Hi, When a subdevice is registered with v4l2_async_register_subdev_sensor_common and the main driver is unloaded and reloaded, it does not register a node for the subdevice since the devonde is not set to null. in v4l2_device_register_subdev_nodes the sd is skipped if sd->devnode.

This patch solves this issue as well.

Dafna

On 19.02.20 16:25, Dafna Hirschfeld wrote:

sd->devnode is released after calling v4l2_subdev_release. Therefore it should be set to NULL so that the subdev won't hold a pointer to a released object. This fixes a reference after free bug in function v4l2_device_unregister_subdev

Cc: stable@vger.kernel.org Fixes: 0e43734d4c46e ("media: v4l2-subdev: add release() internal op") Signed-off-by: Dafna Hirschfeld dafna.hirschfeld@collabora.com Reviewed-by: Ezequiel Garcia ezequiel@collabora.com

---

changes since v2:

• since this is a regresion fix, I added Fixes and Cc to stable tags,
• change the commit title and log to be more clear.

changes since v3: move the sd->devnode = NULL; line below the call to the release cb so that it can still use it.

drivers/media/v4l2-core/v4l2-device.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/drivers/media/v4l2-core/v4l2-device.c b/drivers/media/v4l2-core/v4l2-device.c index 63d6b147b21e..41da73ce2e98 100644 --- a/drivers/media/v4l2-core/v4l2-device.c +++ b/drivers/media/v4l2-core/v4l2-device.c @@ -179,6 +179,7 @@ static void v4l2_subdev_release(struct v4l2_subdev *sd) if (sd->internal_ops && sd->internal_ops->release) sd->internal_ops->release(sd);

• sd->devnode = NULL; module_put(owner); }