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added afl_custom_fuzz_count

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This commit is contained in:
van Hauser 2020-08-24 17:32:41 +02:00
parent a7c3f252d5
commit c7f0d30668
9 changed files with 178 additions and 82 deletions
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12
GNUmakefile
View File

@ -37,18 +37,18 @@ MANPAGES=$(foreach p, $(PROGS) $(SH_PROGS), $(p).8) afl-as.8
ASAN_OPTIONS=detect_leaks=0
ifeq "$(findstring android, $(shell $(CC) --version 2>/dev/null))" ""
ifeq "$(shell echo 'int main() {return 0; }' | $(CC) $(CFLAGS) -Werror -x c - -flto=full -o .test 2>/dev/null && echo 1 || echo 0 ; rm -f .test )" "1"
ifeq "$(shell echo 'int main() {return 0; }' | $(CC) $(CFLAGS) -Werror -x c - -flto=full -o .test 2>/dev/null && echo 1 || echo 0 ; rm -f .test )" "1"
CFLAGS_FLTO ?= -flto=full
else
ifeq "$(shell echo 'int main() {return 0; }' | $(CC) $(CFLAGS) -Werror -x c - -flto=thin -o .test 2>/dev/null && echo 1 || echo 0 ; rm -f .test )" "1"
CFLAGS_FLTO ?= -flto=thin
else
ifeq "$(shell echo 'int main() {return 0; }' | $(CC) $(CFLAGS) -Werror -x c - -flto -o .test 2>/dev/null && echo 1 || echo 0 ; rm -f .test )" "1"
ifeq "$(shell echo 'int main() {return 0; }' | $(CC) $(CFLAGS) -Werror -x c - -flto=thin -o .test 2>/dev/null && echo 1 || echo 0 ; rm -f .test )" "1"
CFLAGS_FLTO ?= -flto=thin
else
ifeq "$(shell echo 'int main() {return 0; }' | $(CC) $(CFLAGS) -Werror -x c - -flto -o .test 2>/dev/null && echo 1 || echo 0 ; rm -f .test )" "1"
CFLAGS_FLTO ?= -flto
endif
endif
endif
endif
endif
ifeq "$(shell echo 'int main() {return 0; }' | $(CC) -fno-move-loop-invariants -fdisable-tree-cunrolli -x c - -o .test 2>/dev/null && echo 1 || echo 0 ; rm -f .test )" "1"
SPECIAL_PERFORMANCE += -fno-move-loop-invariants -fdisable-tree-cunrolli

3
docs/Changelog.md
View File

@ -18,6 +18,9 @@ sending a mail to <afl-users+subscribe@googlegroups.com>.
dict entries without recompiling.
- AFL_FORKSRV_INIT_TMOUT env variable added to control the time to wait for
the forkserver to come up without the need to increase the overall timeout.
- custom mutators:
- added afl_custom_fuzz_count/fuzz_count function to allow specifying the
number of fuzz attempts for custom_fuzz
- llvm_mode:
- Ported SanCov to LTO, and made it the default for LTO. better
instrumentation locations

9
docs/custom_mutators.md
View File

@ -32,6 +32,7 @@ performed with the custom mutator.
C/C++:
```c
void *afl_custom_init(afl_t *afl, unsigned int seed);
uint32_t afl_custom_fuzz_count(void *data, const u8 *buf, size_t buf_size);
size_t afl_custom_fuzz(void *data, uint8_t *buf, size_t buf_size, u8 **out_buf, uint8_t *add_buf, size_t add_buf_size, size_t max_size);
size_t afl_custom_post_process(void *data, uint8_t *buf, size_t buf_size, uint8_t **out_buf);
int32_t afl_custom_init_trim(void *data, uint8_t *buf, size_t buf_size);
@ -49,6 +50,9 @@ Python:
def init(seed):
pass
def fuzz_count(buf, add_buf, max_size):
return cnt
def fuzz(buf, add_buf, max_size):
return mutated_out
@ -88,6 +92,11 @@ def queue_new_entry(filename_new_queue, filename_orig_queue):
This method determines whether the custom fuzzer should fuzz the current
queue entry or not
- `fuzz_count` (optional):
This method can be used to instruct afl-fuzz how often to perform a fuzz
attempt on this input data.
- `fuzz` (optional):
This method performs custom mutations on a given input. It also accepts an

20
include/afl-fuzz.h
View File

@ -288,6 +288,7 @@ enum {
enum {
/* 00 */ PY_FUNC_INIT,
/* 01 */ PY_FUNC_FUZZ_COUNT,
/* 01 */ PY_FUNC_FUZZ,
/* 02 */ PY_FUNC_POST_PROCESS,
/* 03 */ PY_FUNC_INIT_TRIM,
@ -679,6 +680,24 @@ struct custom_mutator {
*/
void *(*afl_custom_init)(afl_state_t *afl, unsigned int seed);
/**
* This method is called just before fuzzing a queue entry with the custom
* mutator, and receives the initial buffer. It should return the number of
* fuzzes to perform.
*
* A value of 0 means no fuzzing of this queue entry.
*
* The function is now allowed to change the data.
*
* (Optional)
*
* @param data pointer returned in afl_custom_init for this fuzz case
* @param buf Buffer containing the test case
* @param buf_size Size of the test case
* @return The amount of fuzzes to perform on this queue entry, 0 = skip
*/
u32 (*afl_custom_fuzz_count)(void *data, const u8 *buf, size_t buf_size);
/**
* Perform custom mutations on a given input
*
@ -867,6 +886,7 @@ u8 trim_case_custom(afl_state_t *, struct queue_entry *q, u8 *in_buf,
struct custom_mutator *load_custom_mutator_py(afl_state_t *, char *);
void finalize_py_module(void *);
u32 fuzz_count_py(void *, const u8 *, size_t);
size_t post_process_py(void *, u8 *, size_t, u8 **);
s32 init_trim_py(void *, u8 *, size_t);
s32 post_trim_py(void *, u8);

2
src/afl-forkserver.c
View File

@ -634,7 +634,7 @@ void afl_fsrv_start(afl_forkserver_t *fsrv, char **argv,
if (fsrv->add_extra_func == NULL || fsrv->afl_ptr == NULL) {
// this is not afl-fuzz - we deny and return
// this is not afl-fuzz - or it is cmplog - we deny and return
if (fsrv->use_shmem_fuzz) {
status = (FS_OPT_ENABLED | FS_OPT_SHDMEM_FUZZ);

4
src/afl-fuzz-extras.c
View File

@ -251,7 +251,7 @@ static void extras_check_and_sort(afl_state_t *afl, u32 min_len, u32 max_len,
if (afl->extras_cnt > afl->max_det_extras) {
OKF("More than %d tokens - will use them probabilistically.",
afl->max_det_extras);
afl->max_det_extras);
}
@ -406,7 +406,7 @@ void add_extra(afl_state_t *afl, u8 *mem, u32 len) {
if (afl->extras_cnt == afl->max_det_extras + 1) {
OKF("More than %d tokens - will use them probabilistically.",
afl->max_det_extras);
afl->max_det_extras);
}

5
src/afl-fuzz-mutators.c
View File

@ -166,6 +166,11 @@ struct custom_mutator *load_custom_mutator(afl_state_t *afl, const char *fn) {
}
/* "afl_custom_fuzz_count", optional */
mutator->afl_custom_fuzz_count = dlsym(dh, "afl_custom_fuzz_count");
if (!mutator->afl_custom_fuzz_count)
ACTF("optional symbol 'afl_custom_fuzz_count' not found.");
/* "afl_custom_deinit", optional for backward compatibility */
mutator->afl_custom_deinit = dlsym(dh, "afl_custom_deinit");
if (!mutator->afl_custom_deinit)

161
src/afl-fuzz-one.c
View File

@ -1672,7 +1672,7 @@ custom_mutator_stage:
if (afl->stage_max < HAVOC_MIN) { afl->stage_max = HAVOC_MIN; }
const u32 max_seed_size = MAX_FILE;
const u32 max_seed_size = MAX_FILE, saved_max = afl->stage_max;
orig_hit_cnt = afl->queued_paths + afl->unique_crashes;
@ -1680,104 +1680,119 @@ custom_mutator_stage:
if (el->afl_custom_fuzz) {
if (el->afl_custom_fuzz_count)
afl->stage_max = el->afl_custom_fuzz_count(el->data, out_buf, len);
else
afl->stage_max = saved_max;
has_custom_fuzz = true;
afl->stage_short = el->name_short;
for (afl->stage_cur = 0; afl->stage_cur < afl->stage_max;
++afl->stage_cur) {
if (afl->stage_max) {
struct queue_entry *target;
u32 tid;
u8 * new_buf;
for (afl->stage_cur = 0; afl->stage_cur < afl->stage_max;
++afl->stage_cur) {
retry_external_pick:
/* Pick a random other queue entry for passing to external API */
struct queue_entry *target;
u32 tid;
u8 * new_buf;
do {
retry_external_pick:
/* Pick a random other queue entry for passing to external API */
tid = rand_below(afl, afl->queued_paths);
do {
} while (tid == afl->current_entry && afl->queued_paths > 1);
tid = rand_below(afl, afl->queued_paths);
target = afl->queue;
} while (tid == afl->current_entry && afl->queued_paths > 1);
while (tid >= 100) {
target = afl->queue;
target = target->next_100;
tid -= 100;
while (tid >= 100) {
}
while (tid--) {
target = target->next;
}
/* Make sure that the target has a reasonable length. */
while (target && (target->len < 2 || target == afl->queue_cur) &&
afl->queued_paths > 3) {
target = target->next;
++afl->splicing_with;
}
if (!target) { goto retry_external_pick; }
/* Read the additional testcase into a new buffer. */
fd = open(target->fname, O_RDONLY);
if (unlikely(fd < 0)) { PFATAL("Unable to open '%s'", target->fname); }
new_buf = afl_realloc(AFL_BUF_PARAM(out_scratch), target->len);
if (unlikely(!new_buf)) { PFATAL("alloc"); }
ck_read(fd, new_buf, target->len, target->fname);
close(fd);
u8 *mutated_buf = NULL;
size_t mutated_size =
el->afl_custom_fuzz(el->data, out_buf, len, &mutated_buf, new_buf,
target->len, max_seed_size);
if (unlikely(!mutated_buf)) {
FATAL("Error in custom_fuzz. Size returned: %zd", mutated_size);
}
if (mutated_size > 0) {
if (common_fuzz_stuff(afl, mutated_buf, (u32)mutated_size)) {
goto abandon_entry;
target = target->next_100;
tid -= 100;
}
/* If we're finding new stuff, let's run for a bit longer, limits
permitting. */
while (tid--) {
if (afl->queued_paths != havoc_queued) {
target = target->next;
if (perf_score <= afl->havoc_max_mult * 100) {
}
afl->stage_max *= 2;
perf_score *= 2;
/* Make sure that the target has a reasonable length. */
while (target && (target->len < 2 || target == afl->queue_cur) &&
afl->queued_paths > 3) {
target = target->next;
++afl->splicing_with;
}
if (!target) { goto retry_external_pick; }
/* Read the additional testcase into a new buffer. */
fd = open(target->fname, O_RDONLY);
if (unlikely(fd < 0)) {
PFATAL("Unable to open '%s'", target->fname);
}
new_buf = afl_realloc(AFL_BUF_PARAM(out_scratch), target->len);
if (unlikely(!new_buf)) { PFATAL("alloc"); }
ck_read(fd, new_buf, target->len, target->fname);
close(fd);
u8 *mutated_buf = NULL;
size_t mutated_size =
el->afl_custom_fuzz(el->data, out_buf, len, &mutated_buf, new_buf,
target->len, max_seed_size);
if (unlikely(!mutated_buf)) {
FATAL("Error in custom_fuzz. Size returned: %zd", mutated_size);
}
if (mutated_size > 0) {
if (common_fuzz_stuff(afl, mutated_buf, (u32)mutated_size)) {
goto abandon_entry;
}
havoc_queued = afl->queued_paths;
/* If we're finding new stuff, let's run for a bit longer, limits
permitting. */
if (afl->queued_paths != havoc_queued) {
if (perf_score <= afl->havoc_max_mult * 100) {
afl->stage_max *= 2;
perf_score *= 2;
}
havoc_queued = afl->queued_paths;
}
}
}
/* `(afl->)out_buf` may have been changed by the call to custom_fuzz
*/
/* TODO: Only do this when `mutated_buf` == `out_buf`? Branch vs
* Memcpy.
*/
memcpy(out_buf, in_buf, len);
/* `(afl->)out_buf` may have been changed by the call to custom_fuzz */
/* TODO: Only do this when `mutated_buf` == `out_buf`? Branch vs Memcpy.
*/
memcpy(out_buf, in_buf, len);
}
}

44
src/afl-fuzz-python.c
View File

@ -347,6 +347,12 @@ struct custom_mutator *load_custom_mutator_py(afl_state_t *afl,
}
if (py_functions[PY_FUNC_FUZZ_COUNT]) {
mutator->afl_custom_fuzz_count = fuzz_count_py;
}
if (py_functions[PY_FUNC_POST_TRIM]) {
mutator->afl_custom_post_trim = post_trim_py;
@ -477,6 +483,44 @@ s32 init_trim_py(void *py_mutator, u8 *buf, size_t buf_size) {
}
u32 fuzz_count_py(void *py_mutator, const u8 *buf, size_t buf_size) {
PyObject *py_args, *py_value;
py_args = PyTuple_New(1);
py_value = PyByteArray_FromStringAndSize(buf, buf_size);
if (!py_value) {
Py_DECREF(py_args);
FATAL("Failed to convert arguments");
}
PyTuple_SetItem(py_args, 0, py_value);
py_value = PyObject_CallObject(
((py_mutator_t *)py_mutator)->py_functions[PY_FUNC_FUZZ_COUNT], py_args);
Py_DECREF(py_args);
if (py_value != NULL) {
#if PY_MAJOR_VERSION >= 3
u32 retcnt = (u32)PyLong_AsLong(py_value);
#else
u32 retcnt = PyInt_AsLong(py_value);
#endif
Py_DECREF(py_value);
return retcnt;
} else {
PyErr_Print();
FATAL("Call failed");
}
}
s32 post_trim_py(void *py_mutator, u8 success) {
PyObject *py_args, *py_value;