How did the use after free not blowup in the last 3 years since it was modified?

src/mod/applications/mod_fifo/mod_fifo.c

@@ -1637,7 +1637,6 @@ static void *SWITCH_THREAD_FUNC o_thread_run(switch_thread_t *thread, void *obj)
 	fifo_execute_sql_queued(&sql, SWITCH_TRUE, SWITCH_TRUE);
 
 	status = switch_ivr_originate(NULL, &session, &cause, originate_string, h->timeout, NULL, NULL, NULL, NULL, ovars, SOF_NONE, NULL);
-	free(originate_string);
 
 	if (status != SWITCH_STATUS_SUCCESS) {
 
@@ -1694,6 +1693,10 @@ static void *SWITCH_THREAD_FUNC o_thread_run(switch_thread_t *thread, void *obj)
 
   end:
 
+	if ( originate_string ){
+		switch_safe_free(originate_string);
+	}
+
 	switch_event_destroy(&ovars);
 	if (node) {
 		switch_mutex_lock(node->update_mutex);