From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Kees Cook <keescook@chromium.org>
Cc:     LEROY Christophe <christophe.leroy@csgroup.eu>,
        kernel test robot <lkp@intel.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Paul Mackerras <paulus@samba.org>,
        Sudeep Holla <sudeep.holla@arm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Nicholas Piggin <npiggin@gmail.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "linux-hardening@vger.kernel.org" <linux-hardening@vger.kernel.org>
Subject: Re: [PATCH] powerpc/signal32: Use struct_group() to zero spe regs
In-Reply-To: <202111221247.B385EA2A8@keescook>
References: <20211118203604.1288379-1-keescook@chromium.org>
 <1e312cbd-cd52-ddce-f839-db765173c526@csgroup.eu>
 <87ilwkrbhz.fsf@mpe.ellerman.id.au> <202111221247.B385EA2A8@keescook>
Date:   Wed, 24 Nov 2021 11:08:25 +1100
Message-ID: <8735nmquti.fsf@mpe.ellerman.id.au>
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Kees Cook <keescook@chromium.org> writes:
> On Mon, Nov 22, 2021 at 04:43:36PM +1100, Michael Ellerman wrote:
>> LEROY Christophe <christophe.leroy@csgroup.eu> writes:
>> > Le 18/11/2021 =C3=A0 21:36, Kees Cook a =C3=A9crit=C2=A0:
>> >> In preparation for FORTIFY_SOURCE performing compile-time and run-time
>> >> field bounds checking for memset(), avoid intentionally writing across
>> >> neighboring fields.
>> >>=20
>> >> Add a struct_group() for the spe registers so that memset() can corre=
ctly reason
>> >> about the size:
>> >>=20
>> >>     In function 'fortify_memset_chk',
>> >>         inlined from 'restore_user_regs.part.0' at arch/powerpc/kerne=
l/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=3Dattribute-w=
arning]
>> >>       195 |    __write_overflow_field();
>> >>           |    ^~~~~~~~~~~~~~~~~~~~~~~~
>> >>=20
>> >> Reported-by: kernel test robot <lkp@intel.com>
>> >> Signed-off-by: Kees Cook <keescook@chromium.org>
>> >
>> > Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
>>=20
>> Acked-by: Michael Ellerman <mpe@ellerman.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.

cheers