[PATCH] net: sched: fix potential null pointer deref

From: Jianhao Xu
Date: Thu Jun 09 2022 - 22:16:29 EST


mq_queue_get() may return NULL, a check is needed to avoid using
the NULL pointer.

Signed-off-by: Jianhao Xu <jianhao_xu@xxxxxxxxxxxxxxxx>
---
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