From patchwork Tue Aug 28 10:13:47 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wolfram Sang X-Patchwork-Id: 10578147 X-Patchwork-Delegate: geert@linux-m68k.org Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 59AC75A4 for ; Tue, 28 Aug 2018 10:21:55 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4B193295BF for ; Tue, 28 Aug 2018 10:21:55 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 3ED76295C5; Tue, 28 Aug 2018 10:21:55 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D46F2295C2 for ; Tue, 28 Aug 2018 10:21:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727345AbeH1OMv (ORCPT ); Tue, 28 Aug 2018 10:12:51 -0400 Received: from sauhun.de ([88.99.104.3]:39098 "EHLO pokefinder.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727124AbeH1OMv (ORCPT ); Tue, 28 Aug 2018 10:12:51 -0400 Received: from localhost (p54B335A5.dip0.t-ipconnect.de [84.179.53.165]) by pokefinder.org (Postfix) with ESMTPSA id E9BC132F502; Tue, 28 Aug 2018 12:14:10 +0200 (CEST) From: Wolfram Sang To: linux-watchdog@vger.kernel.org Cc: linux-renesas-soc@vger.kernel.org, Yoshihiro Shimoda , Fabrizio Castro , Wolfram Sang Subject: [PATCH 1/2] watchdog: core: fix null pointer dereference when releasing cdev Date: Tue, 28 Aug 2018 12:13:47 +0200 Message-Id: <20180828101348.12443-2-wsa+renesas@sang-engineering.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20180828101348.12443-1-wsa+renesas@sang-engineering.com> References: <20180828101348.12443-1-wsa+renesas@sang-engineering.com> Sender: linux-renesas-soc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-renesas-soc@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP watchdog_stop() calls watchdog_update_worker() which needs a valid wdd->wd_data pointer. So, when unregistering the cdev, clear the pointers after we call watchdog_stop(), not before. Fixes: bb292ac1c602 ("watchdog: Introduce watchdog_stop_on_unregister helper") Signed-off-by: Wolfram Sang Reviewed-by: Guenter Roeck Reviewed-by: Fabrizio Castro --- drivers/watchdog/watchdog_dev.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index ffbdc4642ea5..f6c24b22b37c 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -1019,16 +1019,16 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd) old_wd_data = NULL; } - mutex_lock(&wd_data->lock); - wd_data->wdd = NULL; - wdd->wd_data = NULL; - mutex_unlock(&wd_data->lock); - if (watchdog_active(wdd) && test_bit(WDOG_STOP_ON_UNREGISTER, &wdd->status)) { watchdog_stop(wdd); } + mutex_lock(&wd_data->lock); + wd_data->wdd = NULL; + wdd->wd_data = NULL; + mutex_unlock(&wd_data->lock); + hrtimer_cancel(&wd_data->timer); kthread_cancel_work_sync(&wd_data->work);