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From: Yunsheng Lin <linyunsheng@huawei.com>
To: <jhs@mojatatu.com>, <xiyou.wangcong@gmail.com>,
	<jiri@resnulli.us>, <davem@davemloft.net>, <kuba@kernel.org>
Cc: <netdev@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
	<linuxarm@huawei.com>
Subject: [PATCH net-next] net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc
Date: Tue, 1 Sep 2020 08:55:18 +0800	[thread overview]
Message-ID: <1598921718-79505-1-git-send-email-linyunsheng@huawei.com> (raw)

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.

Avoid the above concurrent op by calling synchronize_rcu_tasks()
after assigning new qdisc to dev_queue->qdisc and before calling
qdisc_deactivate() to make sure skb with larger queue_mapping
enqueued to old qdisc will always be reset when qdisc_deactivate()
is called.

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
---
 net/sched/sch_generic.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/sched/sch_generic.c b/net/sched/sch_generic.c
index 265a61d..6e42237 100644
--- a/net/sched/sch_generic.c
+++ b/net/sched/sch_generic.c
@@ -1160,8 +1160,13 @@ static void dev_deactivate_queue(struct net_device *dev,
 
 	qdisc = rtnl_dereference(dev_queue->qdisc);
 	if (qdisc) {
-		qdisc_deactivate(qdisc);
 		rcu_assign_pointer(dev_queue->qdisc, qdisc_default);
+
+		/* Make sure lockless qdisc enqueuing is done with the
+		 * old qdisc in __dev_xmit_skb().
+		 */
+		synchronize_rcu_tasks();
+		qdisc_deactivate(qdisc);
 	}
 }
 
-- 
2.8.1


             reply	other threads:[~2020-09-01  0:59 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-09-01  0:55 Yunsheng Lin [this message]
2020-09-01  6:48 ` Eric Dumazet
2020-09-01  7:27   ` Yunsheng Lin
2020-09-01 18:34     ` David Miller
2020-09-02  1:43       ` Yunsheng Lin
2020-09-01 18:24 ` Cong Wang
2020-09-02  1:42   ` Yunsheng Lin
2020-09-02  4:41     ` Cong Wang
2020-09-02  6:34       ` Yunsheng Lin
2020-09-02  7:32         ` Eric Dumazet
2020-09-02  8:14           ` Yunsheng Lin
2020-09-02  9:20             ` Eric Dumazet
2020-09-03  1:14               ` Yunsheng Lin
2020-09-03  7:24                 ` Eric Dumazet
2020-09-04  8:10                   ` Yunsheng Lin
2020-09-03  0:35         ` Cong Wang
2020-09-03  1:21           ` Yunsheng Lin
2020-09-03  1:48             ` Cong Wang
2020-09-03  2:22               ` Yunsheng Lin
2020-09-03  2:53                 ` Cong Wang
2020-09-04  1:30                   ` John Fastabend
2020-09-04  8:08                     ` Yunsheng Lin
2020-09-06  8:52 ` [net] 6fd0d0dede: hwsim.ap_ht40_5ghz_switch.fail kernel test robot

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