media: vim2m: Register video device after setting up internals

Prevent NULL (or close to NULL) pointer dereference in various places by
registering the video device only when the V4L2 m2m framework has been set
up.

Fixes: commit 96d8eab5 ("V4L/DVB: [v5,2/2] v4l: Add a mem-to-mem videobuf framework test device")
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>

drivers/media/test-drivers/vim2m.c

@@ -1325,12 +1325,6 @@ static int vim2m_probe(struct platform_device *pdev)
 	vfd->lock = &dev->dev_mutex;
 	vfd->v4l2_dev = &dev->v4l2_dev;
 
-	ret = video_register_device(vfd, VFL_TYPE_VIDEO, 0);
-	if (ret) {
-		v4l2_err(&dev->v4l2_dev, "Failed to register video device\n");
-		goto error_v4l2;
-	}
-
 	video_set_drvdata(vfd, dev);
 	v4l2_info(&dev->v4l2_dev,
 		  "Device registered as /dev/video%d\n", vfd->num);
@@ -1345,6 +1339,12 @@ static int vim2m_probe(struct platform_device *pdev)
 		goto error_dev;
 	}
 
+	ret = video_register_device(vfd, VFL_TYPE_VIDEO, 0);
+	if (ret) {
+		v4l2_err(&dev->v4l2_dev, "Failed to register video device\n");
+		goto error_m2m;
+	}
+
 #ifdef CONFIG_MEDIA_CONTROLLER
 	dev->mdev.dev = &pdev->dev;
 	strscpy(dev->mdev.model, "vim2m", sizeof(dev->mdev.model));
@@ -1358,7 +1358,7 @@ static int vim2m_probe(struct platform_device *pdev)
 						 MEDIA_ENT_F_PROC_VIDEO_SCALER);
 	if (ret) {
 		v4l2_err(&dev->v4l2_dev, "Failed to init mem2mem media controller\n");
-		goto error_dev;
+		goto error_v4l2;
 	}
 
 	ret = media_device_register(&dev->mdev);
@@ -1373,11 +1373,13 @@ static int vim2m_probe(struct platform_device *pdev)
 error_m2m_mc:
 	v4l2_m2m_unregister_media_controller(dev->m2m_dev);
 #endif
-error_dev:
+error_v4l2:
 	video_unregister_device(&dev->vfd);
 	/* vim2m_device_release called by video_unregister_device to release various objects */
 	return ret;
-error_v4l2:
+error_m2m:
+	v4l2_m2m_release(dev->m2m_dev);
+error_dev:
 	v4l2_device_unregister(&dev->v4l2_dev);
 error_free:
 	kfree(dev);