linux-kernel - [PATCH 1/5] HID: bigben_remove: manually unregister leds

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Message-Id: <20230125-hid-unregister-leds-v1-1-9a5192dcef16@diag.uniroma1.it>
Date:   Thu, 26 Jan 2023 00:24:53 +0000
From:   Pietro Borrello <borrello@...g.uniroma1.it>
To:     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>
Cc:     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>,
        Pietro Borrello <borrello@...g.uniroma1.it>
Subject: [PATCH 1/5] HID: bigben_remove: manually unregister leds

Unregister the LED controllers before device removal, as
bigben_set_led() may schedule bigben->worker after the structure has
been freed, causing a use-after-free.

Fixes: 4eb1b01de5b9 ("HID: hid-bigbenff: fix race condition for scheduled work during removal")
Signed-off-by: Pietro Borrello <borrello@...g.uniroma1.it>
---
 drivers/hid/hid-bigbenff.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/hid/hid-bigbenff.c b/drivers/hid/hid-bigbenff.c
index e8b16665860d..d3201b755595 100644
--- a/drivers/hid/hid-bigbenff.c
+++ b/drivers/hid/hid-bigbenff.c
@@ -306,9 +306,14 @@ static enum led_brightness bigben_get_led(struct led_classdev *led)
 
 static void bigben_remove(struct hid_device *hid)
 {
+	int n;
 	struct bigben_device *bigben = hid_get_drvdata(hid);
 
 	bigben->removed = true;
+	for (n = 0; n < NUM_LEDS; n++) {
+		if (bigben->leds[n])
+			devm_led_classdev_unregister(&hid->dev, bigben->leds[n]);
+	}
 	cancel_work_sync(&bigben->worker);
 	hid_hw_stop(hid);
 }

-- 
2.25.1