From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751523AbdKTPrJ (ORCPT ); Mon, 20 Nov 2017 10:47:09 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:39776 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751359AbdKTPrG (ORCPT ); Mon, 20 Nov 2017 10:47:06 -0500 Subject: Re: [PATCH] apparmor: initialized returned struct aa_perms To: Arnd Bergmann Cc: James Morris , "Serge E. Hallyn" , Kees Cook , Stephen Rothwell , Seth Arnold , Michal Hocko , Vlastimil Babka , LSM List , Linux Kernel Mailing List References: <20170915195620.1561044-1-arnd@arndb.de> From: John Johansen Organization: Canonical Message-ID: <4759b591-6603-7424-1758-fd0d23e6efed@canonical.com> Date: Mon, 20 Nov 2017 07:47:00 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/20/2017 06:00 AM, Arnd Bergmann wrote: > On Mon, Sep 25, 2017 at 4:29 PM, John Johansen > wrote: >> On 09/15/2017 03:55 PM, Arnd Bergmann wrote: >>> gcc-4.4 points out suspicious code in compute_mnt_perms, where >>> the aa_perms structure is only partially initialized before getting >>> returned: >>> >>> security/apparmor/mount.c: In function 'compute_mnt_perms': >>> security/apparmor/mount.c:227: error: 'perms.prompt' is used uninitialized in this function >>> security/apparmor/mount.c:227: error: 'perms.hide' is used uninitialized in this function >>> security/apparmor/mount.c:227: error: 'perms.cond' is used uninitialized in this function >>> security/apparmor/mount.c:227: error: 'perms.complain' is used uninitialized in this function >>> security/apparmor/mount.c:227: error: 'perms.stop' is used uninitialized in this function >>> security/apparmor/mount.c:227: error: 'perms.deny' is used uninitialized in this function >>> >>> Returning or assigning partially initialized structures is a bit tricky, >>> in particular it is explicitly allowed in c99 to assign a partially >>> intialized structure to another, as long as only members are read that >>> have been initialized earlier. Looking at what various compilers do here, >>> the version that produced the warning copied unintialized stack data, >>> while newer versions (and also clang) either set the other members to >>> zero or don't update the parts of the return buffer that are not modified >>> in the temporary structure, but they never warn about this. >>> >>> In case of apparmor, it seems better to be a little safer and always >>> initialize the aa_perms structure. Most users already do that, this >>> changes the remaining ones, including the one instance that I got the >>> warning for. >>> >>> Fixes: fa488437d0f9 ("apparmor: add mount mediation") >>> Signed-off-by: Arnd Bergmann >> >> I've pulled this into apparmor-next > > It apparently never made it into mainline. What happened? > > Arnd > Its in apparmor-next and is going with today's pull request