[PATCH v2] media: imx-mipi-csis: Check csis_fmt validity before use

[Laurent Pinchart]

Hi Marek,

On Wed, Feb 15, 2023 at 12:32:33AM +0100, Marek Vasut wrote:
> The find_csis_format() may return NULL in case supported format is not
> found, check the return value of find_csis_format() before using the
> result to avoid NULL pointer dereference.
> 
> Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Fixes: 11927d0fd0d0 ("media: imx-mipi-csis: Use V4L2 subdev active state")
> Signed-off-by: Marek Vasut <marex at denx.de>
> ---
> Cc: Fabio Estevam <festevam at gmail.com>
> Cc: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
> Cc: Mauro Carvalho Chehab <mchehab at kernel.org>
> Cc: NXP Linux Team <linux-imx at nxp.com>
> Cc: Pengutronix Kernel Team <kernel at pengutronix.de>
> Cc: Philipp Zabel <p.zabel at pengutronix.de>
> Cc: Rui Miguel Silva <rmfrfs at gmail.com>
> Cc: Sascha Hauer <s.hauer at pengutronix.de>
> Cc: Shawn Guo <shawnguo at kernel.org>
> Cc: linux-arm-kernel at lists.infradead.org
> Cc: linux-media at vger.kernel.org
> ---
> V2: Add blank line
> ---
>  drivers/media/platform/nxp/imx-mipi-csis.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/media/platform/nxp/imx-mipi-csis.c b/drivers/media/platform/nxp/imx-mipi-csis.c
> index e99633565463e..2731ae94cb031 100644
> --- a/drivers/media/platform/nxp/imx-mipi-csis.c
> +++ b/drivers/media/platform/nxp/imx-mipi-csis.c
> @@ -1109,6 +1109,9 @@ static int mipi_csis_get_frame_desc(struct v4l2_subdev *sd, unsigned int pad,
>  	csis_fmt = find_csis_format(fmt->code);
>  	v4l2_subdev_unlock_state(state);
>  
> +	if (!csis_fmt)
> +		return -EINVAL;

I miss this when reviewing v1, would -EPIPE be a better error code ?
Essentially, this error occurs when trying to start a pipeline where the
sensor has been configured to produce a format not supported by the
CSI-2 receiver. -EINVAL being used everywhere, it makes it more
difficult for users to figure out where the failure may come from. We
already use -EPIPE in many places when validating the pipeline, so I
think it would be an appropriate option here.

If you're fine with this there's no need to send a v3, I'll update the
error code in the pull request.

> +
>  	fd->type = V4L2_MBUS_FRAME_DESC_TYPE_PARALLEL;
>  	fd->num_entries = 1;
>  

-- 
Regards,

Laurent Pinchart