linux-kernel - Re: [PATCH] powerpc/signal32: Use struct

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Message-ID: <202112011054.B56B09FEF@keescook>
Date:   Wed, 1 Dec 2021 10:55:05 -0800
From:   Kees Cook <keescook@...omium.org>
To:     Michael Ellerman <mpe@...erman.id.au>
Cc:     LEROY Christophe <christophe.leroy@...roup.eu>,
        kernel test robot <lkp@...el.com>,
        Benjamin Herrenschmidt <benh@...nel.crashing.org>,
        Paul Mackerras <paulus@...ba.org>,
        Sudeep Holla <sudeep.holla@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Nicholas Piggin <npiggin@...il.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@...ux.ibm.com>,
        "Eric W. Biederman" <ebiederm@...ssion.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "linux-hardening@...r.kernel.org" <linux-hardening@...r.kernel.org>
Subject: Re: [PATCH] powerpc/signal32: Use struct_group() to zero spe regs

On Wed, Nov 24, 2021 at 11:08:25AM +1100, Michael Ellerman wrote:
> Kees Cook <keescook@...omium.org> writes:
> > On Mon, Nov 22, 2021 at 04:43:36PM +1100, Michael Ellerman wrote:
> >> LEROY Christophe <christophe.leroy@...roup.eu> writes:
> >> > Le 18/11/2021 à 21:36, Kees Cook a écrit :
> >> >> In preparation for FORTIFY_SOURCE performing compile-time and run-time
> >> >> field bounds checking for memset(), avoid intentionally writing across
> >> >> neighboring fields.
> >> >> 
> >> >> Add a struct_group() for the spe registers so that memset() can correctly reason
> >> >> about the size:
> >> >> 
> >> >>     In function 'fortify_memset_chk',
> >> >>         inlined from 'restore_user_regs.part.0' at arch/powerpc/kernel/signal_32.c:539:3:
> >> >>     >> include/linux/fortify-string.h:195:4: error: call to '__write_overflow_field' declared with attribute warning: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Werror=attribute-warning]
> >> >>       195 |    __write_overflow_field();
> >> >>           |    ^~~~~~~~~~~~~~~~~~~~~~~~
> >> >> 
> >> >> Reported-by: kernel test robot <lkp@...el.com>
> >> >> Signed-off-by: Kees Cook <keescook@...omium.org>
> >> >
> >> > Reviewed-by: Christophe Leroy <christophe.leroy@...roup.eu>
> >> 
> >> Acked-by: Michael Ellerman <mpe@...erman.id.au>
> >
> > Thanks! Should I take this via my tree, or do you want to take it via
> > ppc?
> 
> I don't mind. If it's easier for you to take it as part of an existing
> series then do that, otherwise I can pick it up.

Most of the other patches are going via other maintainers, so I'd love
it if ppc could snag this one too. :)

Thanks!

-Kees

-- 
Kees Cook