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From:   Roderick Colenbrander <thunderbird2k@gmail.com>
Date:   Wed, 25 Jan 2023 16:47:07 -0800
Message-ID: <CAEc3jaDRzvw4wqomWTZ4QiGT7ndm0u+LQuqDTOWB=B-6w=2yzg@mail.gmail.com>
Subject: Re: [PATCH 3/5] HID: dualsense_remove: manually unregister leds
To:     Pietro Borrello <borrello@diag.uniroma1.it>
Cc:     Jiri Kosina <jikos@kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        Hanno Zulla <kontakt@hanno.de>, Pavel Machek <pavel@ucw.cz>,
        Lee Jones <lee@kernel.org>,
        Roderick Colenbrander <roderick.colenbrander@sony.com>,
        Sven Eckelmann <sven@narfation.org>,
        linux-leds@vger.kernel.org,
        Cristiano Giuffrida <c.giuffrida@vu.nl>,
        "Bos, H.J." <h.j.bos@vu.nl>, Jakob Koschel <jkl820.git@gmail.com>,
        linux-input@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jiri Kosina <jkosina@suse.cz>,
        Roderick Colenbrander <roderick@gaikai.com>
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Precedence: bulk

One other little note. For completeness I guess we need a similar
patch for the multicolor led class.

On Wed, Jan 25, 2023 at 4:43 PM Roderick Colenbrander
<thunderbird2k@gmail.com> wrote:
>
> 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@diag.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@diag.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