From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933728AbcLNX35 (ORCPT ); Wed, 14 Dec 2016 18:29:57 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:38750 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933491AbcLNX34 (ORCPT ); Wed, 14 Dec 2016 18:29:56 -0500 Date: Wed, 14 Dec 2016 15:30:06 -0800 From: Greg KH To: Mark Salyzyn Cc: Cong Wang , LKML , aneesh.kumar@linux.vnet.ibm.com, Jan Kara Subject: Re: CVE-2016-7097 causes acl leak Message-ID: <20161214233006.GB24234@kroah.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3db72683-e810-38f8-87c8-dc7fa6a50aa6@android.com> User-Agent: Mutt/1.7.2 (2016-11-26) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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