From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757786Ab2JAXDq (ORCPT ); Mon, 1 Oct 2012 19:03:46 -0400 Received: from 1wt.eu ([62.212.114.60]:35683 "EHLO 1wt.eu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752597Ab2JAXDo (ORCPT ); Mon, 1 Oct 2012 19:03:44 -0400 Message-Id: <20121001225158.929563132@1wt.eu> User-Agent: quilt/0.48-1 Date: Tue, 02 Oct 2012 00:52:28 +0200 From: Willy Tarreau To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: stable@kernel.org, Sebastian Andrzej Siewior , Alan Stern , Oliver Neukum , Ming Lei , Greg Kroah-Hartman , "David S. Miller" , Willy Tarreau Subject: [ 031/180] usbnet: increase URB reference count before usb_unlink_urb In-Reply-To: <6a854f579a99b4fe2efaca1057e8ae22@local> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.32-longterm 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: stable@kernel.org 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: Willy Tarreau --- drivers/net/usb/usbnet.c | 9 +++++++++ 1 files changed, 9 insertions(+), 0 deletions(-) diff --git a/drivers/net/usb/usbnet.c b/drivers/net/usb/usbnet.c index da33dce..a92a415 100644 --- a/drivers/net/usb/usbnet.c +++ b/drivers/net/usb/usbnet.c @@ -584,6 +584,14 @@ static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q) 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 @@ -592,6 +600,7 @@ static int unlink_urbs (struct usbnet *dev, struct sk_buff_head *q) devdbg (dev, "unlink urb err, %d", retval); else count++; + usb_put_urb(urb); spin_lock_irqsave(&q->lock, flags); } spin_unlock_irqrestore (&q->lock, flags); -- 1.7.2.1.45.g54fbc