usbnet: increase URB reference count before usb_unlink_urb
authortom.leiming@gmail.com <tom.leiming@gmail.com>
Thu, 22 Mar 2012 03:22:18 +0000 (03:22 +0000)
committerDavid S. Miller <davem@davemloft.net>
Thu, 22 Mar 2012 23:32:34 +0000 (19:32 -0400)
commit0956a8c20b23d429e79ff86d4325583fc06f9eb4
tree65adc5a7fc8b19ca046ba661692a75a65fd04e88
parent1265fd616782ef03b98fd19f65c2b47fcd4ea11f
usbnet: increase URB reference count before usb_unlink_urb

Commit 4231d47e6fe69f061f96c98c30eaf9fb4c14b96d(net/usbnet: avoid
recursive locking in usbnet_stop()) fixes the recursive locking
problem by releasing the skb queue lock, but it makes usb_unlink_urb
racing with defer_bh, and the URB to being unlinked may be freed before
or during calling usb_unlink_urb, so use-after-free problem may be
triggerd inside usb_unlink_urb.

The patch fixes the use-after-free problem by increasing URB
reference count with skb queue lock held before calling
usb_unlink_urb, so the URB won't be freed until return from
usb_unlink_urb.

Cc: stable@kernel.org
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Oliver Neukum <oliver@neukum.org>
Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/usb/usbnet.c