srv0srv.c:

  Fix a seg fault if a lock wait timeout is exceeded at the some time someone grants the lock

innobase/srv/srv0srv.c

@@ -2144,13 +2144,17 @@ loop:
 				/* Timeout exceeded or a wrap-around in system
 				time counter: cancel the lock request queued
 				by the transaction and release possible
-				other transactions waiting behind */
+				other transactions waiting behind; it is
+				possible that the lock has already been
+				granted: in that case do nothing */
 
+			        if (thr_get_trx(slot->thr)->wait_lock) {
 				        lock_cancel_waiting_and_release(
 				          thr_get_trx(slot->thr)->wait_lock);
 			        }
 			}
 		}
+	}
 
 	os_event_reset(srv_lock_timeout_thread_event);