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llvm-project/compiler-rt/lib/fuzzer/FuzzerMutate.cpp

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//===- FuzzerMutate.cpp - Mutate a test input -----------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// Mutate a test input.
//===----------------------------------------------------------------------===//
#include "FuzzerDefs.h"
#include "FuzzerExtFunctions.h"
#include "FuzzerIO.h"
#include "FuzzerMutate.h"
#include "FuzzerOptions.h"
#include "FuzzerTracePC.h"
namespace fuzzer {
const size_t Dictionary::kMaxDictSize;
static void PrintASCII(const Word &W, const char *PrintAfter) {
PrintASCII(W.data(), W.size(), PrintAfter);
}
MutationDispatcher::MutationDispatcher(Random &Rand,
const FuzzingOptions &Options)
: Rand(Rand), Options(Options) {
DefaultMutators.insert(
DefaultMutators.begin(),
{
{&MutationDispatcher::Mutate_EraseBytes, "EraseBytes"},
{&MutationDispatcher::Mutate_InsertByte, "InsertByte"},
{&MutationDispatcher::Mutate_InsertRepeatedBytes,
"InsertRepeatedBytes"},
{&MutationDispatcher::Mutate_ChangeByte, "ChangeByte"},
{&MutationDispatcher::Mutate_ChangeBit, "ChangeBit"},
{&MutationDispatcher::Mutate_ShuffleBytes, "ShuffleBytes"},
{&MutationDispatcher::Mutate_ChangeASCIIInteger, "ChangeASCIIInt"},
{&MutationDispatcher::Mutate_ChangeBinaryInteger, "ChangeBinInt"},
{&MutationDispatcher::Mutate_CopyPart, "CopyPart"},
{&MutationDispatcher::Mutate_CrossOver, "CrossOver"},
{&MutationDispatcher::Mutate_AddWordFromManualDictionary,
"ManualDict"},
{&MutationDispatcher::Mutate_AddWordFromPersistentAutoDictionary,
"PersAutoDict"},
});
if(Options.UseCmp)
DefaultMutators.push_back(
{&MutationDispatcher::Mutate_AddWordFromTORC, "CMP"});
if (EF->LLVMFuzzerCustomMutator)
Mutators.push_back({&MutationDispatcher::Mutate_Custom, "Custom"});
else
Mutators = DefaultMutators;
if (EF->LLVMFuzzerCustomCrossOver)
Mutators.push_back(
{&MutationDispatcher::Mutate_CustomCrossOver, "CustomCrossOver"});
}
static char RandCh(Random &Rand) {
if (Rand.RandBool()) return Rand(256);
const char Special[] = "!*'();:@&=+$,/?%#[]012Az-`~.\xff\x00";
return Special[Rand(sizeof(Special) - 1)];
}
size_t MutationDispatcher::Mutate_Custom(uint8_t *Data, size_t Size,
size_t MaxSize) {
return EF->LLVMFuzzerCustomMutator(Data, Size, MaxSize, Rand.Rand());
}
size_t MutationDispatcher::Mutate_CustomCrossOver(uint8_t *Data, size_t Size,
size_t MaxSize) {
if (Size == 0)
return 0;
if (!CrossOverWith) return 0;
const Unit &Other = *CrossOverWith;
if (Other.empty())
return 0;
CustomCrossOverInPlaceHere.resize(MaxSize);
auto &U = CustomCrossOverInPlaceHere;
size_t NewSize = EF->LLVMFuzzerCustomCrossOver(
Data, Size, Other.data(), Other.size(), U.data(), U.size(), Rand.Rand());
if (!NewSize)
return 0;
assert(NewSize <= MaxSize && "CustomCrossOver returned overisized unit");
memcpy(Data, U.data(), NewSize);
return NewSize;
}
size_t MutationDispatcher::Mutate_ShuffleBytes(uint8_t *Data, size_t Size,
size_t MaxSize) {
if (Size > MaxSize || Size == 0) return 0;
size_t ShuffleAmount =
Rand(std::min(Size, (size_t)8)) + 1; // [1,8] and <= Size.
size_t ShuffleStart = Rand(Size - ShuffleAmount);
assert(ShuffleStart + ShuffleAmount <= Size);
std::shuffle(Data + ShuffleStart, Data + ShuffleStart + ShuffleAmount, Rand);
return Size;
}
size_t MutationDispatcher::Mutate_EraseBytes(uint8_t *Data, size_t Size,
size_t MaxSize) {
if (Size <= 1) return 0;
size_t N = Rand(Size / 2) + 1;
assert(N < Size);
size_t Idx = Rand(Size - N + 1);
// Erase Data[Idx:Idx+N].
memmove(Data + Idx, Data + Idx + N, Size - Idx - N);
// Printf("Erase: %zd %zd => %zd; Idx %zd\n", N, Size, Size - N, Idx);
return Size - N;
}
size_t MutationDispatcher::Mutate_InsertByte(uint8_t *Data, size_t Size,
size_t MaxSize) {
if (Size >= MaxSize) return 0;
size_t Idx = Rand(Size + 1);
// Insert new value at Data[Idx].
memmove(Data + Idx + 1, Data + Idx, Size - Idx);
Data[Idx] = RandCh(Rand);
return Size + 1;
}
size_t MutationDispatcher::Mutate_InsertRepeatedBytes(uint8_t *Data,
size_t Size,
size_t MaxSize) {
const size_t kMinBytesToInsert = 3;
if (Size + kMinBytesToInsert >= MaxSize) return 0;
size_t MaxBytesToInsert = std::min(MaxSize - Size, (size_t)128);
size_t N = Rand(MaxBytesToInsert - kMinBytesToInsert + 1) + kMinBytesToInsert;
assert(Size + N <= MaxSize && N);
size_t Idx = Rand(Size + 1);
// Insert new values at Data[Idx].
memmove(Data + Idx + N, Data + Idx, Size - Idx);
// Give preference to 0x00 and 0xff.
uint8_t Byte = Rand.RandBool() ? Rand(256) : (Rand.RandBool() ? 0 : 255);
for (size_t i = 0; i < N; i++)
Data[Idx + i] = Byte;
return Size + N;
}
size_t MutationDispatcher::Mutate_ChangeByte(uint8_t *Data, size_t Size,
size_t MaxSize) {
if (Size > MaxSize) return 0;
size_t Idx = Rand(Size);
Data[Idx] = RandCh(Rand);
return Size;
}
size_t MutationDispatcher::Mutate_ChangeBit(uint8_t *Data, size_t Size,
size_t MaxSize) {
if (Size > MaxSize) return 0;
size_t Idx = Rand(Size);
Data[Idx] ^= 1 << Rand(8);
return Size;
}
size_t MutationDispatcher::Mutate_AddWordFromManualDictionary(uint8_t *Data,
size_t Size,
size_t MaxSize) {
return AddWordFromDictionary(ManualDictionary, Data, Size, MaxSize);
}
size_t MutationDispatcher::ApplyDictionaryEntry(uint8_t *Data, size_t Size,
size_t MaxSize,
DictionaryEntry &DE) {
const Word &W = DE.GetW();
bool UsePositionHint = DE.HasPositionHint() &&
DE.GetPositionHint() + W.size() < Size &&
Rand.RandBool();
if (Rand.RandBool()) { // Insert W.
if (Size + W.size() > MaxSize) return 0;
size_t Idx = UsePositionHint ? DE.GetPositionHint() : Rand(Size + 1);
memmove(Data + Idx + W.size(), Data + Idx, Size - Idx);
memcpy(Data + Idx, W.data(), W.size());
Size += W.size();
} else { // Overwrite some bytes with W.
if (W.size() > Size) return 0;
size_t Idx = UsePositionHint ? DE.GetPositionHint() : Rand(Size - W.size());
memcpy(Data + Idx, W.data(), W.size());
}
return Size;
}
// Somewhere in the past we have observed a comparison instructions
// with arguments Arg1 Arg2. This function tries to guess a dictionary
// entry that will satisfy that comparison.
// It first tries to find one of the arguments (possibly swapped) in the
// input and if it succeeds it creates a DE with a position hint.
// Otherwise it creates a DE with one of the arguments w/o a position hint.
DictionaryEntry MutationDispatcher::MakeDictionaryEntryFromCMP(
const void *Arg1, const void *Arg2,
const void *Arg1Mutation, const void *Arg2Mutation,
size_t ArgSize, const uint8_t *Data,
size_t Size) {
bool HandleFirst = Rand.RandBool();
const void *ExistingBytes, *DesiredBytes;
Word W;
const uint8_t *End = Data + Size;
for (int Arg = 0; Arg < 2; Arg++) {
ExistingBytes = HandleFirst ? Arg1 : Arg2;
DesiredBytes = HandleFirst ? Arg2Mutation : Arg1Mutation;
HandleFirst = !HandleFirst;
W.Set(reinterpret_cast<const uint8_t*>(DesiredBytes), ArgSize);
const size_t kMaxNumPositions = 8;
size_t Positions[kMaxNumPositions];
size_t NumPositions = 0;
for (const uint8_t *Cur = Data;
Cur < End && NumPositions < kMaxNumPositions; Cur++) {
Cur =
(const uint8_t *)SearchMemory(Cur, End - Cur, ExistingBytes, ArgSize);
if (!Cur) break;
Positions[NumPositions++] = Cur - Data;
}
if (!NumPositions) continue;
return DictionaryEntry(W, Positions[Rand(NumPositions)]);
}
DictionaryEntry DE(W);
return DE;
}
template <class T>
DictionaryEntry MutationDispatcher::MakeDictionaryEntryFromCMP(
T Arg1, T Arg2, const uint8_t *Data, size_t Size) {
if (Rand.RandBool()) Arg1 = Bswap(Arg1);
if (Rand.RandBool()) Arg2 = Bswap(Arg2);
T Arg1Mutation = Arg1 + Rand(-1, 1);
T Arg2Mutation = Arg2 + Rand(-1, 1);
return MakeDictionaryEntryFromCMP(&Arg1, &Arg2, &Arg1Mutation, &Arg2Mutation,
sizeof(Arg1), Data, Size);
}
DictionaryEntry MutationDispatcher::MakeDictionaryEntryFromCMP(
const Word &Arg1, const Word &Arg2, const uint8_t *Data, size_t Size) {
return MakeDictionaryEntryFromCMP(Arg1.data(), Arg2.data(), Arg1.data(),
Arg2.data(), Arg1.size(), Data, Size);
}
size_t MutationDispatcher::Mutate_AddWordFromTORC(
uint8_t *Data, size_t Size, size_t MaxSize) {
Word W;
DictionaryEntry DE;
switch (Rand(4)) {
case 0: {
auto X = TPC.TORC8.Get(Rand.Rand());
DE = MakeDictionaryEntryFromCMP(X.A, X.B, Data, Size);
} break;
case 1: {
auto X = TPC.TORC4.Get(Rand.Rand());
if ((X.A >> 16) == 0 && (X.B >> 16) == 0 && Rand.RandBool())
DE = MakeDictionaryEntryFromCMP((uint16_t)X.A, (uint16_t)X.B, Data, Size);
else
DE = MakeDictionaryEntryFromCMP(X.A, X.B, Data, Size);
} break;
case 2: {
auto X = TPC.TORCW.Get(Rand.Rand());
DE = MakeDictionaryEntryFromCMP(X.A, X.B, Data, Size);
} break;
case 3: if (Options.UseMemmem) {
auto X = TPC.MMT.Get(Rand.Rand());
DE = DictionaryEntry(X);
} break;
default:
assert(0);
}
if (!DE.GetW().size()) return 0;
Size = ApplyDictionaryEntry(Data, Size, MaxSize, DE);
if (!Size) return 0;
DictionaryEntry &DERef =
CmpDictionaryEntriesDeque[CmpDictionaryEntriesDequeIdx++ %
kCmpDictionaryEntriesDequeSize];
DERef = DE;
CurrentDictionaryEntrySequence.push_back(&DERef);
return Size;
}
size_t MutationDispatcher::Mutate_AddWordFromPersistentAutoDictionary(
uint8_t *Data, size_t Size, size_t MaxSize) {
return AddWordFromDictionary(PersistentAutoDictionary, Data, Size, MaxSize);
}
size_t MutationDispatcher::AddWordFromDictionary(Dictionary &D, uint8_t *Data,
size_t Size, size_t MaxSize) {
if (Size > MaxSize) return 0;
if (D.empty()) return 0;
DictionaryEntry &DE = D[Rand(D.size())];
Size = ApplyDictionaryEntry(Data, Size, MaxSize, DE);
if (!Size) return 0;
DE.IncUseCount();
CurrentDictionaryEntrySequence.push_back(&DE);
return Size;
}
// Overwrites part of To[0,ToSize) with a part of From[0,FromSize).
// Returns ToSize.
size_t MutationDispatcher::CopyPartOf(const uint8_t *From, size_t FromSize,
uint8_t *To, size_t ToSize) {
// Copy From[FromBeg, FromBeg + CopySize) into To[ToBeg, ToBeg + CopySize).
size_t ToBeg = Rand(ToSize);
size_t CopySize = Rand(ToSize - ToBeg) + 1;
assert(ToBeg + CopySize <= ToSize);
CopySize = std::min(CopySize, FromSize);
size_t FromBeg = Rand(FromSize - CopySize + 1);
assert(FromBeg + CopySize <= FromSize);
memmove(To + ToBeg, From + FromBeg, CopySize);
return ToSize;
}
// Inserts part of From[0,ToSize) into To.
// Returns new size of To on success or 0 on failure.
size_t MutationDispatcher::InsertPartOf(const uint8_t *From, size_t FromSize,
uint8_t *To, size_t ToSize,
size_t MaxToSize) {
if (ToSize >= MaxToSize) return 0;
size_t AvailableSpace = MaxToSize - ToSize;
size_t MaxCopySize = std::min(AvailableSpace, FromSize);
size_t CopySize = Rand(MaxCopySize) + 1;
size_t FromBeg = Rand(FromSize - CopySize + 1);
assert(FromBeg + CopySize <= FromSize);
size_t ToInsertPos = Rand(ToSize + 1);
assert(ToInsertPos + CopySize <= MaxToSize);
size_t TailSize = ToSize - ToInsertPos;
if (To == From) {
MutateInPlaceHere.resize(MaxToSize);
memcpy(MutateInPlaceHere.data(), From + FromBeg, CopySize);
memmove(To + ToInsertPos + CopySize, To + ToInsertPos, TailSize);
memmove(To + ToInsertPos, MutateInPlaceHere.data(), CopySize);
} else {
memmove(To + ToInsertPos + CopySize, To + ToInsertPos, TailSize);
memmove(To + ToInsertPos, From + FromBeg, CopySize);
}
return ToSize + CopySize;
}
size_t MutationDispatcher::Mutate_CopyPart(uint8_t *Data, size_t Size,
size_t MaxSize) {
if (Size > MaxSize || Size == 0) return 0;
// If Size == MaxSize, `InsertPartOf(...)` will
// fail so there's no point using it in this case.
if (Size == MaxSize || Rand.RandBool())
return CopyPartOf(Data, Size, Data, Size);
else
return InsertPartOf(Data, Size, Data, Size, MaxSize);
}
size_t MutationDispatcher::Mutate_ChangeASCIIInteger(uint8_t *Data, size_t Size,
size_t MaxSize) {
if (Size > MaxSize) return 0;
size_t B = Rand(Size);
while (B < Size && !isdigit(Data[B])) B++;
if (B == Size) return 0;
size_t E = B;
while (E < Size && isdigit(Data[E])) E++;
assert(B < E);
// now we have digits in [B, E).
// strtol and friends don't accept non-zero-teminated data, parse it manually.
uint64_t Val = Data[B] - '0';
for (size_t i = B + 1; i < E; i++)
Val = Val * 10 + Data[i] - '0';
// Mutate the integer value.
switch(Rand(5)) {
case 0: Val++; break;
case 1: Val--; break;
case 2: Val /= 2; break;
case 3: Val *= 2; break;
case 4: Val = Rand(Val * Val); break;
default: assert(0);
}
// Just replace the bytes with the new ones, don't bother moving bytes.
for (size_t i = B; i < E; i++) {
size_t Idx = E + B - i - 1;
assert(Idx >= B && Idx < E);
Data[Idx] = (Val % 10) + '0';
Val /= 10;
}
return Size;
}
template<class T>
size_t ChangeBinaryInteger(uint8_t *Data, size_t Size, Random &Rand) {
if (Size < sizeof(T)) return 0;
size_t Off = Rand(Size - sizeof(T) + 1);
assert(Off + sizeof(T) <= Size);
T Val;
if (Off < 64 && !Rand(4)) {
Val = Size;
if (Rand.RandBool())
Val = Bswap(Val);
} else {
memcpy(&Val, Data + Off, sizeof(Val));
T Add = Rand(21);
Add -= 10;
if (Rand.RandBool())
Val = Bswap(T(Bswap(Val) + Add)); // Add assuming different endiannes.
else
Val = Val + Add; // Add assuming current endiannes.
if (Add == 0 || Rand.RandBool()) // Maybe negate.
Val = -Val;
}
memcpy(Data + Off, &Val, sizeof(Val));
return Size;
}
size_t MutationDispatcher::Mutate_ChangeBinaryInteger(uint8_t *Data,
size_t Size,
size_t MaxSize) {
if (Size > MaxSize) return 0;
switch (Rand(4)) {
case 3: return ChangeBinaryInteger<uint64_t>(Data, Size, Rand);
case 2: return ChangeBinaryInteger<uint32_t>(Data, Size, Rand);
case 1: return ChangeBinaryInteger<uint16_t>(Data, Size, Rand);
case 0: return ChangeBinaryInteger<uint8_t>(Data, Size, Rand);
default: assert(0);
}
return 0;
}
size_t MutationDispatcher::Mutate_CrossOver(uint8_t *Data, size_t Size,
size_t MaxSize) {
if (Size > MaxSize) return 0;
if (Size == 0) return 0;
if (!CrossOverWith) return 0;
const Unit &O = *CrossOverWith;
if (O.empty()) return 0;
MutateInPlaceHere.resize(MaxSize);
auto &U = MutateInPlaceHere;
size_t NewSize = 0;
switch(Rand(3)) {
case 0:
NewSize = CrossOver(Data, Size, O.data(), O.size(), U.data(), U.size());
break;
case 1:
NewSize = InsertPartOf(O.data(), O.size(), U.data(), U.size(), MaxSize);
if (!NewSize)
NewSize = CopyPartOf(O.data(), O.size(), U.data(), U.size());
break;
case 2:
NewSize = CopyPartOf(O.data(), O.size(), U.data(), U.size());
break;
default: assert(0);
}
assert(NewSize > 0 && "CrossOver returned empty unit");
assert(NewSize <= MaxSize && "CrossOver returned overisized unit");
memcpy(Data, U.data(), NewSize);
return NewSize;
}
void MutationDispatcher::StartMutationSequence() {
CurrentMutatorSequence.clear();
CurrentDictionaryEntrySequence.clear();
}
// Copy successful dictionary entries to PersistentAutoDictionary.
void MutationDispatcher::RecordSuccessfulMutationSequence() {
for (auto DE : CurrentDictionaryEntrySequence) {
// PersistentAutoDictionary.AddWithSuccessCountOne(DE);
DE->IncSuccessCount();
assert(DE->GetW().size());
// Linear search is fine here as this happens seldom.
if (!PersistentAutoDictionary.ContainsWord(DE->GetW()))
PersistentAutoDictionary.push_back({DE->GetW(), 1});
}
}
void MutationDispatcher::PrintRecommendedDictionary() {
Vector<DictionaryEntry> V;
for (auto &DE : PersistentAutoDictionary)
if (!ManualDictionary.ContainsWord(DE.GetW()))
V.push_back(DE);
if (V.empty()) return;
Printf("###### Recommended dictionary. ######\n");
for (auto &DE: V) {
assert(DE.GetW().size());
Printf("\"");
PrintASCII(DE.GetW(), "\"");
Printf(" # Uses: %zd\n", DE.GetUseCount());
}
Printf("###### End of recommended dictionary. ######\n");
}
void MutationDispatcher::PrintMutationSequence() {
Printf("MS: %zd ", CurrentMutatorSequence.size());
for (auto M : CurrentMutatorSequence)
Printf("%s-", M.Name);
if (!CurrentDictionaryEntrySequence.empty()) {
Printf(" DE: ");
for (auto DE : CurrentDictionaryEntrySequence) {
Printf("\"");
PrintASCII(DE->GetW(), "\"-");
}
}
}
size_t MutationDispatcher::Mutate(uint8_t *Data, size_t Size, size_t MaxSize) {
return MutateImpl(Data, Size, MaxSize, Mutators);
}
size_t MutationDispatcher::DefaultMutate(uint8_t *Data, size_t Size,
size_t MaxSize) {
return MutateImpl(Data, Size, MaxSize, DefaultMutators);
}
// Mutates Data in place, returns new size.
size_t MutationDispatcher::MutateImpl(uint8_t *Data, size_t Size,
size_t MaxSize,
Vector<Mutator> &Mutators) {
assert(MaxSize > 0);
// Some mutations may fail (e.g. can't insert more bytes if Size == MaxSize),
// in which case they will return 0.
// Try several times before returning un-mutated data.
for (int Iter = 0; Iter < 100; Iter++) {
auto M = Mutators[Rand(Mutators.size())];
size_t NewSize = (this->*(M.Fn))(Data, Size, MaxSize);
if (NewSize && NewSize <= MaxSize) {
if (Options.OnlyASCII)
ToASCII(Data, NewSize);
CurrentMutatorSequence.push_back(M);
return NewSize;
}
}
*Data = ' ';
return 1; // Fallback, should not happen frequently.
}
// Mask represents the set of Data bytes that are worth mutating.
size_t MutationDispatcher::MutateWithMask(uint8_t *Data, size_t Size,
size_t MaxSize,
const Vector<uint8_t> &Mask) {
size_t MaskedSize = std::min(Size, Mask.size());
// * Copy the worthy bytes into a temporary array T
// * Mutate T
// * Copy T back.
// This is totally unoptimized.
auto &T = MutateWithMaskTemp;
if (T.size() < Size)
T.resize(Size);
size_t OneBits = 0;
for (size_t I = 0; I < MaskedSize; I++)
if (Mask[I])
T[OneBits++] = Data[I];
if (!OneBits) return 0;
assert(!T.empty());
size_t NewSize = Mutate(T.data(), OneBits, OneBits);
assert(NewSize <= OneBits);
(void)NewSize;
// Even if NewSize < OneBits we still use all OneBits bytes.
for (size_t I = 0, J = 0; I < MaskedSize; I++)
if (Mask[I])
Data[I] = T[J++];
return Size;
}
void MutationDispatcher::AddWordToManualDictionary(const Word &W) {
ManualDictionary.push_back(
{W, std::numeric_limits<size_t>::max()});
}
} // namespace fuzzer
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