linux-kernel - Re: [PATCH v2 net] net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc

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Message-Id: <20200910.123913.1333297432408477303.davem@davemloft.net>
Date:   Thu, 10 Sep 2020 12:39:13 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     linyunsheng@...wei.com
Cc:     jhs@...atatu.com, xiyou.wangcong@...il.com, jiri@...nulli.us,
        kuba@...nel.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, linuxarm@...wei.com,
        john.fastabend@...il.com, eric.dumazet@...il.com
Subject: Re: [PATCH v2 net] net: sch_generic: aviod concurrent reset and
 enqueue op for lockless qdisc

From: Yunsheng Lin <linyunsheng@...wei.com>
Date: Tue, 8 Sep 2020 19:02:34 +0800

> Currently there is concurrent reset and enqueue operation for the
> same lockless qdisc when there is no lock to synchronize the
> q->enqueue() in __dev_xmit_skb() with the qdisc reset operation in
> qdisc_deactivate() called by dev_deactivate_queue(), which may cause
> out-of-bounds access for priv->ring[] in hns3 driver if user has
> requested a smaller queue num when __dev_xmit_skb() still enqueue a
> skb with a larger queue_mapping after the corresponding qdisc is
> reset, and call hns3_nic_net_xmit() with that skb later.
> 
> Reused the existing synchronize_net() in dev_deactivate_many() to
> make sure skb with larger queue_mapping enqueued to old qdisc(which
> is saved in dev_queue->qdisc_sleeping) will always be reset when
> dev_reset_queue() is called.
> 
> Fixes: 6b3ba9146fe6 ("net: sched: allow qdiscs to handle locking")
> Signed-off-by: Yunsheng Lin <linyunsheng@...wei.com>
> ---
> ChangeLog V2:
> 	Reuse existing synchronize_net().

Applied and queued up for -stable, thank you.