User defined kill signal value (#678)

* Adding AFL_KILL_SIGNAL environment variable

Controlling the kill signal used to end forked processes.

* Checking validity of AFL_KILL_SIGNAL env variable

This commit also sets a valid value in the environment to avoid
duplicating code in at_exit(). Changing data type of
fsrv->kill_signal to u8 to match last_kill_signal.

* Adding afl_kill_signal to AFL (environment) state

This commit simply introduces a struct member for future use. The
env variable is not used from the afl struct but from fsrv, where
its validity is checked, resulting in a FATAL in case of errors.

1 files changed, 11 insertions, 2 deletions

diff --git a/src/afl-fuzz.c b/src/afl-fuzz.c
index 063134fb..00625f2e 100644
--- a/src/afl-fuzz.c
+++ b/src/afl-fuzz.c
@@ -76,8 +76,17 @@ static void at_exit() {
 
   }
 
-  if (pid1 > 0) { kill(pid1, SIGKILL); }
-  if (pid2 > 0) { kill(pid2, SIGKILL); }
+  u8 kill_signal = SIGKILL;
+
+  /* AFL_KILL_SIGNAL should already be initialized by afl_fsrv_init() */
+  if (getenv("AFL_KILL_SIGNAL")) {
+
+    kill_signal = atoi(getenv("AFL_KILL_SIGNAL"));
+
+  }
+
+  if (pid1 > 0) { kill(pid1, kill_signal); }
+  if (pid2 > 0) { kill(pid2, kill_signal); }
 
 }