fix array-index-out-of-bounds in taprio_change

syzbot report an array-index-out-of-bounds in taprio_change
index 16 is out of range for type '__u16 [16]'
that's because mqprio->num_tc is lager than TC_MAX_QUEUE,so we check
the return value of netdev_set_num_tc.

Reported-by: syzbot+2b3e5fb6c7ef285a94f6@syzkaller.appspotmail.com
Signed-off-by: Haimin Zhang <tcs_kernel@tencent.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 9c79374..1ab2fc9 100644 (file)
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1513,7 +1513,9 @@ static int taprio_change(struct Qdisc *sch, struct nlattr *opt,
        taprio_set_picos_per_byte(dev, q);
 
        if (mqprio) {
-               netdev_set_num_tc(dev, mqprio->num_tc);
+               err = netdev_set_num_tc(dev, mqprio->num_tc);
+               if (err)
+                       goto free_sched;
                for (i = 0; i < mqprio->num_tc; i++)
                        netdev_set_tc_queue(dev, i,
                                            mqprio->count[i],