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 <202305301600.EEF0BAAD@keescook>
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From:   Song Liu <song@kernel.org>
Date:   Tue, 30 May 2023 16:39:32 -0700
Message-ID: <CAPhsuW4Z73azgqXVekYtibqOSKsx8XPU1FVwvZ7XOU5Qee7oAQ@mail.gmail.com>
Subject: Re: [PATCH v2] md/raid5: Convert stripe_head's "dev" to flexible
 array member
To:     Kees Cook <keescook@chromium.org>
Cc:     Christoph Hellwig <hch@infradead.org>, linux-raid@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org
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On Tue, May 30, 2023 at 4:00=E2=80=AFPM Kees Cook <keescook@chromium.org> w=
rote:
>
> On Tue, May 23, 2023 at 10:43:52AM -0700, Song Liu wrote:
> > On Mon, May 22, 2023 at 2:21=E2=80=AFPM Kees Cook <keescook@chromium.or=
g> wrote:
> > >
> > > Replace old-style 1-element array of "dev" in struct stripe_head with
> > > modern C99 flexible array. In the future, we can additionally annotat=
e
> > > it with the run-time size, found in the "disks" member.
> > >
> > > Cc: Christoph Hellwig <hch@infradead.org>
> > > Cc: linux-raid@vger.kernel.org
> > > Signed-off-by: Kees Cook <keescook@chromium.org>
> > > ---
> > > It looks like this memory calculation:
> > >
> > >         memory =3D conf->min_nr_stripes * (sizeof(struct stripe_head)=
 +
> > >                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 10=
24;
> > >
> > > ... was already buggy (i.e. it included the single "dev" bytes in the
> > > result). However, I'm not entirely sure if that is the right analysis=
,
> > > since "dev" is not related to struct bio nor PAGE_SIZE?
> > >
> > > v1: https://lore.kernel.org/all/20230517233313.never.130-kees@kernel.=
org/
> > > v2: use new struct_size_t() helper from
> > >     https://lore.kernel.org/lkml/20230522211810.never.421-kees@kernel=
.org/
> >
> > LTGM. Thanks!
>
> Thanks!
>
> > I will hold this for a while until struct_size_t() merged.
>
> Since my tree will introduce struct_size_t(), I will just carry it
> there.

Sounds good! You can add

Acked-by: Song Liu <song@kernel.org>

Thanks,
Song