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

[Guoniu Zhou <guoniu.zhou@oss.nxp.com>]

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@vger.kernel.org
Signed-off-by: Guoniu Zhou <guoniu.zhou@oss.nxp.com>
---
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