From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-1133089-1521806036-2-7384687872247915316 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, HEADER_FROM_DIFFERENT_DOMAINS 0.25, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='UTF-8' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1521806036; b=Wm4BEeRdW+rYiLenrATT4G293L0gRQqaMnjPIZOQEQ1bIHj msnyl1hTbP/cyqbWn9Yi0hjMmEdml/6/+I75r+wOxK3ThM2TyOwLy8EmdnsTciKq IQpPw1+Uzx7ZhDtQgeDbrYjBqEkJ86c0jyZol61ML+VDYMaUGknYahh3diMJsWq9 So95zHvLaamL+UXFo1REaF545PLanKS2VVu63bDJZIytrZGfl8WKIMFJgtfmErch hwWhnBBuQh7U4azQQcPqlOa/0bu+hMpninUY+zq0cLuC0tJ7wWIClX9OZI7o/1uU lykIevbLhDZfAcggsWexUnMH33SfThlHXBi57DQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-type:sender :list-id; s=arctest; t=1521806036; bh=qmvxrf9OopyHZubcjUAOqpdxNr +SmUH+A6BOnfE7h74=; b=k7UOOFl+weJt4SqKnEqLg6KAkFzntmQ0ctlqq6SaBR yV+4JKjCuRtyzp3ZVJhV+qjLDkZXB+19BbM8ech0ehVvPqyhsxkt6OnPrjhivq7F vhtsxJ1I5YqYz3e/oNOIdA83gQlW9h1RAmtDpTfPRkXep25Pcgrja70lroP0uV3a tdqJv39ql+IiFw706aj57Byq6TffovtGWYA+stCYuTPYl3316uaZNshhogqsg0CX LfuZOmyvESsWJMUPwR+0sgkruG0YM7c320k7E+LdCk/vJk36xCu4PqkLDAwH6HsJ MfNwlcfrhSfSKnMnUqYrCkPp3tzDbtuA80EN7OHbxEAQ== ARC-Authentication-Results: i=1; mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 Authentication-Results: mx3.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=linuxfoundation.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=fail; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=linuxfoundation.org header.result=pass header_is_org_domain=yes; x-vs=clean score=-100 state=0 X-ME-VSCategory: clean Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753968AbeCWKBm (ORCPT ); Fri, 23 Mar 2018 06:01:42 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:37988 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751966AbeCWKBk (ORCPT ); Fri, 23 Mar 2018 06:01:40 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Guenter Roeck , Wim Van Sebroeck , Sasha Levin Subject: [PATCH 4.14 22/77] watchdog: Fix potential kref imbalance when opening watchdog Date: Fri, 23 Mar 2018 10:53:56 +0100 Message-Id: <20180323094143.684670232@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180323094142.260022880@linuxfoundation.org> References: <20180323094142.260022880@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Guenter Roeck [ Upstream commit 4bcd615fad6adddc68b058d498b30a9e0e0db77a ] If a watchdog driver's open function sets WDOG_HW_RUNNING with the expectation that the watchdog can not be stopped, but then stops the watchdog anyway in its stop function, kref_get() wil not be called in watchdog_open(). If the watchdog then stops on close, WDOG_HW_RUNNING will be cleared and kref_put() will be called, causing a kref imbalance. As result the character device data structure will be released, which in turn will cause the system to crash on the next call to watchdog_open(). Fixes: ee142889e32f5 ("watchdog: Introduce WDOG_HW_RUNNING flag") Signed-off-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/watchdog/watchdog_dev.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -768,6 +768,7 @@ static int watchdog_open(struct inode *i { struct watchdog_core_data *wd_data; struct watchdog_device *wdd; + bool hw_running; int err; /* Get the corresponding watchdog device */ @@ -787,7 +788,8 @@ static int watchdog_open(struct inode *i * If the /dev/watchdog device is open, we don't want the module * to be unloaded. */ - if (!watchdog_hw_running(wdd) && !try_module_get(wdd->ops->owner)) { + hw_running = watchdog_hw_running(wdd); + if (!hw_running && !try_module_get(wdd->ops->owner)) { err = -EBUSY; goto out_clear; } @@ -798,7 +800,7 @@ static int watchdog_open(struct inode *i file->private_data = wd_data; - if (!watchdog_hw_running(wdd)) + if (!hw_running) kref_get(&wd_data->kref); /* dev/watchdog is a virtual (and thus non-seekable) filesystem */