netdev - [PATCH] [net/sched] Fix null pointer deref skb in tc_ctl

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Message-Id: <20200618014328.28668-1-gaurav1086@gmail.com>
Date:   Wed, 17 Jun 2020 21:43:28 -0400
From:   Gaurav Singh <gaurav1086@...il.com>
To:     gaurav1086@...il.com, Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        netdev@...r.kernel.org (open list:TC subsystem),
        linux-kernel@...r.kernel.org (open list)
Subject: [PATCH] [net/sched] Fix null pointer deref skb in tc_ctl_action

Add null check for skb

Signed-off-by: Gaurav Singh <gaurav1086@...il.com>
---
 net/sched/act_api.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/sched/act_api.c b/net/sched/act_api.c
index 8ac7eb0a8309..fd584821d75a 100644
--- a/net/sched/act_api.c
+++ b/net/sched/act_api.c
@@ -1473,9 +1473,12 @@ static const struct nla_policy tcaa_policy[TCA_ROOT_MAX + 1] = {
 static int tc_ctl_action(struct sk_buff *skb, struct nlmsghdr *n,
 			 struct netlink_ext_ack *extack)
 {
+	if (!skb)
+		return 0;
+
 	struct net *net = sock_net(skb->sk);
 	struct nlattr *tca[TCA_ROOT_MAX + 1];
-	u32 portid = skb ? NETLINK_CB(skb).portid : 0;
+	u32 portid = NETLINK_CB(skb).portid;
 	int ret = 0, ovr = 0;
 
 	if ((n->nlmsg_type != RTM_GETACTION) &&
-- 
2.17.1