Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH] media: em28xx: Fix race condition between open and init
 function
To:     Igor Matheus Andrade Torrente <igormtorrente@gmail.com>,
        mchehab@kernel.org
Cc:     syzbot+b2391895514ed9ef4a8e@syzkaller.appspotmail.com,
        linux-media@vger.kernel.org,
        linux-kernel-mentees@lists.linuxfoundation.org,
        linux-kernel@vger.kernel.org,
        Shuah Khan <skhan@linuxfoundation.org>
References: <20210408121041.6655-1-igormtorrente@gmail.com>
From:   Shuah Khan <skhan@linuxfoundation.org>
Message-ID: <5dd8a1f8-51f9-c4a9-e6e2-cc06e5615d01@linuxfoundation.org>
Date:   Thu, 8 Apr 2021 11:37:08 -0600
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.7.1
MIME-Version: 1.0
In-Reply-To: <20210408121041.6655-1-igormtorrente@gmail.com>
Content-Type: text/plain; charset=utf-8; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 4/8/21 6:10 AM, Igor Matheus Andrade Torrente wrote:
> Fixes a race condition - for lack of a more precise term - between
> em28xx_v4l2_open and em28xx_v4l2_init, by detaching the v4l2_dev,
> media_pad and vdev structs from the em28xx_v4l2, and managing the
> lifetime of those objects more dynamicaly.
> 
> The race happens when a thread[1] - containing the em28xx_v4l2_init()
> code - calls the v4l2_mc_create_media_graph(), and it return a error,
> if a thread[2] - running v4l2_open() - pass the verification point
> and reaches the em28xx_v4l2_open() before the thread[1] finishes
> the v4l2 subsystem deregistration, thread[1] will free all resources
> before the em28xx_v4l2_open() can process their things,
> because the em28xx_v4l2_init() has the dev->lock. And all this lead
> the thread[2] to cause a user-after-free.
> 

Have you tried this patch with em28xx device? You will have to take into
account the dependencies between the subdevs using the v4l2_dev.

Also try rmmod invidual drivers - what happens if you were to rmmod a
subdev driver? With v4l2_dev is not embedded in v4l2, this could open
up memory leaks or user-after-frees.

> Reported-and-tested-by: syzbot+b2391895514ed9ef4a8e@syzkaller.appspotmail.com
> Signed-off-by: Igor Matheus Andrade Torrente <igormtorrente@gmail.com>
> ---
>   drivers/media/usb/em28xx/em28xx-camera.c |   4 +-
>   drivers/media/usb/em28xx/em28xx-video.c  | 188 ++++++++++++++---------
>   drivers/media/usb/em28xx/em28xx.h        |   6 +-
>   3 files changed, 123 insertions(+), 75 deletions(-)
> 
> diff --git a/drivers/media/usb/em28xx/em28xx-camera.c b/drivers/media/usb/em28xx/em28xx-camera.c
> index d1e66b503f4d..436c5a8cbbb6 100644
> --- a/drivers/media/usb/em28xx/em28xx-camera.c
> +++ b/drivers/media/usb/em28xx/em28xx-camera.c
> @@ -340,7 +340,7 @@ int em28xx_init_camera(struct em28xx *dev)
>   		v4l2->sensor_xtal = 4300000;
>   		pdata.xtal = v4l2->sensor_xtal;
>   		if (NULL ==
> -		    v4l2_i2c_new_subdev_board(&v4l2->v4l2_dev, adap,
> +		    v4l2_i2c_new_subdev_board(v4l2->v4l2_dev, adap,
>   					      &mt9v011_info, NULL))
>   			return -ENODEV;
>   		v4l2->vinmode = EM28XX_VINMODE_RGB8_GRBG;
> @@ -394,7 +394,7 @@ int em28xx_init_camera(struct em28xx *dev)
>   		v4l2->sensor_yres = 480;
>   
>   		subdev =
> -		     v4l2_i2c_new_subdev_board(&v4l2->v4l2_dev, adap,
> +		     v4l2_i2c_new_subdev_board(v4l2->v4l2_dev, adap,
>   					       &ov2640_info, NULL);
>   		if (!subdev)
>   			return -ENODEV;
> diff --git a/drivers/media/usb/em28xx/em28xx-video.c b/drivers/media/usb/em28xx/em28xx-video.c
> index 6b84c3413e83..e1febb2bf06b 100644
> --- a/drivers/media/usb/em28xx/em28xx-video.c
> +++ b/drivers/media/usb/em28xx/em28xx-video.c
> @@ -184,7 +184,7 @@ static int em28xx_vbi_supported(struct em28xx *dev)
>    */
>   static void em28xx_wake_i2c(struct em28xx *dev)
>   {
> -	struct v4l2_device *v4l2_dev = &dev->v4l2->v4l2_dev;
> +	struct v4l2_device *v4l2_dev = dev->v4l2->v4l2_dev;
>   
>   	v4l2_device_call_all(v4l2_dev, 0, core,  reset, 0);
>   	v4l2_device_call_all(v4l2_dev, 0, video, s_routing,
> @@ -974,9 +974,17 @@ static void em28xx_v4l2_create_entities(struct em28xx *dev)
>   	struct em28xx_v4l2 *v4l2 = dev->v4l2;
>   	int ret, i;
>   
> +	v4l2->video_pad = kzalloc(sizeof(*v4l2->video_pad), GFP_KERNEL);
> +	if (!v4l2->video_pad) {
> +		dev_err(&dev->intf->dev,
> +			"failed to allocate video pad memory!\n");
> +		v4l2->vdev->entity.num_pads = 0;
> +		return;
> +	}
> +
>   	/* Initialize Video, VBI and Radio pads */
> -	v4l2->video_pad.flags = MEDIA_PAD_FL_SINK;
> -	ret = media_entity_pads_init(&v4l2->vdev.entity, 1, &v4l2->video_pad);
> +	v4l2->video_pad->flags = MEDIA_PAD_FL_SINK;
> +	ret = media_entity_pads_init(&v4l2->vdev->entity, 1, v4l2->video_pad);
>   	if (ret < 0)
>   		dev_err(&dev->intf->dev,
>   			"failed to initialize video media entity!\n");
> @@ -1132,11 +1140,11 @@ int em28xx_start_analog_streaming(struct vb2_queue *vq, unsigned int count)
>   			f.type = V4L2_TUNER_RADIO;
>   		else
>   			f.type = V4L2_TUNER_ANALOG_TV;
> -		v4l2_device_call_all(&v4l2->v4l2_dev,
> +		v4l2_device_call_all(v4l2->v4l2_dev,
>   				     0, tuner, s_frequency, &f);
>   
>   		/* Enable video stream at TV decoder */
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_stream, 1);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_stream, 1);
>   	}
>   
>   	v4l2->streaming_users++;
> @@ -1157,7 +1165,7 @@ static void em28xx_stop_streaming(struct vb2_queue *vq)
>   
>   	if (v4l2->streaming_users-- == 1) {
>   		/* Disable video stream at TV decoder */
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_stream, 0);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_stream, 0);
>   
>   		/* Last active user, so shutdown all the URBS */
>   		em28xx_uninit_usb_xfer(dev, EM28XX_ANALOG_MODE);
> @@ -1192,7 +1200,7 @@ void em28xx_stop_vbi_streaming(struct vb2_queue *vq)
>   
>   	if (v4l2->streaming_users-- == 1) {
>   		/* Disable video stream at TV decoder */
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_stream, 0);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_stream, 0);
>   
>   		/* Last active user, so shutdown all the URBS */
>   		em28xx_uninit_usb_xfer(dev, EM28XX_ANALOG_MODE);
> @@ -1286,7 +1294,7 @@ static int em28xx_vb2_setup(struct em28xx *dev)
>   
>   static void video_mux(struct em28xx *dev, int index)
>   {
> -	struct v4l2_device *v4l2_dev = &dev->v4l2->v4l2_dev;
> +	struct v4l2_device *v4l2_dev = dev->v4l2->v4l2_dev;
>   
>   	dev->ctl_input = index;
>   	dev->ctl_ainput = INPUT(index)->amux;
> @@ -1565,7 +1573,7 @@ static int vidioc_querystd(struct file *file, void *priv, v4l2_std_id *norm)
>   {
>   	struct em28xx *dev = video_drvdata(file);
>   
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, video, querystd, norm);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, video, querystd, norm);
>   
>   	return 0;
>   }
> @@ -1596,7 +1604,7 @@ static int vidioc_s_std(struct file *file, void *priv, v4l2_std_id norm)
>   		      &v4l2->hscale, &v4l2->vscale);
>   
>   	em28xx_resolution_set(dev);
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_std, v4l2->norm);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_std, v4l2->norm);
>   
>   	return 0;
>   }
> @@ -1616,7 +1624,7 @@ static int vidioc_g_parm(struct file *file, void *priv,
>   	p->parm.capture.readbuffers = EM28XX_MIN_BUF;
>   	p->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
>   	if (dev->is_webcam) {
> -		rc = v4l2_device_call_until_err(&v4l2->v4l2_dev, 0,
> +		rc = v4l2_device_call_until_err(v4l2->v4l2_dev, 0,
>   						video, g_frame_interval, &ival);
>   		if (!rc)
>   			p->parm.capture.timeperframe = ival.interval;
> @@ -1648,7 +1656,7 @@ static int vidioc_s_parm(struct file *file, void *priv,
>   	memset(&p->parm, 0, sizeof(p->parm));
>   	p->parm.capture.readbuffers = EM28XX_MIN_BUF;
>   	p->parm.capture.capability = V4L2_CAP_TIMEPERFRAME;
> -	rc = v4l2_device_call_until_err(&dev->v4l2->v4l2_dev, 0,
> +	rc = v4l2_device_call_until_err(dev->v4l2->v4l2_dev, 0,
>   					video, s_frame_interval, &ival);
>   	if (!rc)
>   		p->parm.capture.timeperframe = ival.interval;
> @@ -1675,7 +1683,7 @@ static int vidioc_enum_input(struct file *file, void *priv,
>   	if (INPUT(n)->type == EM28XX_VMUX_TELEVISION)
>   		i->type = V4L2_INPUT_TYPE_TUNER;
>   
> -	i->std = dev->v4l2->vdev.tvnorms;
> +	i->std = dev->v4l2->vdev->tvnorms;
>   	/* webcams do not have the STD API */
>   	if (dev->is_webcam)
>   		i->capabilities = 0;
> @@ -1839,7 +1847,7 @@ static int vidioc_g_tuner(struct file *file, void *priv,
>   
>   	strscpy(t->name, "Tuner", sizeof(t->name));
>   
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
>   	return 0;
>   }
>   
> @@ -1851,7 +1859,7 @@ static int vidioc_s_tuner(struct file *file, void *priv,
>   	if (t->index != 0)
>   		return -EINVAL;
>   
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
>   	return 0;
>   }
>   
> @@ -1878,8 +1886,8 @@ static int vidioc_s_frequency(struct file *file, void *priv,
>   	if (f->tuner != 0)
>   		return -EINVAL;
>   
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, s_frequency, f);
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, g_frequency, &new_freq);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, s_frequency, f);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, g_frequency, &new_freq);
>   	v4l2->frequency = new_freq.frequency;
>   
>   	return 0;
> @@ -1897,7 +1905,7 @@ static int vidioc_g_chip_info(struct file *file, void *priv,
>   		strscpy(chip->name, "ac97", sizeof(chip->name));
>   	else
>   		strscpy(chip->name,
> -			dev->v4l2->v4l2_dev.name, sizeof(chip->name));
> +			dev->v4l2->v4l2_dev->name, sizeof(chip->name));
>   	return 0;
>   }
>   
> @@ -2095,7 +2103,7 @@ static int radio_g_tuner(struct file *file, void *priv,
>   
>   	strscpy(t->name, "Radio", sizeof(t->name));
>   
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, tuner, g_tuner, t);
>   
>   	return 0;
>   }
> @@ -2108,7 +2116,7 @@ static int radio_s_tuner(struct file *file, void *priv,
>   	if (t->index != 0)
>   		return -EINVAL;
>   
> -	v4l2_device_call_all(&dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
> +	v4l2_device_call_all(dev->v4l2->v4l2_dev, 0, tuner, s_tuner, t);
>   
>   	return 0;
>   }
> @@ -2160,6 +2168,11 @@ static int em28xx_v4l2_open(struct file *filp)
>   	if (mutex_lock_interruptible(&dev->lock))
>   		return -ERESTARTSYS;
>   
> +	if (!dev->v4l2) {
> +		mutex_unlock(&dev->lock);
> +		return -ENODEV;
> +	}
> +
>   	ret = v4l2_fh_open(filp);
>   	if (ret) {
>   		dev_err(&dev->intf->dev,
> @@ -2184,7 +2197,7 @@ static int em28xx_v4l2_open(struct file *filp)
>   
>   	if (vdev->vfl_type == VFL_TYPE_RADIO) {
>   		em28xx_videodbg("video_open: setting radio device\n");
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, s_radio);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, s_radio);
>   	}
>   
>   	kref_get(&dev->ref);
> @@ -2222,7 +2235,7 @@ static int em28xx_v4l2_fini(struct em28xx *dev)
>   
>   	mutex_lock(&dev->lock);
>   
> -	v4l2_device_disconnect(&v4l2->v4l2_dev);
> +	v4l2_device_disconnect(v4l2->v4l2_dev);
>   
>   	em28xx_uninit_usb_xfer(dev, EM28XX_ANALOG_MODE);
>   
> @@ -2238,14 +2251,15 @@ static int em28xx_v4l2_fini(struct em28xx *dev)
>   			 video_device_node_name(&v4l2->vbi_dev));
>   		video_unregister_device(&v4l2->vbi_dev);
>   	}
> -	if (video_is_registered(&v4l2->vdev)) {
> +	if (video_is_registered(v4l2->vdev)) {
>   		dev_info(&dev->intf->dev, "V4L2 device %s deregistered\n",
> -			 video_device_node_name(&v4l2->vdev));
> -		video_unregister_device(&v4l2->vdev);
> +			 video_device_node_name(v4l2->vdev));
> +		video_unregister_device(v4l2->vdev);
>   	}
>   
>   	v4l2_ctrl_handler_free(&v4l2->ctrl_handler);
> -	v4l2_device_unregister(&v4l2->v4l2_dev);
> +	v4l2_device_unregister(v4l2->v4l2_dev);
> +	v4l2_device_put(v4l2->v4l2_dev);
>   
>   	kref_put(&v4l2->ref, em28xx_free_v4l2);
>   
> @@ -2305,7 +2319,7 @@ static int em28xx_v4l2_close(struct file *filp)
>   			goto exit;
>   
>   		/* Save some power by putting tuner to sleep */
> -		v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, standby);
> +		v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, standby);
>   
>   		/* do this before setting alternate! */
>   		em28xx_set_mode(dev, EM28XX_SUSPEND);
> @@ -2330,6 +2344,17 @@ static int em28xx_v4l2_close(struct file *filp)
>   	return 0;
>   }
>   
> +void em28xx_vdev_release(struct video_device *vdev)
> +{
> +#ifdef CONFIG_MEDIA_CONTROLLER
> +	int i;
> +
> +	for (i = 0; i < vdev->entity.num_pads; i++)
> +		kfree(&vdev->entity.pads[i]);
> +#endif
> +	kfree(vdev);
> +}
> +
>   static const struct v4l2_file_operations em28xx_v4l_fops = {
>   	.owner         = THIS_MODULE,
>   	.open          = em28xx_v4l2_open,
> @@ -2387,7 +2412,7 @@ static const struct v4l2_ioctl_ops video_ioctl_ops = {
>   static const struct video_device em28xx_video_template = {
>   	.fops		= &em28xx_v4l_fops,
>   	.ioctl_ops	= &video_ioctl_ops,
> -	.release	= video_device_release_empty,
> +	.release	= em28xx_vdev_release,
>   	.tvnorms	= V4L2_STD_ALL,
>   };
>   
> @@ -2445,7 +2470,7 @@ static void em28xx_vdev_init(struct em28xx *dev,
>   			     const char *type_name)
>   {
>   	*vfd		= *template;
> -	vfd->v4l2_dev	= &dev->v4l2->v4l2_dev;
> +	vfd->v4l2_dev	= dev->v4l2->v4l2_dev;
>   	vfd->lock	= &dev->lock;
>   	if (dev->is_webcam)
>   		vfd->tvnorms = 0;
> @@ -2459,7 +2484,7 @@ static void em28xx_vdev_init(struct em28xx *dev,
>   static void em28xx_tuner_setup(struct em28xx *dev, unsigned short tuner_addr)
>   {
>   	struct em28xx_v4l2      *v4l2 = dev->v4l2;
> -	struct v4l2_device      *v4l2_dev = &v4l2->v4l2_dev;
> +	struct v4l2_device      *v4l2_dev = v4l2->v4l2_dev;
>   	struct tuner_setup      tun_setup;
>   	struct v4l2_frequency   f;
>   
> @@ -2517,6 +2542,11 @@ static void em28xx_tuner_setup(struct em28xx *dev, unsigned short tuner_addr)
>   	v4l2_device_call_all(v4l2_dev, 0, tuner, s_frequency, &f);
>   }
>   
> +void em28xx_v4l2_dev_release(struct v4l2_device *v4l2_dev)
> +{
> +	kfree(v4l2_dev);
> +}
> +
>   static int em28xx_v4l2_init(struct em28xx *dev)
>   {
>   	u8 val;
> @@ -2541,26 +2571,35 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   
>   	v4l2 = kzalloc(sizeof(*v4l2), GFP_KERNEL);
>   	if (!v4l2) {
> -		mutex_unlock(&dev->lock);
> -		return -ENOMEM;
> +		ret = -ENOMEM;
> +		goto v4l2_error;
>   	}
> +
>   	kref_init(&v4l2->ref);
>   	v4l2->dev = dev;
>   	dev->v4l2 = v4l2;
>   
> +	v4l2->v4l2_dev = kzalloc(sizeof(*v4l2->v4l2_dev), GFP_KERNEL);
> +	if (!v4l2->v4l2_dev) {
> +		ret = -ENOMEM;
> +		goto v4l2_dev_error;
> +	}
> +
> +	v4l2->v4l2_dev->release = em28xx_v4l2_dev_release;
> +
>   #ifdef CONFIG_MEDIA_CONTROLLER
> -	v4l2->v4l2_dev.mdev = dev->media_dev;
> +	v4l2->v4l2_dev->mdev = dev->media_dev;
>   #endif
> -	ret = v4l2_device_register(&dev->intf->dev, &v4l2->v4l2_dev);
> +	ret = v4l2_device_register(&dev->intf->dev, v4l2->v4l2_dev);
>   	if (ret < 0) {
>   		dev_err(&dev->intf->dev,
>   			"Call to v4l2_device_register() failed!\n");
> -		goto err;
> +		goto v4l2_device_register_error;
>   	}
>   
>   	hdl = &v4l2->ctrl_handler;
>   	v4l2_ctrl_handler_init(hdl, 8);
> -	v4l2->v4l2_dev.ctrl_handler = hdl;
> +	v4l2->v4l2_dev->ctrl_handler = hdl;
>   
>   	if (dev->is_webcam)
>   		v4l2->progressive = true;
> @@ -2575,22 +2614,22 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   	/* request some modules */
>   
>   	if (dev->has_msp34xx)
> -		v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> +		v4l2_i2c_new_subdev(v4l2->v4l2_dev,
>   				    &dev->i2c_adap[dev->def_i2c_bus],
>   				    "msp3400", 0, msp3400_addrs);
>   
>   	if (dev->board.decoder == EM28XX_SAA711X)
> -		v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> +		v4l2_i2c_new_subdev(v4l2->v4l2_dev,
>   				    &dev->i2c_adap[dev->def_i2c_bus],
>   				    "saa7115_auto", 0, saa711x_addrs);
>   
>   	if (dev->board.decoder == EM28XX_TVP5150)
> -		v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> +		v4l2_i2c_new_subdev(v4l2->v4l2_dev,
>   				    &dev->i2c_adap[dev->def_i2c_bus],
>   				    "tvp5150", 0, tvp5150_addrs);
>   
>   	if (dev->board.adecoder == EM28XX_TVAUDIO)
> -		v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> +		v4l2_i2c_new_subdev(v4l2->v4l2_dev,
>   				    &dev->i2c_adap[dev->def_i2c_bus],
>   				    "tvaudio", dev->board.tvaudio_addr, NULL);
>   
> @@ -2601,13 +2640,13 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   		int has_demod = (dev->board.tda9887_conf & TDA9887_PRESENT);
>   
>   		if (dev->board.radio.type)
> -			v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> +			v4l2_i2c_new_subdev(v4l2->v4l2_dev,
>   					    &dev->i2c_adap[dev->def_i2c_bus],
>   					    "tuner", dev->board.radio_addr,
>   					    NULL);

Add null check for v4l2_i2c_new_subdev() and error handling. It was okay
check error prior to this change to allocating v4l2_dev. Now this has
to be handled as a error leg.

>   
>   		if (has_demod)
> -			v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> +			v4l2_i2c_new_subdev(v4l2->v4l2_dev,
>   					    &dev->i2c_adap[dev->def_i2c_bus],
>   					    "tuner", 0,
>   					    v4l2_i2c_tuner_addrs(ADDRS_DEMOD));

Same here:

Add null check for v4l2_i2c_new_subdev() and error handling. It was okay
check error prior to this change to allocating v4l2_dev. Now this has
to be handled as a error leg.

> @@ -2616,7 +2655,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   				has_demod ? ADDRS_TV_WITH_DEMOD : ADDRS_TV;
>   			struct v4l2_subdev *sd;
>   
> -			sd = v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> +			sd = v4l2_i2c_new_subdev(v4l2->v4l2_dev,
>   						 &dev->i2c_adap[dev->def_i2c_bus],
>   						 "tuner", 0,
>   						 v4l2_i2c_tuner_addrs(type));
> @@ -2624,7 +2663,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   			if (sd)
>   				tuner_addr = v4l2_i2c_subdev_addr(sd);

Add null check for v4l2_i2c_new_subdev() and error handling. It was okay
check error prior to this change to allocating v4l2_dev. Now this has
to be handled as a error leg.

>   		} else {
> -			v4l2_i2c_new_subdev(&v4l2->v4l2_dev,
> +			v4l2_i2c_new_subdev(v4l2->v4l2_dev,
>   					    &dev->i2c_adap[dev->def_i2c_bus],
>   					    "tuner", tuner_addr, NULL);

Add null check for v4l2_i2c_new_subdev() and error handling. It was okay
check error prior to this change to allocating v4l2_dev. Now this has
to be handled as a error leg.

>   		}
> @@ -2686,7 +2725,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   
>   	/* set default norm */
>   	v4l2->norm = V4L2_STD_PAL;
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, video, s_std, v4l2->norm);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, video, s_std, v4l2->norm);
>   	v4l2->interlaced_fieldmode = EM28XX_INTERLACED_DEFAULT;
>   
>   	/* Analog specific initialization */
> @@ -2756,40 +2795,45 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   		goto unregister_dev;
>   
>   	/* allocate and fill video video_device struct */
> -	em28xx_vdev_init(dev, &v4l2->vdev, &em28xx_video_template, "video");
> +	v4l2->vdev = kzalloc(sizeof(*v4l2->vdev), GFP_KERNEL);
> +	if (!v4l2->vdev) {
> +		ret = -ENOMEM;
> +		goto unregister_dev;
> +	}
> +
> +	em28xx_vdev_init(dev, v4l2->vdev, &em28xx_video_template, "video");
>   	mutex_init(&v4l2->vb_queue_lock);
>   	mutex_init(&v4l2->vb_vbi_queue_lock);
> -	v4l2->vdev.queue = &v4l2->vb_vidq;
> -	v4l2->vdev.queue->lock = &v4l2->vb_queue_lock;
> -	v4l2->vdev.device_caps = V4L2_CAP_READWRITE | V4L2_CAP_VIDEO_CAPTURE |
> +	v4l2->vdev->queue = &v4l2->vb_vidq;
> +	v4l2->vdev->queue->lock = &v4l2->vb_queue_lock;
> +	v4l2->vdev->device_caps = V4L2_CAP_READWRITE | V4L2_CAP_VIDEO_CAPTURE |
>   				 V4L2_CAP_STREAMING;
>   	if (dev->int_audio_type != EM28XX_INT_AUDIO_NONE)
> -		v4l2->vdev.device_caps |= V4L2_CAP_AUDIO;
> +		v4l2->vdev->device_caps |= V4L2_CAP_AUDIO;
>   	if (dev->tuner_type != TUNER_ABSENT)
> -		v4l2->vdev.device_caps |= V4L2_CAP_TUNER;
> -
> +		v4l2->vdev->device_caps |= V4L2_CAP_TUNER;
>   
>   	/* disable inapplicable ioctls */
>   	if (dev->is_webcam) {
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_QUERYSTD);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_G_STD);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_STD);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_QUERYSTD);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_G_STD);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_STD);
>   	} else {
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_PARM);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_PARM);
>   	}
>   	if (dev->tuner_type == TUNER_ABSENT) {
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_G_TUNER);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_TUNER);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_G_FREQUENCY);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_FREQUENCY);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_G_TUNER);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_TUNER);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_G_FREQUENCY);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_FREQUENCY);
>   	}
>   	if (dev->int_audio_type == EM28XX_INT_AUDIO_NONE) {
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_G_AUDIO);
> -		v4l2_disable_ioctl(&v4l2->vdev, VIDIOC_S_AUDIO);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_G_AUDIO);
> +		v4l2_disable_ioctl(v4l2->vdev, VIDIOC_S_AUDIO);
>   	}
>   
>   	/* register v4l2 video video_device */
> -	ret = video_register_device(&v4l2->vdev, VFL_TYPE_VIDEO,
> +	ret = video_register_device(v4l2->vdev, VFL_TYPE_VIDEO,
>   				    video_nr[dev->devno]);
>   	if (ret) {
>   		dev_err(&dev->intf->dev,
> @@ -2863,7 +2907,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   
>   	dev_info(&dev->intf->dev,
>   		 "V4L2 video device registered as %s\n",
> -		 video_device_node_name(&v4l2->vdev));
> +		 video_device_node_name(v4l2->vdev));
>   
>   	if (video_is_registered(&v4l2->vbi_dev))
>   		dev_info(&dev->intf->dev,
> @@ -2871,7 +2915,7 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   			 video_device_node_name(&v4l2->vbi_dev));
>   
>   	/* Save some power by putting tuner to sleep */
> -	v4l2_device_call_all(&v4l2->v4l2_dev, 0, tuner, standby);
> +	v4l2_device_call_all(v4l2->v4l2_dev, 0, tuner, standby);
>   
>   	/* initialize videobuf2 stuff */
>   	em28xx_vb2_setup(dev);
> @@ -2897,18 +2941,22 @@ static int em28xx_v4l2_init(struct em28xx *dev)
>   			 video_device_node_name(&v4l2->vbi_dev));
>   		video_unregister_device(&v4l2->vbi_dev);
>   	}
> -	if (video_is_registered(&v4l2->vdev)) {
> +	if (video_is_registered(v4l2->vdev)) {
>   		dev_info(&dev->intf->dev,
>   			 "V4L2 device %s deregistered\n",
> -			 video_device_node_name(&v4l2->vdev));
> -		video_unregister_device(&v4l2->vdev);
> +			 video_device_node_name(v4l2->vdev));
> +		video_unregister_device(v4l2->vdev);
>   	}
>   
>   	v4l2_ctrl_handler_free(&v4l2->ctrl_handler);
> -	v4l2_device_unregister(&v4l2->v4l2_dev);
> -err:
> +	v4l2_device_unregister(v4l2->v4l2_dev);
> +
> +v4l2_device_register_error:
> +	v4l2_device_put(v4l2->v4l2_dev);
> +v4l2_dev_error:
>   	dev->v4l2 = NULL;
>   	kref_put(&v4l2->ref, em28xx_free_v4l2);
> +v4l2_error:
>   	mutex_unlock(&dev->lock);
>   	return ret;
>   }
> diff --git a/drivers/media/usb/em28xx/em28xx.h b/drivers/media/usb/em28xx/em28xx.h
> index 6648e11f1271..dbcc297b5a0d 100644
> --- a/drivers/media/usb/em28xx/em28xx.h
> +++ b/drivers/media/usb/em28xx/em28xx.h
> @@ -552,10 +552,10 @@ struct em28xx_v4l2 {
>   	struct kref ref;
>   	struct em28xx *dev;
>   
> -	struct v4l2_device v4l2_dev;
> +	struct v4l2_device *v4l2_dev;
>   	struct v4l2_ctrl_handler ctrl_handler;
>   
> -	struct video_device vdev;
> +	struct video_device *vdev;
>   	struct video_device vbi_dev;
>   	struct video_device radio_dev;
>   
> @@ -601,7 +601,7 @@ struct em28xx_v4l2 {
>   	unsigned int field_count;
>   
>   #ifdef CONFIG_MEDIA_CONTROLLER
> -	struct media_pad video_pad, vbi_pad;
> +	struct media_pad *video_pad, vbi_pad;
>   	struct media_entity *decoder;
>   #endif
>   };
> 

thanks,
-- Shuah