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 //===----------------------------------------------------------------------===//
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/Scalar.h"
44 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
45 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
46 #include "llvm/Transforms/Utils/Cloning.h"
47 #include "llvm/Transforms/Utils/Local.h"
48 #include "llvm/Transforms/Utils/ModuleUtils.h"
49 #include <algorithm>
50 #include <string>
51 #include <system_error>
53 using namespace llvm;
55 #define DEBUG_TYPE "asan"
57 static const uint64_t kDefaultShadowScale = 3;
58 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
59 static const uint64_t kIOSShadowOffset32 = 1ULL << 30;
60 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
61 static const uint64_t kSmallX86_64ShadowOffset = 0x7FFF8000; // < 2G.
62 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
63 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
64 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 36;
65 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
66 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
68 static const size_t kMinStackMallocSize = 1 << 6; // 64B
69 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
70 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
71 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
73 static const char *const kAsanModuleCtorName = "asan.module_ctor";
74 static const char *const kAsanModuleDtorName = "asan.module_dtor";
75 static const uint64_t kAsanCtorAndDtorPriority = 1;
76 static const char *const kAsanReportErrorTemplate = "__asan_report_";
77 static const char *const kAsanReportLoadN = "__asan_report_load_n";
78 static const char *const kAsanReportStoreN = "__asan_report_store_n";
79 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
80 static const char *const kAsanUnregisterGlobalsName =
81 "__asan_unregister_globals";
82 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
83 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
84 static const char *const kAsanInitName = "__asan_init_v4";
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";
97 static const char *const kAsanOptionDetectUAR =
98 "__asan_option_detect_stack_use_after_return";
100 #ifndef NDEBUG
101 static const int kAsanStackAfterReturnMagic = 0xf5;
102 #endif
104 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
105 static const size_t kNumberOfAccessSizes = 5;
107 // Command-line flags.
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<bool> ClInitializers("asan-initialization-order",
137 cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(true));
138 static cl::opt<bool> ClInvalidPointerPairs("asan-detect-invalid-pointer-pair",
139 cl::desc("Instrument <, <=, >, >=, - with pointer operands"),
140 cl::Hidden, cl::init(false));
141 static cl::opt<unsigned> ClRealignStack("asan-realign-stack",
142 cl::desc("Realign stack to the value of this flag (power of two)"),
143 cl::Hidden, cl::init(32));
144 static cl::opt<int> ClInstrumentationWithCallsThreshold(
145 "asan-instrumentation-with-call-threshold",
146 cl::desc("If the function being instrumented contains more than "
147 "this number of memory accesses, use callbacks instead of "
148 "inline checks (-1 means never use callbacks)."),
149 cl::Hidden, cl::init(7000));
150 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
151 "asan-memory-access-callback-prefix",
152 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
153 cl::init("__asan_"));
155 // This is an experimental feature that will allow to choose between
156 // instrumented and non-instrumented code at link-time.
157 // If this option is on, just before instrumenting a function we create its
158 // clone; if the function is not changed by asan the clone is deleted.
159 // If we end up with a clone, we put the instrumented function into a section
160 // called "ASAN" and the uninstrumented function into a section called "NOASAN".
161 //
162 // This is still a prototype, we need to figure out a way to keep two copies of
163 // a function so that the linker can easily choose one of them.
164 static cl::opt<bool> ClKeepUninstrumented("asan-keep-uninstrumented-functions",
165 cl::desc("Keep uninstrumented copies of functions"),
166 cl::Hidden, cl::init(false));
168 // These flags allow to change the shadow mapping.
169 // The shadow mapping looks like
170 // Shadow = (Mem >> scale) + (1 << offset_log)
171 static cl::opt<int> ClMappingScale("asan-mapping-scale",
172 cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
174 // Optimization flags. Not user visible, used mostly for testing
175 // and benchmarking the tool.
176 static cl::opt<bool> ClOpt("asan-opt",
177 cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
178 static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
179 cl::desc("Instrument the same temp just once"), cl::Hidden,
180 cl::init(true));
181 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
182 cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
184 static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
185 cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
186 cl::Hidden, cl::init(false));
188 // Debug flags.
189 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
190 cl::init(0));
191 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
192 cl::Hidden, cl::init(0));
193 static cl::opt<std::string> ClDebugFunc("asan-debug-func",
194 cl::Hidden, cl::desc("Debug func"));
195 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
196 cl::Hidden, cl::init(-1));
197 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
198 cl::Hidden, cl::init(-1));
200 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
201 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
202 STATISTIC(NumOptimizedAccessesToGlobalArray,
203 "Number of optimized accesses to global arrays");
204 STATISTIC(NumOptimizedAccessesToGlobalVar,
205 "Number of optimized accesses to global vars");
207 namespace {
208 /// Frontend-provided metadata for source location.
209 struct LocationMetadata {
210 StringRef Filename;
211 int LineNo;
212 int ColumnNo;
214 LocationMetadata() : Filename(), LineNo(0), ColumnNo(0) {}
216 bool empty() const { return Filename.empty(); }
218 void parse(MDNode *MDN) {
219 assert(MDN->getNumOperands() == 3);
220 MDString *MDFilename = cast<MDString>(MDN->getOperand(0));
221 Filename = MDFilename->getString();
222 LineNo = cast<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
223 ColumnNo = cast<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
224 }
225 };
227 /// Frontend-provided metadata for global variables.
228 class GlobalsMetadata {
229 public:
230 struct Entry {
231 Entry()
232 : SourceLoc(), Name(), IsDynInit(false),
233 IsBlacklisted(false) {}
234 LocationMetadata SourceLoc;
235 StringRef Name;
236 bool IsDynInit;
237 bool IsBlacklisted;
238 };
240 GlobalsMetadata() : inited_(false) {}
242 void init(Module& M) {
243 assert(!inited_);
244 inited_ = true;
245 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
246 if (!Globals)
247 return;
248 for (auto MDN : Globals->operands()) {
249 // Metadata node contains the global and the fields of "Entry".
250 assert(MDN->getNumOperands() == 5);
251 Value *V = MDN->getOperand(0);
252 // The optimizer may optimize away a global entirely.
253 if (!V)
254 continue;
255 GlobalVariable *GV = cast<GlobalVariable>(V);
256 // We can already have an entry for GV if it was merged with another
257 // global.
258 Entry &E = Entries[GV];
259 if (Value *Loc = MDN->getOperand(1))
260 E.SourceLoc.parse(cast<MDNode>(Loc));
261 if (Value *Name = MDN->getOperand(2)) {
262 MDString *MDName = cast<MDString>(Name);
263 E.Name = MDName->getString();
264 }
265 ConstantInt *IsDynInit = cast<ConstantInt>(MDN->getOperand(3));
266 E.IsDynInit |= IsDynInit->isOne();
267 ConstantInt *IsBlacklisted = cast<ConstantInt>(MDN->getOperand(4));
268 E.IsBlacklisted |= IsBlacklisted->isOne();
269 }
270 }
272 /// Returns metadata entry for a given global.
273 Entry get(GlobalVariable *G) const {
274 auto Pos = Entries.find(G);
275 return (Pos != Entries.end()) ? Pos->second : Entry();
276 }
278 private:
279 bool inited_;
280 DenseMap<GlobalVariable*, Entry> Entries;
281 };
283 /// This struct defines the shadow mapping using the rule:
284 /// shadow = (mem >> Scale) ADD-or-OR Offset.
285 struct ShadowMapping {
286 int Scale;
287 uint64_t Offset;
288 bool OrShadowOffset;
289 };
291 static ShadowMapping getShadowMapping(const Module &M, int LongSize) {
292 llvm::Triple TargetTriple(M.getTargetTriple());
293 bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
294 bool IsIOS = TargetTriple.isiOS();
295 bool IsFreeBSD = TargetTriple.getOS() == llvm::Triple::FreeBSD;
296 bool IsLinux = TargetTriple.getOS() == llvm::Triple::Linux;
297 bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64 ||
298 TargetTriple.getArch() == llvm::Triple::ppc64le;
299 bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
300 bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
301 TargetTriple.getArch() == llvm::Triple::mipsel;
302 bool IsMIPS64 = TargetTriple.getArch() == llvm::Triple::mips64 ||
303 TargetTriple.getArch() == llvm::Triple::mips64el;
305 ShadowMapping Mapping;
307 if (LongSize == 32) {
308 if (IsAndroid)
309 Mapping.Offset = 0;
310 else if (IsMIPS32)
311 Mapping.Offset = kMIPS32_ShadowOffset32;
312 else if (IsFreeBSD)
313 Mapping.Offset = kFreeBSD_ShadowOffset32;
314 else if (IsIOS)
315 Mapping.Offset = kIOSShadowOffset32;
316 else
317 Mapping.Offset = kDefaultShadowOffset32;
318 } else { // LongSize == 64
319 if (IsPPC64)
320 Mapping.Offset = kPPC64_ShadowOffset64;
321 else if (IsFreeBSD)
322 Mapping.Offset = kFreeBSD_ShadowOffset64;
323 else if (IsLinux && IsX86_64)
324 Mapping.Offset = kSmallX86_64ShadowOffset;
325 else if (IsMIPS64)
326 Mapping.Offset = kMIPS64_ShadowOffset64;
327 else
328 Mapping.Offset = kDefaultShadowOffset64;
329 }
331 Mapping.Scale = kDefaultShadowScale;
332 if (ClMappingScale) {
333 Mapping.Scale = ClMappingScale;
334 }
336 // OR-ing shadow offset if more efficient (at least on x86) if the offset
337 // is a power of two, but on ppc64 we have to use add since the shadow
338 // offset is not necessary 1/8-th of the address space.
339 Mapping.OrShadowOffset = !IsPPC64 && !(Mapping.Offset & (Mapping.Offset - 1));
341 return Mapping;
342 }
344 static size_t RedzoneSizeForScale(int MappingScale) {
345 // Redzone used for stack and globals is at least 32 bytes.
346 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
347 return std::max(32U, 1U << MappingScale);
348 }
350 /// AddressSanitizer: instrument the code in module to find memory bugs.
351 struct AddressSanitizer : public FunctionPass {
352 AddressSanitizer() : FunctionPass(ID) {}
353 const char *getPassName() const override {
354 return "AddressSanitizerFunctionPass";
355 }
356 void instrumentMop(Instruction *I, bool UseCalls);
357 void instrumentPointerComparisonOrSubtraction(Instruction *I);
358 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
359 Value *Addr, uint32_t TypeSize, bool IsWrite,
360 Value *SizeArgument, bool UseCalls);
361 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
362 Value *ShadowValue, uint32_t TypeSize);
363 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
364 bool IsWrite, size_t AccessSizeIndex,
365 Value *SizeArgument);
366 void instrumentMemIntrinsic(MemIntrinsic *MI);
367 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
368 bool runOnFunction(Function &F) override;
369 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
370 bool doInitialization(Module &M) override;
371 static char ID; // Pass identification, replacement for typeid
373 private:
374 void initializeCallbacks(Module &M);
376 bool LooksLikeCodeInBug11395(Instruction *I);
377 bool GlobalIsLinkerInitialized(GlobalVariable *G);
379 LLVMContext *C;
380 const DataLayout *DL;
381 int LongSize;
382 Type *IntptrTy;
383 ShadowMapping Mapping;
384 Function *AsanCtorFunction;
385 Function *AsanInitFunction;
386 Function *AsanHandleNoReturnFunc;
387 Function *AsanPtrCmpFunction, *AsanPtrSubFunction;
388 // This array is indexed by AccessIsWrite and log2(AccessSize).
389 Function *AsanErrorCallback[2][kNumberOfAccessSizes];
390 Function *AsanMemoryAccessCallback[2][kNumberOfAccessSizes];
391 // This array is indexed by AccessIsWrite.
392 Function *AsanErrorCallbackSized[2],
393 *AsanMemoryAccessCallbackSized[2];
394 Function *AsanMemmove, *AsanMemcpy, *AsanMemset;
395 InlineAsm *EmptyAsm;
396 GlobalsMetadata GlobalsMD;
398 friend struct FunctionStackPoisoner;
399 };
401 class AddressSanitizerModule : public ModulePass {
402 public:
403 AddressSanitizerModule() : ModulePass(ID) {}
404 bool runOnModule(Module &M) override;
405 static char ID; // Pass identification, replacement for typeid
406 const char *getPassName() const override {
407 return "AddressSanitizerModule";
408 }
410 private:
411 void initializeCallbacks(Module &M);
413 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M);
414 bool ShouldInstrumentGlobal(GlobalVariable *G);
415 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
416 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
417 size_t MinRedzoneSizeForGlobal() const {
418 return RedzoneSizeForScale(Mapping.Scale);
419 }
421 GlobalsMetadata GlobalsMD;
422 Type *IntptrTy;
423 LLVMContext *C;
424 const DataLayout *DL;
425 ShadowMapping Mapping;
426 Function *AsanPoisonGlobals;
427 Function *AsanUnpoisonGlobals;
428 Function *AsanRegisterGlobals;
429 Function *AsanUnregisterGlobals;
430 };
432 // Stack poisoning does not play well with exception handling.
433 // When an exception is thrown, we essentially bypass the code
434 // that unpoisones the stack. This is why the run-time library has
435 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
436 // stack in the interceptor. This however does not work inside the
437 // actual function which catches the exception. Most likely because the
438 // compiler hoists the load of the shadow value somewhere too high.
439 // This causes asan to report a non-existing bug on 453.povray.
440 // It sounds like an LLVM bug.
441 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
442 Function &F;
443 AddressSanitizer &ASan;
444 DIBuilder DIB;
445 LLVMContext *C;
446 Type *IntptrTy;
447 Type *IntptrPtrTy;
448 ShadowMapping Mapping;
450 SmallVector<AllocaInst*, 16> AllocaVec;
451 SmallVector<Instruction*, 8> RetVec;
452 unsigned StackAlignment;
454 Function *AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
455 *AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
456 Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
458 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
459 struct AllocaPoisonCall {
460 IntrinsicInst *InsBefore;
461 AllocaInst *AI;
462 uint64_t Size;
463 bool DoPoison;
464 };
465 SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
467 // Maps Value to an AllocaInst from which the Value is originated.
468 typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
469 AllocaForValueMapTy AllocaForValue;
471 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
472 : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
473 IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
474 Mapping(ASan.Mapping),
475 StackAlignment(1 << Mapping.Scale) {}
477 bool runOnFunction() {
478 if (!ClStack) return false;
479 // Collect alloca, ret, lifetime instructions etc.
480 for (BasicBlock *BB : depth_first(&F.getEntryBlock()))
481 visit(*BB);
483 if (AllocaVec.empty()) return false;
485 initializeCallbacks(*F.getParent());
487 poisonStack();
489 if (ClDebugStack) {
490 DEBUG(dbgs() << F);
491 }
492 return true;
493 }
495 // Finds all static Alloca instructions and puts
496 // poisoned red zones around all of them.
497 // Then unpoison everything back before the function returns.
498 void poisonStack();
500 // ----------------------- Visitors.
501 /// \brief Collect all Ret instructions.
502 void visitReturnInst(ReturnInst &RI) {
503 RetVec.push_back(&RI);
504 }
506 /// \brief Collect Alloca instructions we want (and can) handle.
507 void visitAllocaInst(AllocaInst &AI) {
508 if (!isInterestingAlloca(AI)) return;
510 StackAlignment = std::max(StackAlignment, AI.getAlignment());
511 AllocaVec.push_back(&AI);
512 }
514 /// \brief Collect lifetime intrinsic calls to check for use-after-scope
515 /// errors.
516 void visitIntrinsicInst(IntrinsicInst &II) {
517 if (!ClCheckLifetime) return;
518 Intrinsic::ID ID = II.getIntrinsicID();
519 if (ID != Intrinsic::lifetime_start &&
520 ID != Intrinsic::lifetime_end)
521 return;
522 // Found lifetime intrinsic, add ASan instrumentation if necessary.
523 ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
524 // If size argument is undefined, don't do anything.
525 if (Size->isMinusOne()) return;
526 // Check that size doesn't saturate uint64_t and can
527 // be stored in IntptrTy.
528 const uint64_t SizeValue = Size->getValue().getLimitedValue();
529 if (SizeValue == ~0ULL ||
530 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
531 return;
532 // Find alloca instruction that corresponds to llvm.lifetime argument.
533 AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
534 if (!AI) return;
535 bool DoPoison = (ID == Intrinsic::lifetime_end);
536 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
537 AllocaPoisonCallVec.push_back(APC);
538 }
540 // ---------------------- Helpers.
541 void initializeCallbacks(Module &M);
543 // Check if we want (and can) handle this alloca.
544 bool isInterestingAlloca(AllocaInst &AI) const {
545 return (!AI.isArrayAllocation() && AI.isStaticAlloca() &&
546 AI.getAllocatedType()->isSized() &&
547 // alloca() may be called with 0 size, ignore it.
548 getAllocaSizeInBytes(&AI) > 0);
549 }
551 uint64_t getAllocaSizeInBytes(AllocaInst *AI) const {
552 Type *Ty = AI->getAllocatedType();
553 uint64_t SizeInBytes = ASan.DL->getTypeAllocSize(Ty);
554 return SizeInBytes;
555 }
556 /// Finds alloca where the value comes from.
557 AllocaInst *findAllocaForValue(Value *V);
558 void poisonRedZones(ArrayRef<uint8_t> ShadowBytes, IRBuilder<> &IRB,
559 Value *ShadowBase, bool DoPoison);
560 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
562 void SetShadowToStackAfterReturnInlined(IRBuilder<> &IRB, Value *ShadowBase,
563 int Size);
564 };
566 } // namespace
568 char AddressSanitizer::ID = 0;
569 INITIALIZE_PASS(AddressSanitizer, "asan",
570 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
571 false, false)
572 FunctionPass *llvm::createAddressSanitizerFunctionPass() {
573 return new AddressSanitizer();
574 }
576 char AddressSanitizerModule::ID = 0;
577 INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
578 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
579 "ModulePass", false, false)
580 ModulePass *llvm::createAddressSanitizerModulePass() {
581 return new AddressSanitizerModule();
582 }
584 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
585 size_t Res = countTrailingZeros(TypeSize / 8);
586 assert(Res < kNumberOfAccessSizes);
587 return Res;
588 }
590 // \brief Create a constant for Str so that we can pass it to the run-time lib.
591 static GlobalVariable *createPrivateGlobalForString(
592 Module &M, StringRef Str, bool AllowMerging) {
593 Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
594 // We use private linkage for module-local strings. If they can be merged
595 // with another one, we set the unnamed_addr attribute.
596 GlobalVariable *GV =
597 new GlobalVariable(M, StrConst->getType(), true,
598 GlobalValue::PrivateLinkage, StrConst, kAsanGenPrefix);
599 if (AllowMerging)
600 GV->setUnnamedAddr(true);
601 GV->setAlignment(1); // Strings may not be merged w/o setting align 1.
602 return GV;
603 }
605 /// \brief Create a global describing a source location.
606 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
607 LocationMetadata MD) {
608 Constant *LocData[] = {
609 createPrivateGlobalForString(M, MD.Filename, true),
610 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
611 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
612 };
613 auto LocStruct = ConstantStruct::getAnon(LocData);
614 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
615 GlobalValue::PrivateLinkage, LocStruct,
616 kAsanGenPrefix);
617 GV->setUnnamedAddr(true);
618 return GV;
619 }
621 static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
622 return G->getName().find(kAsanGenPrefix) == 0;
623 }
625 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
626 // Shadow >> scale
627 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
628 if (Mapping.Offset == 0)
629 return Shadow;
630 // (Shadow >> scale) | offset
631 if (Mapping.OrShadowOffset)
632 return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
633 else
634 return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
635 }
637 // Instrument memset/memmove/memcpy
638 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
639 IRBuilder<> IRB(MI);
640 if (isa<MemTransferInst>(MI)) {
641 IRB.CreateCall3(
642 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
643 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
644 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
645 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
646 } else if (isa<MemSetInst>(MI)) {
647 IRB.CreateCall3(
648 AsanMemset,
649 IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
650 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
651 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false));
652 }
653 MI->eraseFromParent();
654 }
656 // If I is an interesting memory access, return the PointerOperand
657 // and set IsWrite/Alignment. Otherwise return NULL.
658 static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
659 unsigned *Alignment) {
660 // Skip memory accesses inserted by another instrumentation.
661 if (I->getMetadata("nosanitize"))
662 return nullptr;
663 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
664 if (!ClInstrumentReads) return nullptr;
665 *IsWrite = false;
666 *Alignment = LI->getAlignment();
667 return LI->getPointerOperand();
668 }
669 if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
670 if (!ClInstrumentWrites) return nullptr;
671 *IsWrite = true;
672 *Alignment = SI->getAlignment();
673 return SI->getPointerOperand();
674 }
675 if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
676 if (!ClInstrumentAtomics) return nullptr;
677 *IsWrite = true;
678 *Alignment = 0;
679 return RMW->getPointerOperand();
680 }
681 if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
682 if (!ClInstrumentAtomics) return nullptr;
683 *IsWrite = true;
684 *Alignment = 0;
685 return XCHG->getPointerOperand();
686 }
687 return nullptr;
688 }
690 static bool isPointerOperand(Value *V) {
691 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
692 }
694 // This is a rough heuristic; it may cause both false positives and
695 // false negatives. The proper implementation requires cooperation with
696 // the frontend.
697 static bool isInterestingPointerComparisonOrSubtraction(Instruction *I) {
698 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
699 if (!Cmp->isRelational())
700 return false;
701 } else if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
702 if (BO->getOpcode() != Instruction::Sub)
703 return false;
704 } else {
705 return false;
706 }
707 if (!isPointerOperand(I->getOperand(0)) ||
708 !isPointerOperand(I->getOperand(1)))
709 return false;
710 return true;
711 }
713 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
714 // If a global variable does not have dynamic initialization we don't
715 // have to instrument it. However, if a global does not have initializer
716 // at all, we assume it has dynamic initializer (in other TU).
717 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
718 }
720 void
721 AddressSanitizer::instrumentPointerComparisonOrSubtraction(Instruction *I) {
722 IRBuilder<> IRB(I);
723 Function *F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
724 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
725 for (int i = 0; i < 2; i++) {
726 if (Param[i]->getType()->isPointerTy())
727 Param[i] = IRB.CreatePointerCast(Param[i], IntptrTy);
728 }
729 IRB.CreateCall2(F, Param[0], Param[1]);
730 }
732 void AddressSanitizer::instrumentMop(Instruction *I, bool UseCalls) {
733 bool IsWrite = false;
734 unsigned Alignment = 0;
735 Value *Addr = isInterestingMemoryAccess(I, &IsWrite, &Alignment);
736 assert(Addr);
737 if (ClOpt && ClOptGlobals) {
738 if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
739 // If initialization order checking is disabled, a simple access to a
740 // dynamically initialized global is always valid.
741 if (!ClInitializers || GlobalIsLinkerInitialized(G)) {
742 NumOptimizedAccessesToGlobalVar++;
743 return;
744 }
745 }
746 ConstantExpr *CE = dyn_cast<ConstantExpr>(Addr);
747 if (CE && CE->isGEPWithNoNotionalOverIndexing()) {
748 if (GlobalVariable *G = dyn_cast<GlobalVariable>(CE->getOperand(0))) {
749 if (CE->getOperand(1)->isNullValue() && GlobalIsLinkerInitialized(G)) {
750 NumOptimizedAccessesToGlobalArray++;
751 return;
752 }
753 }
754 }
755 }
757 Type *OrigPtrTy = Addr->getType();
758 Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
760 assert(OrigTy->isSized());
761 uint32_t TypeSize = DL->getTypeStoreSizeInBits(OrigTy);
763 assert((TypeSize % 8) == 0);
765 if (IsWrite)
766 NumInstrumentedWrites++;
767 else
768 NumInstrumentedReads++;
770 unsigned Granularity = 1 << Mapping.Scale;
771 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
772 // if the data is properly aligned.
773 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
774 TypeSize == 128) &&
775 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
776 return instrumentAddress(I, I, Addr, TypeSize, IsWrite, nullptr, UseCalls);
777 // Instrument unusual size or unusual alignment.
778 // We can not do it with a single check, so we do 1-byte check for the first
779 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
780 // to report the actual access size.
781 IRBuilder<> IRB(I);
782 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
783 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
784 if (UseCalls) {
785 IRB.CreateCall2(AsanMemoryAccessCallbackSized[IsWrite], AddrLong, Size);
786 } else {
787 Value *LastByte = IRB.CreateIntToPtr(
788 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
789 OrigPtrTy);
790 instrumentAddress(I, I, Addr, 8, IsWrite, Size, false);
791 instrumentAddress(I, I, LastByte, 8, IsWrite, Size, false);
792 }
793 }
795 // Validate the result of Module::getOrInsertFunction called for an interface
796 // function of AddressSanitizer. If the instrumented module defines a function
797 // with the same name, their prototypes must match, otherwise
798 // getOrInsertFunction returns a bitcast.
799 static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
800 if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
801 FuncOrBitcast->dump();
802 report_fatal_error("trying to redefine an AddressSanitizer "
803 "interface function");
804 }
806 Instruction *AddressSanitizer::generateCrashCode(
807 Instruction *InsertBefore, Value *Addr,
808 bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
809 IRBuilder<> IRB(InsertBefore);
810 CallInst *Call = SizeArgument
811 ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
812 : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
814 // We don't do Call->setDoesNotReturn() because the BB already has
815 // UnreachableInst at the end.
816 // This EmptyAsm is required to avoid callback merge.
817 IRB.CreateCall(EmptyAsm);
818 return Call;
819 }
821 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
822 Value *ShadowValue,
823 uint32_t TypeSize) {
824 size_t Granularity = 1 << Mapping.Scale;
825 // Addr & (Granularity - 1)
826 Value *LastAccessedByte = IRB.CreateAnd(
827 AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
828 // (Addr & (Granularity - 1)) + size - 1
829 if (TypeSize / 8 > 1)
830 LastAccessedByte = IRB.CreateAdd(
831 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
832 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
833 LastAccessedByte = IRB.CreateIntCast(
834 LastAccessedByte, ShadowValue->getType(), false);
835 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
836 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
837 }
839 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
840 Instruction *InsertBefore, Value *Addr,
841 uint32_t TypeSize, bool IsWrite,
842 Value *SizeArgument, bool UseCalls) {
843 IRBuilder<> IRB(InsertBefore);
844 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
845 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
847 if (UseCalls) {
848 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][AccessSizeIndex],
849 AddrLong);
850 return;
851 }
853 Type *ShadowTy = IntegerType::get(
854 *C, std::max(8U, TypeSize >> Mapping.Scale));
855 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
856 Value *ShadowPtr = memToShadow(AddrLong, IRB);
857 Value *CmpVal = Constant::getNullValue(ShadowTy);
858 Value *ShadowValue = IRB.CreateLoad(
859 IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
861 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
862 size_t Granularity = 1 << Mapping.Scale;
863 TerminatorInst *CrashTerm = nullptr;
865 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
866 // We use branch weights for the slow path check, to indicate that the slow
867 // path is rarely taken. This seems to be the case for SPEC benchmarks.
868 TerminatorInst *CheckTerm =
869 SplitBlockAndInsertIfThen(Cmp, InsertBefore, false,
870 MDBuilder(*C).createBranchWeights(1, 100000));
871 assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
872 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
873 IRB.SetInsertPoint(CheckTerm);
874 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
875 BasicBlock *CrashBlock =
876 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
877 CrashTerm = new UnreachableInst(*C, CrashBlock);
878 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
879 ReplaceInstWithInst(CheckTerm, NewTerm);
880 } else {
881 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, true);
882 }
884 Instruction *Crash = generateCrashCode(
885 CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
886 Crash->setDebugLoc(OrigIns->getDebugLoc());
887 }
889 void AddressSanitizerModule::poisonOneInitializer(Function &GlobalInit,
890 GlobalValue *ModuleName) {
891 // Set up the arguments to our poison/unpoison functions.
892 IRBuilder<> IRB(GlobalInit.begin()->getFirstInsertionPt());
894 // Add a call to poison all external globals before the given function starts.
895 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
896 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
898 // Add calls to unpoison all globals before each return instruction.
899 for (auto &BB : GlobalInit.getBasicBlockList())
900 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
901 CallInst::Create(AsanUnpoisonGlobals, "", RI);
902 }
904 void AddressSanitizerModule::createInitializerPoisonCalls(
905 Module &M, GlobalValue *ModuleName) {
906 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
908 ConstantArray *CA = cast<ConstantArray>(GV->getInitializer());
909 for (Use &OP : CA->operands()) {
910 if (isa<ConstantAggregateZero>(OP))
911 continue;
912 ConstantStruct *CS = cast<ConstantStruct>(OP);
914 // Must have a function or null ptr.
915 if (Function* F = dyn_cast<Function>(CS->getOperand(1))) {
916 if (F->getName() == kAsanModuleCtorName) continue;
917 ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
918 // Don't instrument CTORs that will run before asan.module_ctor.
919 if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
920 poisonOneInitializer(*F, ModuleName);
921 }
922 }
923 }
925 bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
926 Type *Ty = cast<PointerType>(G->getType())->getElementType();
927 DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
929 if (GlobalsMD.get(G).IsBlacklisted) return false;
930 if (!Ty->isSized()) return false;
931 if (!G->hasInitializer()) return false;
932 if (GlobalWasGeneratedByAsan(G)) return false; // Our own global.
933 // Touch only those globals that will not be defined in other modules.
934 // Don't handle ODR linkage types and COMDATs since other modules may be built
935 // without ASan.
936 if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
937 G->getLinkage() != GlobalVariable::PrivateLinkage &&
938 G->getLinkage() != GlobalVariable::InternalLinkage)
939 return false;
940 if (G->hasComdat())
941 return false;
942 // Two problems with thread-locals:
943 // - The address of the main thread's copy can't be computed at link-time.
944 // - Need to poison all copies, not just the main thread's one.
945 if (G->isThreadLocal())
946 return false;
947 // For now, just ignore this Global if the alignment is large.
948 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
950 if (G->hasSection()) {
951 StringRef Section(G->getSection());
952 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
953 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
954 // them.
955 if (Section.startswith("__OBJC,") ||
956 Section.startswith("__DATA, __objc_")) {
957 DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
958 return false;
959 }
960 // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
961 // Constant CFString instances are compiled in the following way:
962 // -- the string buffer is emitted into
963 // __TEXT,__cstring,cstring_literals
964 // -- the constant NSConstantString structure referencing that buffer
965 // is placed into __DATA,__cfstring
966 // Therefore there's no point in placing redzones into __DATA,__cfstring.
967 // Moreover, it causes the linker to crash on OS X 10.7
968 if (Section.startswith("__DATA,__cfstring")) {
969 DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
970 return false;
971 }
972 // The linker merges the contents of cstring_literals and removes the
973 // trailing zeroes.
974 if (Section.startswith("__TEXT,__cstring,cstring_literals")) {
975 DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
976 return false;
977 }
978 if (Section.startswith("__TEXT,__objc_methname,cstring_literals")) {
979 DEBUG(dbgs() << "Ignoring objc_methname cstring global: " << *G << "\n");
980 return false;
981 }
984 // Callbacks put into the CRT initializer/terminator sections
985 // should not be instrumented.
986 // See https://code.google.com/p/address-sanitizer/issues/detail?id=305
987 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
988 if (Section.startswith(".CRT")) {
989 DEBUG(dbgs() << "Ignoring a global initializer callback: " << *G << "\n");
990 return false;
991 }
993 // Globals from llvm.metadata aren't emitted, do not instrument them.
994 if (Section == "llvm.metadata") return false;
995 }
997 return true;
998 }
1000 void AddressSanitizerModule::initializeCallbacks(Module &M) {
1001 IRBuilder<> IRB(*C);
1002 // Declare our poisoning and unpoisoning functions.
1003 AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1004 kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
1005 AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
1006 AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1007 kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
1008 AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
1009 // Declare functions that register/unregister globals.
1010 AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1011 kAsanRegisterGlobalsName, IRB.getVoidTy(),
1012 IntptrTy, IntptrTy, NULL));
1013 AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
1014 AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
1015 kAsanUnregisterGlobalsName,
1016 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1017 AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
1018 }
1020 // This function replaces all global variables with new variables that have
1021 // trailing redzones. It also creates a function that poisons
1022 // redzones and inserts this function into llvm.global_ctors.
1023 bool AddressSanitizerModule::InstrumentGlobals(IRBuilder<> &IRB, Module &M) {
1024 GlobalsMD.init(M);
1026 SmallVector<GlobalVariable *, 16> GlobalsToChange;
1028 for (auto &G : M.globals()) {
1029 if (ShouldInstrumentGlobal(&G))
1030 GlobalsToChange.push_back(&G);
1031 }
1033 size_t n = GlobalsToChange.size();
1034 if (n == 0) return false;
1036 // A global is described by a structure
1037 // size_t beg;
1038 // size_t size;
1039 // size_t size_with_redzone;
1040 // const char *name;
1041 // const char *module_name;
1042 // size_t has_dynamic_init;
1043 // void *source_location;
1044 // We initialize an array of such structures and pass it to a run-time call.
1045 StructType *GlobalStructTy =
1046 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
1047 IntptrTy, IntptrTy, NULL);
1048 SmallVector<Constant *, 16> Initializers(n);
1050 bool HasDynamicallyInitializedGlobals = false;
1052 // We shouldn't merge same module names, as this string serves as unique
1053 // module ID in runtime.
1054 GlobalVariable *ModuleName = createPrivateGlobalForString(
1055 M, M.getModuleIdentifier(), /*AllowMerging*/false);
1057 for (size_t i = 0; i < n; i++) {
1058 static const uint64_t kMaxGlobalRedzone = 1 << 18;
1059 GlobalVariable *G = GlobalsToChange[i];
1061 auto MD = GlobalsMD.get(G);
1062 // Create string holding the global name (use global name from metadata
1063 // if it's available, otherwise just write the name of global variable).
1064 GlobalVariable *Name = createPrivateGlobalForString(
1065 M, MD.Name.empty() ? G->getName() : MD.Name,
1066 /*AllowMerging*/ true);
1068 PointerType *PtrTy = cast<PointerType>(G->getType());
1069 Type *Ty = PtrTy->getElementType();
1070 uint64_t SizeInBytes = DL->getTypeAllocSize(Ty);
1071 uint64_t MinRZ = MinRedzoneSizeForGlobal();
1072 // MinRZ <= RZ <= kMaxGlobalRedzone
1073 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
1074 uint64_t RZ = std::max(MinRZ,
1075 std::min(kMaxGlobalRedzone,
1076 (SizeInBytes / MinRZ / 4) * MinRZ));
1077 uint64_t RightRedzoneSize = RZ;
1078 // Round up to MinRZ
1079 if (SizeInBytes % MinRZ)
1080 RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
1081 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
1082 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
1084 StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
1085 Constant *NewInitializer = ConstantStruct::get(
1086 NewTy, G->getInitializer(),
1087 Constant::getNullValue(RightRedZoneTy), NULL);
1089 // Create a new global variable with enough space for a redzone.
1090 GlobalValue::LinkageTypes Linkage = G->getLinkage();
1091 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
1092 Linkage = GlobalValue::InternalLinkage;
1093 GlobalVariable *NewGlobal = new GlobalVariable(
1094 M, NewTy, G->isConstant(), Linkage,
1095 NewInitializer, "", G, G->getThreadLocalMode());
1096 NewGlobal->copyAttributesFrom(G);
1097 NewGlobal->setAlignment(MinRZ);
1099 Value *Indices2[2];
1100 Indices2[0] = IRB.getInt32(0);
1101 Indices2[1] = IRB.getInt32(0);
1103 G->replaceAllUsesWith(
1104 ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
1105 NewGlobal->takeName(G);
1106 G->eraseFromParent();
1108 Constant *SourceLoc;
1109 if (!MD.SourceLoc.empty()) {
1110 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
1111 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
1112 } else {
1113 SourceLoc = ConstantInt::get(IntptrTy, 0);
1114 }
1116 Initializers[i] = ConstantStruct::get(
1117 GlobalStructTy, ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
1118 ConstantInt::get(IntptrTy, SizeInBytes),
1119 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
1120 ConstantExpr::getPointerCast(Name, IntptrTy),
1121 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
1122 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc, NULL);
1124 if (ClInitializers && MD.IsDynInit)
1125 HasDynamicallyInitializedGlobals = true;
1127 DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
1128 }
1130 ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
1131 GlobalVariable *AllGlobals = new GlobalVariable(
1132 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
1133 ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
1135 // Create calls for poisoning before initializers run and unpoisoning after.
1136 if (HasDynamicallyInitializedGlobals)
1137 createInitializerPoisonCalls(M, ModuleName);
1138 IRB.CreateCall2(AsanRegisterGlobals,
1139 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1140 ConstantInt::get(IntptrTy, n));
1142 // We also need to unregister globals at the end, e.g. when a shared library
1143 // gets closed.
1144 Function *AsanDtorFunction = Function::Create(
1145 FunctionType::get(Type::getVoidTy(*C), false),
1146 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
1147 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
1148 IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
1149 IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
1150 IRB.CreatePointerCast(AllGlobals, IntptrTy),
1151 ConstantInt::get(IntptrTy, n));
1152 appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
1154 DEBUG(dbgs() << M);
1155 return true;
1156 }
1158 bool AddressSanitizerModule::runOnModule(Module &M) {
1159 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1160 if (!DLP)
1161 return false;
1162 DL = &DLP->getDataLayout();
1163 C = &(M.getContext());
1164 int LongSize = DL->getPointerSizeInBits();
1165 IntptrTy = Type::getIntNTy(*C, LongSize);
1166 Mapping = getShadowMapping(M, LongSize);
1167 initializeCallbacks(M);
1169 bool Changed = false;
1171 Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
1172 assert(CtorFunc);
1173 IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
1175 if (ClGlobals)
1176 Changed |= InstrumentGlobals(IRB, M);
1178 return Changed;
1179 }
1181 void AddressSanitizer::initializeCallbacks(Module &M) {
1182 IRBuilder<> IRB(*C);
1183 // Create __asan_report* callbacks.
1184 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1185 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1186 AccessSizeIndex++) {
1187 // IsWrite and TypeSize are encoded in the function name.
1188 std::string Suffix =
1189 (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1190 AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1191 checkInterfaceFunction(
1192 M.getOrInsertFunction(kAsanReportErrorTemplate + Suffix,
1193 IRB.getVoidTy(), IntptrTy, NULL));
1194 AsanMemoryAccessCallback[AccessIsWrite][AccessSizeIndex] =
1195 checkInterfaceFunction(
1196 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + Suffix,
1197 IRB.getVoidTy(), IntptrTy, NULL));
1198 }
1199 }
1200 AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1201 kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1202 AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1203 kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1205 AsanMemoryAccessCallbackSized[0] = checkInterfaceFunction(
1206 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "loadN",
1207 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1208 AsanMemoryAccessCallbackSized[1] = checkInterfaceFunction(
1209 M.getOrInsertFunction(ClMemoryAccessCallbackPrefix + "storeN",
1210 IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1212 AsanMemmove = checkInterfaceFunction(M.getOrInsertFunction(
1213 ClMemoryAccessCallbackPrefix + "memmove", IRB.getInt8PtrTy(),
1214 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1215 AsanMemcpy = checkInterfaceFunction(M.getOrInsertFunction(
1216 ClMemoryAccessCallbackPrefix + "memcpy", IRB.getInt8PtrTy(),
1217 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(), IntptrTy, NULL));
1218 AsanMemset = checkInterfaceFunction(M.getOrInsertFunction(
1219 ClMemoryAccessCallbackPrefix + "memset", IRB.getInt8PtrTy(),
1220 IRB.getInt8PtrTy(), IRB.getInt32Ty(), IntptrTy, NULL));
1222 AsanHandleNoReturnFunc = checkInterfaceFunction(
1223 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1225 AsanPtrCmpFunction = checkInterfaceFunction(M.getOrInsertFunction(
1226 kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1227 AsanPtrSubFunction = checkInterfaceFunction(M.getOrInsertFunction(
1228 kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1229 // We insert an empty inline asm after __asan_report* to avoid callback merge.
1230 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1231 StringRef(""), StringRef(""),
1232 /*hasSideEffects=*/true);
1233 }
1235 // virtual
1236 bool AddressSanitizer::doInitialization(Module &M) {
1237 // Initialize the private fields. No one has accessed them before.
1238 DataLayoutPass *DLP = getAnalysisIfAvailable<DataLayoutPass>();
1239 if (!DLP)
1240 report_fatal_error("data layout missing");
1241 DL = &DLP->getDataLayout();
1243 GlobalsMD.init(M);
1245 C = &(M.getContext());
1246 LongSize = DL->getPointerSizeInBits();
1247 IntptrTy = Type::getIntNTy(*C, LongSize);
1249 AsanCtorFunction = Function::Create(
1250 FunctionType::get(Type::getVoidTy(*C), false),
1251 GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1252 BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1253 // call __asan_init in the module ctor.
1254 IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1255 AsanInitFunction = checkInterfaceFunction(
1256 M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1257 AsanInitFunction->setLinkage(Function::ExternalLinkage);
1258 IRB.CreateCall(AsanInitFunction);
1260 Mapping = getShadowMapping(M, LongSize);
1262 appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
1263 return true;
1264 }
1266 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1267 // For each NSObject descendant having a +load method, this method is invoked
1268 // by the ObjC runtime before any of the static constructors is called.
1269 // Therefore we need to instrument such methods with a call to __asan_init
1270 // at the beginning in order to initialize our runtime before any access to
1271 // the shadow memory.
1272 // We cannot just ignore these methods, because they may call other
1273 // instrumented functions.
1274 if (F.getName().find(" load]") != std::string::npos) {
1275 IRBuilder<> IRB(F.begin()->begin());
1276 IRB.CreateCall(AsanInitFunction);
1277 return true;
1278 }
1279 return false;
1280 }
1282 bool AddressSanitizer::runOnFunction(Function &F) {
1283 if (&F == AsanCtorFunction) return false;
1284 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1285 DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1286 initializeCallbacks(*F.getParent());
1288 // If needed, insert __asan_init before checking for SanitizeAddress attr.
1289 maybeInsertAsanInitAtFunctionEntry(F);
1291 if (!F.hasFnAttribute(Attribute::SanitizeAddress))
1292 return false;
1294 if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1295 return false;
1297 // We want to instrument every address only once per basic block (unless there
1298 // are calls between uses).
1299 SmallSet<Value*, 16> TempsToInstrument;
1300 SmallVector<Instruction*, 16> ToInstrument;
1301 SmallVector<Instruction*, 8> NoReturnCalls;
1302 SmallVector<BasicBlock*, 16> AllBlocks;
1303 SmallVector<Instruction*, 16> PointerComparisonsOrSubtracts;
1304 int NumAllocas = 0;
1305 bool IsWrite;
1306 unsigned Alignment;
1308 // Fill the set of memory operations to instrument.
1309 for (auto &BB : F) {
1310 AllBlocks.push_back(&BB);
1311 TempsToInstrument.clear();
1312 int NumInsnsPerBB = 0;
1313 for (auto &Inst : BB) {
1314 if (LooksLikeCodeInBug11395(&Inst)) return false;
1315 if (Value *Addr =
1316 isInterestingMemoryAccess(&Inst, &IsWrite, &Alignment)) {
1317 if (ClOpt && ClOptSameTemp) {
1318 if (!TempsToInstrument.insert(Addr))
1319 continue; // We've seen this temp in the current BB.
1320 }
1321 } else if (ClInvalidPointerPairs &&
1322 isInterestingPointerComparisonOrSubtraction(&Inst)) {
1323 PointerComparisonsOrSubtracts.push_back(&Inst);
1324 continue;
1325 } else if (isa<MemIntrinsic>(Inst)) {
1326 // ok, take it.
1327 } else {
1328 if (isa<AllocaInst>(Inst))
1329 NumAllocas++;
1330 CallSite CS(&Inst);
1331 if (CS) {
1332 // A call inside BB.
1333 TempsToInstrument.clear();
1334 if (CS.doesNotReturn())
1335 NoReturnCalls.push_back(CS.getInstruction());
1336 }
1337 continue;
1338 }
1339 ToInstrument.push_back(&Inst);
1340 NumInsnsPerBB++;
1341 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1342 break;
1343 }
1344 }
1346 Function *UninstrumentedDuplicate = nullptr;
1347 bool LikelyToInstrument =
1348 !NoReturnCalls.empty() || !ToInstrument.empty() || (NumAllocas > 0);
1349 if (ClKeepUninstrumented && LikelyToInstrument) {
1350 ValueToValueMapTy VMap;
1351 UninstrumentedDuplicate = CloneFunction(&F, VMap, false);
1352 UninstrumentedDuplicate->removeFnAttr(Attribute::SanitizeAddress);
1353 UninstrumentedDuplicate->setName("NOASAN_" + F.getName());
1354 F.getParent()->getFunctionList().push_back(UninstrumentedDuplicate);
1355 }
1357 bool UseCalls = false;
1358 if (ClInstrumentationWithCallsThreshold >= 0 &&
1359 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold)
1360 UseCalls = true;
1362 // Instrument.
1363 int NumInstrumented = 0;
1364 for (auto Inst : ToInstrument) {
1365 if (ClDebugMin < 0 || ClDebugMax < 0 ||
1366 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1367 if (isInterestingMemoryAccess(Inst, &IsWrite, &Alignment))
1368 instrumentMop(Inst, UseCalls);
1369 else
1370 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1371 }
1372 NumInstrumented++;
1373 }
1375 FunctionStackPoisoner FSP(F, *this);
1376 bool ChangedStack = FSP.runOnFunction();
1378 // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1379 // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1380 for (auto CI : NoReturnCalls) {
1381 IRBuilder<> IRB(CI);
1382 IRB.CreateCall(AsanHandleNoReturnFunc);
1383 }
1385 for (auto Inst : PointerComparisonsOrSubtracts) {
1386 instrumentPointerComparisonOrSubtraction(Inst);
1387 NumInstrumented++;
1388 }
1390 bool res = NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1392 DEBUG(dbgs() << "ASAN done instrumenting: " << res << " " << F << "\n");
1394 if (ClKeepUninstrumented) {
1395 if (!res) {
1396 // No instrumentation is done, no need for the duplicate.
1397 if (UninstrumentedDuplicate)
1398 UninstrumentedDuplicate->eraseFromParent();
1399 } else {
1400 // The function was instrumented. We must have the duplicate.
1401 assert(UninstrumentedDuplicate);
1402 UninstrumentedDuplicate->setSection("NOASAN");
1403 assert(!F.hasSection());
1404 F.setSection("ASAN");
1405 }
1406 }
1408 return res;
1409 }
1411 // Workaround for bug 11395: we don't want to instrument stack in functions
1412 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1413 // FIXME: remove once the bug 11395 is fixed.
1414 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1415 if (LongSize != 32) return false;
1416 CallInst *CI = dyn_cast<CallInst>(I);
1417 if (!CI || !CI->isInlineAsm()) return false;
1418 if (CI->getNumArgOperands() <= 5) return false;
1419 // We have inline assembly with quite a few arguments.
1420 return true;
1421 }
1423 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1424 IRBuilder<> IRB(*C);
1425 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
1426 std::string Suffix = itostr(i);
1427 AsanStackMallocFunc[i] = checkInterfaceFunction(
1428 M.getOrInsertFunction(kAsanStackMallocNameTemplate + Suffix, IntptrTy,
1429 IntptrTy, IntptrTy, NULL));
1430 AsanStackFreeFunc[i] = checkInterfaceFunction(M.getOrInsertFunction(
1431 kAsanStackFreeNameTemplate + Suffix, IRB.getVoidTy(), IntptrTy,
1432 IntptrTy, IntptrTy, NULL));
1433 }
1434 AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1435 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1436 AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1437 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1438 }
1440 void
1441 FunctionStackPoisoner::poisonRedZones(ArrayRef<uint8_t> ShadowBytes,
1442 IRBuilder<> &IRB, Value *ShadowBase,
1443 bool DoPoison) {
1444 size_t n = ShadowBytes.size();
1445 size_t i = 0;
1446 // We need to (un)poison n bytes of stack shadow. Poison as many as we can
1447 // using 64-bit stores (if we are on 64-bit arch), then poison the rest
1448 // with 32-bit stores, then with 16-byte stores, then with 8-byte stores.
1449 for (size_t LargeStoreSizeInBytes = ASan.LongSize / 8;
1450 LargeStoreSizeInBytes != 0; LargeStoreSizeInBytes /= 2) {
1451 for (; i + LargeStoreSizeInBytes - 1 < n; i += LargeStoreSizeInBytes) {
1452 uint64_t Val = 0;
1453 for (size_t j = 0; j < LargeStoreSizeInBytes; j++) {
1454 if (ASan.DL->isLittleEndian())
1455 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
1456 else
1457 Val = (Val << 8) | ShadowBytes[i + j];
1458 }
1459 if (!Val) continue;
1460 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1461 Type *StoreTy = Type::getIntNTy(*C, LargeStoreSizeInBytes * 8);
1462 Value *Poison = ConstantInt::get(StoreTy, DoPoison ? Val : 0);
1463 IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, StoreTy->getPointerTo()));
1464 }
1465 }
1466 }
1468 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
1469 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
1470 static int StackMallocSizeClass(uint64_t LocalStackSize) {
1471 assert(LocalStackSize <= kMaxStackMallocSize);
1472 uint64_t MaxSize = kMinStackMallocSize;
1473 for (int i = 0; ; i++, MaxSize *= 2)
1474 if (LocalStackSize <= MaxSize)
1475 return i;
1476 llvm_unreachable("impossible LocalStackSize");
1477 }
1479 // Set Size bytes starting from ShadowBase to kAsanStackAfterReturnMagic.
1480 // We can not use MemSet intrinsic because it may end up calling the actual
1481 // memset. Size is a multiple of 8.
1482 // Currently this generates 8-byte stores on x86_64; it may be better to
1483 // generate wider stores.
1484 void FunctionStackPoisoner::SetShadowToStackAfterReturnInlined(
1485 IRBuilder<> &IRB, Value *ShadowBase, int Size) {
1486 assert(!(Size % 8));
1487 assert(kAsanStackAfterReturnMagic == 0xf5);
1488 for (int i = 0; i < Size; i += 8) {
1489 Value *p = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
1490 IRB.CreateStore(ConstantInt::get(IRB.getInt64Ty(), 0xf5f5f5f5f5f5f5f5ULL),
1491 IRB.CreateIntToPtr(p, IRB.getInt64Ty()->getPointerTo()));
1492 }
1493 }
1495 static DebugLoc getFunctionEntryDebugLocation(Function &F) {
1496 for (const auto &Inst : F.getEntryBlock())
1497 if (!isa<AllocaInst>(Inst))
1498 return Inst.getDebugLoc();
1499 return DebugLoc();
1500 }
1502 void FunctionStackPoisoner::poisonStack() {
1503 int StackMallocIdx = -1;
1504 DebugLoc EntryDebugLocation = getFunctionEntryDebugLocation(F);
1506 assert(AllocaVec.size() > 0);
1507 Instruction *InsBefore = AllocaVec[0];
1508 IRBuilder<> IRB(InsBefore);
1509 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1511 SmallVector<ASanStackVariableDescription, 16> SVD;
1512 SVD.reserve(AllocaVec.size());
1513 for (AllocaInst *AI : AllocaVec) {
1514 ASanStackVariableDescription D = { AI->getName().data(),
1515 getAllocaSizeInBytes(AI),
1516 AI->getAlignment(), AI, 0};
1517 SVD.push_back(D);
1518 }
1519 // Minimal header size (left redzone) is 4 pointers,
1520 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
1521 size_t MinHeaderSize = ASan.LongSize / 2;
1522 ASanStackFrameLayout L;
1523 ComputeASanStackFrameLayout(SVD, 1UL << Mapping.Scale, MinHeaderSize, &L);
1524 DEBUG(dbgs() << L.DescriptionString << " --- " << L.FrameSize << "\n");
1525 uint64_t LocalStackSize = L.FrameSize;
1526 bool DoStackMalloc =
1527 ClUseAfterReturn && LocalStackSize <= kMaxStackMallocSize;
1529 Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1530 AllocaInst *MyAlloca =
1531 new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1532 MyAlloca->setDebugLoc(EntryDebugLocation);
1533 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
1534 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
1535 MyAlloca->setAlignment(FrameAlignment);
1536 assert(MyAlloca->isStaticAlloca());
1537 Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1538 Value *LocalStackBase = OrigStackBase;
1540 if (DoStackMalloc) {
1541 // LocalStackBase = OrigStackBase
1542 // if (__asan_option_detect_stack_use_after_return)
1543 // LocalStackBase = __asan_stack_malloc_N(LocalStackBase, OrigStackBase);
1544 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
1545 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
1546 Constant *OptionDetectUAR = F.getParent()->getOrInsertGlobal(
1547 kAsanOptionDetectUAR, IRB.getInt32Ty());
1548 Value *Cmp = IRB.CreateICmpNE(IRB.CreateLoad(OptionDetectUAR),
1549 Constant::getNullValue(IRB.getInt32Ty()));
1550 Instruction *Term = SplitBlockAndInsertIfThen(Cmp, InsBefore, false);
1551 BasicBlock *CmpBlock = cast<Instruction>(Cmp)->getParent();
1552 IRBuilder<> IRBIf(Term);
1553 IRBIf.SetCurrentDebugLocation(EntryDebugLocation);
1554 LocalStackBase = IRBIf.CreateCall2(
1555 AsanStackMallocFunc[StackMallocIdx],
1556 ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1557 BasicBlock *SetBlock = cast<Instruction>(LocalStackBase)->getParent();
1558 IRB.SetInsertPoint(InsBefore);
1559 IRB.SetCurrentDebugLocation(EntryDebugLocation);
1560 PHINode *Phi = IRB.CreatePHI(IntptrTy, 2);
1561 Phi->addIncoming(OrigStackBase, CmpBlock);
1562 Phi->addIncoming(LocalStackBase, SetBlock);
1563 LocalStackBase = Phi;
1564 }
1566 // Insert poison calls for lifetime intrinsics for alloca.
1567 bool HavePoisonedAllocas = false;
1568 for (const auto &APC : AllocaPoisonCallVec) {
1569 assert(APC.InsBefore);
1570 assert(APC.AI);
1571 IRBuilder<> IRB(APC.InsBefore);
1572 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
1573 HavePoisonedAllocas |= APC.DoPoison;
1574 }
1576 // Replace Alloca instructions with base+offset.
1577 for (const auto &Desc : SVD) {
1578 AllocaInst *AI = Desc.AI;
1579 Value *NewAllocaPtr = IRB.CreateIntToPtr(
1580 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
1581 AI->getType());
1582 replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1583 AI->replaceAllUsesWith(NewAllocaPtr);
1584 }
1586 // The left-most redzone has enough space for at least 4 pointers.
1587 // Write the Magic value to redzone[0].
1588 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1589 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1590 BasePlus0);
1591 // Write the frame description constant to redzone[1].
1592 Value *BasePlus1 = IRB.CreateIntToPtr(
1593 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1594 IntptrPtrTy);
1595 GlobalVariable *StackDescriptionGlobal =
1596 createPrivateGlobalForString(*F.getParent(), L.DescriptionString,
1597 /*AllowMerging*/true);
1598 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1599 IntptrTy);
1600 IRB.CreateStore(Description, BasePlus1);
1601 // Write the PC to redzone[2].
1602 Value *BasePlus2 = IRB.CreateIntToPtr(
1603 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1604 2 * ASan.LongSize/8)),
1605 IntptrPtrTy);
1606 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1608 // Poison the stack redzones at the entry.
1609 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1610 poisonRedZones(L.ShadowBytes, IRB, ShadowBase, true);
1612 // (Un)poison the stack before all ret instructions.
1613 for (auto Ret : RetVec) {
1614 IRBuilder<> IRBRet(Ret);
1615 // Mark the current frame as retired.
1616 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1617 BasePlus0);
1618 if (DoStackMalloc) {
1619 assert(StackMallocIdx >= 0);
1620 // if LocalStackBase != OrigStackBase:
1621 // // In use-after-return mode, poison the whole stack frame.
1622 // if StackMallocIdx <= 4
1623 // // For small sizes inline the whole thing:
1624 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
1625 // **SavedFlagPtr(LocalStackBase) = 0
1626 // else
1627 // __asan_stack_free_N(LocalStackBase, OrigStackBase)
1628 // else
1629 // <This is not a fake stack; unpoison the redzones>
1630 Value *Cmp = IRBRet.CreateICmpNE(LocalStackBase, OrigStackBase);
1631 TerminatorInst *ThenTerm, *ElseTerm;
1632 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
1634 IRBuilder<> IRBPoison(ThenTerm);
1635 if (StackMallocIdx <= 4) {
1636 int ClassSize = kMinStackMallocSize << StackMallocIdx;
1637 SetShadowToStackAfterReturnInlined(IRBPoison, ShadowBase,
1638 ClassSize >> Mapping.Scale);
1639 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
1640 LocalStackBase,
1641 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
1642 Value *SavedFlagPtr = IRBPoison.CreateLoad(
1643 IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
1644 IRBPoison.CreateStore(
1645 Constant::getNullValue(IRBPoison.getInt8Ty()),
1646 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
1647 } else {
1648 // For larger frames call __asan_stack_free_*.
1649 IRBPoison.CreateCall3(AsanStackFreeFunc[StackMallocIdx], LocalStackBase,
1650 ConstantInt::get(IntptrTy, LocalStackSize),
1651 OrigStackBase);
1652 }
1654 IRBuilder<> IRBElse(ElseTerm);
1655 poisonRedZones(L.ShadowBytes, IRBElse, ShadowBase, false);
1656 } else if (HavePoisonedAllocas) {
1657 // If we poisoned some allocas in llvm.lifetime analysis,
1658 // unpoison whole stack frame now.
1659 assert(LocalStackBase == OrigStackBase);
1660 poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1661 } else {
1662 poisonRedZones(L.ShadowBytes, IRBRet, ShadowBase, false);
1663 }
1664 }
1666 // We are done. Remove the old unused alloca instructions.
1667 for (auto AI : AllocaVec)
1668 AI->eraseFromParent();
1669 }
1671 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1672 IRBuilder<> &IRB, bool DoPoison) {
1673 // For now just insert the call to ASan runtime.
1674 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1675 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1676 IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1677 : AsanUnpoisonStackMemoryFunc,
1678 AddrArg, SizeArg);
1679 }
1681 // Handling llvm.lifetime intrinsics for a given %alloca:
1682 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1683 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1684 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1685 // could be poisoned by previous llvm.lifetime.end instruction, as the
1686 // variable may go in and out of scope several times, e.g. in loops).
1687 // (3) if we poisoned at least one %alloca in a function,
1688 // unpoison the whole stack frame at function exit.
1690 AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1691 if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1692 // We're intested only in allocas we can handle.
1693 return isInterestingAlloca(*AI) ? AI : nullptr;
1694 // See if we've already calculated (or started to calculate) alloca for a
1695 // given value.
1696 AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1697 if (I != AllocaForValue.end())
1698 return I->second;
1699 // Store 0 while we're calculating alloca for value V to avoid
1700 // infinite recursion if the value references itself.
1701 AllocaForValue[V] = nullptr;
1702 AllocaInst *Res = nullptr;
1703 if (CastInst *CI = dyn_cast<CastInst>(V))
1704 Res = findAllocaForValue(CI->getOperand(0));
1705 else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1706 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1707 Value *IncValue = PN->getIncomingValue(i);
1708 // Allow self-referencing phi-nodes.
1709 if (IncValue == PN) continue;
1710 AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1711 // AI for incoming values should exist and should all be equal.
1712 if (IncValueAI == nullptr || (Res != nullptr && IncValueAI != Res))
1713 return nullptr;
1714 Res = IncValueAI;
1715 }
1716 }
1717 if (Res)
1718 AllocaForValue[V] = Res;
1719 return Res;
1720 }