media: video-mux: fix null pointer dereferences

devm_kcalloc may fail and return a null pointer. The fix returns
-ENOMEM upon failures to avoid null pointer dereferences.
Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

drivers/media/platform/video-mux.c

@@ -419,9 +419,14 @@ static int video_mux_probe(struct platform_device *pdev)
 	vmux->active = -1;
 	vmux->pads = devm_kcalloc(dev, num_pads, sizeof(*vmux->pads),
 				  GFP_KERNEL);
+	if (!vmux->pads)
+		return -ENOMEM;
+
 	vmux->format_mbus = devm_kcalloc(dev, num_pads,
 					 sizeof(*vmux->format_mbus),
 					 GFP_KERNEL);
+	if (!vmux->format_mbus)
+		return -ENOMEM;
 
 	for (i = 0; i < num_pads; i++) {
 		vmux->pads[i].flags = (i < num_pads - 1) ? MEDIA_PAD_FL_SINK