Refactor to use an alternative method for shared memory.

If USEMMAP is defined, the shared memory segment is created/attached etc.
now by shm_open() and mmap().
This API is hopefully more often available (at least for iOS).

In order to reduce code duplication I have added new files
sharedmem.[ch] which now encapsulate the shared memory method.

This is based on the work of Proteas to support iOS fuzzing (thanks).
866af8ad1c

Currently this is in an experimental status yet. Please report
whether this variant works on 32 and 64 bit and on the supported platforms.

This branch enables USEMMAP and has been tested on Linux.
There is no auto detection for the mmap API yet.
This commit is contained in:
Heiko Eißfeldt
2019-06-30 10:06:20 +02:00
parent c083fd895c
commit d9ff84e39e
10 changed files with 262 additions and 164 deletions

View File

@ -44,6 +44,9 @@
# define CONST_PRIO 0
#endif /* ^USE_TRACE_PC */
#include <sys/mman.h>
#include <fcntl.h>
/* Globals needed by the injected instrumentation. The __afl_area_initial region
is used for instrumentation output before __afl_map_shm() has a chance to run.
@ -71,10 +74,34 @@ static void __afl_map_shm(void) {
hacky .init code to work correctly in projects such as OpenSSL. */
if (id_str) {
#ifdef USEMMAP
const char *shm_file_path = id_str;
int shm_fd = -1;
unsigned char *shm_base = NULL;
/* create the shared memory segment as if it was a file */
shm_fd = shm_open(shm_file_path, O_RDWR, 0600);
if (shm_fd == -1) {
printf("shm_open() failed\n");
exit(1);
}
/* map the shared memory segment to the address space of the process */
shm_base = mmap(0, MAP_SIZE, PROT_READ | PROT_WRITE, MAP_SHARED, shm_fd, 0);
if (shm_base == MAP_FAILED) {
close(shm_fd);
shm_fd = -1;
printf("mmap() failed\n");
exit(2);
}
__afl_area_ptr = shm_base;
#else
u32 shm_id = atoi(id_str);
__afl_area_ptr = shmat(shm_id, NULL, 0);
#endif
/* Whooooops. */