From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937911AbcLOPWe (ORCPT ); Thu, 15 Dec 2016 10:22:34 -0500 Received: from mail-pg0-f51.google.com ([74.125.83.51]:34146 "EHLO mail-pg0-f51.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933253AbcLOPWc (ORCPT ); Thu, 15 Dec 2016 10:22:32 -0500 Subject: Re: CVE-2016-7097 causes acl leak To: Greg KH References: <3a180415-2f02-c9c0-e1e6-519b5d3115b7@android.com> <5c0398cb-9ef2-42f3-0c46-e2e65fe92da9@android.com> <20161214000005.GA29963@kroah.com> <3db72683-e810-38f8-87c8-dc7fa6a50aa6@android.com> <20161214233006.GB24234@kroah.com> Cc: Cong Wang , LKML , aneesh.kumar@linux.vnet.ibm.com, Jan Kara From: Mark Salyzyn Message-ID: <1a0f7aa9-baa9-29de-3d2d-1abc637c1b7b@android.com> Date: Thu, 15 Dec 2016 07:22:30 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.4.0 MIME-Version: 1.0 In-Reply-To: <20161214233006.GB24234@kroah.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/14/2016 03:30 PM, Greg KH wrote: > On Wed, Dec 14, 2016 at 12:20:50PM -0800, Mark Salyzyn wrote: >> On 12/13/2016 04:00 PM, Greg KH wrote: >>> On Tue, Dec 13, 2016 at 03:42:58PM -0800, Mark Salyzyn wrote: >>>> On 12/12/2016 10:26 PM, Cong Wang wrote: >>>>> On Mon, Dec 12, 2016 at 4:26 PM, Mark Salyzyn wrote: >>>>>> The leaks were introduced in 9p, gfs2, jfs and xfs drivers only. >>>>> Only the 9p case is obvious to me: >>>>> >>>>> diff --git a/fs/9p/acl.c b/fs/9p/acl.c >>>>> index b3c2cc7..082d227 100644 >>>>> --- a/fs/9p/acl.c >>>>> +++ b/fs/9p/acl.c >>>>> @@ -277,6 +277,7 @@ static int v9fs_xattr_set_acl(const struct >>>>> xattr_handler *handler, >>>>> case ACL_TYPE_ACCESS: >>>>> if (acl) { >>>>> struct iattr iattr; >>>>> + struct posix_acl *old_acl = acl; >>>>> >>>>> retval = posix_acl_update_mode(inode, >>>>> &iattr.ia_mode, &acl); >>>>> if (retval) >>>>> @@ -287,6 +288,7 @@ static int v9fs_xattr_set_acl(const struct >>>>> xattr_handler *handler, >>>>> * by the mode bits. So don't >>>>> * update ACL. >>>>> */ >>>>> + posix_acl_release(old_acl); >>>>> value = NULL; >>>>> size = 0; >>>>> } >>>>> >>>>> >>>>> The rest are anti-pattern (modifying parameters on stack via address) >>>>> but look correct. >>>> Greg KH: Beware that this similar fix needs to be applied to _backports_ to >>>> stable kernel trees on other filesystem driver that have the same pattern >>>> (with local posix_acl_release(acl) calls). I have found that depending on >>>> vintage these would include this driver 9p, and possibly gfs2, jfs and xfs. >>>> Be aware. >>> I don't understand what you mean here. What needs to be "backported" to >>> the stable tree? What commit in Linus's tree do I pick? If not a >>> commit there, where is it? >>> >>> totally confused, >>> >>> greg k-h >> In 3.10-stable if you took the original CVE-2016-7097 fix it could break >> four file system drivers, the fix for each would 'look like' this one fix >> for the 9p driver. > Did I take the fix in 3.10-stable? What was the git commit id? Is 3.10 > "broken" in this way? Is any other stable kernel broken? > > I still don't have any idea of what is going on here... > > greg k-h Nothing is going on here, it is a heads up, eventually CVE's get backported to stable as we do take them in through those paths. Telling you to be aware that the original commit causes a leak, and my experience has found that the leak affects these four file system drivers. -- Mark