[ 3.5.y.z extended stable ] Patch "net: usb: Fix memory leak on Tx data path" has been added to staging queue

Herton Ronaldo Krzesinski herton.krzesinski at canonical.com
Wed Dec 12 05:11:09 UTC 2012

This is a note to let you know that I have just added a patch titled

    net: usb: Fix memory leak on Tx data path

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:


If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see



>From 834ffb23f3593ed395b8b915ea0f5f7c56620373 Mon Sep 17 00:00:00 2001
From: Hemant Kumar <hemantk at codeaurora.org>
Date: Thu, 25 Oct 2012 18:17:54 +0000
Subject: [PATCH] net: usb: Fix memory leak on Tx data path

commit 39707c2a3ba5011038b363f84d37c8a98d2d9db1 upstream.

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

Signed-off-by: Hemant Kumar <hemantk at codeaurora.org>
Acked-by: Oliver Neukum <oneukum at suse.de>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski at canonical.com>
 drivers/net/usb/usbnet.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c
index f2716a4..a936201 100644
--- a/drivers/net/usb/usbnet.c
+++ b/drivers/net/usb/usbnet.c
@@ -1161,6 +1161,7 @@ netdev_tx_t usbnet_start_xmit (struct sk_buff *skb,
 		usb_anchor_urb(urb, &dev->deferred);
 		/* no use to process more packets */
+		usb_put_urb(urb);
 		spin_unlock_irqrestore(&dev->txq.lock, flags);
 		netdev_dbg(dev->net, "Delaying transmission for resumption\n");
 		goto deferred;
@@ -1313,6 +1314,8 @@ void usbnet_disconnect (struct usb_interface *intf)


+	usb_scuttle_anchored_urbs(&dev->deferred);
 	if (dev->driver_info->unbind)
 		dev->driver_info->unbind (dev, intf);


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