netdev - [PATCH net-next] net: sched: cgroup: verify that filter is not NULL during walk

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Message-Id: <20190215151844.8780-1-vladbu@mellanox.com>
Date:   Fri, 15 Feb 2019 17:18:44 +0200
From:   Vlad Buslov <vladbu@...lanox.com>
To:     netdev@...r.kernel.org
Cc:     idosch@...sch.org, jhs@...atatu.com, xiyou.wangcong@...il.com,
        jiri@...nulli.us, davem@...emloft.net,
        Vlad Buslov <vladbu@...lanox.com>
Subject: [PATCH net-next] net: sched: cgroup: verify that filter is not NULL during walk

Check that filter is not NULL before passing it to tcf_walker->fn()
callback in cls_cgroup_walk(). This can happen when cls_cgroup_change()
failed to set first filter.

Fixes: ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex")
Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
---
 net/sched/cls_cgroup.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/net/sched/cls_cgroup.c b/net/sched/cls_cgroup.c
index 1cef3b416094..02b05066b635 100644
--- a/net/sched/cls_cgroup.c
+++ b/net/sched/cls_cgroup.c
@@ -158,6 +158,8 @@ static void cls_cgroup_walk(struct tcf_proto *tp, struct tcf_walker *arg,
 	if (arg->count < arg->skip)
 		goto skip;
 
+	if (!head)
+		return;
 	if (arg->fn(tp, head, arg) < 0) {
 		arg->stop = 1;
 		return;
-- 
2.13.6