[PATCH 1/2] tracing: Return -EINVAL if WARN_ON(!glob) triggered in event_hist_trigger_parse()

[Ammar Faizi]

If `WARN_ON(!glob)` is ever triggered, we will still continue executing
the next lines. This will trigger the more serious problem, a NULL
pointer dereference bug.

Just return -EINVAL if @glob is NULL.

Signed-off-by: Ammar Faizi <ammarfaizi2@xxxxxxxxxxx>
---
 kernel/trace/trace_events_hist.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 44db5ba9cabb..0b99ad68e3fa 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6186,7 +6186,8 @@ static int event_hist_trigger_parse(struct event_command *cmd_ops,
 
 	lockdep_assert_held(&event_mutex);
 
-	WARN_ON(!glob);
+	if (WARN_ON(!glob))
+		return -EINVAL;
 
 	if (strlen(glob)) {
 		hist_err_clear();
-- 
Ammar Faizi