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Commit a66abe7f authored by Ingo Molnar's avatar Ingo Molnar
Browse files

tracing/events: Fix locking imbalance in the filter code 



Américo Wang noticed that we have a locking imbalance in the
error paths of ftrace_profile_set_filter(), causing potential
leakage of event_mutex.

Also clean up other error codepaths related to event_mutex
while at it.

Plus fix an initialized variable in the subsystem filter code.

Reported-by: default avatarAmérico Wang <xiyou.wangcong@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <2375c9f90910150247u5ccb8e2at58c764e385ffa490@mail.gmail.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent c171b552

kernel/trace/trace_events_filter.c

+15 −11
Original line number Diff line number Diff line
@@ -1230,10 +1230,10 @@ static int replace_system_preds(struct event_subsystem *system, 
				struct filter_parse_state *ps,

				char *filter_string)

{

	struct event_filter *filter = system->filter;

	struct ftrace_event_call *call;

	struct event_filter *filter;

	int err;

	bool fail = true;

	int err;



	list_for_each_entry(call, &ftrace_events, list) {
@@ -1262,7 +1262,7 @@ static int replace_system_preds(struct event_subsystem *system, 


	if (fail) {

		parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);

		return err;

		return -EINVAL;

	}

	return 0;

}
@@ -1281,8 +1281,7 @@ int apply_event_filter(struct ftrace_event_call *call, char *filter_string) 
	if (!strcmp(strstrip(filter_string), "0")) {

		filter_disable_preds(call);

		remove_filter_string(call->filter);

		mutex_unlock(&event_mutex);

		return 0;

		goto out_unlock;

	}



	err = -ENOMEM;
@@ -1330,8 +1329,7 @@ int apply_subsystem_event_filter(struct event_subsystem *system, 
	if (!strcmp(strstrip(filter_string), "0")) {

		filter_free_subsystem_preds(system);

		remove_filter_string(system->filter);

		mutex_unlock(&event_mutex);

		return 0;

		goto out_unlock;

	}



	err = -ENOMEM;
@@ -1386,15 +1384,20 @@ int ftrace_profile_set_filter(struct perf_event *event, int event_id, 
		if (call->id == event_id)

			break;

	}



	err = -EINVAL;

	if (!call)

		return -EINVAL;

		goto out_unlock;



	err = -EEXIST;

	if (event->filter)

		return -EEXIST;

		goto out_unlock;



	filter = __alloc_preds();

	if (IS_ERR(filter))

		return PTR_ERR(filter);

	if (IS_ERR(filter)) {

		err = PTR_ERR(filter);

		goto out_unlock;

	}



	err = -ENOMEM;

	ps = kzalloc(sizeof(*ps), GFP_KERNEL);
@@ -1419,6 +1422,7 @@ int ftrace_profile_set_filter(struct perf_event *event, int event_id, 
	if (err)

		__free_preds(filter);



out_unlock:

	mutex_unlock(&event_mutex);



	return err;