Re: [PATCH v3 4/4] HID: wiimote: fix uaf when hid events are handled during destroy

["David Rheinsberg" <david@readahead.eu>]

Hi

On Wed, Jul 29, 2026, at 6:49 PM, Rafael Passos wrote:
> In wiimote_destroy, in the time between setting WIIPROTO_FLAG_EXITING
> and hid_hw_stop, new events could be handled.
> The new behaviour mirrors hid-playstation's output_worker_initialized
> flag-gate (source of inspiration).
>
> This issue was reported as a pre-existign race condition by sashiko.
> I confirmed it is possible, but very unlikely. It could only happen if
> shutdown is initiated by Linux, and the controller is being used.

`hdev->driver_input_lock` serializes all probe/remove/event callbacks. Can you elaborate how this is triggered?

I can see that external APIs like debugfs and other sysfs registrations can trigger this, but they are deinitialized before cancelling the work, aren't they?

Thanks
David

> Signed-off-by: Rafael Passos <rafael@rcpassos.me>
> ---
>  drivers/hid/hid-wiimote-core.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/hid/hid-wiimote-core.c 
> b/drivers/hid/hid-wiimote-core.c
> index 31ee86affc553..067db8b8a56d1 100644
> --- a/drivers/hid/hid-wiimote-core.c
> +++ b/drivers/hid/hid-wiimote-core.c
> @@ -92,6 +92,9 @@ static void wiimote_queue(struct wiimote_data *wdata, 
> const __u8 *buffer,
>  	 */
> 
>  	spin_lock_irqsave(&wdata->queue.lock, flags);
> +	/* Do not schedule work if controller is exiting */
> +	if ((wdata->state.flags & WIIPROTO_FLAG_EXITING))
> +		goto out_unlock;
> 
>  	memcpy(wdata->queue.outq[wdata->queue.head].data, buffer, count);
>  	wdata->queue.outq[wdata->queue.head].size = count;
> -- 
> 2.53.0