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Commit 23663c87 authored by Tejun Heo's avatar Tejun Heo
Browse files

wimax/i2400m: fix i2400m->wake_tx_skb handling 



i2400m_net_wake_tx() sets ->wake_tx_skb with the given skb if
->wake_tx_ws is not pending; however, i2400m_wake_tx_work() could have
just started execution and haven't fetched -><wake_tx_skb yet.  The
previous packet will be leaked.

Update ->wake_tx_skb handling.

* i2400m_net_wake_tx() now tests whether the previous ->wake_tx_skb
  has been consumed by ->wake_tx_ws instead of testing work_pending().

* i2400m_net_wake_stop() is simplified similarly.  It always puts
  ->wake_tx_skb if non-NULL.

* Spurious ->wake_tx_skb dereference outside critical section dropped
  from i2400m_wake_tx_work().

Only compile tested.

Signed-off-by: default avatarTejun Heo <tj@kernel.org>
Acked-by: default avatarDan Williams <dcbw@redhat.com>
Cc: Inaky Perez-Gonzalez <inaky.perez-gonzalez@intel.com>
Cc: linux-wimax@intel.com
Cc: wimax@linuxwimax.org
parent ad72b3be

drivers/net/wimax/i2400m/netdev.c

+17 −14
Original line number Diff line number Diff line
@@ -156,7 +156,7 @@ void i2400m_wake_tx_work(struct work_struct *ws) 
	struct i2400m *i2400m = container_of(ws, struct i2400m, wake_tx_ws);

	struct net_device *net_dev = i2400m->wimax_dev.net_dev;

	struct device *dev = i2400m_dev(i2400m);

	struct sk_buff *skb = i2400m->wake_tx_skb;

	struct sk_buff *skb;

	unsigned long flags;



	spin_lock_irqsave(&i2400m->tx_lock, flags);
@@ -236,23 +236,26 @@ void i2400m_tx_prep_header(struct sk_buff *skb) 
void i2400m_net_wake_stop(struct i2400m *i2400m)

{

	struct device *dev = i2400m_dev(i2400m);

	struct sk_buff *wake_tx_skb;

	unsigned long flags;



	d_fnstart(3, dev, "(i2400m %p)\n", i2400m);

	/* See i2400m_hard_start_xmit(), references are taken there

	 * and here we release them if the work was still

	 * pending. Note we can't differentiate work not pending vs

	 * never scheduled, so the NULL check does that. */

	if (cancel_work_sync(&i2400m->wake_tx_ws) == 0

	    && i2400m->wake_tx_skb != NULL) {

		unsigned long flags;

		struct sk_buff *wake_tx_skb;

	/*

	 * See i2400m_hard_start_xmit(), references are taken there and

	 * here we release them if the packet was still pending.

	 */

	cancel_work_sync(&i2400m->wake_tx_ws);



	spin_lock_irqsave(&i2400m->tx_lock, flags);

		wake_tx_skb = i2400m->wake_tx_skb;	/* compat help */

		i2400m->wake_tx_skb = NULL;	/* compat help */

	wake_tx_skb = i2400m->wake_tx_skb;

	i2400m->wake_tx_skb = NULL;

	spin_unlock_irqrestore(&i2400m->tx_lock, flags);



	if (wake_tx_skb) {

		i2400m_put(i2400m);

		kfree_skb(wake_tx_skb);

	}



	d_fnend(3, dev, "(i2400m %p) = void\n", i2400m);

}
@@ -288,7 +291,7 @@ int i2400m_net_wake_tx(struct i2400m *i2400m, struct net_device *net_dev, 
	 * and if pending, release those resources. */

	result = 0;

	spin_lock_irqsave(&i2400m->tx_lock, flags);

	if (!work_pending(&i2400m->wake_tx_ws)) {

	if (!i2400m->wake_tx_skb) {

		netif_stop_queue(net_dev);

		i2400m_get(i2400m);

		i2400m->wake_tx_skb = skb_get(skb);	/* transfer ref count */