AFLplusplus/examples/custom_mutators/custom_mutator_helpers.h
2020-03-27 11:06:06 +01:00

272 lines
5.1 KiB
C

#ifndef CUSTOM_MUTATOR_HELPERS
#define CUSTOM_MUTATOR_HELPERS
#include "config.h"
#include "types.h"
#include <stdlib.h>
#define RAND_BELOW(limit) (rand() % (limit))
typedef struct {
} afl_t;
static void surgical_havoc_mutate(u8 *out_buf, s32 begin, s32 end) {
static s8 interesting_8[] = {INTERESTING_8};
static s16 interesting_16[] = {INTERESTING_8, INTERESTING_16};
static s32 interesting_32[] = {INTERESTING_8, INTERESTING_16, INTERESTING_32};
switch (RAND_BELOW(12)) {
case 0: {
/* Flip a single bit somewhere. Spooky! */
s32 bit_idx = ((RAND_BELOW(end - begin) + begin) << 3) + RAND_BELOW(8);
out_buf[bit_idx >> 3] ^= 128 >> (bit_idx & 7);
break;
}
case 1: {
/* Set byte to interesting value. */
u8 val = interesting_8[RAND_BELOW(sizeof(interesting_8))];
out_buf[(RAND_BELOW(end - begin) + begin)] = val;
break;
}
case 2: {
/* Set word to interesting value, randomly choosing endian. */
if (end - begin < 2) break;
s32 byte_idx = (RAND_BELOW(end - begin) + begin);
if (byte_idx >= end - 1) break;
switch (RAND_BELOW(2)) {
case 0:
*(u16 *)(out_buf + byte_idx) =
interesting_16[RAND_BELOW(sizeof(interesting_16) >> 1)];
break;
case 1:
*(u16 *)(out_buf + byte_idx) =
SWAP16(interesting_16[RAND_BELOW(sizeof(interesting_16) >> 1)]);
break;
}
break;
}
case 3: {
/* Set dword to interesting value, randomly choosing endian. */
if (end - begin < 4) break;
s32 byte_idx = (RAND_BELOW(end - begin) + begin);
if (byte_idx >= end - 3) break;
switch (RAND_BELOW(2)) {
case 0:
*(u32 *)(out_buf + byte_idx) =
interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)];
break;
case 1:
*(u32 *)(out_buf + byte_idx) =
SWAP32(interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)]);
break;
}
break;
}
case 4: {
/* Set qword to interesting value, randomly choosing endian. */
if (end - begin < 8) break;
s32 byte_idx = (RAND_BELOW(end - begin) + begin);
if (byte_idx >= end - 7) break;
switch (RAND_BELOW(2)) {
case 0:
*(u64 *)(out_buf + byte_idx) =
(s64)interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)];
break;
case 1:
*(u64 *)(out_buf + byte_idx) = SWAP64(
(s64)interesting_32[RAND_BELOW(sizeof(interesting_32) >> 2)]);
break;
}
break;
}
case 5: {
/* Randomly subtract from byte. */
out_buf[(RAND_BELOW(end - begin) + begin)] -= 1 + RAND_BELOW(ARITH_MAX);
break;
}
case 6: {
/* Randomly add to byte. */
out_buf[(RAND_BELOW(end - begin) + begin)] += 1 + RAND_BELOW(ARITH_MAX);
break;
}
case 7: {
/* Randomly subtract from word, random endian. */
if (end - begin < 2) break;
s32 byte_idx = (RAND_BELOW(end - begin) + begin);
if (byte_idx >= end - 1) break;
if (RAND_BELOW(2)) {
*(u16 *)(out_buf + byte_idx) -= 1 + RAND_BELOW(ARITH_MAX);
} else {
u16 num = 1 + RAND_BELOW(ARITH_MAX);
*(u16 *)(out_buf + byte_idx) =
SWAP16(SWAP16(*(u16 *)(out_buf + byte_idx)) - num);
}
break;
}
case 8: {
/* Randomly add to word, random endian. */
if (end - begin < 2) break;
s32 byte_idx = (RAND_BELOW(end - begin) + begin);
if (byte_idx >= end - 1) break;
if (RAND_BELOW(2)) {
*(u16 *)(out_buf + byte_idx) += 1 + RAND_BELOW(ARITH_MAX);
} else {
u16 num = 1 + RAND_BELOW(ARITH_MAX);
*(u16 *)(out_buf + byte_idx) =
SWAP16(SWAP16(*(u16 *)(out_buf + byte_idx)) + num);
}
break;
}
case 9: {
/* Randomly subtract from dword, random endian. */
if (end - begin < 4) break;
s32 byte_idx = (RAND_BELOW(end - begin) + begin);
if (byte_idx >= end - 3) break;
if (RAND_BELOW(2)) {
*(u32 *)(out_buf + byte_idx) -= 1 + RAND_BELOW(ARITH_MAX);
} else {
u32 num = 1 + RAND_BELOW(ARITH_MAX);
*(u32 *)(out_buf + byte_idx) =
SWAP32(SWAP32(*(u32 *)(out_buf + byte_idx)) - num);
}
break;
}
case 10: {
/* Randomly add to dword, random endian. */
if (end - begin < 4) break;
s32 byte_idx = (RAND_BELOW(end - begin) + begin);
if (byte_idx >= end - 3) break;
if (RAND_BELOW(2)) {
*(u32 *)(out_buf + byte_idx) += 1 + RAND_BELOW(ARITH_MAX);
} else {
u32 num = 1 + RAND_BELOW(ARITH_MAX);
*(u32 *)(out_buf + byte_idx) =
SWAP32(SWAP32(*(u32 *)(out_buf + byte_idx)) + num);
}
break;
}
case 11: {
/* Just set a random byte to a random value. Because,
why not. We use XOR with 1-255 to eliminate the
possibility of a no-op. */
out_buf[(RAND_BELOW(end - begin) + begin)] ^= 1 + RAND_BELOW(255);
break;
}
}
}
#endif