Re: [PATCH] net: nfc: fix deadlock between nfc_unregister_device and rfkill_fop_write

[Krzysztof Kozlowski <krzk@kernel.org>]

On 17/12/2025 09:11, Deepanshu Kartikey wrote:
> 
> rfkill_set_block() calls ops->set_block() (i.e., nfc_rfkill_set_block)
> without releasing rfkill_global_mutex.
> 
> Since rfkill_unregister() also acquires rfkill_global_mutex:
> 
> void rfkill_unregister(struct rfkill *rfkill)
> {
>     ...
>     mutex_lock(&rfkill_global_mutex);
>     rfkill_send_events(rfkill, RFKILL_OP_DEL);
>     list_del_init(&rfkill->node);
>     ...
>     mutex_unlock(&rfkill_global_mutex);
> }
> 
> The unregister path cannot proceed past rfkill_unregister() until any
> ongoing callback completes. Since device_del() is called after
> rfkill_unregister() returns, no UAF should be possible.

Indeed, that's correct. Please mention this briefly in commit msg. The
same as other ABBA remark in register path.


Best regards,
Krzysztof