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From:   Jianhao Xu <jianhao_xu@smail.nju.edu.cn>
To:     jhs@mojatatu.com, xiyou.wangcong@gmail.com, jiri@resnulli.us,
        davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com
Cc:     netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jianhao Xu <jianhao_xu@smail.nju.edu.cn>
Subject: [PATCH] net: sched: fix potential null pointer deref
Date:   Fri, 10 Jun 2022 04:14:45 +0200
Message-Id: <20220610021445.2441579-1-jianhao_xu@smail.nju.edu.cn>
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mq_queue_get() may return NULL, a check is needed to avoid using
the NULL pointer.

Signed-off-by: Jianhao Xu <jianhao_xu@smail.nju.edu.cn>
---
 net/sched/sch_mq.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/sched/sch_mq.c b/net/sched/sch_mq.c
index 83d2e54bf303..9aca4ca82947 100644
--- a/net/sched/sch_mq.c
+++ b/net/sched/sch_mq.c
@@ -201,6 +201,8 @@ static int mq_graft(struct Qdisc *sch, unsigned long cl, struct Qdisc *new,
 static struct Qdisc *mq_leaf(struct Qdisc *sch, unsigned long cl)
 {
 	struct netdev_queue *dev_queue = mq_queue_get(sch, cl);
+	if (!dev_queue)
+		return NULL;
 
 	return dev_queue->qdisc_sleeping;
 }
@@ -218,6 +220,8 @@ static int mq_dump_class(struct Qdisc *sch, unsigned long cl,
 			 struct sk_buff *skb, struct tcmsg *tcm)
 {
 	struct netdev_queue *dev_queue = mq_queue_get(sch, cl);
+	if (!dev_queue)
+		return -1;
 
 	tcm->tcm_parent = TC_H_ROOT;
 	tcm->tcm_handle |= TC_H_MIN(cl);
@@ -229,6 +233,8 @@ static int mq_dump_class_stats(struct Qdisc *sch, unsigned long cl,
 			       struct gnet_dump *d)
 {
 	struct netdev_queue *dev_queue = mq_queue_get(sch, cl);
+	if (!dev_queue)
+		return -1;
 
 	sch = dev_queue->qdisc_sleeping;
 	if (gnet_stats_copy_basic(d, sch->cpu_bstats, &sch->bstats, true) < 0 ||
-- 
2.25.1