linux-kernel - [PATCH 2/2] tracing: Fix use-after-free in hist_register

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Date:	Wed, 29 Jun 2016 19:56:00 -0500
From:	Tom Zanussi <tom.zanussi@...ux.intel.com>
To:	rostedt@...dmis.org
Cc:	dvyukov@...gle.com, linux-kernel@...r.kernel.org,
	Tom Zanussi <tom.zanussi@...ux.intel.com>
Subject: [PATCH 2/2] tracing: Fix use-after-free in hist_register_trigger()

This fixes a use-after-free case flagged by KASAN; make sure the test
happens before the potential free in this case.

Signed-off-by: Tom Zanussi <tom.zanussi@...ux.intel.com>
---
 kernel/trace/trace_events_hist.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/trace/trace_events_hist.c b/kernel/trace/trace_events_hist.c
index 19ae135..f3a960e 100644
--- a/kernel/trace/trace_events_hist.c
+++ b/kernel/trace/trace_events_hist.c
@@ -1441,6 +1441,9 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 		goto out;
 	}
 
+	if (hist_data->attrs->pause)
+		data->paused = true;
+
 	if (named_data) {
 		destroy_hist_data(data->private_data);
 		data->private_data = named_data->private_data;
@@ -1448,9 +1451,6 @@ static int hist_register_trigger(char *glob, struct event_trigger_ops *ops,
 		data->ops = &event_hist_trigger_named_ops;
 	}
 
-	if (hist_data->attrs->pause)
-		data->paused = true;
-
 	if (data->ops->init) {
 		ret = data->ops->init(data->ops, data);
 		if (ret < 0)
-- 
1.9.3