocasUnpoisonFunc;
656 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
657 struct AllocaPoisonCall {
658 IntrinsicInst *InsBefore;
663 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
664 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
666 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
667 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
668 AllocaInst *DynamicAllocaLayout = nullptr;
669 IntrinsicInst *LocalEscapeCall = nullptr;
671 // Maps Value to an AllocaInst from which the Value is originated.
672 typedef DenseMap<Value *, AllocaInst *> AllocaForValueMapTy;
673 AllocaForValueMapTy AllocaForValue;
675 bool HasNonEmptyInlineAsm = false;
676 bool HasReturnsTwiceCall = false;
677 std::unique_ptr<CallInst> EmptyInlineAsm;
679 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
682 DIB(*F.getParent(), /*AllowUnresolved*/ false),
684 IntptrTy(ASan.IntptrTy),
685 IntptrPtrTy(PointerType::get(IntptrTy, 0)),
686 Mapping(ASan.Mapping),
687 StackAlignment(1 << Mapping.Scale),
688 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
690 bool runOnFunction() {
691 if (!ClStack) return false;
692 // Collect alloca, ret, lifetime instructions etc.
693 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
695 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
697 initializeCallbacks(*F.getParent());
699 processDynamicAllocas();
700 processStaticAllocas();
708 // Finds all Alloca instructions and puts
709 // poisoned red zones around all of them.
710 // Then unpoison everything back before the function returns.
711 void processStaticAllocas();
712 void processDynamicAllocas();
714 void createDynamicAllocasInitStorage();
716 // ----------------------- Visitors.
717 /// \brief Collect all Ret instructions.
718 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
720 /// \brief Collect all Resume instructions.
721 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
723 /// \brief Collect all CatchReturnInst instructions.
724 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
726 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
728 IRBuilder<> IRB(InstBefore);
729 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
730 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
731 // need to adjust extracted SP to compute the address of the most recent
732 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
734 if (!isa<ReturnInst>(InstBefore)) {
735 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
736 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
739 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
741 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
745 IRB.CreateCall(AsanAllocasUnpoisonFunc,
746 {IRB.CreateLoad(DynamicAllocaLayout), DynamicAreaPtr});
749 // Unpoison dynamic allocas redzones.
750 void unpoisonDynamicAllocas() {
751 for (auto &Ret : RetVec)
752 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
754 for (auto &StackRestoreInst : StackRestoreVec)
755 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
756 StackRestoreInst->getOperand(0));
759 // Deploy and poison redzones around dynamic alloca call. To do this, we
760 // should replace this call with another one with changed parameters and
761 // replace all its uses with new address, so
762 // addr = alloca type, old_size, align
764 // new_size = (old_size + additional_size) * sizeof(type)
765 // tmp = alloca i8, new_size, max(align, 32)
766 // addr = tmp + 32 (first 32 bytes are for the left redzone).
767 // Additional_size is added to make new memory allocation contain not only
768 // requested memory, but also left, partial and right redzones.
769 void handleDynamicAllocaCall(AllocaInst *AI);
771 /// \brief Collect Alloca instructions we want (and can) handle.
772 void visitAllocaInst(AllocaInst &AI) {
773 if (!ASan.isInterestingAlloca(AI)) {
774 if (AI.isStaticAlloca()) {
775 // Skip over allocas that are present *before* the first instrumented
776 // alloca, we don't want to move those around.
777 if (AllocaVec.empty())
780 StaticAllocasToMoveUp.push_back(&AI);
785 StackAlignment = std::max(StackAlignment, AI.getAlignment());
786 if (!AI.isStaticAlloca())
787 DynamicAllocaVec.push_back(&AI);
789 AllocaVec.push_back(&AI);
792 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
794 void visitIntrinsicInst(IntrinsicInst &II) {
795 Intrinsic::ID ID = II.getIntrinsicID();
796 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
797 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
798 if (!ASan.UseAfterScope)
800 if (ID != Intrinsic::lifetime_start && ID != Intrinsic::lifetime_end)
802 // Found lifetime intrinsic, add ASan instrumentation if necessary.
803 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
804 // If size argument is undefined, don't do anything.
805 if (Size->isMinusOne()) return;
806 // Check that size doesn't saturate uint64_t and can
807 // be stored in IntptrTy.
808 const uint64_t SizeValue = Size->getValue().getLimitedValue();
809 if (SizeValue == ~0ULL ||
810 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
812 // Find alloca instruction that corresponds to llvm.lifetime argument.
813 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
814 if (!AI || !ASan.isInterestingAlloca(*AI))
816 bool DoPoison = (ID == Intrinsic::lifetime_end);
817 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
818 if (AI->isStaticAlloca())
819 StaticAllocaPoisonCallVec.push_back(APC);
820 else if (ClInstrumentDynamicAllocas)
821 DynamicAllocaPoisonCallVec.push_back(APC);
824 void visitCallSite(CallSite CS) {
825 Instruction *I = CS.getInstruction();
826 if (CallInst *CI = dyn_cast<CallInst>(I)) {
827 HasNonEmptyInlineAsm |=
828 CI->isInlineAsm() && !CI->isIdenticalTo(EmptyInlineAsm.get());
829 HasReturnsTwiceCall |= CI->canReturnTwice();
833 // ---------------------- Helpers.
834 void initializeCallbacks(Module &M);
836 bool doesDominateAllExits(const Instruction *I) const {
837 for (auto Ret : RetVec) {
838 if (!ASan.getDominatorTree().dominates(I, Ret)) return false;
843 /// Finds alloca where the value comes from.
844 AllocaInst *findAllocaForValue(Value *V);
846 // Copies bytes from ShadowBytes into shadow memory for indexes where
847 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
848 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
849 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
850 IRBuilder<> &IRB, Value *ShadowBase);
851 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
852 size_t Begin, size_t End, IRBuilder<> &IRB,
854 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
855 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
856 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
858 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
860 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
862 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
863 Instruction *ThenTerm, Value *ValueIfFalse);
866 } // anonymous namespace
868 char AddressSanitizer::ID = 0;
869 INITIALIZE_PASS_BEGIN(
870 AddressSanitizer, "asan",
871 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
873 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
874 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
876 AddressSanitizer, "asan",
877 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
879 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
881 bool UseAfterScope) {
882 assert(!CompileKernel || Recover);
883 return new AddressSanitizer(CompileKernel, Recover, UseAfterScope);
886 char AddressSanitizerModule::ID = 0;
888 AddressSanitizerModule, "asan-module",
889 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
892 ModulePass *llvm::createAddressSanitizerModulePass(bool CompileKernel,
894 assert(!CompileKernel || Recover);
895 return new AddressSanitizerModule(CompileKernel, Recover);
898 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
899 size_t Res = countTrailingZeros(TypeSize / 8);
900 assert(Res < kNumberOfAccessSizes);
904 // \brief Create a constant for Str so that we can pass it to the run-time lib.
905 static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str,
907 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
908 // We use private linkage for module-local strings. If they can be merged
909 // with another one, we set the unnamed_addr attribute.
911 new GlobalVariable(M, StrConst->getType(), true,
912 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
913 if (AllowMerging) GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
914 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
918 /// \brief Create a global describing a source location.
919 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
920 LocationMetadata MD) {
921 Constant *LocData[] = {
922 createPrivateGlobalForString(M, MD.Filename, true),
923 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
924 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
926 auto LocStruct = ConstantStruct::getAnon(LocData);
927 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
928 GlobalValue::PrivateLinkage, LocStruct,
930 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
934 /// \brief Check if \p G has been created by a trusted compiler pass.
935 static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
936 // Do not instrument asan globals.
937 if (G->getName().startswith(kAsanGenPrefix) ||
938 G->getName().startswith(kSanCovGenPrefix) ||
939 G->getName().startswith(kODRGenPrefix))
942 // Do not instrument gcov counter arrays.
943 if (G->getName() == "__llvm_gcov_ctr")
949 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
951 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
952 if (Mapping.Offset == 0) return Shadow;
953 // (Shadow >> scale) | offset
955 if (LocalDynamicShadow)
956 ShadowBase = LocalDynamicShadow;
958 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
959 if (Mapping.OrShadowOffset)
960 return IRB.CreateOr(Shadow, ShadowBase);
962 return IRB.CreateAdd(Shadow, ShadowBase);
965 // Instrument memset/memmove/memcpy
966 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
968 if (isa<MemTransferInst>(MI)) {
970 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
971 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
972 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
973 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
974 } else if (isa<MemSetInst>(MI)) {
977 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
978 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
979 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
981 MI->eraseFromParent();
984 /// Check if we want (and can) handle this alloca.
985 bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
986 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
988 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
989 return PreviouslySeenAllocaInfo->getSecond();
992 (AI.getAllocatedType()->isSized() &&
993 // alloca() may be called with 0 size, ignore it.
994 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
995 // We are only interested in allocas not promotable to registers.
996 // Promotable allocas are common under -O0.
997 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
998 // inalloca allocas are not treated as static, and we don't want
999 // dynamic alloca instrumentation for them as well.
1000 !AI.isUsedWithInAlloca());
1002 ProcessedAllocas[&AI] = IsInteresting;
1003 return IsInteresting;
1006 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
1009 unsigned *Alignment,
1010 Value **MaybeMask) {
1011 // Skip memory accesses inserted by another instrumentation.
1012 if (I->getMetadata("nosanitize")) return nullptr;
1014 // Do not instrument the load fetching the dynamic shadow address.
1015 if (LocalDynamicShadow == I)
1018 Value *PtrOperand = nullptr;
1019 const DataLayout &DL = I->getModule()->getDataLayout();
1020 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1021 if (!ClInstrumentReads) return nullptr;
1023 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
1024 *Alignment = LI->getAlignment();
1025 PtrOperand = LI->getPointerOperand();
1026 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1027 if (!ClInstrumentWrites) return nullptr;
1029 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
1030 *Alignment = SI->getAlignment();
1031 PtrOperand = SI->getPointerOperand();
1032 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1033 if (!ClInstrumentAtomics) return nullptr;
1035 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
1037 PtrOperand = RMW->getPointerOperand();
1038 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1039 if (!ClInstrumentAtomics) return nullptr;
1041 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
1043 PtrOperand = XCHG->getPointerOperand();
1044 } else if (auto CI = dyn_cast<CallInst>(I)) {
1045 auto *F = dyn_cast<Function>(CI->getCalledValue());
1046 if (F && (F->getName().startswith("llvm.masked.load.") ||
1047 F->getName().startswith("llvm.masked.store."))) {
1048 unsigned OpOffset = 0;
1049 if (F->getName().startswith("llvm.masked.store.")) {
1050 if (!ClInstrumentWrites)
1052 // Masked store has an initial operand for the value.
1056 if (!ClInstrumentReads)
1061 auto BasePtr = CI->getOperand(0 + OpOffset);
1062 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1063 *TypeSize = DL.getTypeStoreSizeInBits(Ty);
1064 if (auto AlignmentConstant =
1065 dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1066 *Alignment = (unsigned)AlignmentConstant->getZExtValue();
1068 *Alignment = 1; // No alignment guarantees. We probably got Undef
1070 *MaybeMask = CI->getOperand(2 + OpOffset);
1071 PtrOperand = BasePtr;
1075 // Do not instrument acesses from different address spaces; we cannot deal
1078 Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
1079 if (PtrTy->getPointerAddressSpace() != 0)
1083 // Treat memory accesses to promotable allocas as non-interesting since they
1084 // will not cause memory violations. This greatly speeds up the instrumented
1085 // executable at -O0.
1086 if (ClSkipPromotableAllocas)
1087 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
1088 return isInterestingAlloca(*AI) ? AI : nullptr;
1093 static bool isPointerOperand(Value *V) {
1094 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1097 // This is a rough heuristic; it may cause both false positives and
1098 // false negatives. The proper implementation requires cooperation with
1100 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
1101 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1102 if (!Cmp->isRelational()) return false;
1103 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1104 if (BO->getOpcode() != Instruction::Sub) return false;
1108 return isPointerOperand(I->getOperand(0)) &&
1109 isPointerOperand(I->getOperand(1));
1112 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1113 // If a global variable does not have dynamic initialization we don't
1114 // have to instrument it. However, if a global does not have initializer
1115 // at all, we assume it has dynamic initializer (in other TU).
1116 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1119 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1122 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1123 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1124 for (Value *&i : Param) {
1125 if (i->getType()->isPointerTy())
1126 i = IRB.CreatePointerCast(i, IntptrTy);
1128 IRB.CreateCall(F, Param);
1131 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1132 Instruction *InsertBefore, Value *Addr,
1133 unsigned Alignment, unsigned Granularity,
1134 uint32_t TypeSize, bool IsWrite,
1135 Value *SizeArgument, bool UseCalls,
1137 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1138 // if the data is properly aligned.
1139 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1141 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1142 return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
1143 nullptr, UseCalls, Exp);
1144 Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
1145 IsWrite, nullptr, UseCalls, Exp);
1148 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1149 const DataLayout &DL, Type *IntptrTy,
1150 Value *Mask, Instruction *I,
1151 Value *Addr, unsigned Alignment,
1152 unsigned Granularity, uint32_t TypeSize,
1153 bool IsWrite, Value *SizeArgument,
1154 bool UseCalls, uint32_t Exp) {
1155 auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
1156 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1157 unsigned Num = VTy->getVectorNumElements();
1158 auto Zero = ConstantInt::get(IntptrTy, 0);
1159 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1160 Value *InstrumentedAddress = nullptr;
1161 Instruction *InsertBefore = I;
1162 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
1163 // dyn_cast as we might get UndefValue
1164 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
1165 if (Masked->isNullValue())
1166 // Mask is constant false, so no instrumentation needed.
1168 // If we have a true or undef value, fall through to doInstrumentAddress
1169 // with InsertBefore == I
1173 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
1174 TerminatorInst *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
1175 InsertBefore = ThenTerm;
1178 IRBuilder<> IRB(InsertBefore);
1179 InstrumentedAddress =
1180 IRB.CreateGEP(Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1181 doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
1182 Granularity, ElemTypeSize, IsWrite, SizeArgument,
1187 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1188 Instruction *I, bool UseCalls,
1189 const DataLayout &DL) {
1190 bool IsWrite = false;
1191 unsigned Alignment = 0;
1192 uint64_t TypeSize = 0;
1193 Value *MaybeMask = nullptr;
1195 isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
1198 // Optimization experiments.
1199 // The experiments can be used to evaluate potential optimizations that remove
1200 // instrumentation (assess false negatives). Instead of completely removing
1201 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1202 // experiments that want to remove instrumentation of this instruction).
1203 // If Exp is non-zero, this pass will emit special calls into runtime
1204 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1205 // make runtime terminate the program in a special way (with a different
1206 // exit status). Then you run the new compiler on a buggy corpus, collect
1207 // the special terminations (ideally, you don't see them at all -- no false
1208 // negatives) and make the decision on the optimization.
1209 uint32_t Exp = ClForceExperiment;
1211 if (ClOpt && ClOptGlobals) {
1212 // If initialization order checking is disabled, a simple access to a
1213 // dynamically initialized global is always valid.
1214 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
1215 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1216 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1217 NumOptimizedAccessesToGlobalVar++;
1222 if (ClOpt && ClOptStack) {
1223 // A direct inbounds access to a stack variable is always valid.
1224 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
1225 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1226 NumOptimizedAccessesToStackVar++;
1232 NumInstrumentedWrites++;
1234 NumInstrumentedReads++;
1236 unsigned Granularity = 1 << Mapping.Scale;
1238 instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
1239 Alignment, Granularity, TypeSize, IsWrite,
1240 nullptr, UseCalls, Exp);
1242 doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
1243 IsWrite, nullptr, UseCalls, Exp);
1247 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1248 Value *Addr, bool IsWrite,
1249 size_t AccessSizeIndex,
1250 Value *SizeArgument,
1252 IRBuilder<> IRB(InsertBefore);
1253 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1254 CallInst *Call = nullptr;
1257 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1258 {Addr, SizeArgument});
1260 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1261 {Addr, SizeArgument, ExpVal});
1265 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1267 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1271 // We don't do Call->setDoesNotReturn() because the BB already has
1272 // UnreachableInst at the end.
1273 // This EmptyAsm is required to avoid callback merge.
1274 IRB.CreateCall(EmptyAsm, {});
1278 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1280 uint32_t TypeSize) {
1281 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1282 // Addr & (Granularity - 1)
1283 Value *LastAccessedByte =
1284 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1285 // (Addr & (Granularity - 1)) + size - 1
1286 if (TypeSize / 8 > 1)
1287 LastAccessedByte = IRB.CreateAdd(
1288 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1289 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1291 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1292 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1293 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1296 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1297 Instruction *InsertBefore, Value *Addr,
1298 uint32_t TypeSize, bool IsWrite,
1299 Value *SizeArgument, bool UseCalls,
1301 IRBuilder<> IRB(InsertBefore);
1302 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1303 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1307 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1310 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1311 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1316 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1317 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1318 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1319 Value *CmpVal = Constant::getNullValue(ShadowTy);
1320 Value *ShadowValue =
1321 IRB.CreateLoad(IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1323 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1324 size_t Granularity = 1ULL << Mapping.Scale;
1325 TerminatorInst *CrashTerm = nullptr;
1327 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1328 // We use branch weights for the slow path check, to indicate that the slow
1329 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1330 TerminatorInst *CheckTerm = SplitBlockAndInsertIfThen(
1331 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1332 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1333 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1334 IRB.SetInsertPoint(CheckTerm);
1335 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1337 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1339 BasicBlock *CrashBlock =
1340 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1341 CrashTerm = new UnreachableInst(*C, CrashBlock);
1342 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1343 ReplaceInstWithInst(CheckTerm, NewTerm);
1346 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1349 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1350 AccessSizeIndex, SizeArgument, Exp);
1351 Crash->setDebugLoc(OrigIns->getDebugLoc());
1354 // Instrument unusual size or unusual alignment.
1355 // We can not do it with a single check, so we do 1-byte check for the first
1356 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1357 // to report the actual access size.
1358 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1359 Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
1360 bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1361 IRBuilder<> IRB(InsertBefore);
1362 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1363 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1366 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1369 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1370 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1372 Value *LastByte = IRB.CreateIntToPtr(
1373 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1375 instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
1376 instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
1380 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
1381 GlobalValue *ModuleName) {
1382 // Set up the arguments to our poison/unpoison functions.
1383 IRBuilder<> IRB(&GlobalInit.front(),
1384 GlobalInit.front().getFirstInsertionPt());
1386 // Add a call to poison all external globals before the given function starts.
1387 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1388 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1390 // Add calls to unpoison all globals before each return instruction.
1391 for (auto &BB : GlobalInit.getBasicBlockList())
1392 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1393 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1396 void AddressSanitizerModule::createInitializerPoisonCalls(
1397 Module &M, GlobalValue *ModuleName) {
1398 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1400 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
1401 for (Use &OP : CA->operands()) {
1402 if (isa<ConstantAggregateZero>(OP)) continue;
1403 ConstantStruct *CS = cast<ConstantStruct>(OP);
1405 // Must have a function or null ptr.
1406 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1407 if (F->getName() == kAsanModuleCtorName) continue;
1408 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
1409 // Don't instrument CTORs that will run before asan.module_ctor.
1410 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
1411 poisonOneInitializer(*F, ModuleName);
1416 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
1417 Type *Ty = G->getValueType();
1418 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1420 if (GlobalsMD.get(G).IsBlacklisted) return false;
1421 if (!Ty->isSized()) return false;
1422 if (!G->hasInitializer()) return false;
1423 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1424 // Touch only those globals that will not be defined in other modules.
1425 // Don't handle ODR linkage types and COMDATs since other modules may be built
1427 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
1428 G->getLinkage() != GlobalVariable::PrivateLinkage &&
1429 G->getLinkage() != GlobalVariable::InternalLinkage)
1431 if (G->hasComdat()) return false;
1432 // Two problems with thread-locals:
1433 // - The address of the main thread's copy can't be computed at link-time.
1434 // - Need to poison all copies, not just the main thread's one.
1435 if (G->isThreadLocal()) return false;
1436 // For now, just ignore this Global if the alignment is large.
1437 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1439 if (G->hasSection()) {
1440 StringRef Section = G->getSection();
1442 // Globals from llvm.metadata aren't emitted, do not instrument them.
1443 if (Section == "llvm.metadata") return false;
1444 // Do not instrument globals from special LLVM sections.
1445 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1447 // Do not instrument function pointers to initialization and termination
1448 // routines: dynamic linker will not properly handle redzones.
1449 if (Section.startswith(".preinit_array") ||
1450 Section.startswith(".init_array") ||
1451 Section.startswith(".fini_array")) {
1455 // Callbacks put into the CRT initializer/terminator sections
1456 // should not be instrumented.
1457 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
1458 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1459 if (Section.startswith(".CRT")) {
1460 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
1464 if (TargetTriple.isOSBinFormatMachO()) {
1465 StringRef ParsedSegment, ParsedSection;
1466 unsigned TAA = 0, StubSize = 0;
1468 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1469 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1470 assert(ErrorCode.empty() && "Invalid section specifier.");
1472 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1473 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1475 if (ParsedSegment == "__OBJC" ||
1476 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1477 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1480 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
1481 // Constant CFString instances are compiled in the following way:
1482 // -- the string buffer is emitted into
1483 // __TEXT,__cstring,cstring_literals
1484 // -- the constant NSConstantString structure referencing that buffer
1485 // is placed into __DATA,__cfstring
1486 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1487 // Moreover, it causes the linker to crash on OS X 10.7
1488 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1489 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1492 // The linker merges the contents of cstring_literals and removes the
1494 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1495 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1504 // On Mach-O platforms, we emit global metadata in a separate section of the
1505 // binary in order to allow the linker to properly dead strip. This is only
1506 // supported on recent versions of ld64.
1507 bool AddressSanitizerModule::ShouldUseMachOGlobalsSection() const {
1508 if (!ClUseMachOGlobalsSection)
1511 if (!TargetTriple.isOSBinFormatMachO())
1514 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
1516 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
1518 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
1524 StringRef AddressSanitizerModule::getGlobalMetadataSection() const {
1525 switch (TargetTriple.getObjectFormat()) {
1526 case Triple::COFF: return ".ASAN$GL";
1527 case Triple::ELF: return "asan_globals";
1528 case Triple::MachO: return "__DATA,__asan_globals,regular";
1531 llvm_unreachable("unsupported object format");
1534 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1535 IRBuilder<> IRB(*C);
1537 // Declare our poisoning and unpoisoning functions.
1538 AsanPoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1539 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, nullptr));
1540 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1541 AsanUnpoisonGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1542 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), nullptr));
1543 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1545 // Declare functions that register/unregister globals.
1546 AsanRegisterGlobals = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1547 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1548 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1549 AsanUnregisterGlobals = checkSanitizerInterfaceFunction(
1550 M.getOrInsertFunction(kAsanUnregisterGlobalsName, IRB.getVoidTy(),
1551 IntptrTy, IntptrTy, nullptr));
1552 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1554 // Declare the functions that find globals in a shared object and then invoke
1555 // the (un)register function on them.
1556 AsanRegisterImageGlobals = checkSanitizerInterfaceFunction(
1557 M.getOrInsertFunction(kAsanRegisterImageGlobalsName,
1558 IRB.getVoidTy(), IntptrTy, nullptr));
1559 AsanRegisterImageGlobals->setLinkage(Function::ExternalLinkage);
1561 AsanUnregisterImageGlobals = checkSanitizerInterfaceFunction(
1562 M.getOrInsertFunction(kAsanUnregisterImageGlobalsName,
1563 IRB.getVoidTy(), IntptrTy, nullptr));
1564 AsanUnregisterImageGlobals->setLinkage(Function::ExternalLinkage);
1567 // This function replaces all global variables with new variables that have
1568 // trailing redzones. It also creates a function that poisons
1569 // redzones and inserts this function into llvm.global_ctors.
1570 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1573 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1575 for (auto &G : M.globals()) {
1576 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
1579 size_t n = GlobalsToChange.size();
1580 if (n == 0) return false;
1582 auto &DL = M.getDataLayout();
1583 bool UseComdatMetadata = TargetTriple.isOSBinFormatCOFF();
1584 bool UseMachOGlobalsSection = ShouldUseMachOGlobalsSection();
1585 bool UseMetadataArray = !(UseComdatMetadata || UseMachOGlobalsSection);
1587 // A global is described by a structure
1590 // size_t size_with_redzone;
1591 // const char *name;
1592 // const char *module_name;
1593 // size_t has_dynamic_init;
1594 // void *source_location;
1595 // size_t odr_indicator;
1596 // We initialize an array of such structures and pass it to a run-time call.
1597 StructType *GlobalStructTy =
1598 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1599 IntptrTy, IntptrTy, IntptrTy, nullptr);
1600 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(GlobalStructTy);
1601 assert(isPowerOf2_32(SizeOfGlobalStruct) &&
1602 "global metadata will not be padded appropriately");
1603 SmallVector<Constant *, 16> Initializers(UseMetadataArray ? n : 0);
1605 // On recent Mach-O platforms, use a structure which binds the liveness of
1606 // the global variable to the metadata struct. Keep the list of "Liveness" GV
1607 // created to be added to llvm.compiler.used
1608 StructType *LivenessTy = nullptr;
1609 if (UseMachOGlobalsSection)
1610 LivenessTy = StructType::get(IntptrTy, IntptrTy, nullptr);
1611 SmallVector<GlobalValue *, 16> LivenessGlobals(
1612 UseMachOGlobalsSection ? n : 0);
1614 bool HasDynamicallyInitializedGlobals = false;
1616 // We shouldn't merge same module names, as this string serves as unique
1617 // module ID in runtime.
1618 GlobalVariable *ModuleName = createPrivateGlobalForString(
1619 M, M.getModuleIdentifier(), /*AllowMerging*/ false);
1621 for (size_t i = 0; i < n; i++) {
1622 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1623 GlobalVariable *G = GlobalsToChange[i];
1625 auto MD = GlobalsMD.get(G);
1626 StringRef NameForGlobal = G->getName();
1627 // Create string holding the global name (use global name from metadata
1628 // if it's available, otherwise just write the name of global variable).
1629 GlobalVariable *Name = createPrivateGlobalForString(
1630 M, MD.Name.empty() ? NameForGlobal : MD.Name,
1631 /*AllowMerging*/ true);
1633 Type *Ty = G->getValueType();
1634 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
1635 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1636 // MinRZ <= RZ <= kMaxGlobalRedzone
1637 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1638 uint64_t RZ = std::max(
1639 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
1640 uint64_t RightRedzoneSize = RZ;
1641 // Round up to MinRZ
1642 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1643 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1644 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1646 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, nullptr);
1647 Constant *NewInitializer =
1648 ConstantStruct::get(NewTy, G->getInitializer(),
1649 Constant::getNullValue(RightRedZoneTy), nullptr);
1651 // Create a new global variable with enough space for a redzone.
1652 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1653 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1654 Linkage = GlobalValue::InternalLinkage;
1655 GlobalVariable *NewGlobal =
1656 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
1657 "", G, G->getThreadLocalMode());
1658 NewGlobal->copyAttributesFrom(G);
1659 NewGlobal->setAlignment(MinRZ);
1661 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
1662 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
1664 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
1665 if (Seq && Seq->isCString())
1666 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
1669 // Transfer the debug info. The payload starts at offset zero so we can
1670 // copy the debug info over as is.
1671 SmallVector<DIGlobalVariableExpression *, 1> GVs;
1672 G->getDebugInfo(GVs);
1673 for (auto *GV : GVs)
1674 NewGlobal->addDebugInfo(GV);
1677 Indices2[0] = IRB.getInt32(0);
1678 Indices2[1] = IRB.getInt32(0);
1680 G->replaceAllUsesWith(
1681 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
1682 NewGlobal->takeName(G);
1683 G->eraseFromParent();
1686 if (UseComdatMetadata) {
1687 // Get or create a COMDAT for G so that we can use it with our metadata.
1688 Comdat *C = G->getComdat();
1690 if (!G->hasName()) {
1691 // If G is unnamed, it must be internal. Give it an artificial name
1692 // so we can put it in a comdat.
1693 assert(G->hasLocalLinkage());
1694 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
1696 C = M.getOrInsertComdat(G->getName());
1697 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF.
1698 if (TargetTriple.isOSBinFormatCOFF())
1699 C->setSelectionKind(Comdat::NoDuplicates);
1704 Constant *SourceLoc;
1705 if (!MD.SourceLoc.empty()) {
1706 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1707 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1709 SourceLoc = ConstantInt::get(IntptrTy, 0);
1712 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
1713 GlobalValue *InstrumentedGlobal = NewGlobal;
1715 bool CanUsePrivateAliases =
1716 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO();
1717 if (CanUsePrivateAliases && ClUsePrivateAliasForGlobals) {
1718 // Create local alias for NewGlobal to avoid crash on ODR between
1719 // instrumented and non-instrumented libraries.
1720 auto *GA = GlobalAlias::create(GlobalValue::InternalLinkage,
1721 NameForGlobal + M.getName(), NewGlobal);
1723 // With local aliases, we need to provide another externally visible
1724 // symbol __odr_asan_XXX to detect ODR violation.
1725 auto *ODRIndicatorSym =
1726 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
1727 Constant::getNullValue(IRB.getInt8Ty()),
1728 kODRGenPrefix + NameForGlobal, nullptr,
1729 NewGlobal->getThreadLocalMode());
1731 // Set meaningful attributes for indicator symbol.
1732 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
1733 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
1734 ODRIndicatorSym->setAlignment(1);
1735 ODRIndicator = ODRIndicatorSym;
1736 InstrumentedGlobal = GA;
1739 Constant *Initializer = ConstantStruct::get(
1741 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
1742 ConstantInt::get(IntptrTy, SizeInBytes),
1743 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1744 ConstantExpr::getPointerCast(Name, IntptrTy),
1745 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1746 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
1747 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy), nullptr);
1749 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
1751 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1753 // If we aren't using separate metadata globals, add it to the initializer
1754 // list and continue.
1755 if (UseMetadataArray) {
1756 Initializers[i] = Initializer;
1760 // Create a separate metadata global and put it in the appropriate ASan
1761 // global registration section.
1762 GlobalVariable *Metadata = new GlobalVariable(
1763 M, GlobalStructTy, false, GlobalVariable::InternalLinkage,
1764 Initializer, Twine("__asan_global_") +
1765 GlobalValue::getRealLinkageName(G->getName()));
1766 Metadata->setSection(getGlobalMetadataSection());
1768 // We don't want any padding, but we also need a reasonable alignment.
1769 // The MSVC linker always inserts padding when linking incrementally. We
1770 // cope with that by aligning each struct to its size, which must be a power
1772 Metadata->setAlignment(SizeOfGlobalStruct);
1774 // On platforms that support comdats, put the metadata and the
1775 // instrumented global in the same group. This ensures that the metadata
1776 // is discarded if the instrumented global is discarded.
1777 if (UseComdatMetadata) {
1778 assert(G->hasComdat());
1779 Metadata->setComdat(G->getComdat());
1782 assert(UseMachOGlobalsSection);
1784 // On recent Mach-O platforms, we emit the global metadata in a way that
1785 // allows the linker to properly strip dead globals.
1786 auto LivenessBinder = ConstantStruct::get(
1787 LivenessTy, Initializer->getAggregateElement(0u),
1788 ConstantExpr::getPointerCast(Metadata, IntptrTy), nullptr);
1789 GlobalVariable *Liveness = new GlobalVariable(
1790 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
1791 Twine("__asan_binder_") + G->getName());
1792 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
1793 LivenessGlobals[i] = Liveness;
1796 // Create calls for poisoning before initializers run and unpoisoning after.
1797 if (HasDynamicallyInitializedGlobals)
1798 createInitializerPoisonCalls(M, ModuleName);
1800 // Platforms with a dedicated metadata section don't need to emit any more
1802 if (UseComdatMetadata)
1805 GlobalVariable *AllGlobals = nullptr;
1806 GlobalVariable *RegisteredFlag = nullptr;
1808 if (UseMachOGlobalsSection) {
1809 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
1810 // to look up the loaded image that contains it. Second, we can store in it
1811 // whether registration has already occurred, to prevent duplicate
1814 // common linkage ensures that there is only one global per shared library.
1815 RegisteredFlag = new GlobalVariable(
1816 M, IntptrTy, false, GlobalVariable::CommonLinkage,
1817 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
1818 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
1820 // Update llvm.compiler.used, adding the new liveness globals. This is
1821 // needed so that during LTO these variables stay alive. The alternative
1822 // would be to have the linker handling the LTO symbols, but libLTO
1823 // current API does not expose access to the section for each symbol.
1824 if (!LivenessGlobals.empty())
1825 appendToCompilerUsed(M, LivenessGlobals);
1826 } else if (UseMetadataArray) {
1827 // On platforms that don't have a custom metadata section, we emit an array
1828 // of global metadata structures.
1829 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1830 AllGlobals = new GlobalVariable(
1831 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1832 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1835 // Create a call to register the globals with the runtime.
1836 if (UseMachOGlobalsSection) {
1837 IRB.CreateCall(AsanRegisterImageGlobals,
1838 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1840 IRB.CreateCall(AsanRegisterGlobals,
1841 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1842 ConstantInt::get(IntptrTy, n)});
1845 // We also need to unregister globals at the end, e.g., when a shared library
1847 Function *AsanDtorFunction =
1848 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
1849 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1850 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1851 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1853 if (UseMachOGlobalsSection) {
1854 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
1855 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
1857 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
1858 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
1859 ConstantInt::get(IntptrTy, n)});
1862 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1868 bool AddressSanitizerModule::runOnModule(Module &M) {
1869 C = &(M.getContext());
1870 int LongSize = M.getDataLayout().getPointerSizeInBits();
1871 IntptrTy = Type::getIntNTy(*C, LongSize);
1872 TargetTriple = Triple(M.getTargetTriple());
1873 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1874 initializeCallbacks(M);
1876 bool Changed = false;
1878 // TODO(glider): temporarily disabled globals instrumentation for KASan.
1879 if (ClGlobals && !CompileKernel) {
1880 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1882 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1883 Changed |= InstrumentGlobals(IRB, M);
1889 void AddressSanitizer::initializeCallbacks(Module &M) {
1890 IRBuilder<> IRB(*C);
1891 // Create __asan_report* callbacks.
1892 // IsWrite, TypeSize and Exp are encoded in the function name.
1893 for (int Exp = 0; Exp < 2; Exp++) {
1894 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1895 const std::string TypeStr = AccessIsWrite ? "store" : "load";
1896 const std::string ExpStr = Exp ? "exp_" : "";
1897 const std::string SuffixStr = CompileKernel ? "N" : "_n";
1898 const std::string EndingStr = Recover ? "_noabort" : "";
1899 Type *ExpType = Exp ? Type::getInt32Ty(*C) : nullptr;
1900 AsanErrorCallbackSized[AccessIsWrite][Exp] =
1901 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1902 kAsanReportErrorTemplate + ExpStr + TypeStr + SuffixStr + EndingStr,
1903 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1904 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] =
1905 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1906 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
1907 IRB.getVoidTy(), IntptrTy, IntptrTy, ExpType, nullptr));
1908 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1909 AccessSizeIndex++) {
1910 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
1911 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1912 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1913 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
1914 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1915 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
1916 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1917 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
1918 IRB.getVoidTy(), IntptrTy, ExpType, nullptr));
1923 const std::string MemIntrinCallbackPrefix =
1924 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
1925 AsanMemmove = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1926 MemIntrinCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1927 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1928 AsanMemcpy = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1929 MemIntrinCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1930 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, nullptr));
1931 AsanMemset = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1932 MemIntrinCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1933 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, nullptr));
1935 AsanHandleNoReturnFunc = checkSanitizerInterfaceFunction(
1936 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), nullptr));
1938 AsanPtrCmpFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1939 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1940 AsanPtrSubFunction = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
1941 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
1942 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1943 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1944 StringRef(""), StringRef(""),
1945 /*hasSideEffects=*/true);
1949 bool AddressSanitizer::doInitialization(Module &M) {
1950 // Initialize the private fields. No one has accessed them before.
1954 C = &(M.getContext());
1955 LongSize = M.getDataLayout().getPointerSizeInBits();
1956 IntptrTy = Type::getIntNTy(*C, LongSize);
1957 TargetTriple = Triple(M.getTargetTriple());
1959 if (!CompileKernel) {
1960 std::tie(AsanCtorFunction, AsanInitFunction) =
1961 createSanitizerCtorAndInitFunctions(
1962 M, kAsanModuleCtorName, kAsanInitName,
1963 /*InitArgTypes=*/{}, /*InitArgs=*/{}, kAsanVersionCheckName);
1964 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1966 Mapping = getShadowMapping(TargetTriple, LongSize, CompileKernel);
1970 bool AddressSanitizer::doFinalization(Module &M) {
1975 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1976 // For each NSObject descendant having a +load method, this method is invoked
1977 // by the ObjC runtime before any of the static constructors is called.
1978 // Therefore we need to instrument such methods with a call to __asan_init
1979 // at the beginning in order to initialize our runtime before any access to
1980 // the shadow memory.
1981 // We cannot just ignore these methods, because they may call other
1982 // instrumented functions.
1983 if (F.getName().find(" load]") != std::string::npos) {
1984 IRBuilder<> IRB(&F.front(), F.front().begin());
1985 IRB.CreateCall(AsanInitFunction, {});
1991 void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
1992 // Generate code only when dynamic addressing is needed.
1993 if (Mapping.Offset != kDynamicShadowSentinel)
1996 IRBuilder<> IRB(&F.front().front());
1997 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
1998 kAsanShadowMemoryDynamicAddress, IntptrTy);
1999 LocalDynamicShadow = IRB.CreateLoad(GlobalDynamicAddress);
2002 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
2003 // Find the one possible call to llvm.localescape and pre-mark allocas passed
2004 // to it as uninteresting. This assumes we haven't started processing allocas
2005 // yet. This check is done up front because iterating the use list in
2006 // isInterestingAlloca would be algorithmically slower.
2007 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
2009 // Try to get the declaration of llvm.localescape. If it's not in the module,
2010 // we can exit early.
2011 if (!F.getParent()->getFunction("llvm.localescape")) return;
2013 // Look for a call to llvm.localescape call in the entry block. It can't be in
2015 for (Instruction &I : F.getEntryBlock()) {
2016 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2017 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2018 // We found a call. Mark all the allocas passed in as uninteresting.
2019 for (Value *Arg : II->arg_operands()) {
2020 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2021 assert(AI && AI->isStaticAlloca() &&
2022 "non-static alloca arg to localescape");
2023 ProcessedAllocas[AI] = false;
2030 bool AddressSanitizer::runOnFunction(Function &F) {
2031 if (&F == AsanCtorFunction) return false;
2032 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2033 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2034 if (F.getName().startswith("__asan_")) return false;
2036 bool FunctionModified = false;
2038 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2039 // This function needs to be called even if the function body is not
2041 if (maybeInsertAsanInitAtFunctionEntry(F))
2042 FunctionModified = true;
2044 // Leave if the function doesn't need instrumentation.
2045 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2047 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
2049 initializeCallbacks(*F.getParent());
2050 DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
2052 FunctionStateRAII CleanupObj(this);
2054 maybeInsertDynamicShadowAtFunctionEntry(F);
2056 // We can't instrument allocas used with llvm.localescape. Only static allocas
2057 // can be passed to that intrinsic.
2058 markEscapedLocalAllocas(F);
2060 // We want to instrument every address only once per basic block (unless there
2061 // are calls between uses).
2062 SmallSet<Value *, 16> TempsToInstrument;
2063 SmallVector<Instruction *, 16> ToInstrument;
2064 SmallVector<Instruction *, 8> NoReturnCalls;
2065 SmallVector<BasicBlock *, 16> AllBlocks;
2066 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2071 const TargetLibraryInfo *TLI =
2072 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI();
2074 // Fill the set of memory operations to instrument.
2075 for (auto &BB : F) {
2076 AllBlocks.push_back(&BB);
2077 TempsToInstrument.clear();
2078 int NumInsnsPerBB = 0;
2079 for (auto &Inst : BB) {
2080 if (LooksLikeCodeInBug11395(&Inst)) return false;
2081 Value *MaybeMask = nullptr;
2082 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
2083 &Alignment, &MaybeMask)) {
2084 if (ClOpt && ClOptSameTemp) {
2085 // If we have a mask, skip instrumentation if we've already
2086 // instrumented the full object. But don't add to TempsToInstrument
2087 // because we might get another load/store with a different mask.
2089 if (TempsToInstrument.count(Addr))
2090 continue; // We've seen this (whole) temp in the current BB.
2092 if (!TempsToInstrument.insert(Addr).second)
2093 continue; // We've seen this temp in the current BB.
2096 } else if (ClInvalidPointerPairs &&
2097 isInterestingPointerComparisonOrSubtraction(&Inst)) {
2098 PointerComparisonsOrSubtracts.push_back(&Inst);
2100 } else if (isa<MemIntrinsic>(Inst)) {
2103 if (isa<AllocaInst>(Inst)) NumAllocas++;
2106 // A call inside BB.
2107 TempsToInstrument.clear();
2108 if (CS.doesNotReturn()) NoReturnCalls.push_back(CS.getInstruction());
2110 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2111 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2114 ToInstrument.push_back(&Inst);
2116 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2122 (ClInstrumentationWithCallsThreshold >= 0 &&
2123 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
2124 const DataLayout &DL = F.getParent()->getDataLayout();
2125 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(),
2126 /*RoundToAlign=*/true);
2129 int NumInstrumented = 0;
2130 for (auto Inst : ToInstrument) {
2131 if (ClDebugMin < 0 || ClDebugMax < 0 ||
2132 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
2133 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
2134 instrumentMop(ObjSizeVis, Inst, UseCalls,
2135 F.getParent()->getDataLayout());
2137 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
2142 FunctionStackPoisoner FSP(F, *this);
2143 bool ChangedStack = FSP.runOnFunction();
2145 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
2146 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
2147 for (auto CI : NoReturnCalls) {
2148 IRBuilder<> IRB(CI);
2149 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2152 for (auto Inst : PointerComparisonsOrSubtracts) {
2153 instrumentPointerComparisonOrSubtraction(Inst);
2157 if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
2158 FunctionModified = true;
2160 DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
2163 return FunctionModified;
2166 // Workaround for bug 11395: we don't want to instrument stack in functions
2167 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2168 // FIXME: remove once the bug 11395 is fixed.
2169 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2170 if (LongSize != 32) return false;
2171 CallInst *CI = dyn_cast<CallInst>(I);
2172 if (!CI || !CI->isInlineAsm()) return false;
2173 if (CI->getNumArgOperands() <= 5) return false;
2174 // We have inline assembly with quite a few arguments.
2178 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2179 IRBuilder<> IRB(*C);
2180 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
2181 std::string Suffix = itostr(i);
2182 AsanStackMallocFunc[i] = checkSanitizerInterfaceFunction(
2183 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
2184 IntptrTy, nullptr));
2185 AsanStackFreeFunc[i] = checkSanitizerInterfaceFunction(
2186 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2187 IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2189 if (ASan.UseAfterScope) {
2190 AsanPoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2191 M.getOrInsertFunction(kAsanPoisonStackMemoryName, IRB.getVoidTy(),
2192 IntptrTy, IntptrTy, nullptr));
2193 AsanUnpoisonStackMemoryFunc = checkSanitizerInterfaceFunction(
2194 M.getOrInsertFunction(kAsanUnpoisonStackMemoryName, IRB.getVoidTy(),
2195 IntptrTy, IntptrTy, nullptr));
2198 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2199 std::ostringstream Name;
2200 Name << kAsanSetShadowPrefix;
2201 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2202 AsanSetShadowFunc[Val] =
2203 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2204 Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2207 AsanAllocaPoisonFunc = checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2208 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2209 AsanAllocasUnpoisonFunc =
2210 checkSanitizerInterfaceFunction(M.getOrInsertFunction(
2211 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy, nullptr));
2214 void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2215 ArrayRef<uint8_t> ShadowBytes,
2216 size_t Begin, size_t End,
2218 Value *ShadowBase) {
2222 const size_t LargestStoreSizeInBytes =
2223 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2225 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2227 // Poison given range in shadow using larges store size with out leading and
2228 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2229 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2230 // middle of a store.
2231 for (size_t i = Begin; i < End;) {
2232 if (!ShadowMask[i]) {
2233 assert(!ShadowBytes[i]);
2238 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2239 // Fit store size into the range.
2240 while (StoreSizeInBytes > End - i)
2241 StoreSizeInBytes /= 2;
2243 // Minimize store size by trimming trailing zeros.
2244 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2245 while (j <= StoreSizeInBytes / 2)
2246 StoreSizeInBytes /= 2;
2250 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2252 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
2254 Val = (Val << 8) | ShadowBytes[i + j];
2257 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
2258 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
2259 IRB.CreateAlignedStore(
2260 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
2262 i += StoreSizeInBytes;
2266 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2267 ArrayRef<uint8_t> ShadowBytes,
2268 IRBuilder<> &IRB, Value *ShadowBase) {
2269 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
2272 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2273 ArrayRef<uint8_t> ShadowBytes,
2274 size_t Begin, size_t End,
2275 IRBuilder<> &IRB, Value *ShadowBase) {
2276 assert(ShadowMask.size() == ShadowBytes.size());
2277 size_t Done = Begin;
2278 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
2279 if (!ShadowMask[i]) {
2280 assert(!ShadowBytes[i]);
2283 uint8_t Val = ShadowBytes[i];
2284 if (!AsanSetShadowFunc[Val])
2287 // Skip same values.
2288 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
2291 if (j - i >= ClMaxInlinePoisoningSize) {
2292 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
2293 IRB.CreateCall(AsanSetShadowFunc[Val],
2294 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
2295 ConstantInt::get(IntptrTy, j - i)});
2300 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
2303 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
2304 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
2305 static int StackMallocSizeClass(uint64_t LocalStackSize) {
2306 assert(LocalStackSize <= kMaxStackMallocSize);
2307 uint64_t MaxSize = kMinStackMallocSize;
2308 for (int i = 0;; i++, MaxSize *= 2)
2309 if (LocalStackSize <= MaxSize) return i;
2310 llvm_unreachable("impossible LocalStackSize");
2313 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
2315 Instruction *ThenTerm,
2316 Value *ValueIfFalse) {
2317 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
2318 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
2319 PHI->addIncoming(ValueIfFalse, CondBlock);
2320 BasicBlock *ThenBlock = ThenTerm->getParent();
2321 PHI->addIncoming(ValueIfTrue, ThenBlock);
2325 Value *FunctionStackPoisoner::createAllocaForLayout(
2326 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
2329 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
2330 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
2333 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
2334 nullptr, "MyAlloca");
2335 assert(Alloca->isStaticAlloca());
2337 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
2338 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
2339 Alloca->setAlignment(FrameAlignment);
2340 return IRB.CreatePointerCast(Alloca, IntptrTy);
2343 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
2344 BasicBlock &FirstBB = *F.begin();
2345 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
2346 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
2347 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
2348 DynamicAllocaLayout->setAlignment(32);
2351 void FunctionStackPoisoner::processDynamicAllocas() {
2352 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
2353 assert(DynamicAllocaPoisonCallVec.empty());
2357 // Insert poison calls for lifetime intrinsics for dynamic allocas.
2358 for (const auto &APC : DynamicAllocaPoisonCallVec) {
2359 assert(APC.InsBefore);
2361 assert(ASan.isInterestingAlloca(*APC.AI));
2362 assert(!APC.AI->isStaticAlloca());
2364 IRBuilder<> IRB(APC.InsBefore);
2365 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
2366 // Dynamic allocas will be unpoisoned unconditionally below in
2367 // unpoisonDynamicAllocas.
2368 // Flag that we need unpoison static allocas.
2371 // Handle dynamic allocas.
2372 createDynamicAllocasInitStorage();
2373 for (auto &AI : DynamicAllocaVec)
2374 handleDynamicAllocaCall(AI);
2375 unpoisonDynamicAllocas();
2378 void FunctionStackPoisoner::processStaticAllocas() {
2379 if (AllocaVec.empty()) {
2380 assert(StaticAllocaPoisonCallVec.empty());
2384 int StackMallocIdx = -1;
2385 DebugLoc EntryDebugLocation;
2386 if (auto SP = F.getSubprogram())
2387 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
2389 Instruction *InsBefore = AllocaVec[0];
2390 IRBuilder<> IRB(InsBefore);
2391 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2393 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
2394 // debug info is broken, because only entry-block allocas are treated as
2395 // regular stack slots.
2396 auto InsBeforeB = InsBefore->getParent();
2397 assert(InsBeforeB == &F.getEntryBlock());
2398 for (auto *AI : StaticAllocasToMoveUp)
2399 if (AI->getParent() == InsBeforeB)
2400 AI->moveBefore(InsBefore);
2402 // If we have a call to llvm.localescape, keep it in the entry block.
2403 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
2405 SmallVector<ASanStackVariableDescription, 16> SVD;
2406 SVD.reserve(AllocaVec.size());
2407 for (AllocaInst *AI : AllocaVec) {
2408 ASanStackVariableDescription D = {AI->getName().data(),
2409 ASan.getAllocaSizeInBytes(*AI),
2418 // Minimal header size (left redzone) is 4 pointers,
2419 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
2420 size_t MinHeaderSize = ASan.LongSize / 2;
2421 const ASanStackFrameLayout &L =
2422 ComputeASanStackFrameLayout(SVD, 1ULL << Mapping.Scale, MinHeaderSize);
2424 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
2425 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
2426 for (auto &Desc : SVD)
2427 AllocaToSVDMap[Desc.AI] = &Desc;
2429 // Update SVD with information from lifetime intrinsics.
2430 for (const auto &APC : StaticAllocaPoisonCallVec) {
2431 assert(APC.InsBefore);
2433 assert(ASan.isInterestingAlloca(*APC.AI));
2434 assert(APC.AI->isStaticAlloca());
2436 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2437 Desc.LifetimeSize = Desc.Size;
2438 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
2439 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
2440 if (LifetimeLoc->getFile() == FnLoc->getFile())
2441 if (unsigned Line = LifetimeLoc->getLine())
2442 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
2447 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
2448 DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
2449 uint64_t LocalStackSize = L.FrameSize;
2450 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
2451 LocalStackSize <= kMaxStackMallocSize;
2452 bool DoDynamicAlloca = ClDynamicAllocaStack;
2453 // Don't do dynamic alloca or stack malloc if:
2454 // 1) There is inline asm: too often it makes assumptions on which registers
2456 // 2) There is a returns_twice call (typically setjmp), which is
2457 // optimization-hostile, and doesn't play well with introduced indirect
2458 // register-relative calculation of local variable addresses.
2459 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2460 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
2462 Value *StaticAlloca =
2463 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
2466 Value *LocalStackBase;
2468 if (DoStackMalloc) {
2469 // void *FakeStack = __asan_option_detect_stack_use_after_return
2470 // ? __asan_stack_malloc_N(LocalStackSize)
2472 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
2473 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
2474 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
2475 Value *UseAfterReturnIsEnabled =
2476 IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUseAfterReturn),
2477 Constant::getNullValue(IRB.getInt32Ty()));
2479 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
2480 IRBuilder<> IRBIf(Term);
2481 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2482 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
2483 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
2484 Value *FakeStackValue =
2485 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
2486 ConstantInt::get(IntptrTy, LocalStackSize));
2487 IRB.SetInsertPoint(InsBefore);
2488 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2489 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
2490 ConstantInt::get(IntptrTy, 0));
2492 Value *NoFakeStack =
2493 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
2494 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
2495 IRBIf.SetInsertPoint(Term);
2496 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
2497 Value *AllocaValue =
2498 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
2499 IRB.SetInsertPoint(InsBefore);
2500 IRB.SetCurrentDebugLocation(EntryDebugLocation);
2501 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
2503 // void *FakeStack = nullptr;
2504 // void *LocalStackBase = alloca(LocalStackSize);
2505 FakeStack = ConstantInt::get(IntptrTy, 0);
2507 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
2510 // Replace Alloca instructions with base+offset.
2511 for (const auto &Desc : SVD) {
2512 AllocaInst *AI = Desc.AI;
2513 Value *NewAllocaPtr = IRB.CreateIntToPtr(
2514 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
2516 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB, /*Deref=*/true);
2517 AI->replaceAllUsesWith(NewAllocaPtr);
2520 // The left-most redzone has enough space for at least 4 pointers.
2521 // Write the Magic value to redzone[0].
2522 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
2523 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
2525 // Write the frame description constant to redzone[1].
2526 Value *BasePlus1 = IRB.CreateIntToPtr(
2527 IRB.CreateAdd(LocalStackBase,
2528 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
2530 GlobalVariable *StackDescriptionGlobal =
2531 createPrivateGlobalForString(*F.getParent(), DescriptionString,
2532 /*AllowMerging*/ true);
2533 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
2534 IRB.CreateStore(Description, BasePlus1);
2535 // Write the PC to redzone[2].
2536 Value *BasePlus2 = IRB.CreateIntToPtr(
2537 IRB.CreateAdd(LocalStackBase,
2538 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
2540 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
2542 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
2544 // Poison the stack red zones at the entry.
2545 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
2546 // As mask we must use most poisoned case: red zones and after scope.
2547 // As bytes we can use either the same or just red zones only.
2548 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
2550 if (!StaticAllocaPoisonCallVec.empty()) {
2551 const auto &ShadowInScope = GetShadowBytes(SVD, L);
2553 // Poison static allocas near lifetime intrinsics.
2554 for (const auto &APC : StaticAllocaPoisonCallVec) {
2555 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
2556 assert(Desc.Offset % L.Granularity == 0);
2557 size_t Begin = Desc.Offset / L.Granularity;
2558 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
2560 IRBuilder<> IRB(APC.InsBefore);
2561 copyToShadow(ShadowAfterScope,
2562 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
2567 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
2568 SmallVector<uint8_t, 64> ShadowAfterReturn;
2570 // (Un)poison the stack before all ret instructions.
2571 for (auto Ret : RetVec) {
2572 IRBuilder<> IRBRet(Ret);
2573 // Mark the current frame as retired.
2574 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
2576 if (DoStackMalloc) {
2577 assert(StackMallocIdx >= 0);
2578 // if FakeStack != 0 // LocalStackBase == FakeStack
2579 // // In use-after-return mode, poison the whole stack frame.
2580 // if StackMallocIdx <= 4
2581 // // For small sizes inline the whole thing:
2582 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
2583 // **SavedFlagPtr(FakeStack) = 0
2585 // __asan_stack_free_N(FakeStack, LocalStackSize)
2587 // <This is not a fake stack; unpoison the redzones>
2589 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
2590 TerminatorInst *ThenTerm, *ElseTerm;
2591 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
2593 IRBuilder<> IRBPoison(ThenTerm);
2594 if (StackMallocIdx <= 4) {
2595 int ClassSize = kMinStackMallocSize << StackMallocIdx;
2596 ShadowAfterReturn.resize(ClassSize / L.Granularity,
2597 kAsanStackUseAfterReturnMagic);
2598 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
2600 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
2602 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
2603 Value *SavedFlagPtr = IRBPoison.CreateLoad(
2604 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
2605 IRBPoison.CreateStore(
2606 Constant::getNullValue(IRBPoison.getInt8Ty()),
2607 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
2609 // For larger frames call __asan_stack_free_*.
2610 IRBPoison.CreateCall(
2611 AsanStackFreeFunc[StackMallocIdx],
2612 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
2615 IRBuilder<> IRBElse(ElseTerm);
2616 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
2618 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
2622 // We are done. Remove the old unused alloca instructions.
2623 for (auto AI : AllocaVec) AI->eraseFromParent();
2626 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
2627 IRBuilder<> &IRB, bool DoPoison) {
2628 // For now just insert the call to ASan runtime.
2629 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
2630 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
2632 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
2633 {AddrArg, SizeArg});
2636 // Handling llvm.lifetime intrinsics for a given %alloca:
2637 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
2638 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
2639 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
2640 // could be poisoned by previous llvm.lifetime.end instruction, as the
2641 // variable may go in and out of scope several times, e.g. in loops).
2642 // (3) if we poisoned at least one %alloca in a function,
2643 // unpoison the whole stack frame at function exit.
2645 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
2646 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
2647 // We're interested only in allocas we can handle.
2648 return ASan.isInterestingAlloca(*AI) ? AI : nullptr;
2649 // See if we've already calculated (or started to calculate) alloca for a
2651 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
2652 if (I != AllocaForValue.end()) return I->second;
2653 // Store 0 while we're calculating alloca for value V to avoid
2654 // infinite recursion if the value references itself.
2655 AllocaForValue[V] = nullptr;
2656 AllocaInst *Res = nullptr;
2657 if (CastInst *CI = dyn_cast<CastInst>(V))
2658 Res = findAllocaForValue(CI->getOperand(0));
2659 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
2660 for (Value *IncValue : PN->incoming_values()) {
2661 // Allow self-referencing phi-nodes.
2662 if (IncValue == PN) continue;
2663 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
2664 // AI for incoming values should exist and should all be equal.
2665 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
2669 } else if (GetElementPtrInst *EP = dyn_cast<GetElementPtrInst>(V)) {
2670 Res = findAllocaForValue(EP->getPointerOperand());
2672 DEBUG(dbgs() << "Alloca search canceled on unknown instruction: " << *V << "\n");
2674 if (Res) AllocaForValue[V] = Res;
2678 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
2679 IRBuilder<> IRB(AI);
2681 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
2682 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
2684 Value *Zero = Constant::getNullValue(IntptrTy);
2685 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
2686 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
2688 // Since we need to extend alloca with additional memory to locate
2689 // redzones, and OldSize is number of allocated blocks with
2690 // ElementSize size, get allocated memory size in bytes by
2691 // OldSize * ElementSize.
2692 const unsigned ElementSize =
2693 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
2695 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
2696 ConstantInt::get(IntptrTy, ElementSize));
2698 // PartialSize = OldSize % 32
2699 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
2701 // Misalign = kAllocaRzSize - PartialSize;
2702 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
2704 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
2705 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
2706 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
2708 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
2709 // Align is added to locate left redzone, PartialPadding for possible
2710 // partial redzone and kAllocaRzSize for right redzone respectively.
2711 Value *AdditionalChunkSize = IRB.CreateAdd(
2712 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
2714 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
2716 // Insert new alloca with new NewSize and Align params.
2717 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
2718 NewAlloca->setAlignment(Align);
2720 // NewAddress = Address + Align
2721 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
2722 ConstantInt::get(IntptrTy, Align));
2724 // Insert __asan_alloca_poison call for new created alloca.
2725 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
2727 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
2728 // for unpoisoning stuff.
2729 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
2731 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
2733 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
2734 AI->replaceAllUsesWith(NewAddressPtr);
2736 // We are done. Erase old alloca from parent.
2737 AI->eraseFromParent();
2740 // isSafeAccess returns true if Addr is always inbounds with respect to its
2741 // base object. For example, it is a field access or an array access with
2742 // constant inbounds index.
2743 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
2744 Value *Addr, uint64_t TypeSize) const {
2745 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
2746 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
2747 uint64_t Size = SizeOffset.first.getZExtValue();
2748 int64_t Offset = SizeOffset.second.getSExtValue();
2749 // Three checks are required to ensure safety:
2750 // . Offset >= 0 (since the offset is given from the base ptr)
2751 // . Size >= Offset (unsigned)
2752 // . Size - Offset >= NeededSize (unsigned)
2753 return Offset >= 0 && Size >= uint64_t(Offset) &&
2754 Size - uint64_t(Offset) >= TypeSize / 8;