Re: [PATCH v2 1/6] media: nxp: imx8-isi: Fix stream ID validation bypass in crossbar routing

[Frank Li]

On Mon, Jul 20, 2026 at 11:34:03AM +0800, Guoniu Zhou wrote:
> The crossbar routing validation has a critical bug where it validates
> the wrong routing table, allowing userspace to bypass validation entirely.
>
> The __mxc_isi_crossbar_set_routing() function is called to validate and
> apply a new routing table from userspace. However, the validation loop
> iterates over state->routing (the currently active routing table) instead
> of the routing parameter (the new table being validated):
>
>     for_each_active_route(&state->routing, route) {
>
> This means userspace can submit any invalid routing configuration and it
> will pass validation as long as the currently active routing is valid.
> This is a security issue as it allows userspace to configure routes that
> violate hardware constraints, potentially causing undefined hardware
> behavior.
>
> Fix by validating the routing table that will actually be applied.
>
> Fixes: cf21f328fcaf ("media: nxp: Add i.MX8 ISI driver")
> Cc: stable@xxxxxxxxxxxxxxx
> Signed-off-by: Guoniu Zhou <guoniu.zhou@xxxxxxxxxxx>
> ---

Reviewed-by: Frank Li <Frank.Li@xxxxxxx>

> Changes in v2:
> - Split v1 patch 1/5 into two patches: this patch fixes the core
>   for_each_active_route() bug, next patch adds additional stream
>   validation (Frank Li)
> ---
>  drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c | 2 +-
>  1 file changed, 1 insertion(+), 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 c580c831972e..84871bceb31d 100644
> --- a/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> +++ b/drivers/media/platform/nxp/imx8-isi/imx8-isi-crossbar.c
> @@ -107,7 +107,7 @@ static int __mxc_isi_crossbar_set_routing(struct v4l2_subdev *sd,
>  		return ret;
>
>  	/* The memory input can be routed to the first pipeline only. */
> -	for_each_active_route(&state->routing, route) {
> +	for_each_active_route(routing, route) {
>  		if (route->sink_pad == xbar->num_sinks - 1 &&
>  		    route->source_pad != xbar->num_sinks) {
>  			dev_dbg(xbar->isi->dev,
>
> --
> 2.34.1
>
>