Re: [PATCH] media: em28xx: Fix race condition between open and init function

From: Igor Torrente
Date: Fri Apr 09 2021 - 09:40:37 EST




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@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Igor Matheus Andrade Torrente <igormtorrente@xxxxxxxxx>
---
  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