Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932793AbbEEB5a (ORCPT ); Mon, 4 May 2015 21:57:30 -0400 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:51870 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932427AbbEEBti (ORCPT ); Mon, 4 May 2015 21:49:38 -0400 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, "Alan Stern" , "Joe Lawrence" , "Greg Kroah-Hartman" Date: Tue, 05 May 2015 02:16:39 +0100 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) Subject: [PATCH 3.2 024/221] USB: fix use-after-free bug in usb_hcd_unlink_urb() In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.249 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2279 Lines: 70 3.2.69-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Alan Stern commit c99197902da284b4b723451c1471c45b18537cde upstream. The usb_hcd_unlink_urb() routine in hcd.c contains two possible use-after-free errors. The dev_dbg() statement at the end of the routine dereferences urb and urb->dev even though both structures may have been deallocated. This patch fixes the problem by storing urb->dev in a local variable (avoiding the dereference of urb) and moving the dev_dbg() up before the usb_put_dev() call. Signed-off-by: Alan Stern Reported-by: Joe Lawrence Tested-by: Joe Lawrence Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/usb/core/hcd.c | 16 ++++++++-------- 1 file changed, 8 insertions(+), 8 deletions(-) --- a/drivers/usb/core/hcd.c +++ b/drivers/usb/core/hcd.c @@ -1542,6 +1542,7 @@ static int unlink1(struct usb_hcd *hcd, int usb_hcd_unlink_urb (struct urb *urb, int status) { struct usb_hcd *hcd; + struct usb_device *udev = urb->dev; int retval = -EIDRM; unsigned long flags; @@ -1553,20 +1554,19 @@ int usb_hcd_unlink_urb (struct urb *urb, spin_lock_irqsave(&hcd_urb_unlink_lock, flags); if (atomic_read(&urb->use_count) > 0) { retval = 0; - usb_get_dev(urb->dev); + usb_get_dev(udev); } spin_unlock_irqrestore(&hcd_urb_unlink_lock, flags); if (retval == 0) { hcd = bus_to_hcd(urb->dev->bus); retval = unlink1(hcd, urb, status); - usb_put_dev(urb->dev); + if (retval == 0) + retval = -EINPROGRESS; + else if (retval != -EIDRM && retval != -EBUSY) + dev_dbg(&udev->dev, "hcd_unlink_urb %p fail %d\n", + urb, retval); + usb_put_dev(udev); } - - if (retval == 0) - retval = -EINPROGRESS; - else if (retval != -EIDRM && retval != -EBUSY) - dev_dbg(&urb->dev->dev, "hcd_unlink_urb %p fail %d\n", - urb, retval); return retval; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/