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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+2b3e5fb6c7ef285a94f6@syzkaller.appspotmail.com,
        Haimin Zhang <tcs_kernel@tencent.com>,
        "David S. Miller" <davem@davemloft.net>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.4 172/260] fix array-index-out-of-bounds in taprio_change
Date:   Mon, 20 Sep 2021 18:43:10 +0200
Message-Id: <20210920163936.929306054@linuxfoundation.org>
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From: Haimin Zhang <tcs_kernel@tencent.com>

[ Upstream commit efe487fce3061d94222c6501d7be3aa549b3dc78 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 a4de4853c79d..da9ed0613eb7 100644
--- a/net/sched/sch_taprio.c
+++ b/net/sched/sch_taprio.c
@@ -1503,7 +1503,9 @@ 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],
-- 
2.30.2