AddressSanitizer.cpp revision 5085eb80abe29320fa8922c10b36249f5163f45d 
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#define DEBUG_TYPE "asan"
17
18#include "BlackList.h"
19#include "llvm/Function.h"
20#include "llvm/IRBuilder.h"
21#include "llvm/InlineAsm.h"
22#include "llvm/IntrinsicInst.h"
23#include "llvm/LLVMContext.h"
24#include "llvm/Module.h"
25#include "llvm/Type.h"
26#include "llvm/ADT/ArrayRef.h"
27#include "llvm/ADT/OwningPtr.h"
28#include "llvm/ADT/SmallSet.h"
29#include "llvm/ADT/SmallString.h"
30#include "llvm/ADT/SmallVector.h"
31#include "llvm/ADT/StringExtras.h"
32#include "llvm/ADT/Triple.h"
33#include "llvm/Support/CommandLine.h"
34#include "llvm/Support/DataTypes.h"
35#include "llvm/Support/Debug.h"
36#include "llvm/Support/raw_ostream.h"
37#include "llvm/Support/system_error.h"
38#include "llvm/DataLayout.h"
39#include "llvm/Target/TargetMachine.h"
40#include "llvm/Transforms/Instrumentation.h"
41#include "llvm/Transforms/Utils/BasicBlockUtils.h"
42#include "llvm/Transforms/Utils/ModuleUtils.h"
43
44#include <string>
45#include <algorithm>
46
47using namespace llvm;
48
49static const uint64_t kDefaultShadowScale = 3;
50static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
51static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
52static const uint64_t kDefaultShadowOffsetAndroid = 0;
53
54static const size_t kMaxStackMallocSize = 1 << 16;  // 64K
55static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
56static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
57
58static const char *kAsanModuleCtorName = "asan.module_ctor";
59static const char *kAsanModuleDtorName = "asan.module_dtor";
60static const int   kAsanCtorAndCtorPriority = 1;
61static const char *kAsanReportErrorTemplate = "__asan_report_";
62static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
63static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
64static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
65static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
66static const char *kAsanInitName = "__asan_init";
67static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
68static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
69static const char *kAsanMappingScaleName = "__asan_mapping_scale";
70static const char *kAsanStackMallocName = "__asan_stack_malloc";
71static const char *kAsanStackFreeName = "__asan_stack_free";
72static const char *kAsanGenPrefix = "__asan_gen_";
73
74static const int kAsanStackLeftRedzoneMagic = 0xf1;
75static const int kAsanStackMidRedzoneMagic = 0xf2;
76static const int kAsanStackRightRedzoneMagic = 0xf3;
77static const int kAsanStackPartialRedzoneMagic = 0xf4;
78
79// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
80static const size_t kNumberOfAccessSizes = 5;
81
82// Command-line flags.
83
84// This flag may need to be replaced with -f[no-]asan-reads.
85static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
86       cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
87static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
88       cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
89static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
90       cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
91       cl::Hidden, cl::init(true));
92static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
93       cl::desc("use instrumentation with slow path for all accesses"),
94       cl::Hidden, cl::init(false));
95// This flag limits the number of instructions to be instrumented
96// in any given BB. Normally, this should be set to unlimited (INT_MAX),
97// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
98// set it to 10000.
99static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
100       cl::init(10000),
101       cl::desc("maximal number of instructions to instrument in any given BB"),
102       cl::Hidden);
103// This flag may need to be replaced with -f[no]asan-stack.
104static cl::opt<bool> ClStack("asan-stack",
105       cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
106// This flag may need to be replaced with -f[no]asan-use-after-return.
107static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
108       cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
109// This flag may need to be replaced with -f[no]asan-globals.
110static cl::opt<bool> ClGlobals("asan-globals",
111       cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
112static cl::opt<bool> ClInitializers("asan-initialization-order",
113       cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
114static cl::opt<bool> ClMemIntrin("asan-memintrin",
115       cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
116// This flag may need to be replaced with -fasan-blacklist.
117static cl::opt<std::string>  ClBlackListFile("asan-blacklist",
118       cl::desc("File containing the list of functions to ignore "
119                "during instrumentation"), cl::Hidden);
120
121// These flags allow to change the shadow mapping.
122// The shadow mapping looks like
123//    Shadow = (Mem >> scale) + (1 << offset_log)
124static cl::opt<int> ClMappingScale("asan-mapping-scale",
125       cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
126static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
127       cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
128
129// Optimization flags. Not user visible, used mostly for testing
130// and benchmarking the tool.
131static cl::opt<bool> ClOpt("asan-opt",
132       cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
133static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
134       cl::desc("Instrument the same temp just once"), cl::Hidden,
135       cl::init(true));
136static cl::opt<bool> ClOptGlobals("asan-opt-globals",
137       cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
138
139// Debug flags.
140static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
141                            cl::init(0));
142static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
143                                 cl::Hidden, cl::init(0));
144static cl::opt<std::string> ClDebugFunc("asan-debug-func",
145                                        cl::Hidden, cl::desc("Debug func"));
146static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
147                               cl::Hidden, cl::init(-1));
148static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
149                               cl::Hidden, cl::init(-1));
150
151namespace {
152/// A set of dynamically initialized globals extracted from metadata.
153class SetOfDynamicallyInitializedGlobals {
154 public:
155  void Init(Module& M) {
156    // Clang generates metadata identifying all dynamically initialized globals.
157    NamedMDNode *DynamicGlobals =
158        M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
159    if (!DynamicGlobals)
160      return;
161    for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
162      MDNode *MDN = DynamicGlobals->getOperand(i);
163      assert(MDN->getNumOperands() == 1);
164      Value *VG = MDN->getOperand(0);
165      // The optimizer may optimize away a global entirely, in which case we
166      // cannot instrument access to it.
167      if (!VG)
168        continue;
169      DynInitGlobals.insert(cast<GlobalVariable>(VG));
170    }
171  }
172  bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
173 private:
174  SmallSet<GlobalValue*, 32> DynInitGlobals;
175};
176
177static int MappingScale() {
178  return ClMappingScale ? ClMappingScale : kDefaultShadowScale;
179}
180
181static size_t RedzoneSize() {
182  // Redzone used for stack and globals is at least 32 bytes.
183  // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
184  return std::max(32U, 1U << MappingScale());
185}
186
187/// AddressSanitizer: instrument the code in module to find memory bugs.
188struct AddressSanitizer : public FunctionPass {
189  AddressSanitizer();
190  virtual const char *getPassName() const {
191    return "AddressSanitizerFunctionPass";
192  }
193  void instrumentMop(Instruction *I);
194  void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
195                         Value *Addr, uint32_t TypeSize, bool IsWrite);
196  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
197                           Value *ShadowValue, uint32_t TypeSize);
198  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
199                                 bool IsWrite, size_t AccessSizeIndex);
200  bool instrumentMemIntrinsic(MemIntrinsic *MI);
201  void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
202                                   Value *Size,
203                                   Instruction *InsertBefore, bool IsWrite);
204  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
205  bool runOnFunction(Function &F);
206  void createInitializerPoisonCalls(Module &M,
207                                    Value *FirstAddr, Value *LastAddr);
208  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
209  bool poisonStackInFunction(Function &F);
210  virtual bool doInitialization(Module &M);
211  static char ID;  // Pass identification, replacement for typeid
212
213 private:
214  uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
215    Type *Ty = AI->getAllocatedType();
216    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
217    return SizeInBytes;
218  }
219  uint64_t getAlignedSize(uint64_t SizeInBytes) {
220    size_t RZ = RedzoneSize();
221    return ((SizeInBytes + RZ - 1) / RZ) * RZ;
222  }
223  uint64_t getAlignedAllocaSize(AllocaInst *AI) {
224    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
225    return getAlignedSize(SizeInBytes);
226  }
227
228  bool ShouldInstrumentGlobal(GlobalVariable *G);
229  void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
230                   Value *ShadowBase, bool DoPoison);
231  bool LooksLikeCodeInBug11395(Instruction *I);
232  void FindDynamicInitializers(Module &M);
233
234  LLVMContext *C;
235  DataLayout *TD;
236  uint64_t MappingOffset;
237  int LongSize;
238  Type *IntptrTy;
239  Type *IntptrPtrTy;
240  Function *AsanCtorFunction;
241  Function *AsanInitFunction;
242  Function *AsanStackMallocFunc, *AsanStackFreeFunc;
243  Function *AsanHandleNoReturnFunc;
244  OwningPtr<BlackList> BL;
245  // This array is indexed by AccessIsWrite and log2(AccessSize).
246  Function *AsanErrorCallback[2][kNumberOfAccessSizes];
247  InlineAsm *EmptyAsm;
248  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
249};
250
251class AddressSanitizerModule : public ModulePass {
252 public:
253  bool runOnModule(Module &M);
254  static char ID;  // Pass identification, replacement for typeid
255  AddressSanitizerModule() : ModulePass(ID) { }
256  virtual const char *getPassName() const {
257    return "AddressSanitizerModule";
258  }
259 private:
260  bool ShouldInstrumentGlobal(GlobalVariable *G);
261  void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
262                                    Value *LastAddr);
263
264  OwningPtr<BlackList> BL;
265  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
266  Type *IntptrTy;
267  LLVMContext *C;
268  DataLayout *TD;
269};
270
271}  // namespace
272
273char AddressSanitizer::ID = 0;
274INITIALIZE_PASS(AddressSanitizer, "asan",
275    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
276    false, false)
277AddressSanitizer::AddressSanitizer() : FunctionPass(ID) { }
278FunctionPass *llvm::createAddressSanitizerFunctionPass() {
279  return new AddressSanitizer();
280}
281
282char AddressSanitizerModule::ID = 0;
283INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
284    "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
285    "ModulePass", false, false)
286ModulePass *llvm::createAddressSanitizerModulePass() {
287  return new AddressSanitizerModule();
288}
289
290static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
291  size_t Res = CountTrailingZeros_32(TypeSize / 8);
292  assert(Res < kNumberOfAccessSizes);
293  return Res;
294}
295
296// Create a constant for Str so that we can pass it to the run-time lib.
297static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
298  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
299  return new GlobalVariable(M, StrConst->getType(), true,
300                            GlobalValue::PrivateLinkage, StrConst,
301                            kAsanGenPrefix);
302}
303
304static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
305  return G->getName().find(kAsanGenPrefix) == 0;
306}
307
308Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
309  // Shadow >> scale
310  Shadow = IRB.CreateLShr(Shadow, MappingScale());
311  if (MappingOffset == 0)
312    return Shadow;
313  // (Shadow >> scale) | offset
314  return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
315                                               MappingOffset));
316}
317
318void AddressSanitizer::instrumentMemIntrinsicParam(
319    Instruction *OrigIns,
320    Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
321  // Check the first byte.
322  {
323    IRBuilder<> IRB(InsertBefore);
324    instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
325  }
326  // Check the last byte.
327  {
328    IRBuilder<> IRB(InsertBefore);
329    Value *SizeMinusOne = IRB.CreateSub(
330        Size, ConstantInt::get(Size->getType(), 1));
331    SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
332    Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
333    Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
334    instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
335  }
336}
337
338// Instrument memset/memmove/memcpy
339bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
340  Value *Dst = MI->getDest();
341  MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
342  Value *Src = MemTran ? MemTran->getSource() : 0;
343  Value *Length = MI->getLength();
344
345  Constant *ConstLength = dyn_cast<Constant>(Length);
346  Instruction *InsertBefore = MI;
347  if (ConstLength) {
348    if (ConstLength->isNullValue()) return false;
349  } else {
350    // The size is not a constant so it could be zero -- check at run-time.
351    IRBuilder<> IRB(InsertBefore);
352
353    Value *Cmp = IRB.CreateICmpNE(Length,
354                                  Constant::getNullValue(Length->getType()));
355    InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
356  }
357
358  instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
359  if (Src)
360    instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
361  return true;
362}
363
364// If I is an interesting memory access, return the PointerOperand
365// and set IsWrite. Otherwise return NULL.
366static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
367  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
368    if (!ClInstrumentReads) return NULL;
369    *IsWrite = false;
370    return LI->getPointerOperand();
371  }
372  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
373    if (!ClInstrumentWrites) return NULL;
374    *IsWrite = true;
375    return SI->getPointerOperand();
376  }
377  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
378    if (!ClInstrumentAtomics) return NULL;
379    *IsWrite = true;
380    return RMW->getPointerOperand();
381  }
382  if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
383    if (!ClInstrumentAtomics) return NULL;
384    *IsWrite = true;
385    return XCHG->getPointerOperand();
386  }
387  return NULL;
388}
389
390void AddressSanitizer::instrumentMop(Instruction *I) {
391  bool IsWrite = false;
392  Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
393  assert(Addr);
394  if (ClOpt && ClOptGlobals) {
395    if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
396      // If initialization order checking is disabled, a simple access to a
397      // dynamically initialized global is always valid.
398      if (!ClInitializers)
399        return;
400      // If a global variable does not have dynamic initialization we don't
401      // have to instrument it.  However, if a global does not have initailizer
402      // at all, we assume it has dynamic initializer (in other TU).
403      if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
404        return;
405    }
406  }
407
408  Type *OrigPtrTy = Addr->getType();
409  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
410
411  assert(OrigTy->isSized());
412  uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
413
414  if (TypeSize != 8  && TypeSize != 16 &&
415      TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
416    // Ignore all unusual sizes.
417    return;
418  }
419
420  IRBuilder<> IRB(I);
421  instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
422}
423
424// Validate the result of Module::getOrInsertFunction called for an interface
425// function of AddressSanitizer. If the instrumented module defines a function
426// with the same name, their prototypes must match, otherwise
427// getOrInsertFunction returns a bitcast.
428static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
429  if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
430  FuncOrBitcast->dump();
431  report_fatal_error("trying to redefine an AddressSanitizer "
432                     "interface function");
433}
434
435Instruction *AddressSanitizer::generateCrashCode(
436    Instruction *InsertBefore, Value *Addr,
437    bool IsWrite, size_t AccessSizeIndex) {
438  IRBuilder<> IRB(InsertBefore);
439  CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
440                                  Addr);
441  // We don't do Call->setDoesNotReturn() because the BB already has
442  // UnreachableInst at the end.
443  // This EmptyAsm is required to avoid callback merge.
444  IRB.CreateCall(EmptyAsm);
445  return Call;
446}
447
448Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
449                                            Value *ShadowValue,
450                                            uint32_t TypeSize) {
451  size_t Granularity = 1 << MappingScale();
452  // Addr & (Granularity - 1)
453  Value *LastAccessedByte = IRB.CreateAnd(
454      AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
455  // (Addr & (Granularity - 1)) + size - 1
456  if (TypeSize / 8 > 1)
457    LastAccessedByte = IRB.CreateAdd(
458        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
459  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
460  LastAccessedByte = IRB.CreateIntCast(
461      LastAccessedByte, ShadowValue->getType(), false);
462  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
463  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
464}
465
466void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
467                                         IRBuilder<> &IRB, Value *Addr,
468                                         uint32_t TypeSize, bool IsWrite) {
469  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
470
471  Type *ShadowTy  = IntegerType::get(
472      *C, std::max(8U, TypeSize >> MappingScale()));
473  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
474  Value *ShadowPtr = memToShadow(AddrLong, IRB);
475  Value *CmpVal = Constant::getNullValue(ShadowTy);
476  Value *ShadowValue = IRB.CreateLoad(
477      IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
478
479  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
480  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
481  size_t Granularity = 1 << MappingScale();
482  TerminatorInst *CrashTerm = 0;
483
484  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
485    TerminatorInst *CheckTerm =
486        SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
487    assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
488    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
489    IRB.SetInsertPoint(CheckTerm);
490    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
491    BasicBlock *CrashBlock =
492        BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
493    CrashTerm = new UnreachableInst(*C, CrashBlock);
494    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
495    ReplaceInstWithInst(CheckTerm, NewTerm);
496  } else {
497    CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
498  }
499
500  Instruction *Crash =
501      generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
502  Crash->setDebugLoc(OrigIns->getDebugLoc());
503}
504
505void AddressSanitizerModule::createInitializerPoisonCalls(
506    Module &M, Value *FirstAddr, Value *LastAddr) {
507  // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
508  Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
509  // If that function is not present, this TU contains no globals, or they have
510  // all been optimized away
511  if (!GlobalInit)
512    return;
513
514  // Set up the arguments to our poison/unpoison functions.
515  IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
516
517  // Declare our poisoning and unpoisoning functions.
518  Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
519      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
520  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
521  Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
522      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
523  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
524
525  // Add a call to poison all external globals before the given function starts.
526  IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
527
528  // Add calls to unpoison all globals before each return instruction.
529  for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
530      I != E; ++I) {
531    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
532      CallInst::Create(AsanUnpoisonGlobals, "", RI);
533    }
534  }
535}
536
537bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
538  Type *Ty = cast<PointerType>(G->getType())->getElementType();
539  DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
540
541  if (BL->isIn(*G)) return false;
542  if (!Ty->isSized()) return false;
543  if (!G->hasInitializer()) return false;
544  if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
545  // Touch only those globals that will not be defined in other modules.
546  // Don't handle ODR type linkages since other modules may be built w/o asan.
547  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
548      G->getLinkage() != GlobalVariable::PrivateLinkage &&
549      G->getLinkage() != GlobalVariable::InternalLinkage)
550    return false;
551  // Two problems with thread-locals:
552  //   - The address of the main thread's copy can't be computed at link-time.
553  //   - Need to poison all copies, not just the main thread's one.
554  if (G->isThreadLocal())
555    return false;
556  // For now, just ignore this Alloca if the alignment is large.
557  if (G->getAlignment() > RedzoneSize()) return false;
558
559  // Ignore all the globals with the names starting with "\01L_OBJC_".
560  // Many of those are put into the .cstring section. The linker compresses
561  // that section by removing the spare \0s after the string terminator, so
562  // our redzones get broken.
563  if ((G->getName().find("\01L_OBJC_") == 0) ||
564      (G->getName().find("\01l_OBJC_") == 0)) {
565    DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
566    return false;
567  }
568
569  if (G->hasSection()) {
570    StringRef Section(G->getSection());
571    // Ignore the globals from the __OBJC section. The ObjC runtime assumes
572    // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
573    // them.
574    if ((Section.find("__OBJC,") == 0) ||
575        (Section.find("__DATA, __objc_") == 0)) {
576      DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
577      return false;
578    }
579    // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
580    // Constant CFString instances are compiled in the following way:
581    //  -- the string buffer is emitted into
582    //     __TEXT,__cstring,cstring_literals
583    //  -- the constant NSConstantString structure referencing that buffer
584    //     is placed into __DATA,__cfstring
585    // Therefore there's no point in placing redzones into __DATA,__cfstring.
586    // Moreover, it causes the linker to crash on OS X 10.7
587    if (Section.find("__DATA,__cfstring") == 0) {
588      DEBUG(dbgs() << "Ignoring CFString: " << *G);
589      return false;
590    }
591  }
592
593  return true;
594}
595
596// This function replaces all global variables with new variables that have
597// trailing redzones. It also creates a function that poisons
598// redzones and inserts this function into llvm.global_ctors.
599bool AddressSanitizerModule::runOnModule(Module &M) {
600  if (!ClGlobals) return false;
601  TD = getAnalysisIfAvailable<DataLayout>();
602  if (!TD)
603    return false;
604  BL.reset(new BlackList(ClBlackListFile));
605  DynamicallyInitializedGlobals.Init(M);
606  C = &(M.getContext());
607  IntptrTy = Type::getIntNTy(*C, TD->getPointerSizeInBits());
608
609  SmallVector<GlobalVariable *, 16> GlobalsToChange;
610
611  for (Module::GlobalListType::iterator G = M.global_begin(),
612       E = M.global_end(); G != E; ++G) {
613    if (ShouldInstrumentGlobal(G))
614      GlobalsToChange.push_back(G);
615  }
616
617  size_t n = GlobalsToChange.size();
618  if (n == 0) return false;
619
620  // A global is described by a structure
621  //   size_t beg;
622  //   size_t size;
623  //   size_t size_with_redzone;
624  //   const char *name;
625  //   size_t has_dynamic_init;
626  // We initialize an array of such structures and pass it to a run-time call.
627  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
628                                               IntptrTy, IntptrTy,
629                                               IntptrTy, NULL);
630  SmallVector<Constant *, 16> Initializers(n), DynamicInit;
631
632
633  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
634  assert(CtorFunc);
635  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
636
637  // The addresses of the first and last dynamically initialized globals in
638  // this TU.  Used in initialization order checking.
639  Value *FirstDynamic = 0, *LastDynamic = 0;
640
641  for (size_t i = 0; i < n; i++) {
642    GlobalVariable *G = GlobalsToChange[i];
643    PointerType *PtrTy = cast<PointerType>(G->getType());
644    Type *Ty = PtrTy->getElementType();
645    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
646    size_t RZ = RedzoneSize();
647    uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
648    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
649    // Determine whether this global should be poisoned in initialization.
650    bool GlobalHasDynamicInitializer =
651        DynamicallyInitializedGlobals.Contains(G);
652    // Don't check initialization order if this global is blacklisted.
653    GlobalHasDynamicInitializer &= !BL->isInInit(*G);
654
655    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
656    Constant *NewInitializer = ConstantStruct::get(
657        NewTy, G->getInitializer(),
658        Constant::getNullValue(RightRedZoneTy), NULL);
659
660    SmallString<2048> DescriptionOfGlobal = G->getName();
661    DescriptionOfGlobal += " (";
662    DescriptionOfGlobal += M.getModuleIdentifier();
663    DescriptionOfGlobal += ")";
664    GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
665
666    // Create a new global variable with enough space for a redzone.
667    GlobalVariable *NewGlobal = new GlobalVariable(
668        M, NewTy, G->isConstant(), G->getLinkage(),
669        NewInitializer, "", G, G->getThreadLocalMode());
670    NewGlobal->copyAttributesFrom(G);
671    NewGlobal->setAlignment(RZ);
672
673    Value *Indices2[2];
674    Indices2[0] = IRB.getInt32(0);
675    Indices2[1] = IRB.getInt32(0);
676
677    G->replaceAllUsesWith(
678        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
679    NewGlobal->takeName(G);
680    G->eraseFromParent();
681
682    Initializers[i] = ConstantStruct::get(
683        GlobalStructTy,
684        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
685        ConstantInt::get(IntptrTy, SizeInBytes),
686        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
687        ConstantExpr::getPointerCast(Name, IntptrTy),
688        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
689        NULL);
690
691    // Populate the first and last globals declared in this TU.
692    if (ClInitializers && GlobalHasDynamicInitializer) {
693      LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
694      if (FirstDynamic == 0)
695        FirstDynamic = LastDynamic;
696    }
697
698    DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
699  }
700
701  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
702  GlobalVariable *AllGlobals = new GlobalVariable(
703      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
704      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
705
706  // Create calls for poisoning before initializers run and unpoisoning after.
707  if (ClInitializers && FirstDynamic && LastDynamic)
708    createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
709
710  Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
711      kAsanRegisterGlobalsName, IRB.getVoidTy(),
712      IntptrTy, IntptrTy, NULL));
713  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
714
715  IRB.CreateCall2(AsanRegisterGlobals,
716                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
717                  ConstantInt::get(IntptrTy, n));
718
719  // We also need to unregister globals at the end, e.g. when a shared library
720  // gets closed.
721  Function *AsanDtorFunction = Function::Create(
722      FunctionType::get(Type::getVoidTy(*C), false),
723      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
724  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
725  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
726  Function *AsanUnregisterGlobals =
727      checkInterfaceFunction(M.getOrInsertFunction(
728          kAsanUnregisterGlobalsName,
729          IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
730  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
731
732  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
733                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
734                       ConstantInt::get(IntptrTy, n));
735  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
736
737  DEBUG(dbgs() << M);
738  return true;
739}
740
741// virtual
742bool AddressSanitizer::doInitialization(Module &M) {
743  // Initialize the private fields. No one has accessed them before.
744  TD = getAnalysisIfAvailable<DataLayout>();
745
746  if (!TD)
747    return false;
748  BL.reset(new BlackList(ClBlackListFile));
749  DynamicallyInitializedGlobals.Init(M);
750
751  C = &(M.getContext());
752  LongSize = TD->getPointerSizeInBits();
753  IntptrTy = Type::getIntNTy(*C, LongSize);
754  IntptrPtrTy = PointerType::get(IntptrTy, 0);
755
756  AsanCtorFunction = Function::Create(
757      FunctionType::get(Type::getVoidTy(*C), false),
758      GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
759  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
760  // call __asan_init in the module ctor.
761  IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
762  AsanInitFunction = checkInterfaceFunction(
763      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
764  AsanInitFunction->setLinkage(Function::ExternalLinkage);
765  IRB.CreateCall(AsanInitFunction);
766
767  // Create __asan_report* callbacks.
768  for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
769    for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
770         AccessSizeIndex++) {
771      // IsWrite and TypeSize are encoded in the function name.
772      std::string FunctionName = std::string(kAsanReportErrorTemplate) +
773          (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
774      // If we are merging crash callbacks, they have two parameters.
775      AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
776          checkInterfaceFunction(M.getOrInsertFunction(
777              FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
778    }
779  }
780
781  AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
782      kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
783  AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
784      kAsanStackFreeName, IRB.getVoidTy(),
785      IntptrTy, IntptrTy, IntptrTy, NULL));
786  AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
787      kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
788
789  // We insert an empty inline asm after __asan_report* to avoid callback merge.
790  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
791                            StringRef(""), StringRef(""),
792                            /*hasSideEffects=*/true);
793
794  llvm::Triple targetTriple(M.getTargetTriple());
795  bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
796
797  MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
798    (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
799  if (ClMappingOffsetLog >= 0) {
800    if (ClMappingOffsetLog == 0) {
801      // special case
802      MappingOffset = 0;
803    } else {
804      MappingOffset = 1ULL << ClMappingOffsetLog;
805    }
806  }
807
808
809  if (ClMappingOffsetLog >= 0) {
810    // Tell the run-time the current values of mapping offset and scale.
811    GlobalValue *asan_mapping_offset =
812        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
813                       ConstantInt::get(IntptrTy, MappingOffset),
814                       kAsanMappingOffsetName);
815    // Read the global, otherwise it may be optimized away.
816    IRB.CreateLoad(asan_mapping_offset, true);
817  }
818  if (ClMappingScale) {
819    GlobalValue *asan_mapping_scale =
820        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
821                           ConstantInt::get(IntptrTy, MappingScale()),
822                           kAsanMappingScaleName);
823    // Read the global, otherwise it may be optimized away.
824    IRB.CreateLoad(asan_mapping_scale, true);
825  }
826
827  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
828
829  return true;
830}
831
832bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
833  // For each NSObject descendant having a +load method, this method is invoked
834  // by the ObjC runtime before any of the static constructors is called.
835  // Therefore we need to instrument such methods with a call to __asan_init
836  // at the beginning in order to initialize our runtime before any access to
837  // the shadow memory.
838  // We cannot just ignore these methods, because they may call other
839  // instrumented functions.
840  if (F.getName().find(" load]") != std::string::npos) {
841    IRBuilder<> IRB(F.begin()->begin());
842    IRB.CreateCall(AsanInitFunction);
843    return true;
844  }
845  return false;
846}
847
848// Check both the call and the callee for doesNotReturn().
849static bool isNoReturnCall(CallInst *CI) {
850  if (CI->doesNotReturn()) return true;
851  Function *F = CI->getCalledFunction();
852  if (F && F->doesNotReturn()) return true;
853  return false;
854}
855
856bool AddressSanitizer::runOnFunction(Function &F) {
857  if (BL->isIn(F)) return false;
858  if (&F == AsanCtorFunction) return false;
859  DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
860
861  // If needed, insert __asan_init before checking for AddressSafety attr.
862  maybeInsertAsanInitAtFunctionEntry(F);
863
864  if (!F.getFnAttributes().hasAttribute(Attributes::AddressSafety))
865    return false;
866
867  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
868    return false;
869
870  // We want to instrument every address only once per basic block (unless there
871  // are calls between uses).
872  SmallSet<Value*, 16> TempsToInstrument;
873  SmallVector<Instruction*, 16> ToInstrument;
874  SmallVector<Instruction*, 8> NoReturnCalls;
875  bool IsWrite;
876
877  // Fill the set of memory operations to instrument.
878  for (Function::iterator FI = F.begin(), FE = F.end();
879       FI != FE; ++FI) {
880    TempsToInstrument.clear();
881    int NumInsnsPerBB = 0;
882    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
883         BI != BE; ++BI) {
884      if (LooksLikeCodeInBug11395(BI)) return false;
885      if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
886        if (ClOpt && ClOptSameTemp) {
887          if (!TempsToInstrument.insert(Addr))
888            continue;  // We've seen this temp in the current BB.
889        }
890      } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
891        // ok, take it.
892      } else {
893        if (CallInst *CI = dyn_cast<CallInst>(BI)) {
894          // A call inside BB.
895          TempsToInstrument.clear();
896          if (isNoReturnCall(CI)) {
897            NoReturnCalls.push_back(CI);
898          }
899        }
900        continue;
901      }
902      ToInstrument.push_back(BI);
903      NumInsnsPerBB++;
904      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
905        break;
906    }
907  }
908
909  // Instrument.
910  int NumInstrumented = 0;
911  for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
912    Instruction *Inst = ToInstrument[i];
913    if (ClDebugMin < 0 || ClDebugMax < 0 ||
914        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
915      if (isInterestingMemoryAccess(Inst, &IsWrite))
916        instrumentMop(Inst);
917      else
918        instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
919    }
920    NumInstrumented++;
921  }
922
923  bool ChangedStack = poisonStackInFunction(F);
924
925  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
926  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
927  for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
928    Instruction *CI = NoReturnCalls[i];
929    IRBuilder<> IRB(CI);
930    IRB.CreateCall(AsanHandleNoReturnFunc);
931  }
932  DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
933
934  return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
935}
936
937static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
938  if (ShadowRedzoneSize == 1) return PoisonByte;
939  if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
940  if (ShadowRedzoneSize == 4)
941    return (PoisonByte << 24) + (PoisonByte << 16) +
942        (PoisonByte << 8) + (PoisonByte);
943  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
944}
945
946static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
947                                            size_t Size,
948                                            size_t RZSize,
949                                            size_t ShadowGranularity,
950                                            uint8_t Magic) {
951  for (size_t i = 0; i < RZSize;
952       i+= ShadowGranularity, Shadow++) {
953    if (i + ShadowGranularity <= Size) {
954      *Shadow = 0;  // fully addressable
955    } else if (i >= Size) {
956      *Shadow = Magic;  // unaddressable
957    } else {
958      *Shadow = Size - i;  // first Size-i bytes are addressable
959    }
960  }
961}
962
963void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
964                                   IRBuilder<> IRB,
965                                   Value *ShadowBase, bool DoPoison) {
966  size_t ShadowRZSize = RedzoneSize() >> MappingScale();
967  assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
968  Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
969  Type *RZPtrTy = PointerType::get(RZTy, 0);
970
971  Value *PoisonLeft  = ConstantInt::get(RZTy,
972    ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
973  Value *PoisonMid   = ConstantInt::get(RZTy,
974    ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
975  Value *PoisonRight = ConstantInt::get(RZTy,
976    ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
977
978  // poison the first red zone.
979  IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
980
981  // poison all other red zones.
982  uint64_t Pos = RedzoneSize();
983  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
984    AllocaInst *AI = AllocaVec[i];
985    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
986    uint64_t AlignedSize = getAlignedAllocaSize(AI);
987    assert(AlignedSize - SizeInBytes < RedzoneSize());
988    Value *Ptr = NULL;
989
990    Pos += AlignedSize;
991
992    assert(ShadowBase->getType() == IntptrTy);
993    if (SizeInBytes < AlignedSize) {
994      // Poison the partial redzone at right
995      Ptr = IRB.CreateAdd(
996          ShadowBase, ConstantInt::get(IntptrTy,
997                                       (Pos >> MappingScale()) - ShadowRZSize));
998      size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
999      uint32_t Poison = 0;
1000      if (DoPoison) {
1001        PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1002                                        RedzoneSize(),
1003                                        1ULL << MappingScale(),
1004                                        kAsanStackPartialRedzoneMagic);
1005      }
1006      Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1007      IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1008    }
1009
1010    // Poison the full redzone at right.
1011    Ptr = IRB.CreateAdd(ShadowBase,
1012                        ConstantInt::get(IntptrTy, Pos >> MappingScale()));
1013    Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1014    IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1015
1016    Pos += RedzoneSize();
1017  }
1018}
1019
1020// Workaround for bug 11395: we don't want to instrument stack in functions
1021// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1022// FIXME: remove once the bug 11395 is fixed.
1023bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1024  if (LongSize != 32) return false;
1025  CallInst *CI = dyn_cast<CallInst>(I);
1026  if (!CI || !CI->isInlineAsm()) return false;
1027  if (CI->getNumArgOperands() <= 5) return false;
1028  // We have inline assembly with quite a few arguments.
1029  return true;
1030}
1031
1032// Find all static Alloca instructions and put
1033// poisoned red zones around all of them.
1034// Then unpoison everything back before the function returns.
1035//
1036// Stack poisoning does not play well with exception handling.
1037// When an exception is thrown, we essentially bypass the code
1038// that unpoisones the stack. This is why the run-time library has
1039// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
1040// stack in the interceptor. This however does not work inside the
1041// actual function which catches the exception. Most likely because the
1042// compiler hoists the load of the shadow value somewhere too high.
1043// This causes asan to report a non-existing bug on 453.povray.
1044// It sounds like an LLVM bug.
1045bool AddressSanitizer::poisonStackInFunction(Function &F) {
1046  if (!ClStack) return false;
1047  SmallVector<AllocaInst*, 16> AllocaVec;
1048  SmallVector<Instruction*, 8> RetVec;
1049  uint64_t TotalSize = 0;
1050
1051  // Filter out Alloca instructions we want (and can) handle.
1052  // Collect Ret instructions.
1053  for (Function::iterator FI = F.begin(), FE = F.end();
1054       FI != FE; ++FI) {
1055    BasicBlock &BB = *FI;
1056    for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
1057         BI != BE; ++BI) {
1058      if (isa<ReturnInst>(BI)) {
1059          RetVec.push_back(BI);
1060          continue;
1061      }
1062
1063      AllocaInst *AI = dyn_cast<AllocaInst>(BI);
1064      if (!AI) continue;
1065      if (AI->isArrayAllocation()) continue;
1066      if (!AI->isStaticAlloca()) continue;
1067      if (!AI->getAllocatedType()->isSized()) continue;
1068      if (AI->getAlignment() > RedzoneSize()) continue;
1069      AllocaVec.push_back(AI);
1070      uint64_t AlignedSize =  getAlignedAllocaSize(AI);
1071      TotalSize += AlignedSize;
1072    }
1073  }
1074
1075  if (AllocaVec.empty()) return false;
1076
1077  uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize();
1078
1079  bool DoStackMalloc = ClUseAfterReturn
1080      && LocalStackSize <= kMaxStackMallocSize;
1081
1082  Instruction *InsBefore = AllocaVec[0];
1083  IRBuilder<> IRB(InsBefore);
1084
1085
1086  Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1087  AllocaInst *MyAlloca =
1088      new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1089  MyAlloca->setAlignment(RedzoneSize());
1090  assert(MyAlloca->isStaticAlloca());
1091  Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1092  Value *LocalStackBase = OrigStackBase;
1093
1094  if (DoStackMalloc) {
1095    LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1096        ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1097  }
1098
1099  // This string will be parsed by the run-time (DescribeStackAddress).
1100  SmallString<2048> StackDescriptionStorage;
1101  raw_svector_ostream StackDescription(StackDescriptionStorage);
1102  StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1103
1104  uint64_t Pos = RedzoneSize();
1105  // Replace Alloca instructions with base+offset.
1106  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1107    AllocaInst *AI = AllocaVec[i];
1108    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1109    StringRef Name = AI->getName();
1110    StackDescription << Pos << " " << SizeInBytes << " "
1111                     << Name.size() << " " << Name << " ";
1112    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1113    assert((AlignedSize % RedzoneSize()) == 0);
1114    AI->replaceAllUsesWith(
1115        IRB.CreateIntToPtr(
1116            IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1117            AI->getType()));
1118    Pos += AlignedSize + RedzoneSize();
1119  }
1120  assert(Pos == LocalStackSize);
1121
1122  // Write the Magic value and the frame description constant to the redzone.
1123  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1124  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1125                  BasePlus0);
1126  Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1127                                   ConstantInt::get(IntptrTy, LongSize/8));
1128  BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1129  GlobalVariable *StackDescriptionGlobal =
1130      createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1131  Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1132  IRB.CreateStore(Description, BasePlus1);
1133
1134  // Poison the stack redzones at the entry.
1135  Value *ShadowBase = memToShadow(LocalStackBase, IRB);
1136  PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
1137
1138  // Unpoison the stack before all ret instructions.
1139  for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1140    Instruction *Ret = RetVec[i];
1141    IRBuilder<> IRBRet(Ret);
1142
1143    // Mark the current frame as retired.
1144    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1145                       BasePlus0);
1146    // Unpoison the stack.
1147    PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
1148
1149    if (DoStackMalloc) {
1150      IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1151                         ConstantInt::get(IntptrTy, LocalStackSize),
1152                         OrigStackBase);
1153    }
1154  }
1155
1156  // We are done. Remove the old unused alloca instructions.
1157  for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1158    AllocaVec[i]->eraseFromParent();
1159
1160  if (ClDebugStack) {
1161    DEBUG(dbgs() << F);
1162  }
1163
1164  return true;
1165}
1166