AddressSanitizer.cpp revision 3e1d45bf44f882f3ee139d452dd50305d831a341 
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 "llvm/Transforms/Instrumentation.h"
19#include "llvm/ADT/ArrayRef.h"
20#include "llvm/ADT/DenseMap.h"
21#include "llvm/ADT/DepthFirstIterator.h"
22#include "llvm/ADT/OwningPtr.h"
23#include "llvm/ADT/SmallSet.h"
24#include "llvm/ADT/SmallString.h"
25#include "llvm/ADT/SmallVector.h"
26#include "llvm/ADT/StringExtras.h"
27#include "llvm/ADT/Triple.h"
28#include "llvm/DIBuilder.h"
29#include "llvm/IR/DataLayout.h"
30#include "llvm/IR/Function.h"
31#include "llvm/IR/IRBuilder.h"
32#include "llvm/IR/InlineAsm.h"
33#include "llvm/IR/IntrinsicInst.h"
34#include "llvm/IR/LLVMContext.h"
35#include "llvm/IR/Module.h"
36#include "llvm/IR/Type.h"
37#include "llvm/InstVisitor.h"
38#include "llvm/Support/CallSite.h"
39#include "llvm/Support/CommandLine.h"
40#include "llvm/Support/DataTypes.h"
41#include "llvm/Support/Debug.h"
42#include "llvm/Support/Endian.h"
43#include "llvm/Support/raw_ostream.h"
44#include "llvm/Support/system_error.h"
45#include "llvm/Transforms/Utils/BasicBlockUtils.h"
46#include "llvm/Transforms/Utils/BlackList.h"
47#include "llvm/Transforms/Utils/Local.h"
48#include "llvm/Transforms/Utils/ModuleUtils.h"
49#include <algorithm>
50#include <string>
51
52using namespace llvm;
53
54static const uint64_t kDefaultShadowScale = 3;
55static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
56static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
57static const uint64_t kDefaultShort64bitShadowOffset = 0x7FFF8000;  // < 2G.
58static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 41;
59static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa8000;
60
61static const size_t kMaxStackMallocSize = 1 << 16;  // 64K
62static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
63static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
64
65static const char *kAsanModuleCtorName = "asan.module_ctor";
66static const char *kAsanModuleDtorName = "asan.module_dtor";
67static const int   kAsanCtorAndCtorPriority = 1;
68static const char *kAsanReportErrorTemplate = "__asan_report_";
69static const char *kAsanReportLoadN = "__asan_report_load_n";
70static const char *kAsanReportStoreN = "__asan_report_store_n";
71static const char *kAsanRegisterGlobalsName = "__asan_register_globals";
72static const char *kAsanUnregisterGlobalsName = "__asan_unregister_globals";
73static const char *kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
74static const char *kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
75static const char *kAsanInitName = "__asan_init_v3";
76static const char *kAsanHandleNoReturnName = "__asan_handle_no_return";
77static const char *kAsanMappingOffsetName = "__asan_mapping_offset";
78static const char *kAsanMappingScaleName = "__asan_mapping_scale";
79static const char *kAsanStackMallocName = "__asan_stack_malloc";
80static const char *kAsanStackFreeName = "__asan_stack_free";
81static const char *kAsanGenPrefix = "__asan_gen_";
82static const char *kAsanPoisonStackMemoryName = "__asan_poison_stack_memory";
83static const char *kAsanUnpoisonStackMemoryName =
84    "__asan_unpoison_stack_memory";
85
86static const int kAsanStackLeftRedzoneMagic = 0xf1;
87static const int kAsanStackMidRedzoneMagic = 0xf2;
88static const int kAsanStackRightRedzoneMagic = 0xf3;
89static const int kAsanStackPartialRedzoneMagic = 0xf4;
90
91// Accesses sizes are powers of two: 1, 2, 4, 8, 16.
92static const size_t kNumberOfAccessSizes = 5;
93
94// Command-line flags.
95
96// This flag may need to be replaced with -f[no-]asan-reads.
97static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
98       cl::desc("instrument read instructions"), cl::Hidden, cl::init(true));
99static cl::opt<bool> ClInstrumentWrites("asan-instrument-writes",
100       cl::desc("instrument write instructions"), cl::Hidden, cl::init(true));
101static cl::opt<bool> ClInstrumentAtomics("asan-instrument-atomics",
102       cl::desc("instrument atomic instructions (rmw, cmpxchg)"),
103       cl::Hidden, cl::init(true));
104static cl::opt<bool> ClAlwaysSlowPath("asan-always-slow-path",
105       cl::desc("use instrumentation with slow path for all accesses"),
106       cl::Hidden, cl::init(false));
107// This flag limits the number of instructions to be instrumented
108// in any given BB. Normally, this should be set to unlimited (INT_MAX),
109// but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
110// set it to 10000.
111static cl::opt<int> ClMaxInsnsToInstrumentPerBB("asan-max-ins-per-bb",
112       cl::init(10000),
113       cl::desc("maximal number of instructions to instrument in any given BB"),
114       cl::Hidden);
115// This flag may need to be replaced with -f[no]asan-stack.
116static cl::opt<bool> ClStack("asan-stack",
117       cl::desc("Handle stack memory"), cl::Hidden, cl::init(true));
118// This flag may need to be replaced with -f[no]asan-use-after-return.
119static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
120       cl::desc("Check return-after-free"), cl::Hidden, cl::init(false));
121// This flag may need to be replaced with -f[no]asan-globals.
122static cl::opt<bool> ClGlobals("asan-globals",
123       cl::desc("Handle global objects"), cl::Hidden, cl::init(true));
124static cl::opt<bool> ClInitializers("asan-initialization-order",
125       cl::desc("Handle C++ initializer order"), cl::Hidden, cl::init(false));
126static cl::opt<bool> ClMemIntrin("asan-memintrin",
127       cl::desc("Handle memset/memcpy/memmove"), cl::Hidden, cl::init(true));
128static cl::opt<bool> ClRealignStack("asan-realign-stack",
129       cl::desc("Realign stack to 32"), cl::Hidden, cl::init(true));
130static cl::opt<std::string> ClBlacklistFile("asan-blacklist",
131       cl::desc("File containing the list of objects to ignore "
132                "during instrumentation"), cl::Hidden);
133
134// These flags allow to change the shadow mapping.
135// The shadow mapping looks like
136//    Shadow = (Mem >> scale) + (1 << offset_log)
137static cl::opt<int> ClMappingScale("asan-mapping-scale",
138       cl::desc("scale of asan shadow mapping"), cl::Hidden, cl::init(0));
139static cl::opt<int> ClMappingOffsetLog("asan-mapping-offset-log",
140       cl::desc("offset of asan shadow mapping"), cl::Hidden, cl::init(-1));
141static cl::opt<bool> ClShort64BitOffset("asan-short-64bit-mapping-offset",
142       cl::desc("Use short immediate constant as the mapping offset for 64bit"),
143       cl::Hidden, cl::init(true));
144
145// Optimization flags. Not user visible, used mostly for testing
146// and benchmarking the tool.
147static cl::opt<bool> ClOpt("asan-opt",
148       cl::desc("Optimize instrumentation"), cl::Hidden, cl::init(true));
149static cl::opt<bool> ClOptSameTemp("asan-opt-same-temp",
150       cl::desc("Instrument the same temp just once"), cl::Hidden,
151       cl::init(true));
152static cl::opt<bool> ClOptGlobals("asan-opt-globals",
153       cl::desc("Don't instrument scalar globals"), cl::Hidden, cl::init(true));
154
155static cl::opt<bool> ClCheckLifetime("asan-check-lifetime",
156       cl::desc("Use llvm.lifetime intrinsics to insert extra checks"),
157       cl::Hidden, cl::init(false));
158
159// Debug flags.
160static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
161                            cl::init(0));
162static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
163                                 cl::Hidden, cl::init(0));
164static cl::opt<std::string> ClDebugFunc("asan-debug-func",
165                                        cl::Hidden, cl::desc("Debug func"));
166static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
167                               cl::Hidden, cl::init(-1));
168static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug man inst"),
169                               cl::Hidden, cl::init(-1));
170
171namespace {
172/// A set of dynamically initialized globals extracted from metadata.
173class SetOfDynamicallyInitializedGlobals {
174 public:
175  void Init(Module& M) {
176    // Clang generates metadata identifying all dynamically initialized globals.
177    NamedMDNode *DynamicGlobals =
178        M.getNamedMetadata("llvm.asan.dynamically_initialized_globals");
179    if (!DynamicGlobals)
180      return;
181    for (int i = 0, n = DynamicGlobals->getNumOperands(); i < n; ++i) {
182      MDNode *MDN = DynamicGlobals->getOperand(i);
183      assert(MDN->getNumOperands() == 1);
184      Value *VG = MDN->getOperand(0);
185      // The optimizer may optimize away a global entirely, in which case we
186      // cannot instrument access to it.
187      if (!VG)
188        continue;
189      DynInitGlobals.insert(cast<GlobalVariable>(VG));
190    }
191  }
192  bool Contains(GlobalVariable *G) { return DynInitGlobals.count(G) != 0; }
193 private:
194  SmallSet<GlobalValue*, 32> DynInitGlobals;
195};
196
197/// This struct defines the shadow mapping using the rule:
198///   shadow = (mem >> Scale) ADD-or-OR Offset.
199struct ShadowMapping {
200  int Scale;
201  uint64_t Offset;
202  bool OrShadowOffset;
203};
204
205static ShadowMapping getShadowMapping(const Module &M, int LongSize,
206                                      bool ZeroBaseShadow) {
207  llvm::Triple TargetTriple(M.getTargetTriple());
208  bool IsAndroid = TargetTriple.getEnvironment() == llvm::Triple::Android;
209  bool IsMacOSX = TargetTriple.getOS() == llvm::Triple::MacOSX;
210  bool IsPPC64 = TargetTriple.getArch() == llvm::Triple::ppc64;
211  bool IsX86_64 = TargetTriple.getArch() == llvm::Triple::x86_64;
212  bool IsMIPS32 = TargetTriple.getArch() == llvm::Triple::mips ||
213                  TargetTriple.getArch() == llvm::Triple::mipsel;
214
215  ShadowMapping Mapping;
216
217  // OR-ing shadow offset if more efficient (at least on x86),
218  // but on ppc64 we have to use add since the shadow offset is not neccesary
219  // 1/8-th of the address space.
220  Mapping.OrShadowOffset = !IsPPC64 && !ClShort64BitOffset;
221
222  Mapping.Offset = (IsAndroid || ZeroBaseShadow) ? 0 :
223      (LongSize == 32 ?
224       (IsMIPS32 ? kMIPS32_ShadowOffset32 : kDefaultShadowOffset32) :
225       IsPPC64 ? kPPC64_ShadowOffset64 : kDefaultShadowOffset64);
226  if (!ZeroBaseShadow && ClShort64BitOffset && IsX86_64 && !IsMacOSX) {
227    assert(LongSize == 64);
228    Mapping.Offset = kDefaultShort64bitShadowOffset;
229  }
230  if (!ZeroBaseShadow && ClMappingOffsetLog >= 0) {
231    // Zero offset log is the special case.
232    Mapping.Offset = (ClMappingOffsetLog == 0) ? 0 : 1ULL << ClMappingOffsetLog;
233  }
234
235  Mapping.Scale = kDefaultShadowScale;
236  if (ClMappingScale) {
237    Mapping.Scale = ClMappingScale;
238  }
239
240  return Mapping;
241}
242
243static size_t RedzoneSizeForScale(int MappingScale) {
244  // Redzone used for stack and globals is at least 32 bytes.
245  // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
246  return std::max(32U, 1U << MappingScale);
247}
248
249/// AddressSanitizer: instrument the code in module to find memory bugs.
250struct AddressSanitizer : public FunctionPass {
251  AddressSanitizer(bool CheckInitOrder = true,
252                   bool CheckUseAfterReturn = false,
253                   bool CheckLifetime = false,
254                   StringRef BlacklistFile = StringRef(),
255                   bool ZeroBaseShadow = false)
256      : FunctionPass(ID),
257        CheckInitOrder(CheckInitOrder || ClInitializers),
258        CheckUseAfterReturn(CheckUseAfterReturn || ClUseAfterReturn),
259        CheckLifetime(CheckLifetime || ClCheckLifetime),
260        BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
261                                            : BlacklistFile),
262        ZeroBaseShadow(ZeroBaseShadow) {}
263  virtual const char *getPassName() const {
264    return "AddressSanitizerFunctionPass";
265  }
266  void instrumentMop(Instruction *I);
267  void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
268                         Value *Addr, uint32_t TypeSize, bool IsWrite,
269                         Value *SizeArgument);
270  Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
271                           Value *ShadowValue, uint32_t TypeSize);
272  Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
273                                 bool IsWrite, size_t AccessSizeIndex,
274                                 Value *SizeArgument);
275  bool instrumentMemIntrinsic(MemIntrinsic *MI);
276  void instrumentMemIntrinsicParam(Instruction *OrigIns, Value *Addr,
277                                   Value *Size,
278                                   Instruction *InsertBefore, bool IsWrite);
279  Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
280  bool runOnFunction(Function &F);
281  bool maybeInsertAsanInitAtFunctionEntry(Function &F);
282  void emitShadowMapping(Module &M, IRBuilder<> &IRB) const;
283  virtual bool doInitialization(Module &M);
284  static char ID;  // Pass identification, replacement for typeid
285
286 private:
287  void initializeCallbacks(Module &M);
288
289  bool ShouldInstrumentGlobal(GlobalVariable *G);
290  bool LooksLikeCodeInBug11395(Instruction *I);
291  void FindDynamicInitializers(Module &M);
292
293  bool CheckInitOrder;
294  bool CheckUseAfterReturn;
295  bool CheckLifetime;
296  SmallString<64> BlacklistFile;
297  bool ZeroBaseShadow;
298
299  LLVMContext *C;
300  DataLayout *TD;
301  int LongSize;
302  Type *IntptrTy;
303  ShadowMapping Mapping;
304  Function *AsanCtorFunction;
305  Function *AsanInitFunction;
306  Function *AsanHandleNoReturnFunc;
307  OwningPtr<BlackList> BL;
308  // This array is indexed by AccessIsWrite and log2(AccessSize).
309  Function *AsanErrorCallback[2][kNumberOfAccessSizes];
310  // This array is indexed by AccessIsWrite.
311  Function *AsanErrorCallbackSized[2];
312  InlineAsm *EmptyAsm;
313  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
314
315  friend struct FunctionStackPoisoner;
316};
317
318class AddressSanitizerModule : public ModulePass {
319 public:
320  AddressSanitizerModule(bool CheckInitOrder = true,
321                         StringRef BlacklistFile = StringRef(),
322                         bool ZeroBaseShadow = false)
323      : ModulePass(ID),
324        CheckInitOrder(CheckInitOrder || ClInitializers),
325        BlacklistFile(BlacklistFile.empty() ? ClBlacklistFile
326                                            : BlacklistFile),
327        ZeroBaseShadow(ZeroBaseShadow) {}
328  bool runOnModule(Module &M);
329  static char ID;  // Pass identification, replacement for typeid
330  virtual const char *getPassName() const {
331    return "AddressSanitizerModule";
332  }
333
334 private:
335  void initializeCallbacks(Module &M);
336
337  bool ShouldInstrumentGlobal(GlobalVariable *G);
338  void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
339  size_t RedzoneSize() const {
340    return RedzoneSizeForScale(Mapping.Scale);
341  }
342
343  bool CheckInitOrder;
344  SmallString<64> BlacklistFile;
345  bool ZeroBaseShadow;
346
347  OwningPtr<BlackList> BL;
348  SetOfDynamicallyInitializedGlobals DynamicallyInitializedGlobals;
349  Type *IntptrTy;
350  LLVMContext *C;
351  DataLayout *TD;
352  ShadowMapping Mapping;
353  Function *AsanPoisonGlobals;
354  Function *AsanUnpoisonGlobals;
355  Function *AsanRegisterGlobals;
356  Function *AsanUnregisterGlobals;
357};
358
359// Stack poisoning does not play well with exception handling.
360// When an exception is thrown, we essentially bypass the code
361// that unpoisones the stack. This is why the run-time library has
362// to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
363// stack in the interceptor. This however does not work inside the
364// actual function which catches the exception. Most likely because the
365// compiler hoists the load of the shadow value somewhere too high.
366// This causes asan to report a non-existing bug on 453.povray.
367// It sounds like an LLVM bug.
368struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
369  Function &F;
370  AddressSanitizer &ASan;
371  DIBuilder DIB;
372  LLVMContext *C;
373  Type *IntptrTy;
374  Type *IntptrPtrTy;
375  ShadowMapping Mapping;
376
377  SmallVector<AllocaInst*, 16> AllocaVec;
378  SmallVector<Instruction*, 8> RetVec;
379  uint64_t TotalStackSize;
380  unsigned StackAlignment;
381
382  Function *AsanStackMallocFunc, *AsanStackFreeFunc;
383  Function *AsanPoisonStackMemoryFunc, *AsanUnpoisonStackMemoryFunc;
384
385  // Stores a place and arguments of poisoning/unpoisoning call for alloca.
386  struct AllocaPoisonCall {
387    IntrinsicInst *InsBefore;
388    uint64_t Size;
389    bool DoPoison;
390  };
391  SmallVector<AllocaPoisonCall, 8> AllocaPoisonCallVec;
392
393  // Maps Value to an AllocaInst from which the Value is originated.
394  typedef DenseMap<Value*, AllocaInst*> AllocaForValueMapTy;
395  AllocaForValueMapTy AllocaForValue;
396
397  FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
398      : F(F), ASan(ASan), DIB(*F.getParent()), C(ASan.C),
399        IntptrTy(ASan.IntptrTy), IntptrPtrTy(PointerType::get(IntptrTy, 0)),
400        Mapping(ASan.Mapping),
401        TotalStackSize(0), StackAlignment(1 << Mapping.Scale) {}
402
403  bool runOnFunction() {
404    if (!ClStack) return false;
405    // Collect alloca, ret, lifetime instructions etc.
406    for (df_iterator<BasicBlock*> DI = df_begin(&F.getEntryBlock()),
407         DE = df_end(&F.getEntryBlock()); DI != DE; ++DI) {
408      BasicBlock *BB = *DI;
409      visit(*BB);
410    }
411    if (AllocaVec.empty()) return false;
412
413    initializeCallbacks(*F.getParent());
414
415    poisonStack();
416
417    if (ClDebugStack) {
418      DEBUG(dbgs() << F);
419    }
420    return true;
421  }
422
423  // Finds all static Alloca instructions and puts
424  // poisoned red zones around all of them.
425  // Then unpoison everything back before the function returns.
426  void poisonStack();
427
428  // ----------------------- Visitors.
429  /// \brief Collect all Ret instructions.
430  void visitReturnInst(ReturnInst &RI) {
431    RetVec.push_back(&RI);
432  }
433
434  /// \brief Collect Alloca instructions we want (and can) handle.
435  void visitAllocaInst(AllocaInst &AI) {
436    if (!isInterestingAlloca(AI)) return;
437
438    StackAlignment = std::max(StackAlignment, AI.getAlignment());
439    AllocaVec.push_back(&AI);
440    uint64_t AlignedSize =  getAlignedAllocaSize(&AI);
441    TotalStackSize += AlignedSize;
442  }
443
444  /// \brief Collect lifetime intrinsic calls to check for use-after-scope
445  /// errors.
446  void visitIntrinsicInst(IntrinsicInst &II) {
447    if (!ASan.CheckLifetime) return;
448    Intrinsic::ID ID = II.getIntrinsicID();
449    if (ID != Intrinsic::lifetime_start &&
450        ID != Intrinsic::lifetime_end)
451      return;
452    // Found lifetime intrinsic, add ASan instrumentation if necessary.
453    ConstantInt *Size = dyn_cast<ConstantInt>(II.getArgOperand(0));
454    // If size argument is undefined, don't do anything.
455    if (Size->isMinusOne()) return;
456    // Check that size doesn't saturate uint64_t and can
457    // be stored in IntptrTy.
458    const uint64_t SizeValue = Size->getValue().getLimitedValue();
459    if (SizeValue == ~0ULL ||
460        !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
461      return;
462    // Find alloca instruction that corresponds to llvm.lifetime argument.
463    AllocaInst *AI = findAllocaForValue(II.getArgOperand(1));
464    if (!AI) return;
465    bool DoPoison = (ID == Intrinsic::lifetime_end);
466    AllocaPoisonCall APC = {&II, SizeValue, DoPoison};
467    AllocaPoisonCallVec.push_back(APC);
468  }
469
470  // ---------------------- Helpers.
471  void initializeCallbacks(Module &M);
472
473  // Check if we want (and can) handle this alloca.
474  bool isInterestingAlloca(AllocaInst &AI) {
475    return (!AI.isArrayAllocation() &&
476            AI.isStaticAlloca() &&
477            AI.getAllocatedType()->isSized());
478  }
479
480  size_t RedzoneSize() const {
481    return RedzoneSizeForScale(Mapping.Scale);
482  }
483  uint64_t getAllocaSizeInBytes(AllocaInst *AI) {
484    Type *Ty = AI->getAllocatedType();
485    uint64_t SizeInBytes = ASan.TD->getTypeAllocSize(Ty);
486    return SizeInBytes;
487  }
488  uint64_t getAlignedSize(uint64_t SizeInBytes) {
489    size_t RZ = RedzoneSize();
490    return ((SizeInBytes + RZ - 1) / RZ) * RZ;
491  }
492  uint64_t getAlignedAllocaSize(AllocaInst *AI) {
493    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
494    return getAlignedSize(SizeInBytes);
495  }
496  /// Finds alloca where the value comes from.
497  AllocaInst *findAllocaForValue(Value *V);
498  void poisonRedZones(const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB,
499                      Value *ShadowBase, bool DoPoison);
500  void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> IRB, bool DoPoison);
501};
502
503}  // namespace
504
505char AddressSanitizer::ID = 0;
506INITIALIZE_PASS(AddressSanitizer, "asan",
507    "AddressSanitizer: detects use-after-free and out-of-bounds bugs.",
508    false, false)
509FunctionPass *llvm::createAddressSanitizerFunctionPass(
510    bool CheckInitOrder, bool CheckUseAfterReturn, bool CheckLifetime,
511    StringRef BlacklistFile, bool ZeroBaseShadow) {
512  return new AddressSanitizer(CheckInitOrder, CheckUseAfterReturn,
513                              CheckLifetime, BlacklistFile, ZeroBaseShadow);
514}
515
516char AddressSanitizerModule::ID = 0;
517INITIALIZE_PASS(AddressSanitizerModule, "asan-module",
518    "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
519    "ModulePass", false, false)
520ModulePass *llvm::createAddressSanitizerModulePass(
521    bool CheckInitOrder, StringRef BlacklistFile, bool ZeroBaseShadow) {
522  return new AddressSanitizerModule(CheckInitOrder, BlacklistFile,
523                                    ZeroBaseShadow);
524}
525
526static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
527  size_t Res = countTrailingZeros(TypeSize / 8);
528  assert(Res < kNumberOfAccessSizes);
529  return Res;
530}
531
532// Create a constant for Str so that we can pass it to the run-time lib.
533static GlobalVariable *createPrivateGlobalForString(Module &M, StringRef Str) {
534  Constant *StrConst = ConstantDataArray::getString(M.getContext(), Str);
535  GlobalVariable *GV = new GlobalVariable(M, StrConst->getType(), true,
536                            GlobalValue::PrivateLinkage, StrConst,
537                            kAsanGenPrefix);
538  GV->setUnnamedAddr(true);  // Ok to merge these.
539  GV->setAlignment(1);  // Strings may not be merged w/o setting align 1.
540  return GV;
541}
542
543static bool GlobalWasGeneratedByAsan(GlobalVariable *G) {
544  return G->getName().find(kAsanGenPrefix) == 0;
545}
546
547Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
548  // Shadow >> scale
549  Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
550  if (Mapping.Offset == 0)
551    return Shadow;
552  // (Shadow >> scale) | offset
553  if (Mapping.OrShadowOffset)
554    return IRB.CreateOr(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
555  else
556    return IRB.CreateAdd(Shadow, ConstantInt::get(IntptrTy, Mapping.Offset));
557}
558
559void AddressSanitizer::instrumentMemIntrinsicParam(
560    Instruction *OrigIns,
561    Value *Addr, Value *Size, Instruction *InsertBefore, bool IsWrite) {
562  IRBuilder<> IRB(InsertBefore);
563  if (Size->getType() != IntptrTy)
564    Size = IRB.CreateIntCast(Size, IntptrTy, false);
565  // Check the first byte.
566  instrumentAddress(OrigIns, InsertBefore, Addr, 8, IsWrite, Size);
567  // Check the last byte.
568  IRB.SetInsertPoint(InsertBefore);
569  Value *SizeMinusOne = IRB.CreateSub(Size, ConstantInt::get(IntptrTy, 1));
570  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
571  Value *AddrLast = IRB.CreateAdd(AddrLong, SizeMinusOne);
572  instrumentAddress(OrigIns, InsertBefore, AddrLast, 8, IsWrite, Size);
573}
574
575// Instrument memset/memmove/memcpy
576bool AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
577  Value *Dst = MI->getDest();
578  MemTransferInst *MemTran = dyn_cast<MemTransferInst>(MI);
579  Value *Src = MemTran ? MemTran->getSource() : 0;
580  Value *Length = MI->getLength();
581
582  Constant *ConstLength = dyn_cast<Constant>(Length);
583  Instruction *InsertBefore = MI;
584  if (ConstLength) {
585    if (ConstLength->isNullValue()) return false;
586  } else {
587    // The size is not a constant so it could be zero -- check at run-time.
588    IRBuilder<> IRB(InsertBefore);
589
590    Value *Cmp = IRB.CreateICmpNE(Length,
591                                  Constant::getNullValue(Length->getType()));
592    InsertBefore = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
593  }
594
595  instrumentMemIntrinsicParam(MI, Dst, Length, InsertBefore, true);
596  if (Src)
597    instrumentMemIntrinsicParam(MI, Src, Length, InsertBefore, false);
598  return true;
599}
600
601// If I is an interesting memory access, return the PointerOperand
602// and set IsWrite. Otherwise return NULL.
603static Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite) {
604  if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
605    if (!ClInstrumentReads) return NULL;
606    *IsWrite = false;
607    return LI->getPointerOperand();
608  }
609  if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
610    if (!ClInstrumentWrites) return NULL;
611    *IsWrite = true;
612    return SI->getPointerOperand();
613  }
614  if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
615    if (!ClInstrumentAtomics) return NULL;
616    *IsWrite = true;
617    return RMW->getPointerOperand();
618  }
619  if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
620    if (!ClInstrumentAtomics) return NULL;
621    *IsWrite = true;
622    return XCHG->getPointerOperand();
623  }
624  return NULL;
625}
626
627void AddressSanitizer::instrumentMop(Instruction *I) {
628  bool IsWrite = false;
629  Value *Addr = isInterestingMemoryAccess(I, &IsWrite);
630  assert(Addr);
631  if (ClOpt && ClOptGlobals) {
632    if (GlobalVariable *G = dyn_cast<GlobalVariable>(Addr)) {
633      // If initialization order checking is disabled, a simple access to a
634      // dynamically initialized global is always valid.
635      if (!CheckInitOrder)
636        return;
637      // If a global variable does not have dynamic initialization we don't
638      // have to instrument it.  However, if a global does not have initailizer
639      // at all, we assume it has dynamic initializer (in other TU).
640      if (G->hasInitializer() && !DynamicallyInitializedGlobals.Contains(G))
641        return;
642    }
643  }
644
645  Type *OrigPtrTy = Addr->getType();
646  Type *OrigTy = cast<PointerType>(OrigPtrTy)->getElementType();
647
648  assert(OrigTy->isSized());
649  uint32_t TypeSize = TD->getTypeStoreSizeInBits(OrigTy);
650
651  assert((TypeSize % 8) == 0);
652
653  // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check.
654  if (TypeSize == 8  || TypeSize == 16 ||
655      TypeSize == 32 || TypeSize == 64 || TypeSize == 128)
656    return instrumentAddress(I, I, Addr, TypeSize, IsWrite, 0);
657  // Instrument unusual size (but still multiple of 8).
658  // We can not do it with a single check, so we do 1-byte check for the first
659  // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
660  // to report the actual access size.
661  IRBuilder<> IRB(I);
662  Value *LastByte =  IRB.CreateIntToPtr(
663      IRB.CreateAdd(IRB.CreatePointerCast(Addr, IntptrTy),
664                    ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
665      OrigPtrTy);
666  Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
667  instrumentAddress(I, I, Addr, 8, IsWrite, Size);
668  instrumentAddress(I, I, LastByte, 8, IsWrite, Size);
669}
670
671// Validate the result of Module::getOrInsertFunction called for an interface
672// function of AddressSanitizer. If the instrumented module defines a function
673// with the same name, their prototypes must match, otherwise
674// getOrInsertFunction returns a bitcast.
675static Function *checkInterfaceFunction(Constant *FuncOrBitcast) {
676  if (isa<Function>(FuncOrBitcast)) return cast<Function>(FuncOrBitcast);
677  FuncOrBitcast->dump();
678  report_fatal_error("trying to redefine an AddressSanitizer "
679                     "interface function");
680}
681
682Instruction *AddressSanitizer::generateCrashCode(
683    Instruction *InsertBefore, Value *Addr,
684    bool IsWrite, size_t AccessSizeIndex, Value *SizeArgument) {
685  IRBuilder<> IRB(InsertBefore);
686  CallInst *Call = SizeArgument
687    ? IRB.CreateCall2(AsanErrorCallbackSized[IsWrite], Addr, SizeArgument)
688    : IRB.CreateCall(AsanErrorCallback[IsWrite][AccessSizeIndex], Addr);
689
690  // We don't do Call->setDoesNotReturn() because the BB already has
691  // UnreachableInst at the end.
692  // This EmptyAsm is required to avoid callback merge.
693  IRB.CreateCall(EmptyAsm);
694  return Call;
695}
696
697Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
698                                            Value *ShadowValue,
699                                            uint32_t TypeSize) {
700  size_t Granularity = 1 << Mapping.Scale;
701  // Addr & (Granularity - 1)
702  Value *LastAccessedByte = IRB.CreateAnd(
703      AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
704  // (Addr & (Granularity - 1)) + size - 1
705  if (TypeSize / 8 > 1)
706    LastAccessedByte = IRB.CreateAdd(
707        LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
708  // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
709  LastAccessedByte = IRB.CreateIntCast(
710      LastAccessedByte, ShadowValue->getType(), false);
711  // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
712  return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
713}
714
715void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
716                                         Instruction *InsertBefore,
717                                         Value *Addr, uint32_t TypeSize,
718                                         bool IsWrite, Value *SizeArgument) {
719  IRBuilder<> IRB(InsertBefore);
720  Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
721
722  Type *ShadowTy  = IntegerType::get(
723      *C, std::max(8U, TypeSize >> Mapping.Scale));
724  Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
725  Value *ShadowPtr = memToShadow(AddrLong, IRB);
726  Value *CmpVal = Constant::getNullValue(ShadowTy);
727  Value *ShadowValue = IRB.CreateLoad(
728      IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
729
730  Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
731  size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
732  size_t Granularity = 1 << Mapping.Scale;
733  TerminatorInst *CrashTerm = 0;
734
735  if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
736    TerminatorInst *CheckTerm =
737        SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), false);
738    assert(dyn_cast<BranchInst>(CheckTerm)->isUnconditional());
739    BasicBlock *NextBB = CheckTerm->getSuccessor(0);
740    IRB.SetInsertPoint(CheckTerm);
741    Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
742    BasicBlock *CrashBlock =
743        BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
744    CrashTerm = new UnreachableInst(*C, CrashBlock);
745    BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
746    ReplaceInstWithInst(CheckTerm, NewTerm);
747  } else {
748    CrashTerm = SplitBlockAndInsertIfThen(cast<Instruction>(Cmp), true);
749  }
750
751  Instruction *Crash = generateCrashCode(
752      CrashTerm, AddrLong, IsWrite, AccessSizeIndex, SizeArgument);
753  Crash->setDebugLoc(OrigIns->getDebugLoc());
754}
755
756void AddressSanitizerModule::createInitializerPoisonCalls(
757    Module &M, GlobalValue *ModuleName) {
758  // We do all of our poisoning and unpoisoning within _GLOBAL__I_a.
759  Function *GlobalInit = M.getFunction("_GLOBAL__I_a");
760  // If that function is not present, this TU contains no globals, or they have
761  // all been optimized away
762  if (!GlobalInit)
763    return;
764
765  // Set up the arguments to our poison/unpoison functions.
766  IRBuilder<> IRB(GlobalInit->begin()->getFirstInsertionPt());
767
768  // Add a call to poison all external globals before the given function starts.
769  Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
770  IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
771
772  // Add calls to unpoison all globals before each return instruction.
773  for (Function::iterator I = GlobalInit->begin(), E = GlobalInit->end();
774      I != E; ++I) {
775    if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator())) {
776      CallInst::Create(AsanUnpoisonGlobals, "", RI);
777    }
778  }
779}
780
781bool AddressSanitizerModule::ShouldInstrumentGlobal(GlobalVariable *G) {
782  Type *Ty = cast<PointerType>(G->getType())->getElementType();
783  DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
784
785  if (BL->isIn(*G)) return false;
786  if (!Ty->isSized()) return false;
787  if (!G->hasInitializer()) return false;
788  if (GlobalWasGeneratedByAsan(G)) return false;  // Our own global.
789  // Touch only those globals that will not be defined in other modules.
790  // Don't handle ODR type linkages since other modules may be built w/o asan.
791  if (G->getLinkage() != GlobalVariable::ExternalLinkage &&
792      G->getLinkage() != GlobalVariable::PrivateLinkage &&
793      G->getLinkage() != GlobalVariable::InternalLinkage)
794    return false;
795  // Two problems with thread-locals:
796  //   - The address of the main thread's copy can't be computed at link-time.
797  //   - Need to poison all copies, not just the main thread's one.
798  if (G->isThreadLocal())
799    return false;
800  // For now, just ignore this Alloca if the alignment is large.
801  if (G->getAlignment() > RedzoneSize()) return false;
802
803  // Ignore all the globals with the names starting with "\01L_OBJC_".
804  // Many of those are put into the .cstring section. The linker compresses
805  // that section by removing the spare \0s after the string terminator, so
806  // our redzones get broken.
807  if ((G->getName().find("\01L_OBJC_") == 0) ||
808      (G->getName().find("\01l_OBJC_") == 0)) {
809    DEBUG(dbgs() << "Ignoring \\01L_OBJC_* global: " << *G);
810    return false;
811  }
812
813  if (G->hasSection()) {
814    StringRef Section(G->getSection());
815    // Ignore the globals from the __OBJC section. The ObjC runtime assumes
816    // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
817    // them.
818    if ((Section.find("__OBJC,") == 0) ||
819        (Section.find("__DATA, __objc_") == 0)) {
820      DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G);
821      return false;
822    }
823    // See http://code.google.com/p/address-sanitizer/issues/detail?id=32
824    // Constant CFString instances are compiled in the following way:
825    //  -- the string buffer is emitted into
826    //     __TEXT,__cstring,cstring_literals
827    //  -- the constant NSConstantString structure referencing that buffer
828    //     is placed into __DATA,__cfstring
829    // Therefore there's no point in placing redzones into __DATA,__cfstring.
830    // Moreover, it causes the linker to crash on OS X 10.7
831    if (Section.find("__DATA,__cfstring") == 0) {
832      DEBUG(dbgs() << "Ignoring CFString: " << *G);
833      return false;
834    }
835  }
836
837  return true;
838}
839
840void AddressSanitizerModule::initializeCallbacks(Module &M) {
841  IRBuilder<> IRB(*C);
842  // Declare our poisoning and unpoisoning functions.
843  AsanPoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
844      kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy, NULL));
845  AsanPoisonGlobals->setLinkage(Function::ExternalLinkage);
846  AsanUnpoisonGlobals = checkInterfaceFunction(M.getOrInsertFunction(
847      kAsanUnpoisonGlobalsName, IRB.getVoidTy(), NULL));
848  AsanUnpoisonGlobals->setLinkage(Function::ExternalLinkage);
849  // Declare functions that register/unregister globals.
850  AsanRegisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
851      kAsanRegisterGlobalsName, IRB.getVoidTy(),
852      IntptrTy, IntptrTy, NULL));
853  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);
854  AsanUnregisterGlobals = checkInterfaceFunction(M.getOrInsertFunction(
855      kAsanUnregisterGlobalsName,
856      IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
857  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);
858}
859
860// This function replaces all global variables with new variables that have
861// trailing redzones. It also creates a function that poisons
862// redzones and inserts this function into llvm.global_ctors.
863bool AddressSanitizerModule::runOnModule(Module &M) {
864  if (!ClGlobals) return false;
865  TD = getAnalysisIfAvailable<DataLayout>();
866  if (!TD)
867    return false;
868  BL.reset(new BlackList(BlacklistFile));
869  if (BL->isIn(M)) return false;
870  C = &(M.getContext());
871  int LongSize = TD->getPointerSizeInBits();
872  IntptrTy = Type::getIntNTy(*C, LongSize);
873  Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
874  initializeCallbacks(M);
875  DynamicallyInitializedGlobals.Init(M);
876
877  SmallVector<GlobalVariable *, 16> GlobalsToChange;
878
879  for (Module::GlobalListType::iterator G = M.global_begin(),
880       E = M.global_end(); G != E; ++G) {
881    if (ShouldInstrumentGlobal(G))
882      GlobalsToChange.push_back(G);
883  }
884
885  size_t n = GlobalsToChange.size();
886  if (n == 0) return false;
887
888  // A global is described by a structure
889  //   size_t beg;
890  //   size_t size;
891  //   size_t size_with_redzone;
892  //   const char *name;
893  //   const char *module_name;
894  //   size_t has_dynamic_init;
895  // We initialize an array of such structures and pass it to a run-time call.
896  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
897                                               IntptrTy, IntptrTy,
898                                               IntptrTy, IntptrTy, NULL);
899  SmallVector<Constant *, 16> Initializers(n), DynamicInit;
900
901
902  Function *CtorFunc = M.getFunction(kAsanModuleCtorName);
903  assert(CtorFunc);
904  IRBuilder<> IRB(CtorFunc->getEntryBlock().getTerminator());
905
906  bool HasDynamicallyInitializedGlobals = false;
907
908  GlobalVariable *ModuleName = createPrivateGlobalForString(
909      M, M.getModuleIdentifier());
910  // We shouldn't merge same module names, as this string serves as unique
911  // module ID in runtime.
912  ModuleName->setUnnamedAddr(false);
913
914  for (size_t i = 0; i < n; i++) {
915    static const uint64_t kMaxGlobalRedzone = 1 << 18;
916    GlobalVariable *G = GlobalsToChange[i];
917    PointerType *PtrTy = cast<PointerType>(G->getType());
918    Type *Ty = PtrTy->getElementType();
919    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
920    uint64_t MinRZ = RedzoneSize();
921    // MinRZ <= RZ <= kMaxGlobalRedzone
922    // and trying to make RZ to be ~ 1/4 of SizeInBytes.
923    uint64_t RZ = std::max(MinRZ,
924                         std::min(kMaxGlobalRedzone,
925                                  (SizeInBytes / MinRZ / 4) * MinRZ));
926    uint64_t RightRedzoneSize = RZ;
927    // Round up to MinRZ
928    if (SizeInBytes % MinRZ)
929      RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
930    assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
931    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
932    // Determine whether this global should be poisoned in initialization.
933    bool GlobalHasDynamicInitializer =
934        DynamicallyInitializedGlobals.Contains(G);
935    // Don't check initialization order if this global is blacklisted.
936    GlobalHasDynamicInitializer &= !BL->isInInit(*G);
937
938    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
939    Constant *NewInitializer = ConstantStruct::get(
940        NewTy, G->getInitializer(),
941        Constant::getNullValue(RightRedZoneTy), NULL);
942
943    GlobalVariable *Name = createPrivateGlobalForString(M, G->getName());
944
945    // Create a new global variable with enough space for a redzone.
946    GlobalVariable *NewGlobal = new GlobalVariable(
947        M, NewTy, G->isConstant(), G->getLinkage(),
948        NewInitializer, "", G, G->getThreadLocalMode());
949    NewGlobal->copyAttributesFrom(G);
950    NewGlobal->setAlignment(MinRZ);
951
952    Value *Indices2[2];
953    Indices2[0] = IRB.getInt32(0);
954    Indices2[1] = IRB.getInt32(0);
955
956    G->replaceAllUsesWith(
957        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
958    NewGlobal->takeName(G);
959    G->eraseFromParent();
960
961    Initializers[i] = ConstantStruct::get(
962        GlobalStructTy,
963        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
964        ConstantInt::get(IntptrTy, SizeInBytes),
965        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
966        ConstantExpr::getPointerCast(Name, IntptrTy),
967        ConstantExpr::getPointerCast(ModuleName, IntptrTy),
968        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
969        NULL);
970
971    // Populate the first and last globals declared in this TU.
972    if (CheckInitOrder && GlobalHasDynamicInitializer)
973      HasDynamicallyInitializedGlobals = true;
974
975    DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
976  }
977
978  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
979  GlobalVariable *AllGlobals = new GlobalVariable(
980      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
981      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");
982
983  // Create calls for poisoning before initializers run and unpoisoning after.
984  if (CheckInitOrder && HasDynamicallyInitializedGlobals)
985    createInitializerPoisonCalls(M, ModuleName);
986  IRB.CreateCall2(AsanRegisterGlobals,
987                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
988                  ConstantInt::get(IntptrTy, n));
989
990  // We also need to unregister globals at the end, e.g. when a shared library
991  // gets closed.
992  Function *AsanDtorFunction = Function::Create(
993      FunctionType::get(Type::getVoidTy(*C), false),
994      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
995  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
996  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
997  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
998                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
999                       ConstantInt::get(IntptrTy, n));
1000  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);
1001
1002  DEBUG(dbgs() << M);
1003  return true;
1004}
1005
1006void AddressSanitizer::initializeCallbacks(Module &M) {
1007  IRBuilder<> IRB(*C);
1008  // Create __asan_report* callbacks.
1009  for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
1010    for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
1011         AccessSizeIndex++) {
1012      // IsWrite and TypeSize are encoded in the function name.
1013      std::string FunctionName = std::string(kAsanReportErrorTemplate) +
1014          (AccessIsWrite ? "store" : "load") + itostr(1 << AccessSizeIndex);
1015      // If we are merging crash callbacks, they have two parameters.
1016      AsanErrorCallback[AccessIsWrite][AccessSizeIndex] =
1017          checkInterfaceFunction(M.getOrInsertFunction(
1018              FunctionName, IRB.getVoidTy(), IntptrTy, NULL));
1019    }
1020  }
1021  AsanErrorCallbackSized[0] = checkInterfaceFunction(M.getOrInsertFunction(
1022              kAsanReportLoadN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1023  AsanErrorCallbackSized[1] = checkInterfaceFunction(M.getOrInsertFunction(
1024              kAsanReportStoreN, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1025
1026  AsanHandleNoReturnFunc = checkInterfaceFunction(M.getOrInsertFunction(
1027      kAsanHandleNoReturnName, IRB.getVoidTy(), NULL));
1028  // We insert an empty inline asm after __asan_report* to avoid callback merge.
1029  EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
1030                            StringRef(""), StringRef(""),
1031                            /*hasSideEffects=*/true);
1032}
1033
1034void AddressSanitizer::emitShadowMapping(Module &M, IRBuilder<> &IRB) const {
1035  // Tell the values of mapping offset and scale to the run-time.
1036  GlobalValue *asan_mapping_offset =
1037      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1038                     ConstantInt::get(IntptrTy, Mapping.Offset),
1039                     kAsanMappingOffsetName);
1040  // Read the global, otherwise it may be optimized away.
1041  IRB.CreateLoad(asan_mapping_offset, true);
1042
1043  GlobalValue *asan_mapping_scale =
1044      new GlobalVariable(M, IntptrTy, true, GlobalValue::LinkOnceODRLinkage,
1045                         ConstantInt::get(IntptrTy, Mapping.Scale),
1046                         kAsanMappingScaleName);
1047  // Read the global, otherwise it may be optimized away.
1048  IRB.CreateLoad(asan_mapping_scale, true);
1049}
1050
1051// virtual
1052bool AddressSanitizer::doInitialization(Module &M) {
1053  // Initialize the private fields. No one has accessed them before.
1054  TD = getAnalysisIfAvailable<DataLayout>();
1055
1056  if (!TD)
1057    return false;
1058  BL.reset(new BlackList(BlacklistFile));
1059  DynamicallyInitializedGlobals.Init(M);
1060
1061  C = &(M.getContext());
1062  LongSize = TD->getPointerSizeInBits();
1063  IntptrTy = Type::getIntNTy(*C, LongSize);
1064
1065  AsanCtorFunction = Function::Create(
1066      FunctionType::get(Type::getVoidTy(*C), false),
1067      GlobalValue::InternalLinkage, kAsanModuleCtorName, &M);
1068  BasicBlock *AsanCtorBB = BasicBlock::Create(*C, "", AsanCtorFunction);
1069  // call __asan_init in the module ctor.
1070  IRBuilder<> IRB(ReturnInst::Create(*C, AsanCtorBB));
1071  AsanInitFunction = checkInterfaceFunction(
1072      M.getOrInsertFunction(kAsanInitName, IRB.getVoidTy(), NULL));
1073  AsanInitFunction->setLinkage(Function::ExternalLinkage);
1074  IRB.CreateCall(AsanInitFunction);
1075
1076  Mapping = getShadowMapping(M, LongSize, ZeroBaseShadow);
1077  emitShadowMapping(M, IRB);
1078
1079  appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndCtorPriority);
1080  return true;
1081}
1082
1083bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
1084  // For each NSObject descendant having a +load method, this method is invoked
1085  // by the ObjC runtime before any of the static constructors is called.
1086  // Therefore we need to instrument such methods with a call to __asan_init
1087  // at the beginning in order to initialize our runtime before any access to
1088  // the shadow memory.
1089  // We cannot just ignore these methods, because they may call other
1090  // instrumented functions.
1091  if (F.getName().find(" load]") != std::string::npos) {
1092    IRBuilder<> IRB(F.begin()->begin());
1093    IRB.CreateCall(AsanInitFunction);
1094    return true;
1095  }
1096  return false;
1097}
1098
1099bool AddressSanitizer::runOnFunction(Function &F) {
1100  if (BL->isIn(F)) return false;
1101  if (&F == AsanCtorFunction) return false;
1102  if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
1103  DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
1104  initializeCallbacks(*F.getParent());
1105
1106  // If needed, insert __asan_init before checking for SanitizeAddress attr.
1107  maybeInsertAsanInitAtFunctionEntry(F);
1108
1109  if (!F.getAttributes().hasAttribute(AttributeSet::FunctionIndex,
1110                                      Attribute::SanitizeAddress))
1111    return false;
1112
1113  if (!ClDebugFunc.empty() && ClDebugFunc != F.getName())
1114    return false;
1115
1116  // We want to instrument every address only once per basic block (unless there
1117  // are calls between uses).
1118  SmallSet<Value*, 16> TempsToInstrument;
1119  SmallVector<Instruction*, 16> ToInstrument;
1120  SmallVector<Instruction*, 8> NoReturnCalls;
1121  bool IsWrite;
1122
1123  // Fill the set of memory operations to instrument.
1124  for (Function::iterator FI = F.begin(), FE = F.end();
1125       FI != FE; ++FI) {
1126    TempsToInstrument.clear();
1127    int NumInsnsPerBB = 0;
1128    for (BasicBlock::iterator BI = FI->begin(), BE = FI->end();
1129         BI != BE; ++BI) {
1130      if (LooksLikeCodeInBug11395(BI)) return false;
1131      if (Value *Addr = isInterestingMemoryAccess(BI, &IsWrite)) {
1132        if (ClOpt && ClOptSameTemp) {
1133          if (!TempsToInstrument.insert(Addr))
1134            continue;  // We've seen this temp in the current BB.
1135        }
1136      } else if (isa<MemIntrinsic>(BI) && ClMemIntrin) {
1137        // ok, take it.
1138      } else {
1139        CallSite CS(BI);
1140        if (CS) {
1141          // A call inside BB.
1142          TempsToInstrument.clear();
1143          if (CS.doesNotReturn())
1144            NoReturnCalls.push_back(CS.getInstruction());
1145        }
1146        continue;
1147      }
1148      ToInstrument.push_back(BI);
1149      NumInsnsPerBB++;
1150      if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB)
1151        break;
1152    }
1153  }
1154
1155  // Instrument.
1156  int NumInstrumented = 0;
1157  for (size_t i = 0, n = ToInstrument.size(); i != n; i++) {
1158    Instruction *Inst = ToInstrument[i];
1159    if (ClDebugMin < 0 || ClDebugMax < 0 ||
1160        (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
1161      if (isInterestingMemoryAccess(Inst, &IsWrite))
1162        instrumentMop(Inst);
1163      else
1164        instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
1165    }
1166    NumInstrumented++;
1167  }
1168
1169  FunctionStackPoisoner FSP(F, *this);
1170  bool ChangedStack = FSP.runOnFunction();
1171
1172  // We must unpoison the stack before every NoReturn call (throw, _exit, etc).
1173  // See e.g. http://code.google.com/p/address-sanitizer/issues/detail?id=37
1174  for (size_t i = 0, n = NoReturnCalls.size(); i != n; i++) {
1175    Instruction *CI = NoReturnCalls[i];
1176    IRBuilder<> IRB(CI);
1177    IRB.CreateCall(AsanHandleNoReturnFunc);
1178  }
1179  DEBUG(dbgs() << "ASAN done instrumenting:\n" << F << "\n");
1180
1181  return NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty();
1182}
1183
1184static uint64_t ValueForPoison(uint64_t PoisonByte, size_t ShadowRedzoneSize) {
1185  if (ShadowRedzoneSize == 1) return PoisonByte;
1186  if (ShadowRedzoneSize == 2) return (PoisonByte << 8) + PoisonByte;
1187  if (ShadowRedzoneSize == 4)
1188    return (PoisonByte << 24) + (PoisonByte << 16) +
1189        (PoisonByte << 8) + (PoisonByte);
1190  llvm_unreachable("ShadowRedzoneSize is either 1, 2 or 4");
1191}
1192
1193static void PoisonShadowPartialRightRedzone(uint8_t *Shadow,
1194                                            size_t Size,
1195                                            size_t RZSize,
1196                                            size_t ShadowGranularity,
1197                                            uint8_t Magic) {
1198  for (size_t i = 0; i < RZSize;
1199       i+= ShadowGranularity, Shadow++) {
1200    if (i + ShadowGranularity <= Size) {
1201      *Shadow = 0;  // fully addressable
1202    } else if (i >= Size) {
1203      *Shadow = Magic;  // unaddressable
1204    } else {
1205      *Shadow = Size - i;  // first Size-i bytes are addressable
1206    }
1207  }
1208}
1209
1210// Workaround for bug 11395: we don't want to instrument stack in functions
1211// with large assembly blobs (32-bit only), otherwise reg alloc may crash.
1212// FIXME: remove once the bug 11395 is fixed.
1213bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
1214  if (LongSize != 32) return false;
1215  CallInst *CI = dyn_cast<CallInst>(I);
1216  if (!CI || !CI->isInlineAsm()) return false;
1217  if (CI->getNumArgOperands() <= 5) return false;
1218  // We have inline assembly with quite a few arguments.
1219  return true;
1220}
1221
1222void FunctionStackPoisoner::initializeCallbacks(Module &M) {
1223  IRBuilder<> IRB(*C);
1224  AsanStackMallocFunc = checkInterfaceFunction(M.getOrInsertFunction(
1225      kAsanStackMallocName, IntptrTy, IntptrTy, IntptrTy, NULL));
1226  AsanStackFreeFunc = checkInterfaceFunction(M.getOrInsertFunction(
1227      kAsanStackFreeName, IRB.getVoidTy(),
1228      IntptrTy, IntptrTy, IntptrTy, NULL));
1229  AsanPoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1230      kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1231  AsanUnpoisonStackMemoryFunc = checkInterfaceFunction(M.getOrInsertFunction(
1232      kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
1233}
1234
1235void FunctionStackPoisoner::poisonRedZones(
1236  const ArrayRef<AllocaInst*> &AllocaVec, IRBuilder<> IRB, Value *ShadowBase,
1237  bool DoPoison) {
1238  size_t ShadowRZSize = RedzoneSize() >> Mapping.Scale;
1239  assert(ShadowRZSize >= 1 && ShadowRZSize <= 4);
1240  Type *RZTy = Type::getIntNTy(*C, ShadowRZSize * 8);
1241  Type *RZPtrTy = PointerType::get(RZTy, 0);
1242
1243  Value *PoisonLeft  = ConstantInt::get(RZTy,
1244    ValueForPoison(DoPoison ? kAsanStackLeftRedzoneMagic : 0LL, ShadowRZSize));
1245  Value *PoisonMid   = ConstantInt::get(RZTy,
1246    ValueForPoison(DoPoison ? kAsanStackMidRedzoneMagic : 0LL, ShadowRZSize));
1247  Value *PoisonRight = ConstantInt::get(RZTy,
1248    ValueForPoison(DoPoison ? kAsanStackRightRedzoneMagic : 0LL, ShadowRZSize));
1249
1250  // poison the first red zone.
1251  IRB.CreateStore(PoisonLeft, IRB.CreateIntToPtr(ShadowBase, RZPtrTy));
1252
1253  // poison all other red zones.
1254  uint64_t Pos = RedzoneSize();
1255  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1256    AllocaInst *AI = AllocaVec[i];
1257    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1258    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1259    assert(AlignedSize - SizeInBytes < RedzoneSize());
1260    Value *Ptr = NULL;
1261
1262    Pos += AlignedSize;
1263
1264    assert(ShadowBase->getType() == IntptrTy);
1265    if (SizeInBytes < AlignedSize) {
1266      // Poison the partial redzone at right
1267      Ptr = IRB.CreateAdd(
1268          ShadowBase, ConstantInt::get(IntptrTy,
1269                                       (Pos >> Mapping.Scale) - ShadowRZSize));
1270      size_t AddressableBytes = RedzoneSize() - (AlignedSize - SizeInBytes);
1271      uint32_t Poison = 0;
1272      if (DoPoison) {
1273        PoisonShadowPartialRightRedzone((uint8_t*)&Poison, AddressableBytes,
1274                                        RedzoneSize(),
1275                                        1ULL << Mapping.Scale,
1276                                        kAsanStackPartialRedzoneMagic);
1277        Poison =
1278            ASan.TD->isLittleEndian()
1279                ? support::endian::byte_swap<uint32_t, support::little>(Poison)
1280                : support::endian::byte_swap<uint32_t, support::big>(Poison);
1281      }
1282      Value *PartialPoison = ConstantInt::get(RZTy, Poison);
1283      IRB.CreateStore(PartialPoison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1284    }
1285
1286    // Poison the full redzone at right.
1287    Ptr = IRB.CreateAdd(ShadowBase,
1288                        ConstantInt::get(IntptrTy, Pos >> Mapping.Scale));
1289    bool LastAlloca = (i == AllocaVec.size() - 1);
1290    Value *Poison = LastAlloca ? PoisonRight : PoisonMid;
1291    IRB.CreateStore(Poison, IRB.CreateIntToPtr(Ptr, RZPtrTy));
1292
1293    Pos += RedzoneSize();
1294  }
1295}
1296
1297void FunctionStackPoisoner::poisonStack() {
1298  uint64_t LocalStackSize = TotalStackSize +
1299                            (AllocaVec.size() + 1) * RedzoneSize();
1300
1301  bool DoStackMalloc = ASan.CheckUseAfterReturn
1302      && LocalStackSize <= kMaxStackMallocSize;
1303
1304  assert(AllocaVec.size() > 0);
1305  Instruction *InsBefore = AllocaVec[0];
1306  IRBuilder<> IRB(InsBefore);
1307
1308
1309  Type *ByteArrayTy = ArrayType::get(IRB.getInt8Ty(), LocalStackSize);
1310  AllocaInst *MyAlloca =
1311      new AllocaInst(ByteArrayTy, "MyAlloca", InsBefore);
1312  if (ClRealignStack && StackAlignment < RedzoneSize())
1313    StackAlignment = RedzoneSize();
1314  MyAlloca->setAlignment(StackAlignment);
1315  assert(MyAlloca->isStaticAlloca());
1316  Value *OrigStackBase = IRB.CreatePointerCast(MyAlloca, IntptrTy);
1317  Value *LocalStackBase = OrigStackBase;
1318
1319  if (DoStackMalloc) {
1320    LocalStackBase = IRB.CreateCall2(AsanStackMallocFunc,
1321        ConstantInt::get(IntptrTy, LocalStackSize), OrigStackBase);
1322  }
1323
1324  // This string will be parsed by the run-time (DescribeAddressIfStack).
1325  SmallString<2048> StackDescriptionStorage;
1326  raw_svector_ostream StackDescription(StackDescriptionStorage);
1327  StackDescription << AllocaVec.size() << " ";
1328
1329  // Insert poison calls for lifetime intrinsics for alloca.
1330  bool HavePoisonedAllocas = false;
1331  for (size_t i = 0, n = AllocaPoisonCallVec.size(); i < n; i++) {
1332    const AllocaPoisonCall &APC = AllocaPoisonCallVec[i];
1333    IntrinsicInst *II = APC.InsBefore;
1334    AllocaInst *AI = findAllocaForValue(II->getArgOperand(1));
1335    assert(AI);
1336    IRBuilder<> IRB(II);
1337    poisonAlloca(AI, APC.Size, IRB, APC.DoPoison);
1338    HavePoisonedAllocas |= APC.DoPoison;
1339  }
1340
1341  uint64_t Pos = RedzoneSize();
1342  // Replace Alloca instructions with base+offset.
1343  for (size_t i = 0, n = AllocaVec.size(); i < n; i++) {
1344    AllocaInst *AI = AllocaVec[i];
1345    uint64_t SizeInBytes = getAllocaSizeInBytes(AI);
1346    StringRef Name = AI->getName();
1347    StackDescription << Pos << " " << SizeInBytes << " "
1348                     << Name.size() << " " << Name << " ";
1349    uint64_t AlignedSize = getAlignedAllocaSize(AI);
1350    assert((AlignedSize % RedzoneSize()) == 0);
1351    Value *NewAllocaPtr = IRB.CreateIntToPtr(
1352            IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
1353            AI->getType());
1354    replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
1355    AI->replaceAllUsesWith(NewAllocaPtr);
1356    Pos += AlignedSize + RedzoneSize();
1357  }
1358  assert(Pos == LocalStackSize);
1359
1360  // The left-most redzone has enough space for at least 4 pointers.
1361  // Write the Magic value to redzone[0].
1362  Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
1363  IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
1364                  BasePlus0);
1365  // Write the frame description constant to redzone[1].
1366  Value *BasePlus1 = IRB.CreateIntToPtr(
1367    IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, ASan.LongSize/8)),
1368    IntptrPtrTy);
1369  GlobalVariable *StackDescriptionGlobal =
1370      createPrivateGlobalForString(*F.getParent(), StackDescription.str());
1371  Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal,
1372                                             IntptrTy);
1373  IRB.CreateStore(Description, BasePlus1);
1374  // Write the PC to redzone[2].
1375  Value *BasePlus2 = IRB.CreateIntToPtr(
1376    IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy,
1377                                                   2 * ASan.LongSize/8)),
1378    IntptrPtrTy);
1379  IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
1380
1381  // Poison the stack redzones at the entry.
1382  Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
1383  poisonRedZones(AllocaVec, IRB, ShadowBase, true);
1384
1385  // Unpoison the stack before all ret instructions.
1386  for (size_t i = 0, n = RetVec.size(); i < n; i++) {
1387    Instruction *Ret = RetVec[i];
1388    IRBuilder<> IRBRet(Ret);
1389    // Mark the current frame as retired.
1390    IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
1391                       BasePlus0);
1392    // Unpoison the stack.
1393    poisonRedZones(AllocaVec, IRBRet, ShadowBase, false);
1394    if (DoStackMalloc) {
1395      // In use-after-return mode, mark the whole stack frame unaddressable.
1396      IRBRet.CreateCall3(AsanStackFreeFunc, LocalStackBase,
1397                         ConstantInt::get(IntptrTy, LocalStackSize),
1398                         OrigStackBase);
1399    } else if (HavePoisonedAllocas) {
1400      // If we poisoned some allocas in llvm.lifetime analysis,
1401      // unpoison whole stack frame now.
1402      assert(LocalStackBase == OrigStackBase);
1403      poisonAlloca(LocalStackBase, LocalStackSize, IRBRet, false);
1404    }
1405  }
1406
1407  // We are done. Remove the old unused alloca instructions.
1408  for (size_t i = 0, n = AllocaVec.size(); i < n; i++)
1409    AllocaVec[i]->eraseFromParent();
1410}
1411
1412void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
1413                                         IRBuilder<> IRB, bool DoPoison) {
1414  // For now just insert the call to ASan runtime.
1415  Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
1416  Value *SizeArg = ConstantInt::get(IntptrTy, Size);
1417  IRB.CreateCall2(DoPoison ? AsanPoisonStackMemoryFunc
1418                           : AsanUnpoisonStackMemoryFunc,
1419                  AddrArg, SizeArg);
1420}
1421
1422// Handling llvm.lifetime intrinsics for a given %alloca:
1423// (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
1424// (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
1425//     invalid accesses) and unpoison it for llvm.lifetime.start (the memory
1426//     could be poisoned by previous llvm.lifetime.end instruction, as the
1427//     variable may go in and out of scope several times, e.g. in loops).
1428// (3) if we poisoned at least one %alloca in a function,
1429//     unpoison the whole stack frame at function exit.
1430
1431AllocaInst *FunctionStackPoisoner::findAllocaForValue(Value *V) {
1432  if (AllocaInst *AI = dyn_cast<AllocaInst>(V))
1433    // We're intested only in allocas we can handle.
1434    return isInterestingAlloca(*AI) ? AI : 0;
1435  // See if we've already calculated (or started to calculate) alloca for a
1436  // given value.
1437  AllocaForValueMapTy::iterator I = AllocaForValue.find(V);
1438  if (I != AllocaForValue.end())
1439    return I->second;
1440  // Store 0 while we're calculating alloca for value V to avoid
1441  // infinite recursion if the value references itself.
1442  AllocaForValue[V] = 0;
1443  AllocaInst *Res = 0;
1444  if (CastInst *CI = dyn_cast<CastInst>(V))
1445    Res = findAllocaForValue(CI->getOperand(0));
1446  else if (PHINode *PN = dyn_cast<PHINode>(V)) {
1447    for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i) {
1448      Value *IncValue = PN->getIncomingValue(i);
1449      // Allow self-referencing phi-nodes.
1450      if (IncValue == PN) continue;
1451      AllocaInst *IncValueAI = findAllocaForValue(IncValue);
1452      // AI for incoming values should exist and should all be equal.
1453      if (IncValueAI == 0 || (Res != 0 && IncValueAI != Res))
1454        return 0;
1455      Res = IncValueAI;
1456    }
1457  }
1458  if (Res != 0)
1459    AllocaForValue[V] = Res;
1460  return Res;
1461}
1462