From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F96D8F74 for ; Sun, 16 Jul 2023 20:03:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0FC75C433C8; Sun, 16 Jul 2023 20:03:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1689537818; bh=oSXOFgtcyXlpIAsrvAp1cvh7AyyhdxLWT25YlAShx8Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NQLW5wfIBDgC6Dlc69EUGJgRpyu52eStVjN0O2WegcxmsjbfSYnJPknTq/4DGUwqn OOlMTnhK+ndJzV1JYm13bEQS6y6OG1eOFyTJYtqvGqr2kXBrkHcuI7qpDg+bbKkNfi Pnd3b1kuQf8FEBS8NJ3+P1sJIO521FwtaSHE0sfQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Duoming Zhou , Dmitry Torokhov , Sasha Levin Subject: [PATCH 6.4 231/800] Input: cyttsp4_core - change del_timer_sync() to timer_shutdown_sync() Date: Sun, 16 Jul 2023 21:41:24 +0200 Message-ID: <20230716194954.455306719@linuxfoundation.org> X-Mailer: git-send-email 2.41.0 In-Reply-To: <20230716194949.099592437@linuxfoundation.org> References: <20230716194949.099592437@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Duoming Zhou [ Upstream commit dbe836576f12743a7d2d170ad4ad4fd324c4d47a ] The watchdog_timer can schedule tx_timeout_task and watchdog_work can also arm watchdog_timer. The process is shown below: ----------- timer schedules work ------------ cyttsp4_watchdog_timer() //timer handler schedule_work(&cd->watchdog_work) ----------- work arms timer ------------ cyttsp4_watchdog_work() //workqueue callback function cyttsp4_start_wd_timer() mod_timer(&cd->watchdog_timer, ...) Although del_timer_sync() and cancel_work_sync() are called in cyttsp4_remove(), the timer and workqueue could still be rearmed. As a result, the possible use after free bugs could happen. The process is shown below: (cleanup routine) | (timer and workqueue routine) cyttsp4_remove() | cyttsp4_watchdog_timer() //timer cyttsp4_stop_wd_timer() | schedule_work() del_timer_sync() | | cyttsp4_watchdog_work() //worker | cyttsp4_start_wd_timer() | mod_timer() cancel_work_sync() | | cyttsp4_watchdog_timer() //timer | schedule_work() del_timer_sync() | kfree(cd) //FREE | | cyttsp4_watchdog_work() // reschedule! | cd-> //USE This patch changes del_timer_sync() to timer_shutdown_sync(), which could prevent rearming of the timer from the workqueue. Fixes: 17fb1563d69b ("Input: cyttsp4 - add core driver for Cypress TMA4XX touchscreen devices") Signed-off-by: Duoming Zhou Link: https://lore.kernel.org/r/20230421082919.8471-1-duoming@zju.edu.cn Signed-off-by: Dmitry Torokhov Signed-off-by: Sasha Levin --- drivers/input/touchscreen/cyttsp4_core.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/input/touchscreen/cyttsp4_core.c b/drivers/input/touchscreen/cyttsp4_core.c index 0cd6f626adec5..7cb26929dc732 100644 --- a/drivers/input/touchscreen/cyttsp4_core.c +++ b/drivers/input/touchscreen/cyttsp4_core.c @@ -1263,9 +1263,8 @@ static void cyttsp4_stop_wd_timer(struct cyttsp4 *cd) * Ensure we wait until the watchdog timer * running on a different CPU finishes */ - del_timer_sync(&cd->watchdog_timer); + timer_shutdown_sync(&cd->watchdog_timer); cancel_work_sync(&cd->watchdog_work); - del_timer_sync(&cd->watchdog_timer); } static void cyttsp4_watchdog_timer(struct timer_list *t) -- 2.39.2