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Date:   Thu, 5 Oct 2023 11:42:38 +0200
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Subject: Re: [PATCH 0/9] drm: Annotate structs with __counted_by
To:     Kees Cook <keescook@chromium.org>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>
Cc:     Alex Deucher <alexdeucher@gmail.com>,
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References: <20230922173110.work.084-kees@kernel.org>
 <169601600138.3014939.8511343741428844249.b4-ty@chromium.org>
 <83cd056c-52ae-01dd-7576-42d41da64c26@gmail.com>
 <CADnq5_Ma2CrLYggJHKFEObsNmUoqJwb2p1xai5DfL=m43U6zEA@mail.gmail.com>
 <202310020952.E7DE0948C0@keescook>
 <10644b5f-b0a7-85ef-0658-2353ee14df0d@gmail.com>
 <202310021107.9BB46FB8E@keescook>
 <0be2dfa4-b6c1-f62a-66e1-615da7aa3c76@amd.com>
 <202310021122.B6DA850FB0@keescook>
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From:   =?UTF-8?Q?Christian_K=C3=B6nig?= <ckoenig.leichtzumerken@gmail.com>
In-Reply-To: <202310021122.B6DA850FB0@keescook>
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Am 02.10.23 um 20:22 schrieb Kees Cook:
> On Mon, Oct 02, 2023 at 08:11:41PM +0200, Christian König wrote:
>> Am 02.10.23 um 20:08 schrieb Kees Cook:
>>> On Mon, Oct 02, 2023 at 08:01:57PM +0200, Christian König wrote:
>>>> Am 02.10.23 um 18:53 schrieb Kees Cook:
>>>>> 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@gmail.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?
>>>> Probably best if the relevant maintainer pick them up individually.
>>>>
>>>> Some of those structures are filled in by firmware/hardware and only the
>>>> maintainers can judge if that value actually matches what the compiler
>>>> needs.
>>>>
>>>> We have cases where individual bits are used as flags or when the size is
>>>> byte swapped etc...
>>>>
>>>> Even Alex and I didn't immediately say how and where that field is actually
>>>> used and had to dig that up. That's where the confusion came from.
>>> Okay, I've dropped them all from my tree. Several had Acks/Reviews, so
>>> hopefully those can get picked up for the DRM tree?
>> I will pick those up to go through drm-misc-next.
>>
>> Going to ping maintainers once more when I'm not sure if stuff is correct or
>> not.
> Sounds great; thanks!

I wasn't 100% sure for the VC4 patch, but pushed the whole set to 
drm-misc-next anyway.

This also means that the patches are now auto merged into the drm-tip 
integration branch and should any build or unit test go boom we should 
notice immediately and can revert it pretty easily.

Thanks,
Christian.

>
> -Kees
>