From: Jiri Pirko <jiri@mellanox.com>
Date: Fri, 18 Aug 2017 10:10:43 +0200
Subject: net: sched: fix p_filter_chain check in tcf_chain_flush
Patch-mainline: v4.13-rc7
Git-commit: acc8b31665b4cc17b35c4fa445427f7e2f6dc86b
References: bsc#1056787

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@mellanox.com>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 net/sched/cls_api.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/sched/cls_api.c
+++ b/net/sched/cls_api.c
@@ -205,7 +205,7 @@ static void tcf_chain_flush(struct tcf_c
 {
 	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);