From mboxrd@z Thu Jan 1 00:00:00 1970 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=-20.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, 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 6AA54C07E9B for ; Mon, 19 Jul 2021 15:06:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 58AB36113B for ; Mon, 19 Jul 2021 15:06:06 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242323AbhGSOZW (ORCPT ); Mon, 19 Jul 2021 10:25:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:56506 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242960AbhGSOWo (ORCPT ); Mon, 19 Jul 2021 10:22:44 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id EC8686113B; Mon, 19 Jul 2021 15:02:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626706971; bh=hkADfCiMoQJ+risbIzZYtyX+fRNEebwVd2J4+7NsjoQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=lvnsE7a9m+ky6GhCSZFTZ1W5tNLOJm2SL0i7suQ/mZBEZV2Uj1H23L42Vg/v0jtn/ cljdQPvBWTJtBYpzepLPPGGHRa3XD1V03qRmYQRwJdoLBMRhQhxYPFIOwvwQf9FZne udvGYBGOwcvFdotagi1K5lbKeLmYJqk3G5NWoW0k= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hulk Robot , Zou Wei , Guenter Roeck , Vladimir Zapolskiy , Wim Van Sebroeck , Sasha Levin Subject: [PATCH 4.4 170/188] watchdog: Fix possible use-after-free by calling del_timer_sync() Date: Mon, 19 Jul 2021 16:52:34 +0200 Message-Id: <20210719144942.056045172@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210719144913.076563739@linuxfoundation.org> References: <20210719144913.076563739@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Zou Wei [ Upstream commit d0212f095ab56672f6f36aabc605bda205e1e0bf ] This driver'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 Acked-by: Vladimir Zapolskiy Link: https://lore.kernel.org/r/1620802676-19701-1-git-send-email-zou_wei@huawei.com Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck Signed-off-by: Sasha Levin --- drivers/watchdog/lpc18xx_wdt.c | 2 +- drivers/watchdog/w83877f_wdt.c | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/watchdog/lpc18xx_wdt.c b/drivers/watchdog/lpc18xx_wdt.c index ab7b8b185d99..fbdc0f32e666 100644 --- a/drivers/watchdog/lpc18xx_wdt.c +++ b/drivers/watchdog/lpc18xx_wdt.c @@ -309,7 +309,7 @@ static int lpc18xx_wdt_remove(struct platform_device *pdev) unregister_restart_handler(&lpc18xx_wdt->restart_handler); dev_warn(&pdev->dev, "I quit now, hardware will probably reboot!\n"); - del_timer(&lpc18xx_wdt->timer); + del_timer_sync(&lpc18xx_wdt->timer); watchdog_unregister_device(&lpc18xx_wdt->wdt_dev); clk_disable_unprepare(lpc18xx_wdt->wdt_clk); diff --git a/drivers/watchdog/w83877f_wdt.c b/drivers/watchdog/w83877f_wdt.c index f0483c75ed32..4b52cf321747 100644 --- a/drivers/watchdog/w83877f_wdt.c +++ b/drivers/watchdog/w83877f_wdt.c @@ -170,7 +170,7 @@ static void wdt_startup(void) static void wdt_turnoff(void) { /* Stop the timer */ - del_timer(&timer); + del_timer_sync(&timer); wdt_change(WDT_DISABLE); -- 2.30.2