linux-kernel - Re: [PATCH v4 3/8] media: v4l2-core: compat: ignore native command codes

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Date:   Fri, 22 Nov 2019 13:29:56 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Sasha Levin <sashal@...nel.org>
Cc:     Mauro Carvalho Chehab <mchehab@...nel.org>,
        Hans Verkuil <hverkuil@...all.nl>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "# 3.4.x" <stable@...r.kernel.org>
Subject: Re: [PATCH v4 3/8] media: v4l2-core: compat: ignore native command codes

On Fri, Nov 22, 2019 at 8:00 AM Sasha Levin <sashal@...nel.org> wrote:
>
> Hi,
>
> [This is an automated email]
>
> This commit has been processed because it contains a -stable tag.
> The stable tag indicates that it's relevant for the following trees: all
>
> The bot has tested the following trees: v5.3.11, v4.19.84, v4.14.154, v4.9.201, v4.4.201.
>
> v5.3.11: Build OK!
> v4.19.84: Build OK!

Ok, good.

> v4.14.154: Failed to apply! Possible dependencies:
>     6dd0394f5fcd ("media: v4l2-compat-ioctl32: better name userspace pointers")
>     fef6cc6b3618 ("media: v4l2-compat-ioctl32: fix several __user annotations")

The fef6cc6b3618 is probably a candidate for backporting (it fixes smatch
and sparse warnings and should have no other effect), the 6dd0394f5fcd
may be a little too big (but also harmless).

The downside of not backporting the patch is that user space code built
with 64-bit time_t would get incorrect data rather than failing with an
error code on older kernels.

I do not expect to see backports of 64-bit time_t support to kernels older
than 4.19, so this probably won't matter much, but in theory it's still
possible that users can run into it.

> v4.9.201: Failed to apply! Possible dependencies:
>     6dd0394f5fcd ("media: v4l2-compat-ioctl32: better name userspace pointers")
>     a56bc171598c ("[media] v4l: compat: Prevent allocating excessive amounts of memory")
>     ba7ed691dcce ("[media] v4l2-compat-ioctl32: VIDIOC_S_EDID should return all fields on error")
>     fb9ffa6a7f7e ("[media] v4l: Add metadata buffer type and format")
>     fef6cc6b3618 ("media: v4l2-compat-ioctl32: fix several __user annotations")
>
> v4.4.201: Failed to apply! Possible dependencies:
>     0579e6e3a326 ("doc-rst: linux_tv: remove whitespaces")
>     17defc282fe6 ("Documentation: add meta-documentation for Sphinx and kernel-doc")
>     22cba31bae9d ("Documentation/sphinx: add basic working Sphinx configuration and build")
>     234d549662a7 ("doc-rst: video: use reference for VIDIOC_ENUMINPUT")
>     5377d91f3e88 ("doc-rst: linux_tv DocBook to reST migration (docs-next)")
>     6dd0394f5fcd ("media: v4l2-compat-ioctl32: better name userspace pointers")
>     7347081e8a52 ("doc-rst: linux_tv: simplify references")
>     789818845202 ("doc-rst: audio: Fix some cross references")
>     94fff0dc5333 ("doc-rst: dmx_fcalls: improve man-like format")
>     9e00ffca8cc7 ("doc-rst: querycap: fix troubles on some references")
>     af4a4d0db8ab ("doc-rst: linux_tv: Replace reference names to match ioctls")
>     c2b66cafdf02 ("[media] v4l: doc: Remove row numbers from tables")
>     e6702ee18e24 ("doc-rst: app-pri: Fix a bad reference")
>     fb9ffa6a7f7e ("[media] v4l: Add metadata buffer type and format")
>
>
> NOTE: The patch will not be queued to stable trees until it is upstream.
>
> How should we proceed with this patch?

I'm happy to provide a hand-backported version of the patch for the older
kernels if Mauro and Hans think we should do that, otherwise I think it's
we're fine with having it on 4.19+.

      Arnd