Message-ID: <202310020952.E7DE0948C0@keescook>
Date:   Mon, 2 Oct 2023 09:53:21 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Alex Deucher <alexdeucher@...il.com>
Cc:     Christian König 
        <ckoenig.leichtzumerken@...il.com>,
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        Christian König <christian.koenig@....com>,
        Zack Rusin <zackr@...are.com>, linux-hardening@...r.kernel.org
Subject: Re: [PATCH 0/9] drm: Annotate structs with __counted_by

On Mon, Oct 02, 2023 at 11:06:19AM -0400, Alex Deucher wrote:
> On Mon, Oct 2, 2023 at 5:20 AM Christian König
> <ckoenig.leichtzumerken@...il.com> wrote:
> >
> > Am 29.09.23 um 21:33 schrieb Kees Cook:
> > > On Fri, 22 Sep 2023 10:32:05 -0700, Kees Cook wrote:
> > >> This is a batch of patches touching drm for preparing for the coming
> > >> implementation by GCC and Clang of the __counted_by attribute. Flexible
> > >> array members annotated with __counted_by can have their accesses
> > >> bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS (for array
> > >> indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family functions).
> > >>
> > >> As found with Coccinelle[1], add __counted_by to structs that would
> > >> benefit from the annotation.
> > >>
> > >> [...]
> > > Since this got Acks, I figure I should carry it in my tree. Let me know
> > > if this should go via drm instead.
> > >
> > > Applied to for-next/hardening, thanks!
> > >
> > > [1/9] drm/amd/pm: Annotate struct smu10_voltage_dependency_table with __counted_by
> > >        https://git.kernel.org/kees/c/a6046ac659d6
> >
> > STOP! In a follow up discussion Alex and I figured out that this won't work.

I'm so confused; from the discussion I saw that Alex said both instances
were false positives?

> >
> > The value in the structure is byte swapped based on some firmware
> > endianness which not necessary matches the CPU endianness.
> 
> SMU10 is APU only so the endianess of the SMU firmware and the CPU
> will always match.

Which I think is what is being said here?

> > Please revert that one from going upstream if it's already on it's way.
> >
> > And because of those reasons I strongly think that patches like this
> > should go through the DRM tree :)

Sure, that's fine -- please let me know. It was others Acked/etc. Who
should carry these patches?

Thanks!

-Kees


> >
> > Regards,
> > Christian.
> >
> > > [2/9] drm/amdgpu/discovery: Annotate struct ip_hw_instance with __counted_by
> > >        https://git.kernel.org/kees/c/4df33089b46f
> > > [3/9] drm/i915/selftests: Annotate struct perf_series with __counted_by
> > >        https://git.kernel.org/kees/c/ffd3f823bdf6
> > > [4/9] drm/msm/dpu: Annotate struct dpu_hw_intr with __counted_by
> > >        https://git.kernel.org/kees/c/2de35a989b76
> > > [5/9] drm/nouveau/pm: Annotate struct nvkm_perfdom with __counted_by
> > >        https://git.kernel.org/kees/c/188aeb08bfaa
> > > [6/9] drm/vc4: Annotate struct vc4_perfmon with __counted_by
> > >        https://git.kernel.org/kees/c/59a54dc896c3
> > > [7/9] drm/virtio: Annotate struct virtio_gpu_object_array with __counted_by
> > >        https://git.kernel.org/kees/c/5cd476de33af
> > > [8/9] drm/vmwgfx: Annotate struct vmw_surface_dirty with __counted_by
> > >        https://git.kernel.org/kees/c/b426f2e5356a
> > > [9/9] drm/v3d: Annotate struct v3d_perfmon with __counted_by
> > >        https://git.kernel.org/kees/c/dc662fa1b0e4
> > >
> > > Take care,
> > >
> >

-- 
Kees Cook

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