From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935071Ab2C3VHE (ORCPT ); Fri, 30 Mar 2012 17:07:04 -0400 Received: from mail-gy0-f174.google.com ([209.85.160.174]:55577 "EHLO mail-gy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935121Ab2C3VGv (ORCPT ); Fri, 30 Mar 2012 17:06:51 -0400 Message-Id: <20120330195732.521933122@linuxfoundation.org> User-Agent: quilt/0.60-19.1 Date: Fri, 30 Mar 2012 12:58:34 -0700 From: Greg KH To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Sebastian Andrzej Siewior , Alan Stern , Oliver Neukum , Dave Jones , Ming Lei , "David S. Miller" Subject: [ 072/108] usbnet: increase URB reference count before usb_unlink_urb In-Reply-To: <20120330195812.GA31833@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: "tom.leiming@gmail.com" commit 0956a8c20b23d429e79ff86d4325583fc06f9eb4 upstream. 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: Sebastian Andrzej Siewior Cc: Alan Stern Cc: Oliver Neukum Reported-by: Dave Jones Signed-off-by: Ming Lei Acked-by: Greg Kroah-Hartman Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- drivers/net/usb/usbnet.c | 9 +++++++++ 1 file changed, 9 insertions(+) --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -585,6 +585,14 @@ static int unlink_urbs (struct usbnet *d entry = (struct skb_data *) skb->cb; urb = entry->urb; + /* + * Get reference count of the URB to avoid it to be + * freed during usb_unlink_urb, which may trigger + * use-after-free problem inside usb_unlink_urb since + * usb_unlink_urb is always racing with .complete + * handler(include defer_bh). + */ + usb_get_urb(urb); spin_unlock_irqrestore(&q->lock, flags); // during some PM-driven resume scenarios, // these (async) unlinks complete immediately @@ -593,6 +601,7 @@ static int unlink_urbs (struct usbnet *d netdev_dbg(dev->net, "unlink urb err, %d\n", retval); else count++; + usb_put_urb(urb); spin_lock_irqsave(&q->lock, flags); } spin_unlock_irqrestore (&q->lock, flags);