Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932293Ab2EDUpb (ORCPT ); Fri, 4 May 2012 16:45:31 -0400 Received: from mail-pz0-f45.google.com ([209.85.210.45]:61380 "EHLO mail-pz0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932279Ab2EDUp2 (ORCPT ); Fri, 4 May 2012 16:45:28 -0400 Message-Id: <20120504204226.884649355@linuxfoundation.org> User-Agent: quilt/0.60-19.1 Date: Fri, 04 May 2012 13:42:53 -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, Oliver Neukum , =?UTF-8?q?Bj=C3=B8rn=20Mork?= Subject: [ 29/75] USB: cdc-wdm: fix race leading leading to memory corruption In-Reply-To: <20120504204258.GA12552@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1857 Lines: 63 3.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Oliver Neukum commit 5c22837adca7c30b66121cf18ad3e160134268d4 upstream. This patch fixes a race whereby a pointer to a buffer would be overwritten while the buffer was in use leading to a double free and a memory leak. This causes crashes. This bug was introduced in 2.6.34 Signed-off-by: Oliver Neukum Tested-by: Bjørn Mork Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-wdm.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -108,8 +108,9 @@ static void wdm_out_callback(struct urb spin_lock(&desc->iuspin); desc->werr = urb->status; spin_unlock(&desc->iuspin); - clear_bit(WDM_IN_USE, &desc->flags); kfree(desc->outbuf); + desc->outbuf = NULL; + clear_bit(WDM_IN_USE, &desc->flags); wake_up(&desc->wait); } @@ -312,7 +313,7 @@ static ssize_t wdm_write if (we < 0) return -EIO; - desc->outbuf = buf = kmalloc(count, GFP_KERNEL); + buf = kmalloc(count, GFP_KERNEL); if (!buf) { rv = -ENOMEM; goto outnl; @@ -376,10 +377,12 @@ static ssize_t wdm_write req->wIndex = desc->inum; req->wLength = cpu_to_le16(count); set_bit(WDM_IN_USE, &desc->flags); + desc->outbuf = buf; rv = usb_submit_urb(desc->command, GFP_KERNEL); if (rv < 0) { kfree(buf); + desc->outbuf = NULL; clear_bit(WDM_IN_USE, &desc->flags); dev_err(&desc->intf->dev, "Tx URB error: %d\n", rv); } else { -- 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/