auto shmem fuzzing (#1541)

* auto shmem fuzzing

* print warning when forcing shmem fuzzing

* typos

* Shmem always

* typo fix

* fixes

Co-authored-by: Dominik Maier <dmnk@google.com>

1 files changed, 21 insertions, 6 deletions

diff --git a/instrumentation/afl-compiler-rt.o.c b/instrumentation/afl-compiler-rt.o.c
index 194d49b0..20069824 100644
--- a/instrumentation/afl-compiler-rt.o.c
+++ b/instrumentation/afl-compiler-rt.o.c
@@ -97,6 +97,7 @@ u8        *__afl_dictionary;
 u8        *__afl_fuzz_ptr;
 static u32 __afl_fuzz_len_dummy;
 u32       *__afl_fuzz_len = &__afl_fuzz_len_dummy;
+int        __afl_sharedmem_fuzzing __attribute__((weak));
 
 u32 __afl_final_loc;
 u32 __afl_map_size = MAP_SIZE;
@@ -119,8 +120,6 @@ __thread PREV_LOC_T __afl_prev_caller[CTX_MAX_K];
 __thread u32        __afl_prev_ctx;
 #endif
 
-int __afl_sharedmem_fuzzing __attribute__((weak));
-
 struct cmp_map *__afl_cmp_map;
 struct cmp_map *__afl_cmp_map_backup;
 
@@ -347,6 +346,22 @@ static void __afl_map_shm(void) {
 
   }
 
+  if (__afl_sharedmem_fuzzing && (!id_str || !getenv(SHM_FUZZ_ENV_VAR) ||
+                                  fcntl(FORKSRV_FD, F_GETFD) == -1 ||
+                                  fcntl(FORKSRV_FD + 1, F_GETFD) == -1)) {
+
+    if (__afl_debug) {
+
+      fprintf(stderr,
+              "DEBUG: running not inside afl-fuzz, disabling shared memory "
+              "testcases\n");
+
+    }
+
+    __afl_sharedmem_fuzzing = 0;
+
+  }
+
   if (!id_str) {
 
     u32 val = 0;
@@ -543,7 +558,7 @@ static void __afl_map_shm(void) {
     if (!__afl_area_ptr_dummy) {
 
       fprintf(stderr,
-              "Error: AFL++ could not aquire %u bytes of memory, exiting!\n",
+              "Error: AFL++ could not acquire %u bytes of memory, exiting!\n",
               __afl_final_loc);
       exit(-1);
 
@@ -757,10 +772,10 @@ static void __afl_start_snapshots(void) {
      assume we're not running in forkserver mode and just execute program. */
 
   status |= (FS_OPT_ENABLED | FS_OPT_SNAPSHOT | FS_OPT_NEWCMPLOG);
-  if (__afl_sharedmem_fuzzing != 0) status |= FS_OPT_SHDMEM_FUZZ;
+  if (__afl_sharedmem_fuzzing) { status |= FS_OPT_SHDMEM_FUZZ; }
   if (__afl_map_size <= FS_OPT_MAX_MAPSIZE)
     status |= (FS_OPT_SET_MAPSIZE(__afl_map_size) | FS_OPT_MAPSIZE);
-  if (__afl_dictionary_len && __afl_dictionary) status |= FS_OPT_AUTODICT;
+  if (__afl_dictionary_len && __afl_dictionary) { status |= FS_OPT_AUTODICT; }
   memcpy(tmp, &status, 4);
 
   if (write(FORKSRV_FD + 1, tmp, 4) != 4) { return; }
@@ -1021,7 +1036,7 @@ static void __afl_start_forkserver(void) {
 
   }
 
-  if (__afl_sharedmem_fuzzing != 0) { status_for_fsrv |= FS_OPT_SHDMEM_FUZZ; }
+  if (__afl_sharedmem_fuzzing) { status_for_fsrv |= FS_OPT_SHDMEM_FUZZ; }
   if (status_for_fsrv) {
 
     status_for_fsrv |= (FS_OPT_ENABLED | FS_OPT_NEWCMPLOG);