On 11/20/19 1:22 PM, 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@xxxxxxxxxxxxxxx
> Fixes: 0e43734d4c46e ("media: v4l2-subdev: add release() internal op")
> Signed-off-by: Dafna Hirschfeld <dafna.hirschfeld@xxxxxxxxxxxxx>
> Reviewed-by: Ezequiel Garcia <ezequiel@xxxxxxxxxxxxx>
> ---
> 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.
>
> 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..2b3595671d62 100644
> --- a/drivers/media/v4l2-core/v4l2-device.c
> +++ b/drivers/media/v4l2-core/v4l2-device.c
> @@ -177,6 +177,7 @@ static void v4l2_subdev_release(struct v4l2_subdev *sd)
> {
> struct module *owner = !sd->owner_v4l2_dev ? sd->owner : NULL;
>
> + sd->devnode = NULL;
> if (sd->internal_ops && sd->internal_ops->release)
> sd->internal_ops->release(sd);
I'd move the sd->devnode = NULL; line here. That way the
sd->internal_ops->release(sd) callback can still use it.
Unless I am missing something?
> module_put(owner);
>
Regards,
Hans
