Re: [PATCH v4 01/19] media: rc: Ensure registered is cleared in error path

[Hans Verkuil <hverkuil+cisco@kernel.org>]

On 08/09/2026 17:51, Sean Young wrote:
> If rc_register_device() fails, ensure that registered is not set to true.
> If lirc_register() succeeded, then userspace could have an open file
> descriptor open. This leads to a use-after-free.
> 
> Fixes: dccc0c3ddf8f ("media: rc: fix race between unregister and urb/irq callbacks")
> Signed-off-by: Sean Young <sean@mess.org>
> Cc: stable@vger.kernel.org
> ---
>  drivers/media/rc/rc-main.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/media/rc/rc-main.c b/drivers/media/rc/rc-main.c
> index d93e98189c1a..1f99540456f1 100644
> --- a/drivers/media/rc/rc-main.c
> +++ b/drivers/media/rc/rc-main.c
> @@ -1934,7 +1934,8 @@ int rc_register_device(struct rc_dev *dev)
>  			goto out_raw;
>  	}
>  
> -	dev->registered = true;
> +	scoped_guard(mutex, &dev->lock)
> +		dev->registered = true;

Is the guard actually needed?

>  
>  	rc = device_add(&dev->dev);
>  	if (rc)
> @@ -1982,6 +1983,8 @@ int rc_register_device(struct rc_dev *dev)
>  out_dev:
>  	device_del(&dev->dev);
>  out_rx_free:
> +	scoped_guard(mutex, &dev->lock)
> +		dev->registered = false;

Same question here. I think the real fix is setting dev->registered to
false, but I'm not sure the guard makes a difference.

The commit log mentions nothing about that change either.

Regards,

	Hans

>  	ir_free_table(&dev->rc_map);
>  out_raw:
>  	ida_free(&rc_ida, minor);