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Subject: Re: [PATCH] media: em28xx: Fix race condition between open and init
 function
To:     Shuah Khan <skhan@linuxfoundation.org>, 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
References: <20210408121041.6655-1-igormtorrente@gmail.com>
 <5dd8a1f8-51f9-c4a9-e6e2-cc06e5615d01@linuxfoundation.org>
From:   Igor Torrente <igormtorrente@gmail.com>
Message-ID: <dc38c3d9-d272-9bcc-7f6a-a4fdf85016e0@gmail.com>
Date:   Fri, 9 Apr 2021 10:40:27 -0300
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On 4/8/21 2:37 PM, Shuah Khan wrote:
> 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.
> 

No, I didn't because I don't have the device.
I was using the syzbot .c that produces this use-after-free.
I will try to modify the .c to test a complete initialization.

Actually, I forgot to put RFC alongside [PATCH].

> 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.
> 

OK. Let me see what I can do.

>> 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.


I will add to all bellow.

> 
>>           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

Thanks,
---
Igor Matheus Andrade Torrente