tracing: Return -EINVAL if WARN_ON(!glob) triggered in event_hist_trigger_parse()

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.

Link: https://lkml.kernel.org/r/20220417185630.199062-2-ammarfaizi2@gnuweeb.org
Cc: Ingo Molnar <mingo@redhat.com>
Cc: GNU/Weeb Mailing List <gwml@vger.gnuweeb.org>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 998dfe2..80c25be 100644 (file)
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -6214,7 +6214,8 @@ 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();