linux-kernel - Re: [PATCH 3/5] HID: dualsense_remove: manually unregister leds

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Date:   Wed, 25 Jan 2023 16:43:52 -0800
From:   Roderick Colenbrander <thunderbird2k@...il.com>
To:     Pietro Borrello <borrello@...g.uniroma1.it>
Cc:     Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Hanno Zulla <kontakt@...no.de>,
        Carlo Caione <carlo@...lessm.com>, Pavel Machek <pavel@....cz>,
        Lee Jones <lee@...nel.org>,
        Roderick Colenbrander <roderick.colenbrander@...y.com>,
        Sven Eckelmann <sven@...fation.org>,
        linux-leds@...r.kernel.org,
        Cristiano Giuffrida <c.giuffrida@...nl>,
        "Bos, H.J." <h.j.bos@...nl>, Jakob Koschel <jkl820.git@...il.com>,
        linux-input@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jiri Kosina <jkosina@...e.cz>,
        Roderick Colenbrander <roderick@...kai.com>
Subject: Re: [PATCH 3/5] HID: dualsense_remove: manually unregister leds

Hi Pietro,

Thanks for your patch. For sure for ds4/dualsense there have been edge
cases around rumble removal and others. Those were prevented by this
'output_worker_initialized' variable, which is checked during the
centralized work scheduling function (dualshock4_schedule_work /
dualsense_schedule_work). That said I don't mind the change as it
prevents the work scheduling functions to get called unnecessarily.

Thanks,
Roderick Colenbrander

On Wed, Jan 25, 2023 at 4:26 PM Pietro Borrello
<borrello@...g.uniroma1.it> wrote:
>
> Unregister the LED controller before device removal, as
> dualsense_player_led_set_brightness() may schedule output_worker
> after the structure has been freed, causing a use-after-free.
>
> Fixes: 8c0ab553b072 ("HID: playstation: expose DualSense player LEDs through LED class.")
> Signed-off-by: Pietro Borrello <borrello@...g.uniroma1.it>
> ---
>  drivers/hid/hid-playstation.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/hid/hid-playstation.c b/drivers/hid/hid-playstation.c
> index 27c40894acab..9e23860b7e95 100644
> --- a/drivers/hid/hid-playstation.c
> +++ b/drivers/hid/hid-playstation.c
> @@ -1503,11 +1503,15 @@ static void dualsense_remove(struct ps_device *ps_dev)
>  {
>         struct dualsense *ds = container_of(ps_dev, struct dualsense, base);
>         unsigned long flags;
> +       int i;
>
>         spin_lock_irqsave(&ds->base.lock, flags);
>         ds->output_worker_initialized = false;
>         spin_unlock_irqrestore(&ds->base.lock, flags);
>
> +       for (i = 0; i < ARRAY_SIZE(ds->player_leds); i++)
> +               devm_led_classdev_unregister(&ps_dev->hdev->dev, &ds->player_leds[i]);
> +
>         cancel_work_sync(&ds->output_worker);
>  }
>
>
> --
> 2.25.1