[PATCH 2/3] trace-cmd: Fix double free error when triggers are configured on multiple events

["Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com>]

When using trace-cmd "-e sched:* -R ..." command to set triggers to the all events
of given subsystem, trace-cmd fails with a double free error.
The problem is in create_event() function, where the config is expanded to the all
events. The same "event->trigger" pointer is copied to all events. Later, when the
trigger is applied, the update_event() frees this pointer multiple times.

Signed-off-by: Tzvetomir Stoyanov (VMware) <tz.stoyanov@gmail.com>
---
 tracecmd/trace-record.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/tracecmd/trace-record.c b/tracecmd/trace-record.c
index ec3bcae9..7dbf599a 100644
--- a/tracecmd/trace-record.c
+++ b/tracecmd/trace-record.c
@@ -2702,7 +2702,8 @@ create_event(struct buffer_instance *instance, char *path, struct event_list *ol
 	else
 		free(p);
 
-	if (event->trigger) {
+	if (old_event->trigger) {
+		event->trigger = strdup(old_event->trigger);
 		ret = asprintf(&p, "%s/trigger", path_dirname);
 		if (ret < 0)
 			die("Failed to allocate trigger path for %s", path);
@@ -2883,6 +2884,7 @@ static void expand_event_instance(struct buffer_instance *instance)
 		event = compressed_list;
 		compressed_list = event->next;
 		expand_event(instance, event);
+		free(event->trigger);
 		free(event);
 	}
 }
-- 
2.25.1