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=-15.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 9E251C4338F for ; Sat, 14 Aug 2021 19:14:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7C7AB60724 for ; Sat, 14 Aug 2021 19:14:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229601AbhHNTOh (ORCPT ); Sat, 14 Aug 2021 15:14:37 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54956 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229494AbhHNTOg (ORCPT ); Sat, 14 Aug 2021 15:14:36 -0400 Received: from mail-pj1-x1033.google.com (mail-pj1-x1033.google.com [IPv6:2607:f8b0:4864:20::1033]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 402D1C061764 for ; Sat, 14 Aug 2021 12:14:08 -0700 (PDT) Received: by mail-pj1-x1033.google.com with SMTP id gz13-20020a17090b0ecdb0290178c0e0ce8bso15084085pjb.1 for ; Sat, 14 Aug 2021 12:14:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=K6P+SxuPkz8jn/H05YhluGjv7NCf/43kOXbbbUxUyl4=; b=mSrmQixlkHSIyoYF2JzUF/ymcz8DrSl/HKZBdy3QmgO1C5tjBux+DSoom1HddSiycw R6HLXcfZY1F5UZMafOWBTe0EOONQwzPp0/qQyVdZwuf1eJ2HCaw+dxGtth+NFAvEV9q5 XJQ7OpWNgmuZEkpOZLhuGNqisnXHHQ39Oqrbme3lFxSYDyTZLwp2/8RLY4mMSNRDLPRo ss+FOuWAXVIxw9g9kf0ocm3bZTJTTAc3ChZgO1LnQRIG/tgSQNVgUyugxRk6L363Qzf/ vUQE5CFrz/93Rl9NBPEmsV9wkecytdmn39YIwJif/HCWF8hjcoueFoajs9YiliU/QJvH nSdQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=K6P+SxuPkz8jn/H05YhluGjv7NCf/43kOXbbbUxUyl4=; b=o6LMkhXiE8oUmHV5h/JTJVLJH+J/eDoMYLMbybKder/OAKl8Dv5iP8M8CHZccHNZsu vfdiPXfD746cNQmbdNW+XC7bx5Qxg2BL8Kifx1eDA9KECDicA2hPLmdgn0ctTbYJRvgW x84M2TY/tqstI1GPIyz2ARPgnCFFi661ixsjgGFnqDdt2ypm/rbV57OiLzXfy8mY3dQz NkrsP2ygsyIX+DUBN+mY1T7ft7ux9/Y2h0P4kb2w2ibcc9AvGxPNyffeBtkTYT+ltHu2 0e1mr+orpj1NRR6VYlr81BQSX5SK+UQ4e7id2DSWbiWVf17KBZEIHokHDjRlweVt9cno rP2A== X-Gm-Message-State: AOAM530/4FQBOGKUW5Exli1Oev1iITeIBxGoKgJD837FBANBep4XBLTX cwYFaak6sPKa30mrMqjJJtG2WoKrVXVyxg== X-Google-Smtp-Source: ABdhPJzeApZKHxMjt5JDow9nzzVkVe/uGOgjOT7ds/zkuOBu7nnASmogpyIIflDHW3cs8TNp5LlthA== X-Received: by 2002:a65:6107:: with SMTP id z7mr7870001pgu.43.1628968447743; Sat, 14 Aug 2021 12:14:07 -0700 (PDT) Received: from stas-Latitude-5300.lan ([2409:10:27a0:2500:3131:a211:8322:1585]) by smtp.gmail.com with ESMTPSA id u13sm6340979pfh.123.2021.08.14.12.14.05 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 14 Aug 2021 12:14:07 -0700 (PDT) From: Stanislav German-Evtushenko To: Wim Van Sebroeck , Guenter Roeck Cc: linux-watchdog@vger.kernel.org, Stanislav German-Evtushenko Subject: [PATCH] watchdog: Device must be opened for writing Date: Sun, 15 Aug 2021 04:13:45 +0900 Message-Id: <20210814191345.27221-1-ginermail@gmail.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-watchdog@vger.kernel.org If userspace opens the watchdog device self-feeding stops. Sometimes opening the device happens by accident, e.g. by mistakenly running grep recursively in a wrong directory which leads to the server being reset. Watchdog device does not handle read operation therefore the issue can be prevented by requiring the device to be opened for writing: - Prevent opening the device without FMODE_WRITE Signed-off-by: Stanislav German-Evtushenko --- drivers/watchdog/watchdog_dev.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c index 3bab32485273..28b88542a4d0 100644 --- a/drivers/watchdog/watchdog_dev.c +++ b/drivers/watchdog/watchdog_dev.c @@ -835,6 +835,10 @@ static int watchdog_open(struct inode *inode, struct file *file) bool hw_running; int err; + /* Must be open for writing */ + if (!(file->f_mode & FMODE_WRITE)) + return -EINVAL; + /* Get the corresponding watchdog device */ if (imajor(inode) == MISC_MAJOR) wd_data = old_wd_data; base-commit: cf813c67d9619fd474c785698cbed543b94209dd -- 2.25.1