linux-hardening - RE: [PATCH RFC] gcc-plugins: Handle GCC version mismatch for OOT modules

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <bb60fe817f5144929a527d1f5768dd1a@AcuMS.aculab.com>
Date:   Mon, 8 Mar 2021 09:39:42 +0000
From:   David Laight <David.Laight@...LAB.COM>
To:     'Josh Poimboeuf' <jpoimboe@...hat.com>,
        Masahiro Yamada <masahiroy@...nel.org>
CC:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>,
        "Linux Kbuild mailing list" <linux-kbuild@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Justin Forbes <jforbes@...hat.com>,
        Ondrej Mosnacek <omosnace@...hat.com>,
        Frank Eigler <fche@...hat.com>,
        Kees Cook <keescook@...omium.org>
Subject: RE: [PATCH RFC] gcc-plugins: Handle GCC version mismatch for OOT
 modules

> - "External modules must be built with the same GCC version"
> 
>   As has been stated repeatedly, by Linus and others, there's no
>   technical reason behind this claim.  It ignores the realities of how
>   distros release the kernel and compiler independently, with separate
>   cadences.  Minor variances in compiler version are ABI compatible.

Aren't major versions ABI compatible?
Otherwise it is a different architecture.

>   Also, for features which are dependent on compiler version, many of
>   those are now enabled by kbuild.  As I suggested to you previously,
>   kbuild should warn when such features get disabled (which can happen
>   due to a compiler/toolchain change or due to a .config copied from
>   another system).

Anything that is just an optimisation (or pessimisation) really
doesn't matter.
AFAICT most of these options are in the latter category.

One think people might do is download a kernel from kernel.org
and then build an extra module for it.
The compiler they have will be completely different.

	David

-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)