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

[Marek Vasut <marex@denx.de>]

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.

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",
-- 
2.42.0