Re: [PATCH] media: nxp: isi: Check whether pad is non-NULL before access

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Marek,

Thank you for the patch.

On Fri, Dec 01, 2023 at 04:06:04PM +0100, Marek Vasut wrote:
> The pad can be NULL if media controller routing is not set up correctly.
> Check whether the pad is NULL before using it, otherwise it is possible
> to achieve NULL pointer dereference.

Could you share more information about how to misconfigure the routing ?

> Fixes: cf21f328fcaf ("media: nxp: Add i.MX8 ISI driver")
> Signed-off-by: Marek Vasut <marex@denx.de>
> ---
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> Cc: Mauro Carvalho Chehab <mchehab@kernel.org>
> Cc: NXP Linux Team <linux-imx@nxp.com>
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: linux-arm-kernel@lists.infradead.org
> Cc: linux-media@vger.kernel.org
> ---
>  drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> index 792f031e032ae..44354931cf8a1 100644
> --- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> +++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> @@ -160,8 +160,14 @@ mxc_isi_crossbar_xlate_streams(struct mxc_isi_crossbar *xbar,
>  	}
>  
>  	pad = media_pad_remote_pad_first(&xbar->pads[sink_pad]);
> -	sd = media_entity_to_v4l2_subdev(pad->entity);
> +	if (!pad) {
> +		dev_dbg(xbar->isi->dev,
> +			"no pad connected to crossbar input %u\n",
> +			sink_pad);
> +		return ERR_PTR(-EPIPE);
> +	}
>  
> +	sd = media_entity_to_v4l2_subdev(pad->entity);
>  	if (!sd) {
>  		dev_dbg(xbar->isi->dev,
>  			"no entity connected to crossbar input %u\n",

-- 
Regards,

Laurent Pinchart