netdev - [PATCH net] sch_sfq: fix null pointer dereference at timer expiration

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Date:   Tue, 28 Nov 2017 14:28:39 +0100
From:   Paolo Abeni <pabeni@...hat.com>
To:     netdev@...r.kernel.org
Cc:     Jamal Hadi Salim <jhs@...atatu.com>,
        Cong Wang <xiyou.wangcong@...il.com>,
        Jiri Pirko <jiri@...nulli.us>,
        "David S. Miller" <davem@...emloft.net>,
        Kees Cook <keescook@...omium.org>
Subject: [PATCH net] sch_sfq: fix null pointer dereference at timer expiration

While converting sch_sfq to use timer_setup(), the commit cdeabbb88134
("net: sched: Convert timers to use timer_setup()") forgot to
initialize the 'sch' field. As a result, the timer callback tries to
dereference a NULL pointer, and the kernel does oops.

Fix it initializing such field at qdisc creation time.

Fixes: cdeabbb88134 ("net: sched: Convert timers to use timer_setup()")
Signed-off-by: Paolo Abeni <pabeni@...hat.com>
---
 net/sched/sch_sfq.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/sched/sch_sfq.c b/net/sched/sch_sfq.c
index 890f4a4564e7..09c1203c1711 100644
--- a/net/sched/sch_sfq.c
+++ b/net/sched/sch_sfq.c
@@ -724,6 +724,7 @@ static int sfq_init(struct Qdisc *sch, struct nlattr *opt)
 	int i;
 	int err;
 
+	q->sch = sch;
 	timer_setup(&q->perturb_timer, sfq_perturbation, TIMER_DEFERRABLE);
 
 	err = tcf_block_get(&q->block, &q->filter_list, sch);
-- 
2.13.6