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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: 6b3ba9146f ("net: sched: allow qdiscs to handle locking")
Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Yunsheng Lin 2020-09-08 19:02:34 +08:00 committed by David S. Miller
parent edecfa98f6
commit 2fb541c862
1 changed files with 33 additions and 15 deletions
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48
net/sched/sch_generic.c
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@ -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)) {