Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:2 as permitted sender) client-ip=2620:137:e000::3:2;
MIME-Version: 1.0
References: <CAPDJoNtU9Vuh87PxDkxo+7M_Kg_K4PPNGksPuW_guFbChYu-jA@mail.gmail.com>
 <20220601155702.176588-1-ariel.miculas@gmail.com> <CAPDJoNvZmeeU+T94rp8BJ0+bH5pDXQCEKPHiQF0Kcu=JrRRfrg@mail.gmail.com>
 <CAPDJoNsb-HtfOQhD6ntZ8Hqx3fv3WAh1U5Jd3GzyN5EwO8znWA@mail.gmail.com>
 <CAPDJoNuR8pNa+rp-PG_eeS14EvpMBLAmjNf9JvL=+0QTpwww-w@mail.gmail.com>
 <d6bd3632-207e-b232-b4a1-0c592a3aaae9@csgroup.eu> <CAPDJoNvADrCj8L2RAthXVbBxMNrjbY_4pnHu0QtKKARgyoQ-QA@mail.gmail.com>
 <9afcdb29-db22-3f5c-b596-da7567b707ff@csgroup.eu>
In-Reply-To: <9afcdb29-db22-3f5c-b596-da7567b707ff@csgroup.eu>
From:   Ariel Miculas <ariel.miculas@gmail.com>
Date:   Wed, 27 Sep 2023 22:35:25 +0300
Message-ID: <CAPDJoNt1xzLHfVYDi09X8Tz-3urrepboW7-S=iM6TpWv=Qih7A@mail.gmail.com>
Subject: Re: Fwd: [PATCH] powerpc/ptrace: Fix buffer overflow when handling
 PTRACE_PEEKUSER and PTRACE_POKEUSER
To:     Christophe Leroy <christophe.leroy@csgroup.eu>
Cc:     "linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Wed, Sep 27, 2023 at 7:01=E2=80=AFPM Christophe Leroy
<christophe.leroy@csgroup.eu> wrote:
>
>
>
> Le 27/09/2023 =C3=A0 17:27, Ariel Miculas a =C3=A9crit :
> > I've forwarded this old email thread for visibility and discussion's
> > sake around my recent blog post [1][2]
>
> Ah, right, it's been superseded by
> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20220609133245.57=
3565-1-mpe@ellerman.id.au/
>
> So I mark the new one superseded as well.
>
> By the way, is your other patch still applicable, ref
> https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20220610102821.25=
2729-1-ariel.miculas@belden.com/
> ?

Well, I think it's better to explicitly access fpscr than to implicitly
overflow fpr into fpscr. Because in the implicit case you need to make sure
fpscr comes directly after fpr and this relationship is never modified (e.g=
.
someone refactors the code and puts fpscr before fpr).

Regards,
Ariel
>
> Thanks
> Christophe
>
> >
> > Regards,
> > Ariel
> >
> > [1] https://news.ycombinator.com/item?id=3D37671991
> > [2] https://www.reddit.com/r/programming/comments/16tf5ne/how_i_got_rob=
bed_of_my_first_kernel_contribution/?ref=3Dshare&ref_source=3Dlink