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: Américo 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: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace_events_filter.c b/kernel/trace/trace_events_filter.c
index e27bb6a..21d3475 100644
--- a/kernel/trace/trace_events_filter.c
+++ b/kernel/trace/trace_events_filter.c
@@ -1230,10 +1230,10 @@
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 @@
if (fail) {
parse_error(ps, FILT_ERR_BAD_SUBSYS_FILTER, 0);
- return err;
+ return -EINVAL;
}
return 0;
}
@@ -1281,8 +1281,7 @@
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 @@
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 @@
if (call->id == event_id)
break;
}
- if (!call)
- return -EINVAL;
+ err = -EINVAL;
+ if (!call)
+ 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 @@
if (err)
__free_preds(filter);
+out_unlock:
mutex_unlock(&event_mutex);
return err;