fix qemu/unicorn oob

docs/Changelog.md

@@ -34,6 +34,8 @@ sending a mail to <afl-users+subscribe@googlegroups.com>.
     - better banner
     - more effective cmplog mode
     - more often update the UI when in input2stage mode
+  - qemu_mode/unicorn_mode: fixed OOB write when using libcompcov,
+      thanks to kotee4ko for reporting!
   - frida_mode:
     - better performance, bug fixes
     - David Carlier added Android support :)

src/afl-sharedmem.c

@@ -242,6 +242,9 @@ u8 *afl_shm_init(sharedmem_t *shm, size_t map_size,
 #else
   u8 *shm_str;
 
+  // handle qemu/unicorn compcov map overwrite
+  if (map_size == MAP_SIZE) { map_size += 8; }
+
   shm->shm_id =
       shmget(IPC_PRIVATE, map_size, IPC_CREAT | IPC_EXCL | DEFAULT_PERMISSION);
   if (shm->shm_id < 0) {