On 1/23/20 12:36 PM, Dafna Hirschfeld wrote:
> Hi
>
> On 22.01.20 17:39, Helen Koike wrote:
>> Hi Dafna,
>>
>> Thanks for the patch.
>>
>> On 1/22/20 2:01 PM, Dafna Hirschfeld wrote:
>>> A use-after-free bug occures when unbinding the device while it streams.
>>> The 'struct vimc_ent_device' allocated for the 'Sensor A' is freed
>>> when calling the sensor's 'rm' callback but the freed pointer is
>>> later accessed in the function 'vimc_streamer_pipeline_terminate'.
>>> To fix this bug, move the release callback of the vimc entities
>>> and vimc_device to the release callback of v4l2_device.
>>> The .rm callback of vimc_ent_config is replaced by two callbacks:
>>>
>>> .unregister - this is called upon removing the device and
>>> it unregisters the entity. This is an optional callback since
>>> subdevices don't need to implement it because they are already
>>> unregistered in v4l2_device_unregister.
>>>
>>> .release - this is called from the release callback of v4l2_device
>>> and it frees the entity.
>>>
>>> This ensures that the entities will be released when the last fh
>>> of any of the devices is closed.
>>>
>>> The commands that cause the crash and the KASAN report:
>>>
>>> media-ctl -d platform:vimc -V '"Sensor A":0[fmt:SBGGR8_1X8/640x480]'
>>> media-ctl -d platform:vimc -V '"Debayer A":0[fmt:SBGGR8_1X8/640x480]'
>>> v4l2-ctl -z platform:vimc -d "RGB/YUV Capture" -v width=1920,height=1440
>>> v4l2-ctl -z platform:vimc -d "Raw Capture 0" -v pixelformat=BA81
>>> v4l2-ctl --stream-mmap --stream-count=1000 -d /dev/video2 &
>>> sleep 1
>>> echo -n vimc.0 >/sys/bus/platform/drivers/vimc/unbind
>>>
>>> [ 188.417934] BUG: KASAN: use-after-free in vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
>>> [ 188.420182] Read of size 8 at addr ffff8881e9c26008 by task bash/185
>>> [ 188.421800]
>>> [ 188.422223] CPU: 0 PID: 185 Comm: bash Not tainted 5.5.0-rc1+ #1
>>> [ 188.423681] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.12.0-1 04/01/2014
>>> [ 188.425938] Call Trace:
>>> [ 188.426610] dump_stack+0x75/0xa0
>>> [ 188.427519] ? vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
>>> [ 188.429057] print_address_description.constprop.6+0x16/0x220
>>> [ 188.430462] ? vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
>>> [ 188.431979] ? vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
>>> [ 188.433455] __kasan_report.cold.9+0x1a/0x40
>>> [ 188.434518] ? vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
>>> [ 188.436010] kasan_report+0xe/0x20
>>> [ 188.436859] vimc_streamer_pipeline_terminate+0x75/0x140 [vimc]
>>> [ 188.438339] vimc_streamer_s_stream+0x8b/0x3c0 [vimc]
>>> [ 188.439576] vimc_cap_stop_streaming+0x22/0x40 [vimc]
>>> [ 188.440863] __vb2_queue_cancel+0x65/0x560 [videobuf2_common]
>>> [ 188.442391] vb2_core_queue_release+0x19/0x50 [videobuf2_common]
>>> [ 188.443974] vimc_cap_rm+0x10/0x20 [vimc]
>>> [ 188.444986] vimc_rm_subdevs+0x9e/0xe0 [vimc]
>>> [ 188.446179] vimc_remove+0x19/0x70 [vimc]
>>> [ 188.447301] platform_drv_remove+0x2f/0x50
>>> [ 188.448468] device_release_driver_internal+0x133/0x260
>>> [ 188.449814] unbind_store+0x121/0x150
>>> [ 188.450726] kernfs_fop_write+0x142/0x230
>>> [ 188.451724] ? sysfs_kf_bin_read+0x100/0x100
>>> [ 188.452826] vfs_write+0xdc/0x230
>>> [ 188.453760] ksys_write+0xaf/0x140
>>> [ 188.454702] ? __ia32_sys_read+0x40/0x40
>>> [ 188.455773] ? __do_page_fault+0x473/0x620
>>> [ 188.456780] do_syscall_64+0x5e/0x1a0
>>> [ 188.457711] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> [ 188.459079] RIP: 0033:0x7f80f1f13504
>>> [ 188.459969] Code: 00 f7 d8 64 89 02 48 c7 c0 ff ff ff ff eb b3 0f 1f 80 00 00 00 00 48 8d 05 f9 61 0d 00 8b 00 85 c0 75 13 b8 01 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 54 c3 0f 1f 00 41 54 49 89
>>> d4 55 48 89 f5 53
>>> [ 188.464445] RSP: 002b:00007ffd7e843b58 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
>>> [ 188.466276] RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00007f80f1f13504
>>> [ 188.467999] RDX: 0000000000000006 RSI: 000055ef2eb21b10 RDI: 0000000000000001
>>> [ 188.469708] RBP: 000055ef2eb21b10 R08: 00007f80f1fe68c0 R09: 00007f80f1e26740
>>> [ 188.471407] R10: 000055ef2eade010 R11: 0000000000000246 R12: 00007f80f1fe5760
>>> [ 188.473381] R13: 0000000000000006 R14: 00007f80f1fe0760 R15: 0000000000000006
>>> [ 188.475107]
>>> [ 188.475500] Allocated by task 473:
>>> [ 188.476351] save_stack+0x19/0x80
>>> [ 188.477201] __kasan_kmalloc.constprop.6+0xc1/0xd0
>>> [ 188.478507] vimc_sen_add+0x36/0x309 [vimc]
>>> [ 188.479649] vimc_probe+0x1e2/0x530 [vimc]
>>> [ 188.480776] platform_drv_probe+0x46/0xa0
>>> [ 188.481829] really_probe+0x16c/0x520
>>> [ 188.482732] driver_probe_device+0x114/0x170
>>> [ 188.483783] device_driver_attach+0x85/0x90
>>> [ 188.484800] __driver_attach+0xa8/0x190
>>> [ 188.485734] bus_for_each_dev+0xe4/0x140
>>> [ 188.486702] bus_add_driver+0x223/0x2d0
>>> [ 188.487715] driver_register+0xca/0x140
>>> [ 188.488767] 0xffffffffc037003d
>>> [ 188.489635] do_one_initcall+0x86/0x28f
>>> [ 188.490702] do_init_module+0xf8/0x340
>>> [ 188.491773] load_module+0x3766/0x3a10
>>> [ 188.492811] __do_sys_finit_module+0x11a/0x1b0
>>> [ 188.494059] do_syscall_64+0x5e/0x1a0
>>> [ 188.495079] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> [ 188.496481]
>>> [ 188.496893] Freed by task 185:
>>> [ 188.497670] save_stack+0x19/0x80
>>> [ 188.498493] __kasan_slab_free+0x125/0x170
>>> [ 188.499486] kfree+0x8c/0x230
>>> [ 188.500254] v4l2_subdev_release+0x64/0x70 [videodev]
>>> [ 188.501498] v4l2_device_release_subdev_node+0x1c/0x30 [videodev]
>>> [ 188.502976] device_release+0x3c/0xd0
>>> [ 188.503867] kobject_put+0xf4/0x240
>>> [ 188.507802] vimc_rm_subdevs+0x9e/0xe0 [vimc]
>>> [ 188.508846] vimc_remove+0x19/0x70 [vimc]
>>> [ 188.509792] platform_drv_remove+0x2f/0x50
>>> [ 188.510752] device_release_driver_internal+0x133/0x260
>>> [ 188.512006] unbind_store+0x121/0x150
>>> [ 188.512899] kernfs_fop_write+0x142/0x230
>>> [ 188.513874] vfs_write+0xdc/0x230
>>> [ 188.514698] ksys_write+0xaf/0x140
>>> [ 188.515523] do_syscall_64+0x5e/0x1a0
>>> [ 188.516543] entry_SYSCALL_64_after_hwframe+0x44/0xa9
>>> [ 188.517710]
>>> [ 188.518034] The buggy address belongs to the object at ffff8881e9c26000
>>> [ 188.518034] which belongs to the cache kmalloc-4k of size 4096
>>> [ 188.520528] The buggy address is located 8 bytes inside of
>>> [ 188.520528] 4096-byte region [ffff8881e9c26000, ffff8881e9c27000)
>>> [ 188.523015] The buggy address belongs to the page:
>>> [ 188.524357] page:ffffea0007a70800 refcount:1 mapcount:0 mapping:ffff8881f6402140 index:0x0 compound_mapcount: 0
>>> [ 188.527058] raw: 0200000000010200 dead000000000100 dead000000000122 ffff8881f6402140
>>> [ 188.528983] raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
>>> [ 188.530883] page dumped because: kasan: bad access detected
>>> [ 188.532336]
>>> [ 188.532720] Memory state around the buggy address:
>>> [ 188.533871] ffff8881e9c25f00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>> [ 188.535631] ffff8881e9c25f80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>>> [ 188.537370] >ffff8881e9c26000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>> [ 188.538996] ^
>>> [ 188.539812] ffff8881e9c26080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>> [ 188.541549] ffff8881e9c26100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>>>
>>> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@xxxxxxxxxxxxx>
>>> ---
>>> drivers/media/platform/vimc/vimc-capture.c | 12 ++---
>>> drivers/media/platform/vimc/vimc-common.c | 2 -
>>> drivers/media/platform/vimc/vimc-common.h | 25 ++++-----
>>> drivers/media/platform/vimc/vimc-core.c | 61 +++++++++++++++-------
>>> drivers/media/platform/vimc/vimc-debayer.c | 19 ++-----
>>> drivers/media/platform/vimc/vimc-scaler.c | 19 ++-----
>>> drivers/media/platform/vimc/vimc-sensor.c | 18 ++-----
>>> 7 files changed, 71 insertions(+), 85 deletions(-)
>>>
>>> diff --git a/drivers/media/platform/vimc/vimc-capture.c b/drivers/media/platform/vimc/vimc-capture.c
>>> index 9a78bb7826a8..c5a645f98c66 100644
>>> --- a/drivers/media/platform/vimc/vimc-capture.c
>>> +++ b/drivers/media/platform/vimc/vimc-capture.c
>>> @@ -325,20 +325,20 @@ static const struct media_entity_operations vimc_cap_mops = {
>>> .link_validate = vimc_vdev_link_validate,
>>> };
>>> -static void vimc_cap_release(struct video_device *vdev)
>>> +void vimc_cap_release(struct vimc_ent_device *ved)
>>> {
>>> struct vimc_cap_device *vcap =
>>> - container_of(vdev, struct vimc_cap_device, vdev);
>>> + container_of(ved, struct vimc_cap_device, ved);
>>> media_entity_cleanup(vcap->ved.ent);
>>> kfree(vcap);
>>> }
>>> -void vimc_cap_rm(struct vimc_device *vimc, struct vimc_ent_device *ved)
>>> +void vimc_cap_unregister(struct vimc_ent_device *ved)
>>> {
>>> - struct vimc_cap_device *vcap;
>>> + struct vimc_cap_device *vcap =
>>> + container_of(ved, struct vimc_cap_device, ved);
>>> - vcap = container_of(ved, struct vimc_cap_device, ved);
>>> vb2_queue_release(&vcap->queue);
>>> video_unregister_device(&vcap->vdev);
>>> }
>>> @@ -449,7 +449,7 @@ struct vimc_ent_device *vimc_cap_add(struct vimc_device *vimc,
>>> vdev = &vcap->vdev;
>>> vdev->device_caps = V4L2_CAP_VIDEO_CAPTURE | V4L2_CAP_STREAMING;
>>> vdev->entity.ops = &vimc_cap_mops;
>>> - vdev->release = vimc_cap_release;
>>> + vdev->release = video_device_release_empty;
>>> vdev->fops = &vimc_cap_fops;
>>> vdev->ioctl_ops = &vimc_cap_ioctl_ops;
>>> vdev->lock = &vcap->lock;
>>> diff --git a/drivers/media/platform/vimc/vimc-common.c b/drivers/media/platform/vimc/vimc-common.c
>>> index 16ce9f3b7c75..c95c17c048f2 100644
>>> --- a/drivers/media/platform/vimc/vimc-common.c
>>> +++ b/drivers/media/platform/vimc/vimc-common.c
>>> @@ -327,7 +327,6 @@ int vimc_ent_sd_register(struct vimc_ent_device *ved,
>>> u32 function,
>>> u16 num_pads,
>>> struct media_pad *pads,
>>> - const struct v4l2_subdev_internal_ops *sd_int_ops,
>>> const struct v4l2_subdev_ops *sd_ops)
>>> {
>>> int ret;
>>> @@ -337,7 +336,6 @@ int vimc_ent_sd_register(struct vimc_ent_device *ved,
>>> /* Initialize the subdev */
>>> v4l2_subdev_init(sd, sd_ops);
>>> - sd->internal_ops = sd_int_ops;
>>> sd->entity.function = function;
>>> sd->entity.ops = &vimc_ent_sd_mops;
>>> sd->owner = THIS_MODULE;
>>> diff --git a/drivers/media/platform/vimc/vimc-common.h b/drivers/media/platform/vimc/vimc-common.h
>>> index 1b6ef7196f3c..616d5a6b0754 100644
>>> --- a/drivers/media/platform/vimc/vimc-common.h
>>> +++ b/drivers/media/platform/vimc/vimc-common.h
>>> @@ -125,16 +125,18 @@ struct vimc_device {
>>> * @name entity name
>>> * @ved pointer to vimc_ent_device (a node in the
>>> * topology)
>>> - * @add subdev add hook - initializes and registers
>>> - * subdev called from vimc-core
>>> - * @rm subdev rm hook - unregisters and frees
>>> - * subdev called from vimc-core
>>> + * @add initializes and registers
>>> + * vim entity - called from vimc-core
>>> + * @unregister unregisters vimc entity - called from vimc-core
>>> + * @release releases vimc entity - called from the v4l2_dev
>>> + * release callback
>>> */
>>
>> Did you test the suggestion I gave in last patch?
>> That instead of adding another callback here, to just remove the release functions of the subdevices,
>> and add a check if the release cb isn't null just before calling it.
>> With this, the release functions of the video nodes would be called first.
>>
> I just tested you suggestion, here is the patch: https://gitlab.collabora.com/dafna/linux/commit/f59bc7c6643ce8f88aa33eb5e9f413a1aca99589
> I get a kasan report:
>
> [ 37.736909] BUG: KASAN: use-after-free in v4l2_device_unregister+0xa7/0xf0 [videodev]
> [ 37.738110] Read of size 4 at addr ffff8881eb3f00bc by task bash/227
> ...
>
> What happen is that the function v4l2_device_unregister loops over the subdevices and unregister them:
>
> /* Unregister subdevs */
> list_for_each_entry_safe(sd, next, &v4l2_dev->subdevs, list) {
> v4l2_device_unregister_subdev(sd);
> if (sd->flags & V4L2_SUBDEV_FL_IS_I2C)
> v4l2_i2c_subdev_unregister(sd);
> else if (sd->flags & V4L2_SUBDEV_FL_IS_SPI)
> v4l2_spi_subdev_unregister(sd);
> }
>
> when unregistering the first subdevice it also immediately calls the release callback because no one holds a fh for
> /dev/v4l2-subdev* , but the release cb releases the memory where the 'sd' in the above loop resides, then when
> referencing it in sd->flags it is after it is already freed.
Urgh. That's a bug in that function. I think the if...else if bit can be moved to
v4l2_subdev_release().
I'm surprised that this hasn't been seen before.
Regards,
Hans
>
> Dafna
>
>> I followed the discussion regarding fhs in media node and video, not that I'm against your changes,
>> but I would like to understand a bit better why the simple fix suggested isn't enough.
>>
>> Thanks
>> Helen
>>
>>> struct vimc_ent_config {
>>> const char *name;
>>> struct vimc_ent_device *(*add)(struct vimc_device *vimc,
>>> const char *vcfg_name);
>>> - void (*rm)(struct vimc_device *vimc, struct vimc_ent_device *ved);
>>> + void (*unregister)(struct vimc_ent_device *ved);
>>> + void (*release)(struct vimc_ent_device *ved);
>>> };
>>> /**
>>> @@ -145,22 +147,23 @@ struct vimc_ent_config {
>>> */
>>> bool vimc_is_source(struct media_entity *ent);
>>> -/* prototypes for vimc_ent_config add and rm hooks */
>>> +/* prototypes for vimc_ent_config hooks */
>>> struct vimc_ent_device *vimc_cap_add(struct vimc_device *vimc,
>>> const char *vcfg_name);
>>> -void vimc_cap_rm(struct vimc_device *vimc, struct vimc_ent_device *ved);
>>> +void vimc_cap_unregister(struct vimc_ent_device *ved);
>>> +void vimc_cap_release(struct vimc_ent_device *ved);
>>> struct vimc_ent_device *vimc_deb_add(struct vimc_device *vimc,
>>> const char *vcfg_name);
>>> -void vimc_deb_rm(struct vimc_device *vimc, struct vimc_ent_device *ved);
>>> +void vimc_deb_release(struct vimc_ent_device *ved);
>>> struct vimc_ent_device *vimc_sca_add(struct vimc_device *vimc,
>>> const char *vcfg_name);
>>> -void vimc_sca_rm(struct vimc_device *vimc, struct vimc_ent_device *ved);
>>> +void vimc_sca_release(struct vimc_ent_device *ved);
>>> struct vimc_ent_device *vimc_sen_add(struct vimc_device *vimc,
>>> const char *vcfg_name);
>>> -void vimc_sen_rm(struct vimc_device *vimc, struct vimc_ent_device *ved);
>>> +void vimc_sen_release(struct vimc_ent_device *ved);
>>> /**
>>> * vimc_pix_map_by_index - get vimc_pix_map struct by its index
>>> @@ -195,7 +198,6 @@ const struct vimc_pix_map *vimc_pix_map_by_pixelformat(u32 pixelformat);
>>> * @num_pads: number of pads to initialize
>>> * @pads: the array of pads of the entity, the caller should set the
>>> flags of the pads
>>> - * @sd_int_ops: pointer to &struct v4l2_subdev_internal_ops
>>> * @sd_ops: pointer to &struct v4l2_subdev_ops.
>>> *
>>> * Helper function initialize and register the struct vimc_ent_device and struct
>>> @@ -208,7 +210,6 @@ int vimc_ent_sd_register(struct vimc_ent_device *ved,
>>> u32 function,
>>> u16 num_pads,
>>> struct media_pad *pads,
>>> - const struct v4l2_subdev_internal_ops *sd_int_ops,
>>> const struct v4l2_subdev_ops *sd_ops);
>>> /**
>>> diff --git a/drivers/media/platform/vimc/vimc-core.c b/drivers/media/platform/vimc/vimc-core.c
>>> index 1c55e0382f09..306f9c293628 100644
>>> --- a/drivers/media/platform/vimc/vimc-core.c
>>> +++ b/drivers/media/platform/vimc/vimc-core.c
>>> @@ -48,48 +48,51 @@ static struct vimc_ent_config ent_config[] = {
>>> {
>>> .name = "Sensor A",
>>> .add = vimc_sen_add,
>>> - .rm = vimc_sen_rm,
>>> + .release = vimc_sen_release,
>>> },
>>> {
>>> .name = "Sensor B",
>>> .add = vimc_sen_add,
>>> - .rm = vimc_sen_rm,
>>> + .release = vimc_sen_release,
>>> },
>>> {
>>> .name = "Debayer A",
>>> .add = vimc_deb_add,
>>> - .rm = vimc_deb_rm,
>>> + .release = vimc_deb_release,
>>> },
>>> {
>>> .name = "Debayer B",
>>> .add = vimc_deb_add,
>>> - .rm = vimc_deb_rm,
>>> + .release = vimc_deb_release,
>>> },
>>> {
>>> .name = "Raw Capture 0",
>>> .add = vimc_cap_add,
>>> - .rm = vimc_cap_rm,
>>> + .unregister = vimc_cap_unregister,
>>> + .release = vimc_cap_release,
>>> },
>>> {
>>> .name = "Raw Capture 1",
>>> .add = vimc_cap_add,
>>> - .rm = vimc_cap_rm,
>>> + .unregister = vimc_cap_unregister,
>>> + .release = vimc_cap_release,
>>> },
>>> {
>>> /* TODO: change this to vimc-input when it is implemented */
>>> .name = "RGB/YUV Input",
>>> .add = vimc_sen_add,
>>> - .rm = vimc_sen_rm,
>>> + .release = vimc_sen_release,
>>> },
>>> {
>>> .name = "Scaler",
>>> .add = vimc_sca_add,
>>> - .rm = vimc_sca_rm,
>>> + .release = vimc_sca_release,
>>> },
>>> {
>>> .name = "RGB/YUV Capture",
>>> .add = vimc_cap_add,
>>> - .rm = vimc_cap_rm,
>>> + .unregister = vimc_cap_unregister,
>>> + .release = vimc_cap_release,
>>> },
>>> };
>>> @@ -175,13 +178,33 @@ static int vimc_add_subdevs(struct vimc_device *vimc)
>>> return 0;
>>> }
>>> -static void vimc_rm_subdevs(struct vimc_device *vimc)
>>> +static void vimc_release_subdevs(struct vimc_device *vimc)
>>> {
>>> unsigned int i;
>>> for (i = 0; i < vimc->pipe_cfg->num_ents; i++)
>>> if (vimc->ent_devs[i])
>>> - vimc->pipe_cfg->ents[i].rm(vimc, vimc->ent_devs[i]);
>>> + vimc->pipe_cfg->ents[i].release(vimc->ent_devs[i]);
>>> +}
>>> +
>>> +static void vimc_unregister_subdevs(struct vimc_device *vimc)
>>> +{
>>> + unsigned int i;
>>> +
>>> + for (i = 0; i < vimc->pipe_cfg->num_ents; i++)
>>> + if (vimc->ent_devs[i] && vimc->pipe_cfg->ents[i].unregister)
>>> + vimc->pipe_cfg->ents[i].unregister(vimc->ent_devs[i]);
>>> +}
>>> +
>>> +static void vimc_v4l2_dev_release(struct v4l2_device *v4l2_dev)
>>> +{
>>> + struct vimc_device *vimc =
>>> + container_of(v4l2_dev, struct vimc_device, v4l2_dev);
>>> +
>>> + vimc_release_subdevs(vimc);
>>> + media_device_cleanup(&vimc->mdev);
>>> + kfree(vimc->ent_devs);
>>> + kfree(vimc);
>>> }
>>> static int vimc_register_devices(struct vimc_device *vimc)
>>> @@ -195,7 +218,6 @@ static int vimc_register_devices(struct vimc_device *vimc)
>>> "v4l2 device register failed (err=%d)\n", ret);
>>> return ret;
>>> }
>>> -
>>> /* allocate ent_devs */
>>> vimc->ent_devs = kcalloc(vimc->pipe_cfg->num_ents,
>>> sizeof(*vimc->ent_devs), GFP_KERNEL);
>>> @@ -236,9 +258,9 @@ static int vimc_register_devices(struct vimc_device *vimc)
>>> err_mdev_unregister:
>>> media_device_unregister(&vimc->mdev);
>>> - media_device_cleanup(&vimc->mdev);
>>> err_rm_subdevs:
>>> - vimc_rm_subdevs(vimc);
>>> + vimc_unregister_subdevs(vimc);
>>> + vimc_release_subdevs(vimc);
>>> kfree(vimc->ent_devs);
>>> err_v4l2_unregister:
>>> v4l2_device_unregister(&vimc->v4l2_dev);
>>> @@ -248,11 +270,9 @@ static int vimc_register_devices(struct vimc_device *vimc)
>>> static void vimc_unregister(struct vimc_device *vimc)
>>> {
>>> + vimc_unregister_subdevs(vimc);
>>> media_device_unregister(&vimc->mdev);
>>> - media_device_cleanup(&vimc->mdev);
>>> v4l2_device_unregister(&vimc->v4l2_dev);
>>> - kfree(vimc->ent_devs);
>>> - kfree(vimc);
>>> }
>>> static int vimc_probe(struct platform_device *pdev)
>>> @@ -285,7 +305,12 @@ static int vimc_probe(struct platform_device *pdev)
>>> kfree(vimc);
>>> return ret;
>>> }
>>> + /*
>>> + * the release cb is set only after successful registration.
>>> + * if the registration fails, we release directly from probe
>>> + */
>>> + vimc->v4l2_dev.release = vimc_v4l2_dev_release;
>>> platform_set_drvdata(pdev, vimc);
>>> return 0;
>>> }
>>> @@ -296,8 +321,8 @@ static int vimc_remove(struct platform_device *pdev)
>>> dev_dbg(&pdev->dev, "remove");
>>> - vimc_rm_subdevs(vimc);
>>> vimc_unregister(vimc);
>>> + v4l2_device_put(&vimc->v4l2_dev);
>>> return 0;
>>> }
>>> diff --git a/drivers/media/platform/vimc/vimc-debayer.c b/drivers/media/platform/vimc/vimc-debayer.c
>>> index 34b98b235880..baf6bf9f65b5 100644
>>> --- a/drivers/media/platform/vimc/vimc-debayer.c
>>> +++ b/drivers/media/platform/vimc/vimc-debayer.c
>>> @@ -494,28 +494,16 @@ static const struct v4l2_ctrl_ops vimc_deb_ctrl_ops = {
>>> .s_ctrl = vimc_deb_s_ctrl,
>>> };
>>> -static void vimc_deb_release(struct v4l2_subdev *sd)
>>> +void vimc_deb_release(struct vimc_ent_device *ved)
>>> {
>>> struct vimc_deb_device *vdeb =
>>> - container_of(sd, struct vimc_deb_device, sd);
>>> + container_of(ved, struct vimc_deb_device, ved);
>>> v4l2_ctrl_handler_free(&vdeb->hdl);
>>> media_entity_cleanup(vdeb->ved.ent);
>>> kfree(vdeb);
>>> }
>>> -static const struct v4l2_subdev_internal_ops vimc_deb_int_ops = {
>>> - .release = vimc_deb_release,
>>> -};
>>> -
>>> -void vimc_deb_rm(struct vimc_device *vimc, struct vimc_ent_device *ved)
>>> -{
>>> - struct vimc_deb_device *vdeb;
>>> -
>>> - vdeb = container_of(ved, struct vimc_deb_device, ved);
>>> - v4l2_device_unregister_subdev(&vdeb->sd);
>>> -}
>>> -
>>> static const struct v4l2_ctrl_config vimc_deb_ctrl_class = {
>>> .flags = V4L2_CTRL_FLAG_READ_ONLY | V4L2_CTRL_FLAG_WRITE_ONLY,
>>> .id = VIMC_CID_VIMC_CLASS,
>>> @@ -563,8 +551,7 @@ struct vimc_ent_device *vimc_deb_add(struct vimc_device *vimc,
>>> ret = vimc_ent_sd_register(&vdeb->ved, &vdeb->sd, v4l2_dev,
>>> vcfg_name,
>>> MEDIA_ENT_F_PROC_VIDEO_PIXEL_ENC_CONV, 2,
>>> - vdeb->pads,
>>> - &vimc_deb_int_ops, &vimc_deb_ops);
>>> + vdeb->pads, &vimc_deb_ops);
>>> if (ret)
>>> goto err_free_hdl;
>>> diff --git a/drivers/media/platform/vimc/vimc-scaler.c b/drivers/media/platform/vimc/vimc-scaler.c
>>> index cb2dc24c3e59..7521439747c5 100644
>>> --- a/drivers/media/platform/vimc/vimc-scaler.c
>>> +++ b/drivers/media/platform/vimc/vimc-scaler.c
>>> @@ -464,27 +464,15 @@ static void *vimc_sca_process_frame(struct vimc_ent_device *ved,
>>> return vsca->src_frame;
>>> };
>>> -static void vimc_sca_release(struct v4l2_subdev *sd)
>>> +void vimc_sca_release(struct vimc_ent_device *ved)
>>> {
>>> struct vimc_sca_device *vsca =
>>> - container_of(sd, struct vimc_sca_device, sd);
>>> + container_of(ved, struct vimc_sca_device, ved);
>>> media_entity_cleanup(vsca->ved.ent);
>>> kfree(vsca);
>>> }
>>> -static const struct v4l2_subdev_internal_ops vimc_sca_int_ops = {
>>> - .release = vimc_sca_release,
>>> -};
>>> -
>>> -void vimc_sca_rm(struct vimc_device *vimc, struct vimc_ent_device *ved)
>>> -{
>>> - struct vimc_sca_device *vsca;
>>> -
>>> - vsca = container_of(ved, struct vimc_sca_device, ved);
>>> - v4l2_device_unregister_subdev(&vsca->sd);
>>> -}
>>> -
>>> struct vimc_ent_device *vimc_sca_add(struct vimc_device *vimc,
>>> const char *vcfg_name)
>>> {
>>> @@ -504,8 +492,7 @@ struct vimc_ent_device *vimc_sca_add(struct vimc_device *vimc,
>>> ret = vimc_ent_sd_register(&vsca->ved, &vsca->sd, v4l2_dev,
>>> vcfg_name,
>>> MEDIA_ENT_F_PROC_VIDEO_SCALER, 2,
>>> - vsca->pads,
>>> - &vimc_sca_int_ops, &vimc_sca_ops);
>>> + vsca->pads, &vimc_sca_ops);
>>> if (ret) {
>>> kfree(vsca);
>>> return NULL;
>>> diff --git a/drivers/media/platform/vimc/vimc-sensor.c b/drivers/media/platform/vimc/vimc-sensor.c
>>> index 9788fe291193..92daee58209e 100644
>>> --- a/drivers/media/platform/vimc/vimc-sensor.c
>>> +++ b/drivers/media/platform/vimc/vimc-sensor.c
>>> @@ -279,10 +279,10 @@ static const struct v4l2_ctrl_ops vimc_sen_ctrl_ops = {
>>> .s_ctrl = vimc_sen_s_ctrl,
>>> };
>>> -static void vimc_sen_release(struct v4l2_subdev *sd)
>>> +void vimc_sen_release(struct vimc_ent_device *ved)
>>> {
>>> struct vimc_sen_device *vsen =
>>> - container_of(sd, struct vimc_sen_device, sd);
>>> + container_of(ved, struct vimc_sen_device, ved);
>>> v4l2_ctrl_handler_free(&vsen->hdl);
>>> tpg_free(&vsen->tpg);
>>> @@ -290,18 +290,6 @@ static void vimc_sen_release(struct v4l2_subdev *sd)
>>> kfree(vsen);
>>> }
>>> -static const struct v4l2_subdev_internal_ops vimc_sen_int_ops = {
>>> - .release = vimc_sen_release,
>>> -};
>>> -
>>> -void vimc_sen_rm(struct vimc_device *vimc, struct vimc_ent_device *ved)
>>> -{
>>> - struct vimc_sen_device *vsen;
>>> -
>>> - vsen = container_of(ved, struct vimc_sen_device, ved);
>>> - v4l2_device_unregister_subdev(&vsen->sd);
>>> -}
>>> -
>>> /* Image Processing Controls */
>>> static const struct v4l2_ctrl_config vimc_sen_ctrl_class = {
>>> .flags = V4L2_CTRL_FLAG_READ_ONLY | V4L2_CTRL_FLAG_WRITE_ONLY,
>>> @@ -365,7 +353,7 @@ struct vimc_ent_device *vimc_sen_add(struct vimc_device *vimc,
>>> ret = vimc_ent_sd_register(&vsen->ved, &vsen->sd, v4l2_dev,
>>> vcfg_name,
>>> MEDIA_ENT_F_CAM_SENSOR, 1, &vsen->pad,
>>> - &vimc_sen_int_ops, &vimc_sen_ops);
>>> + &vimc_sen_ops);
>>> if (ret)
>>> goto err_free_tpg;
>>>
