From patchwork Tue May 11 07:01:35 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zou Wei X-Patchwork-Id: 12249883 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 7C1F7C433ED for ; Tue, 11 May 2021 06:44:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5C7C16187E for ; Tue, 11 May 2021 06:44:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229931AbhEKGps (ORCPT ); Tue, 11 May 2021 02:45:48 -0400 Received: from szxga05-in.huawei.com ([45.249.212.191]:2558 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229807AbhEKGps (ORCPT ); Tue, 11 May 2021 02:45:48 -0400 Received: from DGGEMS413-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4FfSyK0NM3zkWRZ; Tue, 11 May 2021 14:42:01 +0800 (CST) Received: from linux-lmwb.huawei.com (10.175.103.112) by DGGEMS413-HUB.china.huawei.com (10.3.19.213) with Microsoft SMTP Server id 14.3.498.0; Tue, 11 May 2021 14:44:32 +0800 From: Zou Wei To: , CC: , , Zou Wei Subject: [PATCH -next] watchdog: Fix possible use-after-free in wdt_startup() Date: Tue, 11 May 2021 15:01:35 +0800 Message-ID: <1620716495-108352-1-git-send-email-zou_wei@huawei.com> X-Mailer: git-send-email 2.6.2 MIME-Version: 1.0 X-Originating-IP: [10.175.103.112] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org This module's remove path calls del_timer(). However, that function does not wait until the timer handler finishes. This means that the timer handler may still be running after the driver's remove function has finished, which would result in a use-after-free. Fix by calling del_timer_sync(), which makes sure the timer handler has finished, and unable to re-schedule itself. Reported-by: Hulk Robot Signed-off-by: Zou Wei Reviewed-by: Guenter Roeck --- drivers/watchdog/sbc60xxwdt.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/watchdog/sbc60xxwdt.c b/drivers/watchdog/sbc60xxwdt.c index a947a63..7b97480 100644 --- a/drivers/watchdog/sbc60xxwdt.c +++ b/drivers/watchdog/sbc60xxwdt.c @@ -146,7 +146,7 @@ static void wdt_startup(void) static void wdt_turnoff(void) { /* Stop the timer */ - del_timer(&timer); + del_timer_sync(&timer); inb_p(wdt_stop); pr_info("Watchdog timer is now disabled...\n"); }