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Commit 14a0d635 authored by Oliver Neukum's avatar Oliver Neukum Committed by David S. Miller
Browse files

usbnet: include wait queue head in device structure 



This fixes a race which happens by freeing an object on the stack.
Quoting Julius:
> The issue is
> that it calls usbnet_terminate_urbs() before that, which temporarily
> installs a waitqueue in dev->wait in order to be able to wait on the
> tasklet to run and finish up some queues. The waiting itself looks
> okay, but the access to 'dev->wait' is totally unprotected and can
> race arbitrarily. I think in this case usbnet_bh() managed to succeed
> it's dev->wait check just before usbnet_terminate_urbs() sets it back
> to NULL. The latter then finishes and the waitqueue_t structure on its
> stack gets overwritten by other functions halfway through the
> wake_up() call in usbnet_bh().

The fix is to just not allocate the data structure on the stack.
As dev->wait is abused as a flag it also takes a runtime PM change
to fix this bug.

Signed-off-by: default avatarOliver Neukum <oneukum@suse.de>
Reported-by: default avatarGrant Grundler <grundler@google.com>
Tested-by: default avatarGrant Grundler <grundler@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 681daee2

drivers/net/usb/usbnet.c

+19 −14
Original line number Diff line number Diff line
@@ -752,14 +752,12 @@ EXPORT_SYMBOL_GPL(usbnet_unlink_rx_urbs); 
// precondition: never called in_interrupt

static void usbnet_terminate_urbs(struct usbnet *dev)

{

	DECLARE_WAIT_QUEUE_HEAD_ONSTACK(unlink_wakeup);

	DECLARE_WAITQUEUE(wait, current);

	int temp;



	/* ensure there are no more active urbs */

	add_wait_queue(&unlink_wakeup, &wait);

	add_wait_queue(&dev->wait, &wait);

	set_current_state(TASK_UNINTERRUPTIBLE);

	dev->wait = &unlink_wakeup;

	temp = unlink_urbs(dev, &dev->txq) +

		unlink_urbs(dev, &dev->rxq);
@@ -773,15 +771,14 @@ static void usbnet_terminate_urbs(struct usbnet *dev) 
				  "waited for %d urb completions\n", temp);

	}

	set_current_state(TASK_RUNNING);

	dev->wait = NULL;

	remove_wait_queue(&unlink_wakeup, &wait);

	remove_wait_queue(&dev->wait, &wait);

}



int usbnet_stop (struct net_device *net)

{

	struct usbnet		*dev = netdev_priv(net);

	struct driver_info	*info = dev->driver_info;

	int			retval;

	int			retval, pm;



	clear_bit(EVENT_DEV_OPEN, &dev->flags);

	netif_stop_queue (net);
@@ -791,6 +788,8 @@ int usbnet_stop (struct net_device *net) 
		   net->stats.rx_packets, net->stats.tx_packets,

		   net->stats.rx_errors, net->stats.tx_errors);



	/* to not race resume */

	pm = usb_autopm_get_interface(dev->intf);

	/* allow minidriver to stop correctly (wireless devices to turn off

	 * radio etc) */

	if (info->stop) {
@@ -817,6 +816,9 @@ int usbnet_stop (struct net_device *net) 
	dev->flags = 0;

	del_timer_sync (&dev->delay);

	tasklet_kill (&dev->bh);

	if (!pm)

		usb_autopm_put_interface(dev->intf);



	if (info->manage_power &&

	    !test_and_clear_bit(EVENT_NO_RUNTIME_PM, &dev->flags))

		info->manage_power(dev, 0);
@@ -1437,11 +1439,12 @@ static void usbnet_bh (unsigned long param) 
	/* restart RX again after disabling due to high error rate */

	clear_bit(EVENT_RX_KILL, &dev->flags);



	// waiting for all pending urbs to complete?

	if (dev->wait) {

		if ((dev->txq.qlen + dev->rxq.qlen + dev->done.qlen) == 0) {

			wake_up (dev->wait);

		}

	/* waiting for all pending urbs to complete?

	 * only then can we forgo submitting anew

	 */

	if (waitqueue_active(&dev->wait)) {

		if (dev->txq.qlen + dev->rxq.qlen + dev->done.qlen == 0)

			wake_up_all(&dev->wait);



	// or are we maybe short a few urbs?

	} else if (netif_running (dev->net) &&
@@ -1580,6 +1583,7 @@ usbnet_probe (struct usb_interface *udev, const struct usb_device_id *prod) 
	dev->driver_name = name;

	dev->msg_enable = netif_msg_init (msg_level, NETIF_MSG_DRV

				| NETIF_MSG_PROBE | NETIF_MSG_LINK);

	init_waitqueue_head(&dev->wait);

	skb_queue_head_init (&dev->rxq);

	skb_queue_head_init (&dev->txq);

	skb_queue_head_init (&dev->done);
@@ -1791,9 +1795,10 @@ int usbnet_resume (struct usb_interface *intf) 
		spin_unlock_irq(&dev->txq.lock);



		if (test_bit(EVENT_DEV_OPEN, &dev->flags)) {

			/* handle remote wakeup ASAP */

			if (!dev->wait &&

				netif_device_present(dev->net) &&

			/* handle remote wakeup ASAP

			 * we cannot race against stop

			 */

			if (netif_device_present(dev->net) &&

				!timer_pending(&dev->delay) &&

				!test_bit(EVENT_RX_HALT, &dev->flags))

					rx_alloc_submit(dev, GFP_NOIO);

include/linux/usb/usbnet.h

+1 −1
Original line number Diff line number Diff line
@@ -30,7 +30,7 @@ struct usbnet { 
	struct driver_info	*driver_info;

	const char		*driver_name;

	void			*driver_priv;

	wait_queue_head_t	*wait;

	wait_queue_head_t	wait;

	struct mutex		phy_mutex;

	unsigned char		suspend_count;

	unsigned char		pkt_cnt, pkt_err;