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From:   tcs.kernel@gmail.com
To:     vinicius.gomes@intel.com, jhs@mojatatu.com,
        xiyou.wangcong@gmail.com, jiri@resnulli.us, davem@davemloft.net,
        kuba@kernel.org, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     Haimin Zhang <tcs_kernel@tencent.com>
Subject: [PATCH V2] fix array-index-out-of-bounds in taprio_change
Date:   Mon, 30 Aug 2021 11:47:01 +0800
Message-Id: <1630295221-9859-1-git-send-email-tcs_kernel@tencent.com>
Precedence: bulk

From: Haimin Zhang <tcs_kernel@tencent.com>

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>
---
 net/sched/sch_taprio.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/sched/sch_taprio.c b/net/sched/sch_taprio.c
index 9c79374..1ab2fc9 100644
--- 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],
-- 
1.8.3.1