1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
|
//===- FuzzerMutate.cpp - Mutate a test input -----------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// Mutate a test input.
//===----------------------------------------------------------------------===//
#include <cstring>
#include "FuzzerInternal.h"
#include <algorithm>
namespace fuzzer {
typedef size_t (MutationDispatcher::*Mutator)(uint8_t *Data, size_t Size,
size_t Max);
struct MutationDispatcher::Impl {
std::vector<Unit> Dictionary;
std::vector<Mutator> Mutators;
Impl() {
Mutators.push_back(&MutationDispatcher::Mutate_EraseByte);
Mutators.push_back(&MutationDispatcher::Mutate_InsertByte);
Mutators.push_back(&MutationDispatcher::Mutate_ChangeByte);
Mutators.push_back(&MutationDispatcher::Mutate_ChangeBit);
Mutators.push_back(&MutationDispatcher::Mutate_ShuffleBytes);
Mutators.push_back(&MutationDispatcher::Mutate_ChangeASCIIInteger);
}
void AddWordToDictionary(const uint8_t *Word, size_t Size) {
if (Dictionary.empty()) {
Mutators.push_back(&MutationDispatcher::Mutate_AddWordFromDictionary);
}
Dictionary.push_back(Unit(Word, Word + Size));
}
};
static char FlipRandomBit(char X, FuzzerRandomBase &Rand) {
int Bit = Rand(8);
char Mask = 1 << Bit;
char R;
if (X & (1 << Bit))
R = X & ~Mask;
else
R = X | Mask;
assert(R != X);
return R;
}
static char RandCh(FuzzerRandomBase &Rand) {
if (Rand.RandBool()) return Rand(256);
const char *Special = "!*'();:@&=+$,/?%#[]123ABCxyz-`~.";
return Special[Rand(sizeof(Special) - 1)];
}
size_t MutationDispatcher::Mutate_ShuffleBytes(uint8_t *Data, size_t Size,
size_t MaxSize) {
assert(Size);
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::random_shuffle(Data + ShuffleStart, Data + ShuffleStart + ShuffleAmount,
Rand);
return Size;
}
size_t MutationDispatcher::Mutate_EraseByte(uint8_t *Data, size_t Size,
size_t MaxSize) {
assert(Size);
if (Size == 1) return 0;
size_t Idx = Rand(Size);
// Erase Data[Idx].
memmove(Data + Idx, Data + Idx + 1, Size - Idx - 1);
return Size - 1;
}
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_ChangeByte(uint8_t *Data, size_t Size,
size_t MaxSize) {
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) {
size_t Idx = Rand(Size);
Data[Idx] = FlipRandomBit(Data[Idx], Rand);
return Size;
}
size_t MutationDispatcher::Mutate_AddWordFromDictionary(uint8_t *Data,
size_t Size,
size_t MaxSize) {
auto &D = MDImpl->Dictionary;
assert(!D.empty());
if (D.empty()) return 0;
const Unit &Word = D[Rand(D.size())];
if (Size + Word.size() > MaxSize) return 0;
size_t Idx = Rand(Size + 1);
memmove(Data + Idx + Word.size(), Data + Idx, Size - Idx);
memcpy(Data + Idx, Word.data(), Word.size());
return Size + Word.size();
}
size_t MutationDispatcher::Mutate_ChangeASCIIInteger(uint8_t *Data, size_t Size,
size_t MaxSize) {
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;
}
// Mutates Data in place, returns new size.
size_t MutationDispatcher::Mutate(uint8_t *Data, size_t Size, size_t MaxSize) {
assert(MaxSize > 0);
assert(Size <= MaxSize);
if (Size == 0) {
for (size_t i = 0; i < MaxSize; i++)
Data[i] = RandCh(Rand);
return MaxSize;
}
assert(Size > 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 < 10; Iter++) {
size_t MutatorIdx = Rand(MDImpl->Mutators.size());
size_t NewSize =
(this->*(MDImpl->Mutators[MutatorIdx]))(Data, Size, MaxSize);
if (NewSize) return NewSize;
}
return Size;
}
void MutationDispatcher::AddWordToDictionary(const uint8_t *Word, size_t Size) {
MDImpl->AddWordToDictionary(Word, Size);
}
MutationDispatcher::MutationDispatcher(FuzzerRandomBase &Rand) : Rand(Rand) {
MDImpl = new Impl;
}
MutationDispatcher::~MutationDispatcher() { delete MDImpl; }
} // namespace fuzzer
|
