tracing: Fix memory leak in set_trigger_filter()

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@vger.kernel.org
Fixes: bac5fb97a173a ("tracing: Add and use generic set_trigger_filter() implementation")
Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

diff --git a/kernel/trace/trace_events_trigger.c b/kernel/trace/trace_events_trigger.c
index 2152d1e..cd12ecb 100644 (file)
--- a/kernel/trace/trace_events_trigger.c
+++ b/kernel/trace/trace_events_trigger.c
@@ -732,8 +732,10 @@ 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.
+        */
  assign:
        tmp = rcu_access_pointer(data->filter);