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Sat, 29 Aug 2026 07:01:12 -0700 (PDT) From: Jeffin Philip To: dmitry.torokhov@gmail.com Cc: linux-input@vger.kernel.org, linux-kernel@vger.kernel.org, Jeffin Philip , syzbot+1e2ef9bcb29af666b2e6@syzkaller.appspotmail.com Subject: [PATCH v4] Input: atkbd - fix uaf in atkbd_set_repeat_rate Date: Sat, 29 Aug 2026 19:29:59 +0530 Message-ID: <20260829135959.14882-1-jeffinphilip14@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit atkbd_disable() marks atkbd as disabled to prevent any work event to be executed, however this can race with atkbd_event_work(). If a pending work passes the atkbd->enabled check and atkbd_disable() runs after in disconnect, it could dereference dev which is freed in disconnect following atkbd being marked disabled. Fix this by adding disable_delayed_work_sync() which drops all work events preventing any rescheduling after atkbd is marked disabled. Reported-by: syzbot+1e2ef9bcb29af666b2e6@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=1e2ef9bcb29af666b2e6 Fixes: 0ef7a26af127 ("Input: atkbd - fix canceling event_work in disconnect") Signed-off-by: Jeffin Philip --- Changelog: - Changed in v4: Changed location of disable_pending_work_sync() after input_unregister_device() as per Dmitry's suggestion. - Changes in v3: Rewrote the patch to include disable_delayed_work_sync() as per Dmitry's suggestion. - Changes in v2: Added a check for atkbd->enabled so userspace cannot queue events after atkbd_disable. --- drivers/input/keyboard/atkbd.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/drivers/input/keyboard/atkbd.c b/drivers/input/keyboard/atkbd.c index 5736f4bc5a50..41a0d55dae0e 100644 --- a/drivers/input/keyboard/atkbd.c +++ b/drivers/input/keyboard/atkbd.c @@ -966,12 +966,9 @@ static void atkbd_disconnect(struct serio *serio) input_unregister_device(atkbd->dev); /* - * Make sure we don't have a command in flight. - * Note that since atkbd->enabled is false event work will keep - * rescheduling itself until it gets canceled and will not try - * accessing freed input device or serio port. + * Prevent work from being rescheduled after atkbd is marked disabled */ - cancel_delayed_work_sync(&atkbd->event_work); + disable_delayed_work_sync(&atkbd->event_work); serio_close(serio); serio_set_drvdata(serio, NULL); -- 2.55.0