netdev - [patch net] net: sched: fix p_filter_chain check in tcf_chain

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Message-Id: <20170818081043.2130-1-jiri@resnulli.us>
Date:   Fri, 18 Aug 2017 10:10:43 +0200
From:   Jiri Pirko <jiri@...nulli.us>
To:     netdev@...r.kernel.org
Cc:     davem@...emloft.net, jhs@...atatu.com, xiyou.wangcong@...il.com,
        mlxsw@...lanox.com
Subject: [patch net] net: sched: fix p_filter_chain check in tcf_chain_flush

From: Jiri Pirko <jiri@...lanox.com>

The dereference before check is wrong and leads to an oops when
p_filter_chain is NULL. The check needs to be done on the pointer to
prevent NULL dereference.

Fixes: f93e1cdcf42c ("net/sched: fix filter flushing")
Signed-off-by: Jiri Pirko <jiri@...lanox.com>
---
 net/sched/cls_api.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/sched/cls_api.c b/net/sched/cls_api.c
index ebeeb87..eef6b07 100644
--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -190,7 +190,7 @@ static void tcf_chain_flush(struct tcf_chain *chain)
 {
 	struct tcf_proto *tp;
 
-	if (*chain->p_filter_chain)
+	if (chain->p_filter_chain)
 		RCU_INIT_POINTER(*chain->p_filter_chain, NULL);
 	while ((tp = rtnl_dereference(chain->filter_chain)) != NULL) {
 		RCU_INIT_POINTER(chain->filter_chain, tp->next);
-- 
2.9.3