1 //===-- AddressSanitizer.cpp - memory error detector ------------*- C++ -*-===// 2 // 3 // The LLVM Compiler Infrastructure 4 // 5 // This file is distributed under the University of Illinois Open Source 6 // License. See LICENSE.TXT for details. 7 // 8 //===----------------------------------------------------------------------===// 9 // 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 13 // 14 //===----------------------------------------------------------------------===// 15 16 #include "llvm/Transforms/Instrumentation.h" 17 #include "llvm/ADT/ArrayRef.h" 18 #include "llvm/ADT/DenseMap.h" 19 #include "llvm/ADT/DenseSet.h" 20 #include "llvm/ADT/DepthFirstIterator.h" 21 #include "llvm/ADT/SmallSet.h" 22 #include "llvm/ADT/SmallString.h" 23 #include "llvm/ADT/SmallVector.h" 24 #include "llvm/ADT/Statistic.h" 25 #include "llvm/ADT/StringExtras.h" 26 #include "llvm/ADT/Triple.h" 27 #include "llvm/IR/CallSite.h" 28 #include "llvm/IR/DIBuilder.h" 29 #include "llvm/IR/DataLayout.h" 30 #include "llvm/IR/Function.h" 31 #include "llvm/IR/IRBuilder.h" 32 #include "llvm/IR/InlineAsm.h" 33 #include "llvm/IR/InstVisitor.h" 34 #include "llvm/IR/IntrinsicInst.h" 35 #include "llvm/IR/LLVMContext.h" 36 #include "llvm/IR/MDBuilder.h" 37 #include "llvm/IR/Module.h" 38 #include "llvm/IR/Type.h" 39 #include "llvm/Support/CommandLine.h" 40 #include "llvm/Support/DataTypes.h" 41 #include "llvm/Support/Debug.h" 42 #include "llvm/Support/Endian.h" 43 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h" 44 #include "llvm/Transforms/Utils/BasicBlockUtils.h" 45 #include "llvm/Transforms/Utils/Cloning.h" 46 #include "llvm/Transforms/Utils/Local.h" 47 #include "llvm/Transforms/Utils/ModuleUtils.h" 48 #include <algorithm> 49 #include <string> 50 #include <system_error> 51 52 using namespace llvm; 53 54 #define DEBUG_TYPE "asan" 55 56 static const uint64_t kDefaultShadowScale = 3; 57 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29; 58 static const uint64_t kIOSShadowOffset32 = 1ULL << 30; 59 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44; 60 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G. 61 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41; 62 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000; 63 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30; 64 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46; 65 66 static const size_t kMinStackMallocSize = 1 << 6; // 64B 67 static const size_t kMaxStackMallocSize = 1 << 16; // 64K 68 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3; 69 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E; 70 71 static const char *const kAsanModuleCtorName = "asan.module_ctor"; 72 static const char *const kAsanModuleDtorName = "asan.module_dtor"; 73 static const int kAsanCtorAndDtorPriority = 1; 74 static const char *const kAsanReportErrorTemplate = "__asan_report_"; 75 static const char *const kAsanReportLoadN = "__asan_report_load_n"; 76 static const char *const kAsanReportStoreN = "__asan_report_store_n"; 77 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals"; 78 static const char *const kAsanUnregisterGlobalsName = 79 "__asan_unregister_globals"; 80 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init"; 81 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init"; 82 static const char *const kAsanInitName = "__asan_init_v4"; 83 static const char *const kAsanCovModuleInitName = "__sanitizer_cov_module_init"; 84 static const char *const kAsanCovName = "__sanitizer_cov"; 85 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp"; 86 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub"; 87 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return"; 88 static const int kMaxAsanStackMallocSizeClass = 10; 89 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_"; 90 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_"; 91 static const char *const kAsanGenPrefix = "__asan_gen_"; 92 static const char *const kAsanPoisonStackMemoryName = 93 "__asan_poison_stack_memory"; 94 static const char *const kAsanUnpoisonStackMemoryName = 95 "__asan_unpoison_stack_memory"; 96 97 static const char *const kAsanOptionDetectUAR = 98 "__asan_option_detect_stack_use_after_return"; 99 100 #ifndef NDEBUG 101 static const int kAsanStackAfterReturnMagic = 0xf5; 102 #endif 103 104 // Accesses sizes are powers of two: 1, 2, 4, 8, 16. 105 static const size_t kNumberOfAccessSizes = 5; 106 107 // Command-line flags. 108 109 // This flag may need to be replaced with -f[no-]asan-reads. 110 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads", 111 cl::desc("instrument read instructions"), cl::Hidden, cl::init(true)); 112 static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes", 113 cl::desc("instrument write instructions"), cl::Hidden, cl::init(true)); 114 static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics", 115 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), 116 cl::Hidden, cl::init(true)); 117 static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path", 118 cl::desc("use instrumentation with slow path for all accesses"), 119 cl::Hidden, cl::init(false)); 120 // This flag limits the number of instructions to be instrumented 121 // in any given BB. Normally, this should be set to unlimited (INT_MAX), 122 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary 123 // set it to 10000. 124 static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb", 125 cl::init(10000), 126 cl::desc("maximal number of instructions to instrument in any given BB"), 127 cl::Hidden); 128 // This flag may need to be replaced with -f[no]asan-stack. 129 static cl::opt<bool> ClStack("asan-stack", 130 cl::desc("Handle stack memory"), cl::Hidden, cl::init(true)); 131 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return", 132 cl::desc("Check return-after-free"), cl::Hidden, cl::init(true)); 133 // This flag may need to be replaced with -f[no]asan-globals. 134 static cl::opt<bool> ClGlobals("asan-globals", 135 cl::desc("Handle global objects"), cl::Hidden, cl::init(true)); 136 static cl::opt<int> ClCoverage("asan-coverage", 137 cl::desc("ASan coverage. 0: none, 1: entry block, 2: all blocks"), 138 cl::Hidden, cl::init(false)); 139 static cl::opt<int> ClCoverageBlockThreshold("asan-coverage-block-threshold", 140 cl::desc("Add coverage instrumentation only to the entry block if there " 141 "are more than this number of blocks."), 142 cl::Hidden, cl::init(1500)); 143 static cl::opt<bool> ClInitializers("asan-initialization-order", 144 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(true)); 145 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair", 146 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), 147 cl::Hidden, cl::init(false)); 148 static cl::opt<unsigned> ClRealignStack("asan-realign-stack", 149 cl::desc("Realign stack to the value of this flag (power of two)"), 150 cl::Hidden, cl::init(32)); 151 static cl::opt<int> ClInstrumentationWithCallsThreshold( 152 "asan-instrumentation-with-call-threshold", 153 cl::desc("If the function being instrumented contains more than " 154 "this number of memory accesses, use callbacks instead of " 155 "inline checks (-1 means never use callbacks)."), 156 cl::Hidden, cl::init(7000)); 157 static cl::opt<std::string> ClMemoryAccessCallbackPrefix( 158 "asan-memory-access-callback-prefix", 159 cl::desc("Prefix for memory access callbacks"), cl::Hidden, 160 cl::init("__asan_")); 161 162 // This is an experimental feature that will allow to choose between 163 // instrumented and non-instrumented code at link-time. 164 // If this option is on, just before instrumenting a function we create its 165 // clone; if the function is not changed by asan the clone is deleted. 166 // If we end up with a clone, we put the instrumented function into a section 167 // called "ASAN" and the uninstrumented function into a section called "NOASAN". 168 // 169 // This is still a prototype, we need to figure out a way to keep two copies of 170 // a function so that the linker can easily choose one of them. 171 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions", 172 cl::desc("Keep uninstrumented copies of functions"), 173 cl::Hidden, cl::init(false)); 174 175 // These flags allow to change the shadow mapping. 176 // The shadow mapping looks like 177 // Shadow = (Mem >> scale) + (1 << offset_log) 178 static cl::opt<int> ClMappingScale("asan-mapping-scale", 179 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0)); 180 181 // Optimization flags. Not user visible, used mostly for testing 182 // and benchmarking the tool. 183 static cl::opt<bool> ClOpt("asan-opt", 184 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true)); 185 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp", 186 cl::desc("Instrument the same temp just once"), cl::Hidden, 187 cl::init(true)); 188 static cl::opt<bool> ClOptGlobals("asan-opt-globals", 189 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true)); 190 191 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime", 192 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"), 193 cl::Hidden, cl::init(false)); 194 195 // Debug flags. 196 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden, 197 cl::init(0)); 198 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"), 199 cl::Hidden, cl::init(0)); 200 static cl::opt<std::string> ClDebugFunc("asan-debug-func", 201 cl::Hidden, cl::desc("Debug func")); 202 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"), 203 cl::Hidden, cl::init(-1)); 204 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"), 205 cl::Hidden, cl::init(-1)); 206 207 STATISTIC(NumInstrumentedReads, "Number of instrumented reads"); 208 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes"); 209 STATISTIC(NumOptimizedAccessesToGlobalArray, 210 "Number of optimized accesses to global arrays"); 211 STATISTIC(NumOptimizedAccessesToGlobalVar, 212 "Number of optimized accesses to global vars"); 213 214 namespace { 215 /// Frontend-provided metadata for global variables. 216 class GlobalsMetadata { 217 public: 218 GlobalsMetadata() : inited_(false) {} 219 void init(Module& M) { 220 assert(!inited_); 221 inited_ = true; 222 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals"); 223 if (!Globals) 224 return; 225 for (auto MDN : Globals->operands()) { 226 // Format of the metadata node for the global: 227 // { 228 // global, 229 // source_location, 230 // i1 is_dynamically_initialized, 231 // i1 is_blacklisted 232 // } 233 assert(MDN->getNumOperands() == 4); 234 Value *V = MDN->getOperand(0); 235 // The optimizer may optimize away a global entirely. 236 if (!V) 237 continue; 238 GlobalVariable *GV = cast<GlobalVariable>(V); 239 if (Value *Loc = MDN->getOperand(1)) { 240 GlobalVariable *GVLoc = cast<GlobalVariable>(Loc); 241 // We may already know the source location for GV, if it was merged 242 // with another global. 243 if (SourceLocation.insert(std::make_pair(GV, GVLoc)).second) 244 addSourceLocationGlobal(GVLoc); 245 } 246 ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(2)); 247 if (IsDynInit->isOne()) 248 DynInitGlobals.insert(GV); 249 ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(3)); 250 if (IsBlacklisted->isOne()) 251 BlacklistedGlobals.insert(GV); 252 } 253 } 254 255 GlobalVariable *getSourceLocation(GlobalVariable *G) const { 256 auto Pos = SourceLocation.find(G); 257 return (Pos != SourceLocation.end()) ? Pos->second : nullptr; 258 } 259 260 /// Check if the global is dynamically initialized. 261 bool isDynInit(GlobalVariable *G) const { 262 return DynInitGlobals.count(G); 263 } 264 265 /// Check if the global was blacklisted. 266 bool isBlacklisted(GlobalVariable *G) const { 267 return BlacklistedGlobals.count(G); 268 } 269 270 /// Check if the global was generated to describe source location of another 271 /// global (we don't want to instrument them). 272 bool isSourceLocationGlobal(GlobalVariable *G) const { 273 return LocationGlobals.count(G); 274 } 275 276 private: 277 bool inited_; 278 DenseMap<GlobalVariable*, GlobalVariable*> SourceLocation; 279 DenseSet<GlobalVariable*> DynInitGlobals; 280 DenseSet<GlobalVariable*> BlacklistedGlobals; 281 DenseSet<GlobalVariable*> LocationGlobals; 282 283 void addSourceLocationGlobal(GlobalVariable *SourceLocGV) { 284 // Source location global is a struct with layout: 285 // { 286 // filename, 287 // i32 line_number, 288 // i32 column_number, 289 // } 290 LocationGlobals.insert(SourceLocGV); 291 ConstantStruct *Contents = 292 cast<ConstantStruct>(SourceLocGV->getInitializer()); 293 GlobalVariable *FilenameGV = cast<GlobalVariable>(Contents->getOperand(0)); 294 LocationGlobals.insert(FilenameGV); 295 } 296 }; 297 298 /// This struct defines the shadow mapping using the rule: 299 /// shadow = (mem >> Scale) ADD-or-OR Offset. 300 struct ShadowMapping { 301 int Scale; 302 uint64_t Offset; 303 bool OrShadowOffset; 304 }; 305 306 static ShadowMapping getShadowMapping(const Module &M, int LongSize) { 307 llvm::Triple TargetTriple(M.getTargetTriple()); 308 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android; 309 bool IsIOS = TargetTriple.getOS() == llvm::Triple::IOS; 310 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD; 311 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux; 312 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 || 313 TargetTriple.getArch() == llvm::Triple::ppc64le; 314 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64; 315 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips || 316 TargetTriple.getArch() == llvm::Triple::mipsel; 317 318 ShadowMapping Mapping; 319 320 if (LongSize == 32) { 321 if (IsAndroid) 322 Mapping.Offset = 0; 323 else if (IsMIPS32) 324 Mapping.Offset = kMIPS32_ShadowOffset32; 325 else if (IsFreeBSD) 326 Mapping.Offset = kFreeBSD_ShadowOffset32; 327 else if (IsIOS) 328 Mapping.Offset = kIOSShadowOffset32; 329 else 330 Mapping.Offset = kDefaultShadowOffset32; 331 } else { // LongSize == 64 332 if (IsPPC64) 333 Mapping.Offset = kPPC64_ShadowOffset64; 334 else if (IsFreeBSD) 335 Mapping.Offset = kFreeBSD_ShadowOffset64; 336 else if (IsLinux && IsX86_64) 337 Mapping.Offset = kSmallX86_64ShadowOffset; 338 else 339 Mapping.Offset = kDefaultShadowOffset64; 340 } 341 342 Mapping.Scale = kDefaultShadowScale; 343 if (ClMappingScale) { 344 Mapping.Scale = ClMappingScale; 345 } 346 347 // OR-ing shadow offset if more efficient (at least on x86) if the offset 348 // is a power of two, but on ppc64 we have to use add since the shadow 349 // offset is not necessary 1/8-th of the address space. 350 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1)); 351 352 return Mapping; 353 } 354 355 static size_t RedzoneSizeForScale(int MappingScale) { 356 // Redzone used for stack and globals is at least 32 bytes. 357 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively. 358 return std::max(32U, 1U << MappingScale); 359 } 360 361 /// AddressSanitizer: instrument the code in module to find memory bugs. 362 struct AddressSanitizer : public FunctionPass { 363 AddressSanitizer() : FunctionPass(ID) {} 364 const char *getPassName() const override { 365 return "AddressSanitizerFunctionPass"; 366 } 367 void instrumentMop(Instruction *I, bool UseCalls); 368 void instrumentPointerComparisonOrSubtraction(Instruction *I); 369 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore, 370 Value *Addr, uint32_t TypeSize, bool IsWrite, 371 Value *SizeArgument, bool UseCalls); 372 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong, 373 Value *ShadowValue, uint32_t TypeSize); 374 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr, 375 bool IsWrite, size_t AccessSizeIndex, 376 Value *SizeArgument); 377 void instrumentMemIntrinsic(MemIntrinsic *MI); 378 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB); 379 bool runOnFunction(Function &F) override; 380 bool maybeInsertAsanInitAtFunctionEntry(Function &F); 381 bool doInitialization(Module &M) override; 382 static char ID; // Pass identification, replacement for typeid 383 384 private: 385 void initializeCallbacks(Module &M); 386 387 bool LooksLikeCodeInBug11395(Instruction *I); 388 bool GlobalIsLinkerInitialized(GlobalVariable *G); 389 bool InjectCoverage(Function &F, const ArrayRef<BasicBlock*> AllBlocks); 390 void InjectCoverageAtBlock(Function &F, BasicBlock &BB); 391 392 LLVMContext *C; 393 const DataLayout *DL; 394 int LongSize; 395 Type *IntptrTy; 396 ShadowMapping Mapping; 397 Function *AsanCtorFunction; 398 Function *AsanInitFunction; 399 Function *AsanHandleNoReturnFunc; 400 Function *AsanCovFunction; 401 Function *AsanPtrCmpFunction, *AsanPtrSubFunction; 402 // This array is indexed by AccessIsWrite and log2(AccessSize). 403 Function *AsanErrorCallback[2][kNumberOfAccessSizes]; 404 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes]; 405 // This array is indexed by AccessIsWrite. 406 Function *AsanErrorCallbackSized[2], 407 *AsanMemoryAccessCallbackSized[2]; 408 Function *AsanMemmove, *AsanMemcpy, *AsanMemset; 409 InlineAsm *EmptyAsm; 410 GlobalsMetadata GlobalsMD; 411 412 friend struct FunctionStackPoisoner; 413 }; 414 415 class AddressSanitizerModule : public ModulePass { 416 public: 417 AddressSanitizerModule() : ModulePass(ID) {} 418 bool runOnModule(Module &M) override; 419 static char ID; // Pass identification, replacement for typeid 420 const char *getPassName() const override { 421 return "AddressSanitizerModule"; 422 } 423 424 private: 425 void initializeCallbacks(Module &M); 426 427 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M); 428 bool ShouldInstrumentGlobal(GlobalVariable *G); 429 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName); 430 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName); 431 size_t MinRedzoneSizeForGlobal() const { 432 return RedzoneSizeForScale(Mapping.Scale); 433 } 434 435 GlobalsMetadata GlobalsMD; 436 Type *IntptrTy; 437 LLVMContext *C; 438 const DataLayout *DL; 439 ShadowMapping Mapping; 440 Function *AsanPoisonGlobals; 441 Function *AsanUnpoisonGlobals; 442 Function *AsanRegisterGlobals; 443 Function *AsanUnregisterGlobals; 444 Function *AsanCovModuleInit; 445 }; 446 447 // Stack poisoning does not play well with exception handling. 448 // When an exception is thrown, we essentially bypass the code 449 // that unpoisones the stack. This is why the run-time library has 450 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire 451 // stack in the interceptor. This however does not work inside the 452 // actual function which catches the exception. Most likely because the 453 // compiler hoists the load of the shadow value somewhere too high. 454 // This causes asan to report a non-existing bug on 453.povray. 455 // It sounds like an LLVM bug. 456 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> { 457 Function &F; 458 AddressSanitizer &ASan; 459 DIBuilder DIB; 460 LLVMContext *C; 461 Type *IntptrTy; 462 Type *IntptrPtrTy; 463 ShadowMapping Mapping; 464 465 SmallVector<AllocaInst*, 16> AllocaVec; 466 SmallVector<Instruction*, 8> RetVec; 467 unsigned StackAlignment; 468 469 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1], 470 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1]; 471 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc; 472 473 // Stores a place and arguments of poisoning/unpoisoning call for alloca. 474 struct AllocaPoisonCall { 475 IntrinsicInst *InsBefore; 476 AllocaInst *AI; 477 uint64_t Size; 478 bool DoPoison; 479 }; 480 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec; 481 482 // Maps Value to an AllocaInst from which the Value is originated. 483 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy; 484 AllocaForValueMapTy AllocaForValue; 485 486 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan) 487 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C), 488 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)), 489 Mapping(ASan.Mapping), 490 StackAlignment(1 << Mapping.Scale) {} 491 492 bool runOnFunction() { 493 if (!ClStack) return false; 494 // Collect alloca, ret, lifetime instructions etc. 495 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) 496 visit(*BB); 497 498 if (AllocaVec.empty()) return false; 499 500 initializeCallbacks(*F.getParent()); 501 502 poisonStack(); 503 504 if (ClDebugStack) { 505 DEBUG(dbgs() << F); 506 } 507 return true; 508 } 509 510 // Finds all static Alloca instructions and puts 511 // poisoned red zones around all of them. 512 // Then unpoison everything back before the function returns. 513 void poisonStack(); 514 515 // ----------------------- Visitors. 516 /// \brief Collect all Ret instructions. 517 void visitReturnInst(ReturnInst &RI) { 518 RetVec.push_back(&RI); 519 } 520 521 /// \brief Collect Alloca instructions we want (and can) handle. 522 void visitAllocaInst(AllocaInst &AI) { 523 if (!isInterestingAlloca(AI)) return; 524 525 StackAlignment = std::max(StackAlignment, AI.getAlignment()); 526 AllocaVec.push_back(&AI); 527 } 528 529 /// \brief Collect lifetime intrinsic calls to check for use-after-scope 530 /// errors. 531 void visitIntrinsicInst(IntrinsicInst &II) { 532 if (!ClCheckLifetime) return; 533 Intrinsic::ID ID = II.getIntrinsicID(); 534 if (ID != Intrinsic::lifetime_start && 535 ID != Intrinsic::lifetime_end) 536 return; 537 // Found lifetime intrinsic, add ASan instrumentation if necessary. 538 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0)); 539 // If size argument is undefined, don't do anything. 540 if (Size->isMinusOne()) return; 541 // Check that size doesn't saturate uint64_t and can 542 // be stored in IntptrTy. 543 const uint64_t SizeValue = Size->getValue().getLimitedValue(); 544 if (SizeValue == ~0ULL || 545 !ConstantInt::isValueValidForType(IntptrTy, SizeValue)) 546 return; 547 // Find alloca instruction that corresponds to llvm.lifetime argument. 548 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1)); 549 if (!AI) return; 550 bool DoPoison = (ID == Intrinsic::lifetime_end); 551 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison}; 552 AllocaPoisonCallVec.push_back(APC); 553 } 554 555 // ---------------------- Helpers. 556 void initializeCallbacks(Module &M); 557 558 // Check if we want (and can) handle this alloca. 559 bool isInterestingAlloca(AllocaInst &AI) const { 560 return (!AI.isArrayAllocation() && AI.isStaticAlloca() && 561 AI.getAllocatedType()->isSized() && 562 // alloca() may be called with 0 size, ignore it. 563 getAllocaSizeInBytes(&AI) > 0); 564 } 565 566 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const { 567 Type *Ty = AI->getAllocatedType(); 568 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty); 569 return SizeInBytes; 570 } 571 /// Finds alloca where the value comes from. 572 AllocaInst *findAllocaForValue(Value *V); 573 void poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB, 574 Value *ShadowBase, bool DoPoison); 575 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison); 576 577 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase, 578 int Size); 579 }; 580 581 } // namespace 582 583 char AddressSanitizer::ID = 0; 584 INITIALIZE_PASS(AddressSanitizer, "asan", 585 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", 586 false, false) 587 FunctionPass *llvm::createAddressSanitizerFunctionPass() { 588 return new AddressSanitizer(); 589 } 590 591 char AddressSanitizerModule::ID = 0; 592 INITIALIZE_PASS(AddressSanitizerModule, "asan-module", 593 "AddressSanitizer: detects use-after-free and out-of-bounds bugs." 594 "ModulePass", false, false) 595 ModulePass *llvm::createAddressSanitizerModulePass() { 596 return new AddressSanitizerModule(); 597 } 598 599 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) { 600 size_t Res = countTrailingZeros(TypeSize / 8); 601 assert(Res < kNumberOfAccessSizes); 602 return Res; 603 } 604 605 // \brief Create a constant for Str so that we can pass it to the run-time lib. 606 static GlobalVariable *createPrivateGlobalForString( 607 Module &M, StringRef Str, bool AllowMerging) { 608 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str); 609 // We use private linkage for module-local strings. If they can be merged 610 // with another one, we set the unnamed_addr attribute. 611 GlobalVariable *GV = 612 new GlobalVariable(M, StrConst->getType(), true, 613 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix); 614 if (AllowMerging) 615 GV->setUnnamedAddr(true); 616 GV->setAlignment(1); // Strings may not be merged w/o setting align 1. 617 return GV; 618 } 619 620 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) { 621 return G->getName().find(kAsanGenPrefix) == 0; 622 } 623 624 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) { 625 // Shadow >> scale 626 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale); 627 if (Mapping.Offset == 0) 628 return Shadow; 629 // (Shadow >> scale) | offset 630 if (Mapping.OrShadowOffset) 631 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset)); 632 else 633 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset)); 634 } 635 636 // Instrument memset/memmove/memcpy 637 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) { 638 IRBuilder<> IRB(MI); 639 if (isa<MemTransferInst>(MI)) { 640 IRB.CreateCall3( 641 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy, 642 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()), 643 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()), 644 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)); 645 } else if (isa<MemSetInst>(MI)) { 646 IRB.CreateCall3( 647 AsanMemset, 648 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()), 649 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false), 650 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)); 651 } 652 MI->eraseFromParent(); 653 } 654 655 // If I is an interesting memory access, return the PointerOperand 656 // and set IsWrite/Alignment. Otherwise return NULL. 657 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite, 658 unsigned *Alignment) { 659 if (LoadInst *LI = dyn_cast<LoadInst>(I)) { 660 if (!ClInstrumentReads) return nullptr; 661 *IsWrite = false; 662 *Alignment = LI->getAlignment(); 663 return LI->getPointerOperand(); 664 } 665 if (StoreInst *SI = dyn_cast<StoreInst>(I)) { 666 if (!ClInstrumentWrites) return nullptr; 667 *IsWrite = true; 668 *Alignment = SI->getAlignment(); 669 return SI->getPointerOperand(); 670 } 671 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) { 672 if (!ClInstrumentAtomics) return nullptr; 673 *IsWrite = true; 674 *Alignment = 0; 675 return RMW->getPointerOperand(); 676 } 677 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) { 678 if (!ClInstrumentAtomics) return nullptr; 679 *IsWrite = true; 680 *Alignment = 0; 681 return XCHG->getPointerOperand(); 682 } 683 return nullptr; 684 } 685 686 static bool isPointerOperand(Value *V) { 687 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V); 688 } 689 690 // This is a rough heuristic; it may cause both false positives and 691 // false negatives. The proper implementation requires cooperation with 692 // the frontend. 693 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) { 694 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) { 695 if (!Cmp->isRelational()) 696 return false; 697 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) { 698 if (BO->getOpcode() != Instruction::Sub) 699 return false; 700 } else { 701 return false; 702 } 703 if (!isPointerOperand(I->getOperand(0)) || 704 !isPointerOperand(I->getOperand(1))) 705 return false; 706 return true; 707 } 708 709 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) { 710 // If a global variable does not have dynamic initialization we don't 711 // have to instrument it. However, if a global does not have initializer 712 // at all, we assume it has dynamic initializer (in other TU). 713 return G->hasInitializer() && !GlobalsMD.isDynInit(G); 714 } 715 716 void 717 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) { 718 IRBuilder<> IRB(I); 719 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction; 720 Value *Param[2] = {I->getOperand(0), I->getOperand(1)}; 721 for (int i = 0; i < 2; i++) { 722 if (Param[i]->getType()->isPointerTy()) 723 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy); 724 } 725 IRB.CreateCall2(F, Param[0], Param[1]); 726 } 727 728 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) { 729 bool IsWrite = false; 730 unsigned Alignment = 0; 731 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment); 732 assert(Addr); 733 if (ClOpt && ClOptGlobals) { 734 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) { 735 // If initialization order checking is disabled, a simple access to a 736 // dynamically initialized global is always valid. 737 if (!ClInitializers || GlobalIsLinkerInitialized(G)) { 738 NumOptimizedAccessesToGlobalVar++; 739 return; 740 } 741 } 742 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr); 743 if (CE && CE->isGEPWithNoNotionalOverIndexing()) { 744 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) { 745 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) { 746 NumOptimizedAccessesToGlobalArray++; 747 return; 748 } 749 } 750 } 751 } 752 753 Type *OrigPtrTy = Addr->getType(); 754 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType(); 755 756 assert(OrigTy->isSized()); 757 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy); 758 759 assert((TypeSize % 8) == 0); 760 761 if (IsWrite) 762 NumInstrumentedWrites++; 763 else 764 NumInstrumentedReads++; 765 766 unsigned Granularity = 1 << Mapping.Scale; 767 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check 768 // if the data is properly aligned. 769 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 || 770 TypeSize == 128) && 771 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8)) 772 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls); 773 // Instrument unusual size or unusual alignment. 774 // We can not do it with a single check, so we do 1-byte check for the first 775 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able 776 // to report the actual access size. 777 IRBuilder<> IRB(I); 778 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8); 779 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); 780 if (UseCalls) { 781 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size); 782 } else { 783 Value *LastByte = IRB.CreateIntToPtr( 784 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)), 785 OrigPtrTy); 786 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false); 787 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false); 788 } 789 } 790 791 // Validate the result of Module::getOrInsertFunction called for an interface 792 // function of AddressSanitizer. If the instrumented module defines a function 793 // with the same name, their prototypes must match, otherwise 794 // getOrInsertFunction returns a bitcast. 795 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) { 796 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast); 797 FuncOrBitcast->dump(); 798 report_fatal_error("trying to redefine an AddressSanitizer " 799 "interface function"); 800 } 801 802 Instruction *AddressSanitizer::generateCrashCode( 803 Instruction *InsertBefore, Value *Addr, 804 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) { 805 IRBuilder<> IRB(InsertBefore); 806 CallInst *Call = SizeArgument 807 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument) 808 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr); 809 810 // We don't do Call->setDoesNotReturn() because the BB already has 811 // UnreachableInst at the end. 812 // This EmptyAsm is required to avoid callback merge. 813 IRB.CreateCall(EmptyAsm); 814 return Call; 815 } 816 817 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong, 818 Value *ShadowValue, 819 uint32_t TypeSize) { 820 size_t Granularity = 1 << Mapping.Scale; 821 // Addr & (Granularity - 1) 822 Value *LastAccessedByte = IRB.CreateAnd( 823 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1)); 824 // (Addr & (Granularity - 1)) + size - 1 825 if (TypeSize / 8 > 1) 826 LastAccessedByte = IRB.CreateAdd( 827 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)); 828 // (uint8_t) ((Addr & (Granularity-1)) + size - 1) 829 LastAccessedByte = IRB.CreateIntCast( 830 LastAccessedByte, ShadowValue->getType(), false); 831 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue 832 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue); 833 } 834 835 void AddressSanitizer::instrumentAddress(Instruction *OrigIns, 836 Instruction *InsertBefore, Value *Addr, 837 uint32_t TypeSize, bool IsWrite, 838 Value *SizeArgument, bool UseCalls) { 839 IRBuilder<> IRB(InsertBefore); 840 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy); 841 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize); 842 843 if (UseCalls) { 844 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex], 845 AddrLong); 846 return; 847 } 848 849 Type *ShadowTy = IntegerType::get( 850 *C, std::max(8U, TypeSize >> Mapping.Scale)); 851 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0); 852 Value *ShadowPtr = memToShadow(AddrLong, IRB); 853 Value *CmpVal = Constant::getNullValue(ShadowTy); 854 Value *ShadowValue = IRB.CreateLoad( 855 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy)); 856 857 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal); 858 size_t Granularity = 1 << Mapping.Scale; 859 TerminatorInst *CrashTerm = nullptr; 860 861 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) { 862 TerminatorInst *CheckTerm = 863 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false); 864 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional()); 865 BasicBlock *NextBB = CheckTerm->getSuccessor(0); 866 IRB.SetInsertPoint(CheckTerm); 867 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize); 868 BasicBlock *CrashBlock = 869 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB); 870 CrashTerm = new UnreachableInst(*C, CrashBlock); 871 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2); 872 ReplaceInstWithInst(CheckTerm, NewTerm); 873 } else { 874 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true); 875 } 876 877 Instruction *Crash = generateCrashCode( 878 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument); 879 Crash->setDebugLoc(OrigIns->getDebugLoc()); 880 } 881 882 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit, 883 GlobalValue *ModuleName) { 884 // Set up the arguments to our poison/unpoison functions. 885 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt()); 886 887 // Add a call to poison all external globals before the given function starts. 888 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy); 889 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr); 890 891 // Add calls to unpoison all globals before each return instruction. 892 for (auto &BB : GlobalInit.getBasicBlockList()) 893 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator())) 894 CallInst::Create(AsanUnpoisonGlobals, "", RI); 895 } 896 897 void AddressSanitizerModule::createInitializerPoisonCalls( 898 Module &M, GlobalValue *ModuleName) { 899 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors"); 900 901 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer()); 902 for (Use &OP : CA->operands()) { 903 if (isa<ConstantAggregateZero>(OP)) 904 continue; 905 ConstantStruct *CS = cast<ConstantStruct>(OP); 906 907 // Must have a function or null ptr. 908 // (CS->getOperand(0) is the init priority.) 909 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) { 910 if (F->getName() != kAsanModuleCtorName) 911 poisonOneInitializer(*F, ModuleName); 912 } 913 } 914 } 915 916 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) { 917 Type *Ty = cast<PointerType>(G->getType())->getElementType(); 918 DEBUG(dbgs() << "GLOBAL: " << *G << "\n"); 919 920 if (GlobalsMD.isBlacklisted(G)) return false; 921 if (GlobalsMD.isSourceLocationGlobal(G)) return false; 922 if (!Ty->isSized()) return false; 923 if (!G->hasInitializer()) return false; 924 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global. 925 // Touch only those globals that will not be defined in other modules. 926 // Don't handle ODR linkage types and COMDATs since other modules may be built 927 // without ASan. 928 if (G->getLinkage() != GlobalVariable::ExternalLinkage && 929 G->getLinkage() != GlobalVariable::PrivateLinkage && 930 G->getLinkage() != GlobalVariable::InternalLinkage) 931 return false; 932 if (G->hasComdat()) 933 return false; 934 // Two problems with thread-locals: 935 // - The address of the main thread's copy can't be computed at link-time. 936 // - Need to poison all copies, not just the main thread's one. 937 if (G->isThreadLocal()) 938 return false; 939 // For now, just ignore this Global if the alignment is large. 940 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false; 941 942 // Ignore all the globals with the names starting with "\01L_OBJC_". 943 // Many of those are put into the .cstring section. The linker compresses 944 // that section by removing the spare \0s after the string terminator, so 945 // our redzones get broken. 946 if ((G->getName().find("\01L_OBJC_") == 0) || 947 (G->getName().find("\01l_OBJC_") == 0)) { 948 DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G << "\n"); 949 return false; 950 } 951 952 if (G->hasSection()) { 953 StringRef Section(G->getSection()); 954 // Ignore the globals from the __OBJC section. The ObjC runtime assumes 955 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to 956 // them. 957 if (Section.startswith("__OBJC,") || 958 Section.startswith("__DATA, __objc_")) { 959 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n"); 960 return false; 961 } 962 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32 963 // Constant CFString instances are compiled in the following way: 964 // -- the string buffer is emitted into 965 // __TEXT,__cstring,cstring_literals 966 // -- the constant NSConstantString structure referencing that buffer 967 // is placed into __DATA,__cfstring 968 // Therefore there's no point in placing redzones into __DATA,__cfstring. 969 // Moreover, it causes the linker to crash on OS X 10.7 970 if (Section.startswith("__DATA,__cfstring")) { 971 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n"); 972 return false; 973 } 974 // The linker merges the contents of cstring_literals and removes the 975 // trailing zeroes. 976 if (Section.startswith("__TEXT,__cstring,cstring_literals")) { 977 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n"); 978 return false; 979 } 980 981 // Callbacks put into the CRT initializer/terminator sections 982 // should not be instrumented. 983 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305 984 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx 985 if (Section.startswith(".CRT")) { 986 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n"); 987 return false; 988 } 989 990 // Globals from llvm.metadata aren't emitted, do not instrument them. 991 if (Section == "llvm.metadata") return false; 992 } 993 994 return true; 995 } 996 997 void AddressSanitizerModule::initializeCallbacks(Module &M) { 998 IRBuilder<> IRB(*C); 999 // Declare our poisoning and unpoisoning functions. 1000 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction( 1001 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL)); 1002 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage); 1003 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction( 1004 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL)); 1005 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage); 1006 // Declare functions that register/unregister globals. 1007 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction( 1008 kAsanRegisterGlobalsName, IRB.getVoidTy(), 1009 IntptrTy, IntptrTy, NULL)); 1010 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage); 1011 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction( 1012 kAsanUnregisterGlobalsName, 1013 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1014 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage); 1015 AsanCovModuleInit = checkInterfaceFunction(M.getOrInsertFunction( 1016 kAsanCovModuleInitName, 1017 IRB.getVoidTy(), IntptrTy, NULL)); 1018 AsanCovModuleInit->setLinkage(Function::ExternalLinkage); 1019 } 1020 1021 // This function replaces all global variables with new variables that have 1022 // trailing redzones. It also creates a function that poisons 1023 // redzones and inserts this function into llvm.global_ctors. 1024 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) { 1025 GlobalsMD.init(M); 1026 1027 SmallVector<GlobalVariable *, 16> GlobalsToChange; 1028 1029 for (auto &G : M.globals()) { 1030 if (ShouldInstrumentGlobal(&G)) 1031 GlobalsToChange.push_back(&G); 1032 } 1033 1034 size_t n = GlobalsToChange.size(); 1035 if (n == 0) return false; 1036 1037 // A global is described by a structure 1038 // size_t beg; 1039 // size_t size; 1040 // size_t size_with_redzone; 1041 // const char *name; 1042 // const char *module_name; 1043 // size_t has_dynamic_init; 1044 // void *source_location; 1045 // We initialize an array of such structures and pass it to a run-time call. 1046 StructType *GlobalStructTy = 1047 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy, 1048 IntptrTy, IntptrTy, NULL); 1049 SmallVector<Constant *, 16> Initializers(n); 1050 1051 bool HasDynamicallyInitializedGlobals = false; 1052 1053 // We shouldn't merge same module names, as this string serves as unique 1054 // module ID in runtime. 1055 GlobalVariable *ModuleName = createPrivateGlobalForString( 1056 M, M.getModuleIdentifier(), /*AllowMerging*/false); 1057 1058 for (size_t i = 0; i < n; i++) { 1059 static const uint64_t kMaxGlobalRedzone = 1 << 18; 1060 GlobalVariable *G = GlobalsToChange[i]; 1061 PointerType *PtrTy = cast<PointerType>(G->getType()); 1062 Type *Ty = PtrTy->getElementType(); 1063 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty); 1064 uint64_t MinRZ = MinRedzoneSizeForGlobal(); 1065 // MinRZ <= RZ <= kMaxGlobalRedzone 1066 // and trying to make RZ to be ~ 1/4 of SizeInBytes. 1067 uint64_t RZ = std::max(MinRZ, 1068 std::min(kMaxGlobalRedzone, 1069 (SizeInBytes / MinRZ / 4) * MinRZ)); 1070 uint64_t RightRedzoneSize = RZ; 1071 // Round up to MinRZ 1072 if (SizeInBytes % MinRZ) 1073 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ); 1074 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0); 1075 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize); 1076 1077 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL); 1078 Constant *NewInitializer = ConstantStruct::get( 1079 NewTy, G->getInitializer(), 1080 Constant::getNullValue(RightRedZoneTy), NULL); 1081 1082 GlobalVariable *Name = 1083 createPrivateGlobalForString(M, G->getName(), /*AllowMerging*/true); 1084 1085 // Create a new global variable with enough space for a redzone. 1086 GlobalValue::LinkageTypes Linkage = G->getLinkage(); 1087 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage) 1088 Linkage = GlobalValue::InternalLinkage; 1089 GlobalVariable *NewGlobal = new GlobalVariable( 1090 M, NewTy, G->isConstant(), Linkage, 1091 NewInitializer, "", G, G->getThreadLocalMode()); 1092 NewGlobal->copyAttributesFrom(G); 1093 NewGlobal->setAlignment(MinRZ); 1094 1095 Value *Indices2[2]; 1096 Indices2[0] = IRB.getInt32(0); 1097 Indices2[1] = IRB.getInt32(0); 1098 1099 G->replaceAllUsesWith( 1100 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true)); 1101 NewGlobal->takeName(G); 1102 G->eraseFromParent(); 1103 1104 bool GlobalHasDynamicInitializer = GlobalsMD.isDynInit(G); 1105 GlobalVariable *SourceLoc = GlobalsMD.getSourceLocation(G); 1106 1107 Initializers[i] = ConstantStruct::get( 1108 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy), 1109 ConstantInt::get(IntptrTy, SizeInBytes), 1110 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize), 1111 ConstantExpr::getPointerCast(Name, IntptrTy), 1112 ConstantExpr::getPointerCast(ModuleName, IntptrTy), 1113 ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer), 1114 SourceLoc ? ConstantExpr::getPointerCast(SourceLoc, IntptrTy) 1115 : ConstantInt::get(IntptrTy, 0), 1116 NULL); 1117 1118 if (ClInitializers && GlobalHasDynamicInitializer) 1119 HasDynamicallyInitializedGlobals = true; 1120 1121 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n"); 1122 } 1123 1124 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n); 1125 GlobalVariable *AllGlobals = new GlobalVariable( 1126 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage, 1127 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), ""); 1128 1129 // Create calls for poisoning before initializers run and unpoisoning after. 1130 if (HasDynamicallyInitializedGlobals) 1131 createInitializerPoisonCalls(M, ModuleName); 1132 IRB.CreateCall2(AsanRegisterGlobals, 1133 IRB.CreatePointerCast(AllGlobals, IntptrTy), 1134 ConstantInt::get(IntptrTy, n)); 1135 1136 // We also need to unregister globals at the end, e.g. when a shared library 1137 // gets closed. 1138 Function *AsanDtorFunction = Function::Create( 1139 FunctionType::get(Type::getVoidTy(*C), false), 1140 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M); 1141 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction); 1142 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB)); 1143 IRB_Dtor.CreateCall2(AsanUnregisterGlobals, 1144 IRB.CreatePointerCast(AllGlobals, IntptrTy), 1145 ConstantInt::get(IntptrTy, n)); 1146 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority); 1147 1148 DEBUG(dbgs() << M); 1149 return true; 1150 } 1151 1152 bool AddressSanitizerModule::runOnModule(Module &M) { 1153 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); 1154 if (!DLP) 1155 return false; 1156 DL = &DLP->getDataLayout(); 1157 C = &(M.getContext()); 1158 int LongSize = DL->getPointerSizeInBits(); 1159 IntptrTy = Type::getIntNTy(*C, LongSize); 1160 Mapping = getShadowMapping(M, LongSize); 1161 initializeCallbacks(M); 1162 1163 bool Changed = false; 1164 1165 Function *CtorFunc = M.getFunction(kAsanModuleCtorName); 1166 assert(CtorFunc); 1167 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator()); 1168 1169 if (ClCoverage > 0) { 1170 Function *CovFunc = M.getFunction(kAsanCovName); 1171 int nCov = CovFunc ? CovFunc->getNumUses() : 0; 1172 IRB.CreateCall(AsanCovModuleInit, ConstantInt::get(IntptrTy, nCov)); 1173 Changed = true; 1174 } 1175 1176 if (ClGlobals) 1177 Changed |= InstrumentGlobals(IRB, M); 1178 1179 return Changed; 1180 } 1181 1182 void AddressSanitizer::initializeCallbacks(Module &M) { 1183 IRBuilder<> IRB(*C); 1184 // Create __asan_report* callbacks. 1185 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) { 1186 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes; 1187 AccessSizeIndex++) { 1188 // IsWrite and TypeSize are encoded in the function name. 1189 std::string Suffix = 1190 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex); 1191 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] = 1192 checkInterfaceFunction( 1193 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix, 1194 IRB.getVoidTy(), IntptrTy, NULL)); 1195 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] = 1196 checkInterfaceFunction( 1197 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix, 1198 IRB.getVoidTy(), IntptrTy, NULL)); 1199 } 1200 } 1201 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction( 1202 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1203 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction( 1204 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1205 1206 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction( 1207 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN", 1208 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1209 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction( 1210 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN", 1211 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1212 1213 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction( 1214 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(), 1215 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL)); 1216 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction( 1217 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(), 1218 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL)); 1219 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction( 1220 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(), 1221 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL)); 1222 1223 AsanHandleNoReturnFunc = checkInterfaceFunction( 1224 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL)); 1225 AsanCovFunction = checkInterfaceFunction(M.getOrInsertFunction( 1226 kAsanCovName, IRB.getVoidTy(), NULL)); 1227 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction( 1228 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1229 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction( 1230 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1231 // We insert an empty inline asm after __asan_report* to avoid callback merge. 1232 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false), 1233 StringRef(""), StringRef(""), 1234 /*hasSideEffects=*/true); 1235 } 1236 1237 // virtual 1238 bool AddressSanitizer::doInitialization(Module &M) { 1239 // Initialize the private fields. No one has accessed them before. 1240 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>(); 1241 if (!DLP) 1242 report_fatal_error("data layout missing"); 1243 DL = &DLP->getDataLayout(); 1244 1245 GlobalsMD.init(M); 1246 1247 C = &(M.getContext()); 1248 LongSize = DL->getPointerSizeInBits(); 1249 IntptrTy = Type::getIntNTy(*C, LongSize); 1250 1251 AsanCtorFunction = Function::Create( 1252 FunctionType::get(Type::getVoidTy(*C), false), 1253 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M); 1254 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction); 1255 // call __asan_init in the module ctor. 1256 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB)); 1257 AsanInitFunction = checkInterfaceFunction( 1258 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL)); 1259 AsanInitFunction->setLinkage(Function::ExternalLinkage); 1260 IRB.CreateCall(AsanInitFunction); 1261 1262 Mapping = getShadowMapping(M, LongSize); 1263 1264 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority); 1265 return true; 1266 } 1267 1268 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) { 1269 // For each NSObject descendant having a +load method, this method is invoked 1270 // by the ObjC runtime before any of the static constructors is called. 1271 // Therefore we need to instrument such methods with a call to __asan_init 1272 // at the beginning in order to initialize our runtime before any access to 1273 // the shadow memory. 1274 // We cannot just ignore these methods, because they may call other 1275 // instrumented functions. 1276 if (F.getName().find(" load]") != std::string::npos) { 1277 IRBuilder<> IRB(F.begin()->begin()); 1278 IRB.CreateCall(AsanInitFunction); 1279 return true; 1280 } 1281 return false; 1282 } 1283 1284 void AddressSanitizer::InjectCoverageAtBlock(Function &F, BasicBlock &BB) { 1285 BasicBlock::iterator IP = BB.getFirstInsertionPt(), BE = BB.end(); 1286 // Skip static allocas at the top of the entry block so they don't become 1287 // dynamic when we split the block. If we used our optimized stack layout, 1288 // then there will only be one alloca and it will come first. 1289 for (; IP != BE; ++IP) { 1290 AllocaInst *AI = dyn_cast<AllocaInst>(IP); 1291 if (!AI || !AI->isStaticAlloca()) 1292 break; 1293 } 1294 1295 DebugLoc EntryLoc = IP->getDebugLoc().getFnDebugLoc(*C); 1296 IRBuilder<> IRB(IP); 1297 IRB.SetCurrentDebugLocation(EntryLoc); 1298 Type *Int8Ty = IRB.getInt8Ty(); 1299 GlobalVariable *Guard = new GlobalVariable( 1300 *F.getParent(), Int8Ty, false, GlobalValue::PrivateLinkage, 1301 Constant::getNullValue(Int8Ty), "__asan_gen_cov_" + F.getName()); 1302 LoadInst *Load = IRB.CreateLoad(Guard); 1303 Load->setAtomic(Monotonic); 1304 Load->setAlignment(1); 1305 Value *Cmp = IRB.CreateICmpEQ(Constant::getNullValue(Int8Ty), Load); 1306 Instruction *Ins = SplitBlockAndInsertIfThen( 1307 Cmp, IP, false, MDBuilder(*C).createBranchWeights(1, 100000)); 1308 IRB.SetInsertPoint(Ins); 1309 IRB.SetCurrentDebugLocation(EntryLoc); 1310 // We pass &F to __sanitizer_cov. We could avoid this and rely on 1311 // GET_CALLER_PC, but having the PC of the first instruction is just nice. 1312 IRB.CreateCall(AsanCovFunction); 1313 StoreInst *Store = IRB.CreateStore(ConstantInt::get(Int8Ty, 1), Guard); 1314 Store->setAtomic(Monotonic); 1315 Store->setAlignment(1); 1316 } 1317 1318 // Poor man's coverage that works with ASan. 1319 // We create a Guard boolean variable with the same linkage 1320 // as the function and inject this code into the entry block (-asan-coverage=1) 1321 // or all blocks (-asan-coverage=2): 1322 // if (*Guard) { 1323 // __sanitizer_cov(&F); 1324 // *Guard = 1; 1325 // } 1326 // The accesses to Guard are atomic. The rest of the logic is 1327 // in __sanitizer_cov (it's fine to call it more than once). 1328 // 1329 // This coverage implementation provides very limited data: 1330 // it only tells if a given function (block) was ever executed. 1331 // No counters, no per-edge data. 1332 // But for many use cases this is what we need and the added slowdown 1333 // is negligible. This simple implementation will probably be obsoleted 1334 // by the upcoming Clang-based coverage implementation. 1335 // By having it here and now we hope to 1336 // a) get the functionality to users earlier and 1337 // b) collect usage statistics to help improve Clang coverage design. 1338 bool AddressSanitizer::InjectCoverage(Function &F, 1339 const ArrayRef<BasicBlock *> AllBlocks) { 1340 if (!ClCoverage) return false; 1341 1342 if (ClCoverage == 1 || 1343 (unsigned)ClCoverageBlockThreshold < AllBlocks.size()) { 1344 InjectCoverageAtBlock(F, F.getEntryBlock()); 1345 } else { 1346 for (auto BB : AllBlocks) 1347 InjectCoverageAtBlock(F, *BB); 1348 } 1349 return true; 1350 } 1351 1352 bool AddressSanitizer::runOnFunction(Function &F) { 1353 if (&F == AsanCtorFunction) return false; 1354 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false; 1355 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n"); 1356 initializeCallbacks(*F.getParent()); 1357 1358 // If needed, insert __asan_init before checking for SanitizeAddress attr. 1359 maybeInsertAsanInitAtFunctionEntry(F); 1360 1361 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) 1362 return false; 1363 1364 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName()) 1365 return false; 1366 1367 // We want to instrument every address only once per basic block (unless there 1368 // are calls between uses). 1369 SmallSet<Value*, 16> TempsToInstrument; 1370 SmallVector<Instruction*, 16> ToInstrument; 1371 SmallVector<Instruction*, 8> NoReturnCalls; 1372 SmallVector<BasicBlock*, 16> AllBlocks; 1373 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts; 1374 int NumAllocas = 0; 1375 bool IsWrite; 1376 unsigned Alignment; 1377 1378 // Fill the set of memory operations to instrument. 1379 for (auto &BB : F) { 1380 AllBlocks.push_back(&BB); 1381 TempsToInstrument.clear(); 1382 int NumInsnsPerBB = 0; 1383 for (auto &Inst : BB) { 1384 if (LooksLikeCodeInBug11395(&Inst)) return false; 1385 if (Value *Addr = 1386 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) { 1387 if (ClOpt && ClOptSameTemp) { 1388 if (!TempsToInstrument.insert(Addr)) 1389 continue; // We've seen this temp in the current BB. 1390 } 1391 } else if (ClInvalidPointerPairs && 1392 isInterestingPointerComparisonOrSubtraction(&Inst)) { 1393 PointerComparisonsOrSubtracts.push_back(&Inst); 1394 continue; 1395 } else if (isa<MemIntrinsic>(Inst)) { 1396 // ok, take it. 1397 } else { 1398 if (isa<AllocaInst>(Inst)) 1399 NumAllocas++; 1400 CallSite CS(&Inst); 1401 if (CS) { 1402 // A call inside BB. 1403 TempsToInstrument.clear(); 1404 if (CS.doesNotReturn()) 1405 NoReturnCalls.push_back(CS.getInstruction()); 1406 } 1407 continue; 1408 } 1409 ToInstrument.push_back(&Inst); 1410 NumInsnsPerBB++; 1411 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) 1412 break; 1413 } 1414 } 1415 1416 Function *UninstrumentedDuplicate = nullptr; 1417 bool LikelyToInstrument = 1418 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0); 1419 if (ClKeepUninstrumented && LikelyToInstrument) { 1420 ValueToValueMapTy VMap; 1421 UninstrumentedDuplicate = CloneFunction(&F, VMap, false); 1422 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress); 1423 UninstrumentedDuplicate->setName("NOASAN_" + F.getName()); 1424 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate); 1425 } 1426 1427 bool UseCalls = false; 1428 if (ClInstrumentationWithCallsThreshold >= 0 && 1429 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold) 1430 UseCalls = true; 1431 1432 // Instrument. 1433 int NumInstrumented = 0; 1434 for (auto Inst : ToInstrument) { 1435 if (ClDebugMin < 0 || ClDebugMax < 0 || 1436 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) { 1437 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment)) 1438 instrumentMop(Inst, UseCalls); 1439 else 1440 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst)); 1441 } 1442 NumInstrumented++; 1443 } 1444 1445 FunctionStackPoisoner FSP(F, *this); 1446 bool ChangedStack = FSP.runOnFunction(); 1447 1448 // We must unpoison the stack before every NoReturn call (throw, _exit, etc). 1449 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37 1450 for (auto CI : NoReturnCalls) { 1451 IRBuilder<> IRB(CI); 1452 IRB.CreateCall(AsanHandleNoReturnFunc); 1453 } 1454 1455 for (auto Inst : PointerComparisonsOrSubtracts) { 1456 instrumentPointerComparisonOrSubtraction(Inst); 1457 NumInstrumented++; 1458 } 1459 1460 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty(); 1461 1462 if (InjectCoverage(F, AllBlocks)) 1463 res = true; 1464 1465 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n"); 1466 1467 if (ClKeepUninstrumented) { 1468 if (!res) { 1469 // No instrumentation is done, no need for the duplicate. 1470 if (UninstrumentedDuplicate) 1471 UninstrumentedDuplicate->eraseFromParent(); 1472 } else { 1473 // The function was instrumented. We must have the duplicate. 1474 assert(UninstrumentedDuplicate); 1475 UninstrumentedDuplicate->setSection("NOASAN"); 1476 assert(!F.hasSection()); 1477 F.setSection("ASAN"); 1478 } 1479 } 1480 1481 return res; 1482 } 1483 1484 // Workaround for bug 11395: we don't want to instrument stack in functions 1485 // with large assembly blobs (32-bit only), otherwise reg alloc may crash. 1486 // FIXME: remove once the bug 11395 is fixed. 1487 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) { 1488 if (LongSize != 32) return false; 1489 CallInst *CI = dyn_cast<CallInst>(I); 1490 if (!CI || !CI->isInlineAsm()) return false; 1491 if (CI->getNumArgOperands() <= 5) return false; 1492 // We have inline assembly with quite a few arguments. 1493 return true; 1494 } 1495 1496 void FunctionStackPoisoner::initializeCallbacks(Module &M) { 1497 IRBuilder<> IRB(*C); 1498 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) { 1499 std::string Suffix = itostr(i); 1500 AsanStackMallocFunc[i] = checkInterfaceFunction( 1501 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy, 1502 IntptrTy, IntptrTy, NULL)); 1503 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction( 1504 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy, 1505 IntptrTy, IntptrTy, NULL)); 1506 } 1507 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction( 1508 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1509 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction( 1510 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL)); 1511 } 1512 1513 void 1514 FunctionStackPoisoner::poisonRedZones(const ArrayRef<uint8_t> ShadowBytes, 1515 IRBuilder<> &IRB, Value *ShadowBase, 1516 bool DoPoison) { 1517 size_t n = ShadowBytes.size(); 1518 size_t i = 0; 1519 // We need to (un)poison n bytes of stack shadow. Poison as many as we can 1520 // using 64-bit stores (if we are on 64-bit arch), then poison the rest 1521 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores. 1522 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8; 1523 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) { 1524 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) { 1525 uint64_t Val = 0; 1526 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) { 1527 if (ASan.DL->isLittleEndian()) 1528 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j); 1529 else 1530 Val = (Val << 8) | ShadowBytes[i + j]; 1531 } 1532 if (!Val) continue; 1533 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)); 1534 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8); 1535 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0); 1536 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo())); 1537 } 1538 } 1539 } 1540 1541 // Fake stack allocator (asan_fake_stack.h) has 11 size classes 1542 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass 1543 static int StackMallocSizeClass(uint64_t LocalStackSize) { 1544 assert(LocalStackSize <= kMaxStackMallocSize); 1545 uint64_t MaxSize = kMinStackMallocSize; 1546 for (int i = 0; ; i++, MaxSize *= 2) 1547 if (LocalStackSize <= MaxSize) 1548 return i; 1549 llvm_unreachable("impossible LocalStackSize"); 1550 } 1551 1552 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic. 1553 // We can not use MemSet intrinsic because it may end up calling the actual 1554 // memset. Size is a multiple of 8. 1555 // Currently this generates 8-byte stores on x86_64; it may be better to 1556 // generate wider stores. 1557 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined( 1558 IRBuilder<> &IRB, Value *ShadowBase, int Size) { 1559 assert(!(Size % 8)); 1560 assert(kAsanStackAfterReturnMagic == 0xf5); 1561 for (int i = 0; i < Size; i += 8) { 1562 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)); 1563 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL), 1564 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo())); 1565 } 1566 } 1567 1568 static DebugLoc getFunctionEntryDebugLocation(Function &F) { 1569 for (const auto &Inst : F.getEntryBlock()) 1570 if (!isa<AllocaInst>(Inst)) 1571 return Inst.getDebugLoc(); 1572 return DebugLoc(); 1573 } 1574 1575 void FunctionStackPoisoner::poisonStack() { 1576 int StackMallocIdx = -1; 1577 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F); 1578 1579 assert(AllocaVec.size() > 0); 1580 Instruction *InsBefore = AllocaVec[0]; 1581 IRBuilder<> IRB(InsBefore); 1582 IRB.SetCurrentDebugLocation(EntryDebugLocation); 1583 1584 SmallVector<ASanStackVariableDescription, 16> SVD; 1585 SVD.reserve(AllocaVec.size()); 1586 for (AllocaInst *AI : AllocaVec) { 1587 ASanStackVariableDescription D = { AI->getName().data(), 1588 getAllocaSizeInBytes(AI), 1589 AI->getAlignment(), AI, 0}; 1590 SVD.push_back(D); 1591 } 1592 // Minimal header size (left redzone) is 4 pointers, 1593 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms. 1594 size_t MinHeaderSize = ASan.LongSize / 2; 1595 ASanStackFrameLayout L; 1596 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L); 1597 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n"); 1598 uint64_t LocalStackSize = L.FrameSize; 1599 bool DoStackMalloc = 1600 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize; 1601 1602 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize); 1603 AllocaInst *MyAlloca = 1604 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore); 1605 MyAlloca->setDebugLoc(EntryDebugLocation); 1606 assert((ClRealignStack & (ClRealignStack - 1)) == 0); 1607 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack); 1608 MyAlloca->setAlignment(FrameAlignment); 1609 assert(MyAlloca->isStaticAlloca()); 1610 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy); 1611 Value *LocalStackBase = OrigStackBase; 1612 1613 if (DoStackMalloc) { 1614 // LocalStackBase = OrigStackBase 1615 // if (__asan_option_detect_stack_use_after_return) 1616 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase); 1617 StackMallocIdx = StackMallocSizeClass(LocalStackSize); 1618 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass); 1619 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal( 1620 kAsanOptionDetectUAR, IRB.getInt32Ty()); 1621 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR), 1622 Constant::getNullValue(IRB.getInt32Ty())); 1623 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false); 1624 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent(); 1625 IRBuilder<> IRBIf(Term); 1626 IRBIf.SetCurrentDebugLocation(EntryDebugLocation); 1627 LocalStackBase = IRBIf.CreateCall2( 1628 AsanStackMallocFunc[StackMallocIdx], 1629 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase); 1630 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent(); 1631 IRB.SetInsertPoint(InsBefore); 1632 IRB.SetCurrentDebugLocation(EntryDebugLocation); 1633 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2); 1634 Phi->addIncoming(OrigStackBase, CmpBlock); 1635 Phi->addIncoming(LocalStackBase, SetBlock); 1636 LocalStackBase = Phi; 1637 } 1638 1639 // Insert poison calls for lifetime intrinsics for alloca. 1640 bool HavePoisonedAllocas = false; 1641 for (const auto &APC : AllocaPoisonCallVec) { 1642 assert(APC.InsBefore); 1643 assert(APC.AI); 1644 IRBuilder<> IRB(APC.InsBefore); 1645 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison); 1646 HavePoisonedAllocas |= APC.DoPoison; 1647 } 1648 1649 // Replace Alloca instructions with base+offset. 1650 for (const auto &Desc : SVD) { 1651 AllocaInst *AI = Desc.AI; 1652 Value *NewAllocaPtr = IRB.CreateIntToPtr( 1653 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)), 1654 AI->getType()); 1655 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB); 1656 AI->replaceAllUsesWith(NewAllocaPtr); 1657 } 1658 1659 // The left-most redzone has enough space for at least 4 pointers. 1660 // Write the Magic value to redzone[0]. 1661 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy); 1662 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic), 1663 BasePlus0); 1664 // Write the frame description constant to redzone[1]. 1665 Value *BasePlus1 = IRB.CreateIntToPtr( 1666 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)), 1667 IntptrPtrTy); 1668 GlobalVariable *StackDescriptionGlobal = 1669 createPrivateGlobalForString(*F.getParent(), L.DescriptionString, 1670 /*AllowMerging*/true); 1671 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, 1672 IntptrTy); 1673 IRB.CreateStore(Description, BasePlus1); 1674 // Write the PC to redzone[2]. 1675 Value *BasePlus2 = IRB.CreateIntToPtr( 1676 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, 1677 2 * ASan.LongSize/8)), 1678 IntptrPtrTy); 1679 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2); 1680 1681 // Poison the stack redzones at the entry. 1682 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB); 1683 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true); 1684 1685 // (Un)poison the stack before all ret instructions. 1686 for (auto Ret : RetVec) { 1687 IRBuilder<> IRBRet(Ret); 1688 // Mark the current frame as retired. 1689 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic), 1690 BasePlus0); 1691 if (DoStackMalloc) { 1692 assert(StackMallocIdx >= 0); 1693 // if LocalStackBase != OrigStackBase: 1694 // // In use-after-return mode, poison the whole stack frame. 1695 // if StackMallocIdx <= 4 1696 // // For small sizes inline the whole thing: 1697 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize); 1698 // **SavedFlagPtr(LocalStackBase) = 0 1699 // else 1700 // __asan_stack_free_N(LocalStackBase, OrigStackBase) 1701 // else 1702 // <This is not a fake stack; unpoison the redzones> 1703 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase); 1704 TerminatorInst *ThenTerm, *ElseTerm; 1705 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm); 1706 1707 IRBuilder<> IRBPoison(ThenTerm); 1708 if (StackMallocIdx <= 4) { 1709 int ClassSize = kMinStackMallocSize << StackMallocIdx; 1710 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase, 1711 ClassSize >> Mapping.Scale); 1712 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd( 1713 LocalStackBase, 1714 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8)); 1715 Value *SavedFlagPtr = IRBPoison.CreateLoad( 1716 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy)); 1717 IRBPoison.CreateStore( 1718 Constant::getNullValue(IRBPoison.getInt8Ty()), 1719 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy())); 1720 } else { 1721 // For larger frames call __asan_stack_free_*. 1722 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase, 1723 ConstantInt::get(IntptrTy, LocalStackSize), 1724 OrigStackBase); 1725 } 1726 1727 IRBuilder<> IRBElse(ElseTerm); 1728 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false); 1729 } else if (HavePoisonedAllocas) { 1730 // If we poisoned some allocas in llvm.lifetime analysis, 1731 // unpoison whole stack frame now. 1732 assert(LocalStackBase == OrigStackBase); 1733 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false); 1734 } else { 1735 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false); 1736 } 1737 } 1738 1739 // We are done. Remove the old unused alloca instructions. 1740 for (auto AI : AllocaVec) 1741 AI->eraseFromParent(); 1742 } 1743 1744 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size, 1745 IRBuilder<> &IRB, bool DoPoison) { 1746 // For now just insert the call to ASan runtime. 1747 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy); 1748 Value *SizeArg = ConstantInt::get(IntptrTy, Size); 1749 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc 1750 : AsanUnpoisonStackMemoryFunc, 1751 AddrArg, SizeArg); 1752 } 1753 1754 // Handling llvm.lifetime intrinsics for a given %alloca: 1755 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca. 1756 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect 1757 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory 1758 // could be poisoned by previous llvm.lifetime.end instruction, as the 1759 // variable may go in and out of scope several times, e.g. in loops). 1760 // (3) if we poisoned at least one %alloca in a function, 1761 // unpoison the whole stack frame at function exit. 1762 1763 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) { 1764 if (AllocaInst *AI = dyn_cast<AllocaInst>(V)) 1765 // We're intested only in allocas we can handle. 1766 return isInterestingAlloca(*AI) ? AI : nullptr; 1767 // See if we've already calculated (or started to calculate) alloca for a 1768 // given value. 1769 AllocaForValueMapTy::iterator I = AllocaForValue.find(V); 1770 if (I != AllocaForValue.end()) 1771 return I->second; 1772 // Store 0 while we're calculating alloca for value V to avoid 1773 // infinite recursion if the value references itself. 1774 AllocaForValue[V] = nullptr; 1775 AllocaInst *Res = nullptr; 1776 if (CastInst *CI = dyn_cast<CastInst>(V)) 1777 Res = findAllocaForValue(CI->getOperand(0)); 1778 else if (PHINode *PN = dyn_cast<PHINode>(V)) { 1779 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) { 1780 Value *IncValue = PN->getIncomingValue(i); 1781 // Allow self-referencing phi-nodes. 1782 if (IncValue == PN) continue; 1783 AllocaInst *IncValueAI = findAllocaForValue(IncValue); 1784 // AI for incoming values should exist and should all be equal. 1785 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res)) 1786 return nullptr; 1787 Res = IncValueAI; 1788 } 1789 } 1790 if (Res) 1791 AllocaForValue[V] = Res; 1792 return Res; 1793 } 1794