[PATCH 4.14 12/72] tracing: Fix memory leak in set_trigger_filter()

From: Greg Kroah-Hartman
Date: Thu Dec 20 2018 - 04:25:45 EST

4.14-stable review patch. If anyone has any objections, please let me know.


From: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>

commit 3cec638b3d793b7cacdec5b8072364b41caeb0e1 upstream.

When create_event_filter() fails in set_trigger_filter(), the filter may
still be allocated and needs to be freed. The caller expects the
data->filter to be updated with the new filter, even if the new filter
failed (we could add an error message by setting set_str parameter of
create_event_filter(), but that's another update).

But because the error would just exit, filter was left hanging and
nothing could free it.

Found by kmemleak detector.

Cc: stable@xxxxxxxxxxxxxxx
Fixes: bac5fb97a173a ("tracing: Add and use generic set_trigger_filter() implementation")
Reviewed-by: Tom Zanussi <tom.zanussi@xxxxxxxxxxxxxxx>
Signed-off-by: Steven Rostedt (VMware) <rostedt@xxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

kernel/trace/trace_events_trigger.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -744,8 +744,10 @@ int set_trigger_filter(char *filter_str,

/* The filter is for the 'trigger' event, not the triggered event */
ret = create_event_filter(file->event_call, filter_str, false, &filter);
- if (ret)
- goto out;
+ /*
+ * If create_event_filter() fails, filter still needs to be freed.
+ * Which the calling code will do with data->filter.
+ */
tmp = rcu_access_pointer(data->filter);