Commit 2fb541c8 authored by Yunsheng Lin's avatar Yunsheng Lin Committed by David S. Miller
Browse files

net: sch_generic: aviod concurrent reset and enqueue op for lockless qdisc 



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: 6b3ba914 ("net: sched: allow qdiscs to handle locking")
Signed-off-by: default avatarYunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent edecfa98

net/sched/sch_generic.c

+33 −15
Original line number Diff line number Diff line
@@ -1131,24 +1131,10 @@ EXPORT_SYMBOL(dev_activate); 


static void qdisc_deactivate(struct Qdisc *qdisc)

{

	bool nolock = qdisc->flags & TCQ_F_NOLOCK;



	if (qdisc->flags & TCQ_F_BUILTIN)

		return;

	if (test_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state))

		return;



	if (nolock)

		spin_lock_bh(&qdisc->seqlock);

	spin_lock_bh(qdisc_lock(qdisc));



	set_bit(__QDISC_STATE_DEACTIVATED, &qdisc->state);



	qdisc_reset(qdisc);



	spin_unlock_bh(qdisc_lock(qdisc));

	if (nolock)

		spin_unlock_bh(&qdisc->seqlock);

}



static void dev_deactivate_queue(struct net_device *dev,
@@ -1165,6 +1151,30 @@ static void dev_deactivate_queue(struct net_device *dev, 
	}

}



static void dev_reset_queue(struct net_device *dev,

			    struct netdev_queue *dev_queue,

			    void *_unused)

{

	struct Qdisc *qdisc;

	bool nolock;



	qdisc = dev_queue->qdisc_sleeping;

	if (!qdisc)

		return;



	nolock = qdisc->flags & TCQ_F_NOLOCK;



	if (nolock)

		spin_lock_bh(&qdisc->seqlock);

	spin_lock_bh(qdisc_lock(qdisc));



	qdisc_reset(qdisc);



	spin_unlock_bh(qdisc_lock(qdisc));

	if (nolock)

		spin_unlock_bh(&qdisc->seqlock);

}



static bool some_qdisc_is_busy(struct net_device *dev)

{

	unsigned int i;
@@ -1213,12 +1223,20 @@ void dev_deactivate_many(struct list_head *head) 
		dev_watchdog_down(dev);

	}



	/* Wait for outstanding qdisc-less dev_queue_xmit calls.

	/* Wait for outstanding qdisc-less dev_queue_xmit calls or

	 * outstanding qdisc enqueuing calls.

	 * This is avoided if all devices are in dismantle phase :

	 * Caller will call synchronize_net() for us

	 */

	synchronize_net();



	list_for_each_entry(dev, head, close_list) {

		netdev_for_each_tx_queue(dev, dev_reset_queue, NULL);



		if (dev_ingress_queue(dev))

			dev_reset_queue(dev, dev_ingress_queue(dev), NULL);

	}



	/* Wait for outstanding qdisc_run calls. */

	list_for_each_entry(dev, head, close_list) {

		while (some_qdisc_is_busy(dev)) {

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