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Date: Tue, 18 Aug 2026 08:31:08 +0200
From: Jacopo Mondi <jacopo.mondi@ideasonboard.com>
To: David CARLIER <devnexen@gmail.com>
Cc: Jacopo Mondi <jacopo.mondi@ideasonboard.com>, 
	Mauro Carvalho Chehab <mchehab@kernel.org>, Michael Riesch <michael.riesch@collabora.com>, 
	Daniel Scally <dan.scally@ideasonboard.com>, Laurent Pinchart <laurent.pinchart+renesas@ideasonboard.com>, 
	Hans Verkuil <hverkuil+cisco@kernel.org>, stable@vger.kernel.org, 
	Sakari Ailus <sakari.ailus@linux.intel.com>, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] media: v4l2-isp: reject zero-sized parameter blocks
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In-Reply-To: <CA+XhMqxY3u5YR06j8jX2+wCwX95vQrb5EVH39GvuJXrwA48XWw@mail.gmail.com>

Hi David,

On Mon, Aug 17, 2026 at 05:19:18PM +0100, David CARLIER wrote:
> On Mon, Aug 17, 2026 at 05:56:30PM +0200, Jacopo Mondi wrote:
> > Should we instead deman that all entries provided by the driver are
> > populated by failing validation if info->size == 0 ?
>
> Good idea, and I'd rather keep both in v2 if you don't mind - they
> guard different things.
>
> info->size == 0 is about the driver table, and it lets us answer
> "this driver doesn't handle that type" rather than carrying on with
> an empty entry and a NULL block_validate.

Do you think we should fail validation because the info table has
holes or we should simply skip entries with info->size == 0 ?

I'm leaning towards the latter fwiw

>
> block->size < sizeof(*block) is about the buffer coming from
> userspace: a block's size includes its header, so anything smaller is
> malformed no matter what the table says, and it keeps the loop moving
> without depending on the table at all.
>
> Both are a couple of lines, so dropping either one is no trouble if
> you prefer.
>
> > Right.. you might have seen ?
> > https://patchwork.linuxtv.org/project/linux-media/list/?series=29170
>
> I hadn't, thanks. That takes care of the rppx1 side, so there's
> nothing left for me to send there and I'll stick to the core change.
>
> I'll reword the commit message so it doesn't lean on rppx1, and keep
> Cc: stable unless you disagree.
>

Yes thanks, as v4l2-isp went in in v6.19 this is worth a Fixes tag I
think..


> Cheers.