AddressSanitizer.cpp revision b9a12ea0fd92bfdb4c6eb5af333648a618f68686 
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  void instrumentMop(Instruction *I);
192  void instrumentAddress(Instruction *OrigIns, IRBuilder<> &IRB,
193                         Value *Addr, uint32_t TypeSize, bool IsWrite);
194  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
195                           Value *ShadowValue, uint32_t TypeSize);
196  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
197                                 bool IsWrite, size_t AccessSizeIndex);
198  bool instrumentMemIntrinsic(MemIntrinsic *MI);
199  void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
200                                   Value *Size,
201                                   Instruction *InsertBefore, bool IsWrite);
202  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
203  bool runOnFunction(Function &F);
204  void createInitializerPoisonCalls(Module &M,
205                                    Value *FirstAddr, Value *LastAddr);
206  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
207  bool poisonStackInFunction(Function &F);
208  virtual bool doInitialization(Module &M);
209  virtual bool doFinalization(Module &M);
210  static char ID;  // Pass identification, replacement for typeid
211
212 private:
213  uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
214    Type *Ty = AI->getAllocatedType();
215    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
216    return SizeInBytes;
217  }
218  uint64_t getAlignedSize(uint64_t SizeInBytes) {
219    size_t RZ = RedzoneSize();
220    return ((SizeInBytes + RZ - 1) / RZ) * RZ;
221  }
222  uint64_t getAlignedAllocaSize(AllocaInst *AI) {
223    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
224    return getAlignedSize(SizeInBytes);
225  }
226
227  bool ShouldInstrumentGlobal(GlobalVariable *G);
228  void PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
229                   Value *ShadowBase, bool DoPoison);
230  bool LooksLikeCodeInBug11395(Instruction *I);
231  void FindDynamicInitializers(Module &M);
232
233  LLVMContext *C;
234  DataLayout *TD;
235  uint64_t MappingOffset;
236  int LongSize;
237  Type *IntptrTy;
238  Type *IntptrPtrTy;
239  Function *AsanCtorFunction;
240  Function *AsanInitFunction;
241  Function *AsanStackMallocFunc, *AsanStackFreeFunc;
242  Function *AsanHandleNoReturnFunc;
243  OwningPtr<BlackList> BL;
244  // This array is indexed by AccessIsWrite and log2(AccessSize).
245  Function *AsanErrorCallback[2][kNumberOfAccessSizes];
246  InlineAsm *EmptyAsm;
247  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
248};
249
250// FIXME: inherit this from ModulePass and actually use it as a ModulePass.
251class AddressSanitizerCreateGlobalRedzonesPass {
252 public:
253  bool runOnModule(Module &M, DataLayout *TD);
254 private:
255  bool ShouldInstrumentGlobal(GlobalVariable *G);
256  void createInitializerPoisonCalls(Module &M, Value *FirstAddr,
257                                    Value *LastAddr);
258
259  static char ID;  // Pass identification, replacement for typeid
260  OwningPtr<BlackList> BL;
261  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
262  Type *IntptrTy;
263  LLVMContext *C;
264};
265
266}  // namespace
267
268char AddressSanitizer::ID = 0;
269INITIALIZE_PASS(AddressSanitizer, "asan",
270    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
271    false, false)
272AddressSanitizer::AddressSanitizer() : FunctionPass(ID) { }
273FunctionPass *llvm::createAddressSanitizerPass() {
274  return new AddressSanitizer();
275}
276
277const char *AddressSanitizer::getPassName() const {
278  return "AddressSanitizer";
279}
280
281static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
282  size_t Res = CountTrailingZeros_32(TypeSize / 8);
283  assert(Res < kNumberOfAccessSizes);
284  return Res;
285}
286
287// Create a constant for Str so that we can pass it to the run-time lib.
288static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
289  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
290  return new GlobalVariable(M, StrConst->getType(), true,
291                            GlobalValue::PrivateLinkage, StrConst,
292                            kAsanGenPrefix);
293}
294
295static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
296  return G->getName().find(kAsanGenPrefix) == 0;
297}
298
299Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
300  // Shadow >> scale
301  Shadow = IRB.CreateLShr(Shadow, MappingScale());
302  if (MappingOffset == 0)
303    return Shadow;
304  // (Shadow >> scale) | offset
305  return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy,
306                                               MappingOffset));
307}
308
309void AddressSanitizer::instrumentMemIntrinsicParam(
310    Instruction *OrigIns,
311    Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
312  // Check the first byte.
313  {
314    IRBuilder<> IRB(InsertBefore);
315    instrumentAddress(OrigIns, IRB, Addr, 8, IsWrite);
316  }
317  // Check the last byte.
318  {
319    IRBuilder<> IRB(InsertBefore);
320    Value *SizeMinusOne = IRB.CreateSub(
321        Size, ConstantInt::get(Size->getType(), 1));
322    SizeMinusOne = IRB.CreateIntCast(SizeMinusOne, IntptrTy, false);
323    Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
324    Value *AddrPlusSizeMinisOne = IRB.CreateAdd(AddrLong, SizeMinusOne);
325    instrumentAddress(OrigIns, IRB, AddrPlusSizeMinisOne, 8, IsWrite);
326  }
327}
328
329// Instrument memset/memmove/memcpy
330bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
331  Value *Dst = MI->getDest();
332  MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
333  Value *Src = MemTran ? MemTran->getSource() : 0;
334  Value *Length = MI->getLength();
335
336  Constant *ConstLength = dyn_cast<Constant>(Length);
337  Instruction *InsertBefore = MI;
338  if (ConstLength) {
339    if (ConstLength->isNullValue()) return false;
340  } else {
341    // The size is not a constant so it could be zero -- check at run-time.
342    IRBuilder<> IRB(InsertBefore);
343
344    Value *Cmp = IRB.CreateICmpNE(Length,
345                                  Constant::getNullValue(Length->getType()));
346    InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
347  }
348
349  instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
350  if (Src)
351    instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
352  return true;
353}
354
355// If I is an interesting memory access, return the PointerOperand
356// and set IsWrite. Otherwise return NULL.
357static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
358  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
359    if (!ClInstrumentReads) return NULL;
360    *IsWrite = false;
361    return LI->getPointerOperand();
362  }
363  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
364    if (!ClInstrumentWrites) return NULL;
365    *IsWrite = true;
366    return SI->getPointerOperand();
367  }
368  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
369    if (!ClInstrumentAtomics) return NULL;
370    *IsWrite = true;
371    return RMW->getPointerOperand();
372  }
373  if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
374    if (!ClInstrumentAtomics) return NULL;
375    *IsWrite = true;
376    return XCHG->getPointerOperand();
377  }
378  return NULL;
379}
380
381void AddressSanitizer::instrumentMop(Instruction *I) {
382  bool IsWrite = false;
383  Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
384  assert(Addr);
385  if (ClOpt && ClOptGlobals) {
386    if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
387      // If initialization order checking is disabled, a simple access to a
388      // dynamically initialized global is always valid.
389      if (!ClInitializers)
390        return;
391      // If a global variable does not have dynamic initialization we don't
392      // have to instrument it.  However, if a global does not have initailizer
393      // at all, we assume it has dynamic initializer (in other TU).
394      if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
395        return;
396    }
397  }
398
399  Type *OrigPtrTy = Addr->getType();
400  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
401
402  assert(OrigTy->isSized());
403  uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
404
405  if (TypeSize != 8  && TypeSize != 16 &&
406      TypeSize != 32 && TypeSize != 64 && TypeSize != 128) {
407    // Ignore all unusual sizes.
408    return;
409  }
410
411  IRBuilder<> IRB(I);
412  instrumentAddress(I, IRB, Addr, TypeSize, IsWrite);
413}
414
415// Validate the result of Module::getOrInsertFunction called for an interface
416// function of AddressSanitizer. If the instrumented module defines a function
417// with the same name, their prototypes must match, otherwise
418// getOrInsertFunction returns a bitcast.
419static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
420  if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
421  FuncOrBitcast->dump();
422  report_fatal_error("trying to redefine an AddressSanitizer "
423                     "interface function");
424}
425
426Instruction *AddressSanitizer::generateCrashCode(
427    Instruction *InsertBefore, Value *Addr,
428    bool IsWrite, size_t AccessSizeIndex) {
429  IRBuilder<> IRB(InsertBefore);
430  CallInst *Call = IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex],
431                                  Addr);
432  // We don't do Call->setDoesNotReturn() because the BB already has
433  // UnreachableInst at the end.
434  // This EmptyAsm is required to avoid callback merge.
435  IRB.CreateCall(EmptyAsm);
436  return Call;
437}
438
439Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
440                                            Value *ShadowValue,
441                                            uint32_t TypeSize) {
442  size_t Granularity = 1 << MappingScale();
443  // Addr & (Granularity - 1)
444  Value *LastAccessedByte = IRB.CreateAnd(
445      AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
446  // (Addr & (Granularity - 1)) + size - 1
447  if (TypeSize / 8 > 1)
448    LastAccessedByte = IRB.CreateAdd(
449        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
450  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
451  LastAccessedByte = IRB.CreateIntCast(
452      LastAccessedByte, ShadowValue->getType(), false);
453  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
454  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
455}
456
457void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
458                                         IRBuilder<> &IRB, Value *Addr,
459                                         uint32_t TypeSize, bool IsWrite) {
460  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
461
462  Type *ShadowTy  = IntegerType::get(
463      *C, std::max(8U, TypeSize >> MappingScale()));
464  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
465  Value *ShadowPtr = memToShadow(AddrLong, IRB);
466  Value *CmpVal = Constant::getNullValue(ShadowTy);
467  Value *ShadowValue = IRB.CreateLoad(
468      IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
469
470  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
471  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
472  size_t Granularity = 1 << MappingScale();
473  TerminatorInst *CrashTerm = 0;
474
475  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
476    TerminatorInst *CheckTerm =
477        SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
478    assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
479    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
480    IRB.SetInsertPoint(CheckTerm);
481    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
482    BasicBlock *CrashBlock =
483        BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
484    CrashTerm = new UnreachableInst(*C, CrashBlock);
485    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
486    ReplaceInstWithInst(CheckTerm, NewTerm);
487  } else {
488    CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
489  }
490
491  Instruction *Crash =
492      generateCrashCode(CrashTerm, AddrLong, IsWrite, AccessSizeIndex);
493  Crash->setDebugLoc(OrigIns->getDebugLoc());
494}
495
496void AddressSanitizerCreateGlobalRedzonesPass::createInitializerPoisonCalls(
497    Module &M, Value *FirstAddr, Value *LastAddr) {
498  // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
499  Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
500  // If that function is not present, this TU contains no globals, or they have
501  // all been optimized away
502  if (!GlobalInit)
503    return;
504
505  // Set up the arguments to our poison/unpoison functions.
506  IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
507
508  // Declare our poisoning and unpoisoning functions.
509  Function *AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
510      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
511  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
512  Function *AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
513      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
514  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
515
516  // Add a call to poison all external globals before the given function starts.
517  IRB.CreateCall2(AsanPoisonGlobals, FirstAddr, LastAddr);
518
519  // Add calls to unpoison all globals before each return instruction.
520  for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
521      I != E; ++I) {
522    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
523      CallInst::Create(AsanUnpoisonGlobals, "", RI);
524    }
525  }
526}
527
528bool AddressSanitizerCreateGlobalRedzonesPass::ShouldInstrumentGlobal(
529    GlobalVariable *G) {
530  Type *Ty = cast<PointerType>(G->getType())->getElementType();
531  DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
532
533  if (BL->isIn(*G)) return false;
534  if (!Ty->isSized()) return false;
535  if (!G->hasInitializer()) return false;
536  if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
537  // Touch only those globals that will not be defined in other modules.
538  // Don't handle ODR type linkages since other modules may be built w/o asan.
539  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
540      G->getLinkage() != GlobalVariable::PrivateLinkage &&
541      G->getLinkage() != GlobalVariable::InternalLinkage)
542    return false;
543  // Two problems with thread-locals:
544  //   - The address of the main thread's copy can't be computed at link-time.
545  //   - Need to poison all copies, not just the main thread's one.
546  if (G->isThreadLocal())
547    return false;
548  // For now, just ignore this Alloca if the alignment is large.
549  if (G->getAlignment() > RedzoneSize()) return false;
550
551  // Ignore all the globals with the names starting with "\01L_OBJC_".
552  // Many of those are put into the .cstring section. The linker compresses
553  // that section by removing the spare \0s after the string terminator, so
554  // our redzones get broken.
555  if ((G->getName().find("\01L_OBJC_") == 0) ||
556      (G->getName().find("\01l_OBJC_") == 0)) {
557    DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
558    return false;
559  }
560
561  if (G->hasSection()) {
562    StringRef Section(G->getSection());
563    // Ignore the globals from the __OBJC section. The ObjC runtime assumes
564    // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
565    // them.
566    if ((Section.find("__OBJC,") == 0) ||
567        (Section.find("__DATA, __objc_") == 0)) {
568      DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
569      return false;
570    }
571    // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
572    // Constant CFString instances are compiled in the following way:
573    //  -- the string buffer is emitted into
574    //     __TEXT,__cstring,cstring_literals
575    //  -- the constant NSConstantString structure referencing that buffer
576    //     is placed into __DATA,__cfstring
577    // Therefore there's no point in placing redzones into __DATA,__cfstring.
578    // Moreover, it causes the linker to crash on OS X 10.7
579    if (Section.find("__DATA,__cfstring") == 0) {
580      DEBUG(dbgs() << "Ignoring CFString: " << *G);
581      return false;
582    }
583  }
584
585  return true;
586}
587
588// This function replaces all global variables with new variables that have
589// trailing redzones. It also creates a function that poisons
590// redzones and inserts this function into llvm.global_ctors.
591bool AddressSanitizerCreateGlobalRedzonesPass::runOnModule(Module &M,
592                                                           DataLayout *TD) {
593  BL.reset(new BlackList(ClBlackListFile));
594  DynamicallyInitializedGlobals.Init(M);
595  C = &(M.getContext());
596  IntptrTy = Type::getIntNTy(*C, TD->getPointerSizeInBits());
597
598  SmallVector<GlobalVariable *, 16> GlobalsToChange;
599
600  for (Module::GlobalListType::iterator G = M.global_begin(),
601       E = M.global_end(); G != E; ++G) {
602    if (ShouldInstrumentGlobal(G))
603      GlobalsToChange.push_back(G);
604  }
605
606  size_t n = GlobalsToChange.size();
607  if (n == 0) return false;
608
609  // A global is described by a structure
610  //   size_t beg;
611  //   size_t size;
612  //   size_t size_with_redzone;
613  //   const char *name;
614  //   size_t has_dynamic_init;
615  // We initialize an array of such structures and pass it to a run-time call.
616  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
617                                               IntptrTy, IntptrTy,
618                                               IntptrTy, NULL);
619  SmallVector<Constant *, 16> Initializers(n), DynamicInit;
620
621
622  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
623  assert(CtorFunc);
624  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
625
626  // The addresses of the first and last dynamically initialized globals in
627  // this TU.  Used in initialization order checking.
628  Value *FirstDynamic = 0, *LastDynamic = 0;
629
630  for (size_t i = 0; i < n; i++) {
631    GlobalVariable *G = GlobalsToChange[i];
632    PointerType *PtrTy = cast<PointerType>(G->getType());
633    Type *Ty = PtrTy->getElementType();
634    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
635    size_t RZ = RedzoneSize();
636    uint64_t RightRedzoneSize = RZ + (RZ - (SizeInBytes % RZ));
637    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
638    // Determine whether this global should be poisoned in initialization.
639    bool GlobalHasDynamicInitializer =
640        DynamicallyInitializedGlobals.Contains(G);
641    // Don't check initialization order if this global is blacklisted.
642    GlobalHasDynamicInitializer &= !BL->isInInit(*G);
643
644    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
645    Constant *NewInitializer = ConstantStruct::get(
646        NewTy, G->getInitializer(),
647        Constant::getNullValue(RightRedZoneTy), NULL);
648
649    SmallString<2048> DescriptionOfGlobal = G->getName();
650    DescriptionOfGlobal += " (";
651    DescriptionOfGlobal += M.getModuleIdentifier();
652    DescriptionOfGlobal += ")";
653    GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);
654
655    // Create a new global variable with enough space for a redzone.
656    GlobalVariable *NewGlobal = new GlobalVariable(
657        M, NewTy, G->isConstant(), G->getLinkage(),
658        NewInitializer, "", G, G->getThreadLocalMode());
659    NewGlobal->copyAttributesFrom(G);
660    NewGlobal->setAlignment(RZ);
661
662    Value *Indices2[2];
663    Indices2[0] = IRB.getInt32(0);
664    Indices2[1] = IRB.getInt32(0);
665
666    G->replaceAllUsesWith(
667        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
668    NewGlobal->takeName(G);
669    G->eraseFromParent();
670
671    Initializers[i] = ConstantStruct::get(
672        GlobalStructTy,
673        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
674        ConstantInt::get(IntptrTy, SizeInBytes),
675        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
676        ConstantExpr::getPointerCast(Name, IntptrTy),
677        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
678        NULL);
679
680    // Populate the first and last globals declared in this TU.
681    if (ClInitializers && GlobalHasDynamicInitializer) {
682      LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
683      if (FirstDynamic == 0)
684        FirstDynamic = LastDynamic;
685    }
686
687    DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
688  }
689
690  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
691  GlobalVariable *AllGlobals = new GlobalVariable(
692      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
693      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
694
695  // Create calls for poisoning before initializers run and unpoisoning after.
696  if (ClInitializers && FirstDynamic && LastDynamic)
697    createInitializerPoisonCalls(M, FirstDynamic, LastDynamic);
698
699  Function *AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
700      kAsanRegisterGlobalsName, IRB.getVoidTy(),
701      IntptrTy, IntptrTy, NULL));
702  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
703
704  IRB.CreateCall2(AsanRegisterGlobals,
705                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
706                  ConstantInt::get(IntptrTy, n));
707
708  // We also need to unregister globals at the end, e.g. when a shared library
709  // gets closed.
710  Function *AsanDtorFunction = Function::Create(
711      FunctionType::get(Type::getVoidTy(*C), false),
712      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
713  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
714  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
715  Function *AsanUnregisterGlobals =
716      checkInterfaceFunction(M.getOrInsertFunction(
717          kAsanUnregisterGlobalsName,
718          IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
719  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
720
721  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
722                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
723                       ConstantInt::get(IntptrTy, n));
724  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
725
726  DEBUG(dbgs() << M);
727  return true;
728}
729
730// virtual
731bool AddressSanitizer::doInitialization(Module &M) {
732  // Initialize the private fields. No one has accessed them before.
733  TD = getAnalysisIfAvailable<DataLayout>();
734
735  if (!TD)
736    return false;
737  BL.reset(new BlackList(ClBlackListFile));
738  DynamicallyInitializedGlobals.Init(M);
739
740  C = &(M.getContext());
741  LongSize = TD->getPointerSizeInBits();
742  IntptrTy = Type::getIntNTy(*C, LongSize);
743  IntptrPtrTy = PointerType::get(IntptrTy, 0);
744
745  AsanCtorFunction = Function::Create(
746      FunctionType::get(Type::getVoidTy(*C), false),
747      GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
748  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
749  // call __asan_init in the module ctor.
750  IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
751  AsanInitFunction = checkInterfaceFunction(
752      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
753  AsanInitFunction->setLinkage(Function::ExternalLinkage);
754  IRB.CreateCall(AsanInitFunction);
755
756  // Create __asan_report* callbacks.
757  for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
758    for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
759         AccessSizeIndex++) {
760      // IsWrite and TypeSize are encoded in the function name.
761      std::string FunctionName = std::string(kAsanReportErrorTemplate) +
762          (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
763      // If we are merging crash callbacks, they have two parameters.
764      AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
765          checkInterfaceFunction(M.getOrInsertFunction(
766              FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
767    }
768  }
769
770  AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
771      kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
772  AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
773      kAsanStackFreeName, IRB.getVoidTy(),
774      IntptrTy, IntptrTy, IntptrTy, NULL));
775  AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
776      kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
777
778  // We insert an empty inline asm after __asan_report* to avoid callback merge.
779  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
780                            StringRef(""), StringRef(""),
781                            /*hasSideEffects=*/true);
782
783  llvm::Triple targetTriple(M.getTargetTriple());
784  bool isAndroid = targetTriple.getEnvironment() == llvm::Triple::Android;
785
786  MappingOffset = isAndroid ? kDefaultShadowOffsetAndroid :
787    (LongSize == 32 ? kDefaultShadowOffset32 : kDefaultShadowOffset64);
788  if (ClMappingOffsetLog >= 0) {
789    if (ClMappingOffsetLog == 0) {
790      // special case
791      MappingOffset = 0;
792    } else {
793      MappingOffset = 1ULL << ClMappingOffsetLog;
794    }
795  }
796
797
798  if (ClMappingOffsetLog >= 0) {
799    // Tell the run-time the current values of mapping offset and scale.
800    GlobalValue *asan_mapping_offset =
801        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
802                       ConstantInt::get(IntptrTy, MappingOffset),
803                       kAsanMappingOffsetName);
804    // Read the global, otherwise it may be optimized away.
805    IRB.CreateLoad(asan_mapping_offset, true);
806  }
807  if (ClMappingScale) {
808    GlobalValue *asan_mapping_scale =
809        new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
810                           ConstantInt::get(IntptrTy, MappingScale()),
811                           kAsanMappingScaleName);
812    // Read the global, otherwise it may be optimized away.
813    IRB.CreateLoad(asan_mapping_scale, true);
814  }
815
816  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
817
818  return true;
819}
820
821bool AddressSanitizer::doFinalization(Module &M) {
822  // We transform the globals at the very end so that the optimization analysis
823  // works on the original globals.
824  if (ClGlobals) {
825    // FIXME: instead of doFinalization, run this as a true ModulePass.
826    AddressSanitizerCreateGlobalRedzonesPass Pass;
827    return Pass.runOnModule(M, TD);
828  }
829  return false;
830}
831
832
833bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
834  // For each NSObject descendant having a +load method, this method is invoked
835  // by the ObjC runtime before any of the static constructors is called.
836  // Therefore we need to instrument such methods with a call to __asan_init
837  // at the beginning in order to initialize our runtime before any access to
838  // the shadow memory.
839  // We cannot just ignore these methods, because they may call other
840  // instrumented functions.
841  if (F.getName().find(" load]") != std::string::npos) {
842    IRBuilder<> IRB(F.begin()->begin());
843    IRB.CreateCall(AsanInitFunction);
844    return true;
845  }
846  return false;
847}
848
849bool AddressSanitizer::runOnFunction(Function &F) {
850  if (BL->isIn(F)) return false;
851  if (&F == AsanCtorFunction) return false;
852  DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
853
854  // If needed, insert __asan_init before checking for AddressSafety attr.
855  maybeInsertAsanInitAtFunctionEntry(F);
856
857  if (!F.getFnAttributes().hasAttribute(Attributes::AddressSafety))
858    return false;
859
860  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
861    return false;
862
863  // We want to instrument every address only once per basic block (unless there
864  // are calls between uses).
865  SmallSet<Value*, 16> TempsToInstrument;
866  SmallVector<Instruction*, 16> ToInstrument;
867  SmallVector<Instruction*, 8> NoReturnCalls;
868  bool IsWrite;
869
870  // Fill the set of memory operations to instrument.
871  for (Function::iterator FI = F.begin(), FE = F.end();
872       FI != FE; ++FI) {
873    TempsToInstrument.clear();
874    int NumInsnsPerBB = 0;
875    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
876         BI != BE; ++BI) {
877      if (LooksLikeCodeInBug11395(BI)) return false;
878      if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
879        if (ClOpt && ClOptSameTemp) {
880          if (!TempsToInstrument.insert(Addr))
881            continue;  // We've seen this temp in the current BB.
882        }
883      } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
884        // ok, take it.
885      } else {
886        if (CallInst *CI = dyn_cast<CallInst>(BI)) {
887          // A call inside BB.
888          TempsToInstrument.clear();
889          if (CI->doesNotReturn()) {
890            NoReturnCalls.push_back(CI);
891          }
892        }
893        continue;
894      }
895      ToInstrument.push_back(BI);
896      NumInsnsPerBB++;
897      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
898        break;
899    }
900  }
901
902  // Instrument.
903  int NumInstrumented = 0;
904  for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
905    Instruction *Inst = ToInstrument[i];
906    if (ClDebugMin < 0 || ClDebugMax < 0 ||
907        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
908      if (isInterestingMemoryAccess(Inst, &IsWrite))
909        instrumentMop(Inst);
910      else
911        instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
912    }
913    NumInstrumented++;
914  }
915
916  bool ChangedStack = poisonStackInFunction(F);
917
918  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
919  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
920  for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
921    Instruction *CI = NoReturnCalls[i];
922    IRBuilder<> IRB(CI);
923    IRB.CreateCall(AsanHandleNoReturnFunc);
924  }
925  DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
926
927  return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
928}
929
930static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
931  if (ShadowRedzoneSize == 1) return PoisonByte;
932  if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
933  if (ShadowRedzoneSize == 4)
934    return (PoisonByte << 24) + (PoisonByte << 16) +
935        (PoisonByte << 8) + (PoisonByte);
936  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
937}
938
939static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
940                                            size_t Size,
941                                            size_t RZSize,
942                                            size_t ShadowGranularity,
943                                            uint8_t Magic) {
944  for (size_t i = 0; i < RZSize;
945       i+= ShadowGranularity, Shadow++) {
946    if (i + ShadowGranularity <= Size) {
947      *Shadow = 0;  // fully addressable
948    } else if (i >= Size) {
949      *Shadow = Magic;  // unaddressable
950    } else {
951      *Shadow = Size - i;  // first Size-i bytes are addressable
952    }
953  }
954}
955
956void AddressSanitizer::PoisonStack(const ArrayRef<AllocaInst*> &AllocaVec,
957                                   IRBuilder<> IRB,
958                                   Value *ShadowBase, bool DoPoison) {
959  size_t ShadowRZSize = RedzoneSize() >> MappingScale();
960  assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
961  Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
962  Type *RZPtrTy = PointerType::get(RZTy, 0);
963
964  Value *PoisonLeft  = ConstantInt::get(RZTy,
965    ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
966  Value *PoisonMid   = ConstantInt::get(RZTy,
967    ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
968  Value *PoisonRight = ConstantInt::get(RZTy,
969    ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
970
971  // poison the first red zone.
972  IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
973
974  // poison all other red zones.
975  uint64_t Pos = RedzoneSize();
976  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
977    AllocaInst *AI = AllocaVec[i];
978    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
979    uint64_t AlignedSize = getAlignedAllocaSize(AI);
980    assert(AlignedSize - SizeInBytes < RedzoneSize());
981    Value *Ptr = NULL;
982
983    Pos += AlignedSize;
984
985    assert(ShadowBase->getType() == IntptrTy);
986    if (SizeInBytes < AlignedSize) {
987      // Poison the partial redzone at right
988      Ptr = IRB.CreateAdd(
989          ShadowBase, ConstantInt::get(IntptrTy,
990                                       (Pos >> MappingScale()) - ShadowRZSize));
991      size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
992      uint32_t Poison = 0;
993      if (DoPoison) {
994        PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
995                                        RedzoneSize(),
996                                        1ULL << MappingScale(),
997                                        kAsanStackPartialRedzoneMagic);
998      }
999      Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1000      IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1001    }
1002
1003    // Poison the full redzone at right.
1004    Ptr = IRB.CreateAdd(ShadowBase,
1005                        ConstantInt::get(IntptrTy, Pos >> MappingScale()));
1006    Value *Poison = i == AllocaVec.size() - 1 ? PoisonRight : PoisonMid;
1007    IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1008
1009    Pos += RedzoneSize();
1010  }
1011}
1012
1013// Workaround for bug 11395: we don't want to instrument stack in functions
1014// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1015// FIXME: remove once the bug 11395 is fixed.
1016bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1017  if (LongSize != 32) return false;
1018  CallInst *CI = dyn_cast<CallInst>(I);
1019  if (!CI || !CI->isInlineAsm()) return false;
1020  if (CI->getNumArgOperands() <= 5) return false;
1021  // We have inline assembly with quite a few arguments.
1022  return true;
1023}
1024
1025// Find all static Alloca instructions and put
1026// poisoned red zones around all of them.
1027// Then unpoison everything back before the function returns.
1028//
1029// Stack poisoning does not play well with exception handling.
1030// When an exception is thrown, we essentially bypass the code
1031// that unpoisones the stack. This is why the run-time library has
1032// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
1033// stack in the interceptor. This however does not work inside the
1034// actual function which catches the exception. Most likely because the
1035// compiler hoists the load of the shadow value somewhere too high.
1036// This causes asan to report a non-existing bug on 453.povray.
1037// It sounds like an LLVM bug.
1038bool AddressSanitizer::poisonStackInFunction(Function &F) {
1039  if (!ClStack) return false;
1040  SmallVector<AllocaInst*, 16> AllocaVec;
1041  SmallVector<Instruction*, 8> RetVec;
1042  uint64_t TotalSize = 0;
1043
1044  // Filter out Alloca instructions we want (and can) handle.
1045  // Collect Ret instructions.
1046  for (Function::iterator FI = F.begin(), FE = F.end();
1047       FI != FE; ++FI) {
1048    BasicBlock &BB = *FI;
1049    for (BasicBlock::iterator BI = BB.begin(), BE = BB.end();
1050         BI != BE; ++BI) {
1051      if (isa<ReturnInst>(BI)) {
1052          RetVec.push_back(BI);
1053          continue;
1054      }
1055
1056      AllocaInst *AI = dyn_cast<AllocaInst>(BI);
1057      if (!AI) continue;
1058      if (AI->isArrayAllocation()) continue;
1059      if (!AI->isStaticAlloca()) continue;
1060      if (!AI->getAllocatedType()->isSized()) continue;
1061      if (AI->getAlignment() > RedzoneSize()) continue;
1062      AllocaVec.push_back(AI);
1063      uint64_t AlignedSize =  getAlignedAllocaSize(AI);
1064      TotalSize += AlignedSize;
1065    }
1066  }
1067
1068  if (AllocaVec.empty()) return false;
1069
1070  uint64_t LocalStackSize = TotalSize + (AllocaVec.size() + 1) * RedzoneSize();
1071
1072  bool DoStackMalloc = ClUseAfterReturn
1073      && LocalStackSize <= kMaxStackMallocSize;
1074
1075  Instruction *InsBefore = AllocaVec[0];
1076  IRBuilder<> IRB(InsBefore);
1077
1078
1079  Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1080  AllocaInst *MyAlloca =
1081      new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1082  MyAlloca->setAlignment(RedzoneSize());
1083  assert(MyAlloca->isStaticAlloca());
1084  Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1085  Value *LocalStackBase = OrigStackBase;
1086
1087  if (DoStackMalloc) {
1088    LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1089        ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1090  }
1091
1092  // This string will be parsed by the run-time (DescribeStackAddress).
1093  SmallString<2048> StackDescriptionStorage;
1094  raw_svector_ostream StackDescription(StackDescriptionStorage);
1095  StackDescription << F.getName() << " " << AllocaVec.size() << " ";
1096
1097  uint64_t Pos = RedzoneSize();
1098  // Replace Alloca instructions with base+offset.
1099  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1100    AllocaInst *AI = AllocaVec[i];
1101    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1102    StringRef Name = AI->getName();
1103    StackDescription << Pos << " " << SizeInBytes << " "
1104                     << Name.size() << " " << Name << " ";
1105    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1106    assert((AlignedSize % RedzoneSize()) == 0);
1107    AI->replaceAllUsesWith(
1108        IRB.CreateIntToPtr(
1109            IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1110            AI->getType()));
1111    Pos += AlignedSize + RedzoneSize();
1112  }
1113  assert(Pos == LocalStackSize);
1114
1115  // Write the Magic value and the frame description constant to the redzone.
1116  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1117  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1118                  BasePlus0);
1119  Value *BasePlus1 = IRB.CreateAdd(LocalStackBase,
1120                                   ConstantInt::get(IntptrTy, LongSize/8));
1121  BasePlus1 = IRB.CreateIntToPtr(BasePlus1, IntptrPtrTy);
1122  GlobalVariable *StackDescriptionGlobal =
1123      createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1124  Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
1125  IRB.CreateStore(Description, BasePlus1);
1126
1127  // Poison the stack redzones at the entry.
1128  Value *ShadowBase = memToShadow(LocalStackBase, IRB);
1129  PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRB, ShadowBase, true);
1130
1131  // Unpoison the stack before all ret instructions.
1132  for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1133    Instruction *Ret = RetVec[i];
1134    IRBuilder<> IRBRet(Ret);
1135
1136    // Mark the current frame as retired.
1137    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1138                       BasePlus0);
1139    // Unpoison the stack.
1140    PoisonStack(ArrayRef<AllocaInst*>(AllocaVec), IRBRet, ShadowBase, false);
1141
1142    if (DoStackMalloc) {
1143      IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1144                         ConstantInt::get(IntptrTy, LocalStackSize),
1145                         OrigStackBase);
1146    }
1147  }
1148
1149  // We are done. Remove the old unused alloca instructions.
1150  for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1151    AllocaVec[i]->eraseFromParent();
1152
1153  if (ClDebugStack) {
1154    DEBUG(dbgs() << F);
1155  }
1156
1157  return true;
1158}
1159