net: usb: Fix memory leak on Tx data path

Driver anchors the tx urbs and defers the urb submission if
a transmit request comes when the interface is suspended.
Anchoring urb increments the urb reference count. These
deferred urbs are later accessed by calling usb_get_from_anchor()
for submission during interface resume. usb_get_from_anchor()
unanchors the urb but urb reference count remains same.
This causes the urb reference count to remain non-zero
after usb_free_urb() gets called and urb never gets freed.
Hence call usb_put_urb() after anchoring the urb to properly
balance the reference count for these deferred urbs. Also,
unanchor these deferred urbs during disconnect, to free them
up.

Signed-off-by: Hemant Kumar <[email protected]>
Acked-by: Oliver Neukum <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

Author: Hemant Kumar

drivers/net/usb/usbnet.c

@@ -1158,6 +1158,7 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
 		usb_anchor_urb(urb, &dev->deferred);
 		/* no use to process more packets */
 		netif_stop_queue(net);
+		usb_put_urb(urb);
 		spin_unlock_irqrestore(&dev->txq.lock, flags);
 		netdev_dbg(dev->net, "Delaying transmission for resumption\n");
 		goto deferred;
@@ -1310,6 +1311,8 @@ void usbnet_disconnect (struct usb_interface *intf)
 
 	cancel_work_sync(&dev->kevent);
 
+	usb_scuttle_anchored_urbs(&dev->deferred);
+
 	if (dev->driver_info->unbind)
 		dev->driver_info->unbind (dev, intf);