Date:   Mon, 2 Oct 2023 20:11:41 +0200
From:   Christian König <christian.koenig@....com>
To:     Kees Cook <keescook@...omium.org>,
        Christian König <ckoenig.leichtzumerken@...il.com>
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        linux-hardening@...r.kernel.org
Subject: Re: [PATCH 0/9] drm: Annotate structs with __counted_by

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@...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?
>> 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.

Christian.

>
> Thanks!
>
> -Kees
>

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