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Python mutators: Gracious error handling for illegal return type (#1464)

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* python types error handling

* reverted example change

* more python

* format
This commit is contained in:
Dominik Maier
2022-06-28 10:23:20 +02:00
committed by GitHub
parent c83635e1d2
commit 6705953a49
2 changed files with 80 additions and 14 deletions
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93
src/afl-fuzz-python.c
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@ -28,6 +28,36 @@
/* Python stuff */
#ifdef USE_PYTHON
// Tries to cast a python bytearray or bytes to a char ptr
static inline bool py_bytes(PyObject *py_value, /* out */ char **bytes,
/* out */ size_t *size) {
if (!py_value) { return false; }
*bytes = PyByteArray_AsString(py_value);
if (*bytes) {
// we got a bytearray
*size = PyByteArray_Size(py_value);
} else {
*bytes = PyBytes_AsString(py_value);
if (!*bytes) {
// No valid type returned.
return false;
}
*size = PyBytes_Size(py_value);
}
return true;
}
static void *unsupported(afl_state_t *afl, unsigned int seed) {
(void)afl;
@ -93,12 +123,22 @@ static size_t fuzz_py(void *py_mutator, u8 *buf, size_t buf_size, u8 **out_buf,
if (py_value != NULL) {
mutated_size = PyByteArray_Size(py_value);
char *bytes;
if (!py_bytes(py_value, &bytes, &mutated_size)) {
*out_buf = afl_realloc(BUF_PARAMS(fuzz), mutated_size);
if (unlikely(!*out_buf)) { PFATAL("alloc"); }
FATAL("Python mutator fuzz() should return a bytearray or bytes");
}
if (mutated_size) {
*out_buf = afl_realloc(BUF_PARAMS(fuzz), mutated_size);
if (unlikely(!*out_buf)) { PFATAL("alloc"); }
memcpy(*out_buf, bytes, mutated_size);
}
memcpy(*out_buf, PyByteArray_AsString(py_value), mutated_size);
Py_DECREF(py_value);
return mutated_size;
@ -625,7 +665,7 @@ s32 post_trim_py(void *py_mutator, u8 success) {
size_t trim_py(void *py_mutator, u8 **out_buf) {
PyObject *py_args, *py_value;
size_t ret;
size_t trimmed_size;
py_args = PyTuple_New(0);
py_value = PyObject_CallObject(
@ -634,10 +674,21 @@ size_t trim_py(void *py_mutator, u8 **out_buf) {
if (py_value != NULL) {
ret = PyByteArray_Size(py_value);
*out_buf = afl_realloc(BUF_PARAMS(trim), ret);
if (unlikely(!*out_buf)) { PFATAL("alloc"); }
memcpy(*out_buf, PyByteArray_AsString(py_value), ret);
char *bytes;
if (!py_bytes(py_value, &bytes, &trimmed_size)) {
FATAL("Python mutator fuzz() should return a bytearray");
}
if (trimmed_size) {
*out_buf = afl_realloc(BUF_PARAMS(trim), trimmed_size);
if (unlikely(!*out_buf)) { PFATAL("alloc"); }
memcpy(*out_buf, bytes, trimmed_size);
}
Py_DECREF(py_value);
} else {
@ -647,7 +698,7 @@ size_t trim_py(void *py_mutator, u8 **out_buf) {
}
return ret;
return trimmed_size;
}
@ -692,7 +743,13 @@ size_t havoc_mutation_py(void *py_mutator, u8 *buf, size_t buf_size,
if (py_value != NULL) {
mutated_size = PyByteArray_Size(py_value);
char *bytes;
if (!py_bytes(py_value, &bytes, &mutated_size)) {
FATAL("Python mutator fuzz() should return a bytearray");
}
if (mutated_size <= buf_size) {
/* We reuse the input buf here. */
@ -706,8 +763,6 @@ size_t havoc_mutation_py(void *py_mutator, u8 *buf, size_t buf_size,
}
memcpy(*out_buf, PyByteArray_AsString(py_value), mutated_size);
Py_DECREF(py_value);
return mutated_size;
@ -762,7 +817,17 @@ const char *introspection_py(void *py_mutator) {
} else {
return PyByteArray_AsString(py_value);
char * ret;
size_t len;
if (!py_bytes(py_value, &ret, &len)) {
FATAL(
"Python mutator introspection call returned illegal type (expected "
"bytes or bytearray)");
}
return ret;
}