linux-kernel - [PATCH] input: lkkbd: cancel pending work before freeing device

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Message-Id: <20251211031131.27141-1-ii4gsp@gmail.com>
Date: Thu, 11 Dec 2025 12:11:31 +0900
From: Minseong Kim <ii4gsp@...il.com>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: linux-input@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	stable@...r.kernel.org,
	Minseong Kim <ii4gsp@...il.com>
Subject: [PATCH] input: lkkbd: cancel pending work before freeing device

lkkbd_interrupt() schedules lk->tq with schedule_work(), and the work
handler lkkbd_reinit() dereferences the lkkbd structure and its
serio/input_dev fields.

lkkbd_disconnect() frees the lkkbd structure without cancelling this
work, so the work can run after the structure has been freed, leading
to a potential use-after-free.

Cancel the pending work in lkkbd_disconnect() before unregistering and
freeing the device, following the same pattern as sunkbd.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Reported-by: Minseong Kim <ii4gsp@...il.com>
Cc: stable@...r.kernel.org
Signed-off-by: Minseong Kim <ii4gsp@...il.com>
---
 drivers/input/keyboard/lkkbd.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/input/keyboard/lkkbd.c b/drivers/input/keyboard/lkkbd.c
index c035216dd27c..72c477aab1fc 100644
--- a/drivers/input/keyboard/lkkbd.c
+++ b/drivers/input/keyboard/lkkbd.c
@@ -684,6 +684,8 @@ static void lkkbd_disconnect(struct serio *serio)
 {
 	struct lkkbd *lk = serio_get_drvdata(serio);

+	cancel_work_sync(&lk->tq);
+
 	input_get_device(lk->dev);
 	input_unregister_device(lk->dev);
 	serio_close(serio);
-- 
2.39.5