From: tom.leiming@gmail.com <tom.leiming@gmail.com>
Date: Thu, 22 Mar 2012 03:22:18 +0000 (+0000)
Subject: usbnet: increase URB reference count before usb_unlink_urb
X-Git-Tag: v3.4-rc1~115^2~4
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0956a8c20b23d429e79ff86d4325583fc06f9eb4;p=pandora-kernel.git

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>
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