From d66022cd1623edfd7b43e13c9e973403a811af02 Mon Sep 17 00:00:00 2001
From: Vlad Buslov <vladbu@mellanox.com>
Date: Fri, 15 Feb 2019 17:17:56 +0200
Subject: [PATCH] net: sched: matchall: verify that filter is not NULL in
 mall_walk()

Check that filter is not NULL before passing it to tcf_walker->fn()
callback. This can happen when mall_change() failed to offload filter to
hardware.

Fixes: ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex")
Reported-by: Ido Schimmel <idosch@mellanox.com>
Tested-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Vlad Buslov <vladbu@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 net/sched/cls_matchall.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/sched/cls_matchall.c b/net/sched/cls_matchall.c
index a37137430e61e..1f9d481b0fbbf 100644
--- a/net/sched/cls_matchall.c
+++ b/net/sched/cls_matchall.c
@@ -247,6 +247,9 @@ static void mall_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;
 skip:
-- 
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