linux-kernel - [PATCH v2 4/5] HID: dualshock4_remove: manually unregister leds

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Message-Id: <20230125-hid-unregister-leds-v2-4-514437b19297@diag.uniroma1.it>
Date:   Thu, 26 Jan 2023 12:11:42 +0000
From:   Pietro Borrello <borrello@...g.uniroma1.it>
To:     Roderick Colenbrander <thunderbird2k@...il.com>
Cc:     Pietro Borrello <borrello@...g.uniroma1.it>,
        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>,
        Jiri Kosina <jikos@...nel.org>,
        Benjamin Tissoires <benjamin.tissoires@...hat.com>,
        Hanno Zulla <kontakt@...no.de>, Pavel Machek <pavel@....cz>,
        Lee Jones <lee@...nel.org>,
        Roderick Colenbrander <roderick.colenbrander@...y.com>,
        Sven Eckelmann <sven@...fation.org>
Subject: [PATCH v2 4/5] HID: dualshock4_remove: manually unregister leds

Unregister the LED controllers before device removal, to prevent
unnecessary runs of dualshock4_led_set_brightness().

Fixes: 4521109a8f40 ("HID: playstation: support DualShock4 lightbar.")
Signed-off-by: Pietro Borrello <borrello@...g.uniroma1.it>

---

Contrary to the other patches in this series, failing to unregister
the led controller does not results into a use-after-free thanks
to the output_worker_initialized variable and the spinlock checks.

Changes in v2:
- Clarify UAF
- Link to v1: https://lore.kernel.org/all/20230125-hid-unregister-leds-v1-4-9a5192dcef16@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 f23186ca2d76..b41657842e26 100644
--- a/drivers/hid/hid-playstation.c
+++ b/drivers/hid/hid-playstation.c
@@ -2434,11 +2434,15 @@ static void dualshock4_remove(struct ps_device *ps_dev)
 {
 	struct dualshock4 *ds4 = container_of(ps_dev, struct dualshock4, base);
 	unsigned long flags;
+	int i;
 
 	spin_lock_irqsave(&ds4->base.lock, flags);
 	ds4->output_worker_initialized = false;
 	spin_unlock_irqrestore(&ds4->base.lock, flags);
 
+	for (i = 0; i < ARRAY_SIZE(ds4->lightbar_leds); i++)
+		devm_led_classdev_unregister(&ps_dev->hdev->dev, &ds4->lightbar_leds[i]);
+
 	cancel_work_sync(&ds4->output_worker);
 
 	if (ps_dev->hdev->product == USB_DEVICE_ID_SONY_PS4_CONTROLLER_DONGLE)

-- 
2.25.1