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=-15.4 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 8F2B5C43214 for ; Thu, 29 Jul 2021 16:27:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7775560EC0 for ; Thu, 29 Jul 2021 16:27:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231416AbhG2Q1k (ORCPT ); Thu, 29 Jul 2021 12:27:40 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34394 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229878AbhG2Q1j (ORCPT ); Thu, 29 Jul 2021 12:27:39 -0400 Received: from mail-oo1-xc2e.google.com (mail-oo1-xc2e.google.com [IPv6:2607:f8b0:4864:20::c2e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CCB3CC061765; Thu, 29 Jul 2021 09:27:34 -0700 (PDT) Received: by mail-oo1-xc2e.google.com with SMTP id y16-20020a4ad6500000b0290258a7ff4058so1714105oos.10; Thu, 29 Jul 2021 09:27:34 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=wccDcOIxHNoamIBs8+qI6cGQUyc31knn7IGUD84IWoI=; b=Gi6LIfs9OvoxHljklLH6u2B9MqdkFBOeLMUStKM35DZ710RYV1kO+msYERWa6S3C2G dUuL+42LKQP4hzVVvc2oWyNfpt2NxH/dbnpik+YT8m4pC3RrPiFTNaWLxYIhCcWmqLmD rV6dhmZHY8+j/PRuNy0KFmoxLox25zcM4CX+mjvrSIc2Gz9b5+2QvghrEVI7zhuBikaW yx2KbG7aQoYzmwID0T0Tn+IDftwP7gFw2l5n/0efCVi4XLPVteBQ8MPCIi3LYsugjM4/ 0FWJ0tB/hTa0gj2OrtTahqHRqoTUiMSD6+v6vbXJAz+QwQnWAHmfJzOPOydrPIZLb12P HWsg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:subject:to:cc:references:from:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=wccDcOIxHNoamIBs8+qI6cGQUyc31knn7IGUD84IWoI=; b=UI4QzSD+dcs9pGQBiAz3NbeXZ6LF0U2Ong5BG0Y27N7K+BokGZFR7f+zlkPcatvyJi /0mnbmbMKsMXtzWsKDgFNMnOFNQoCjwnmNk1Oh4l4nwRYuFmPrIgg4I11UyeF0J2BcEo JfniJVg12ERBVBPbTNQq47eCwAa7ZqMmW/GlXL9pBSIrlSn3zpdGp1U4tIKPTAUfSosz TqLzFbzidSqxkYrsBQSXeNLugtLKJhIrgIm+dypQKuRLDDfZM0RjQRx7Qh1CU0V5cHlR z3FTvSaOyyBogfVT1BHTAUI1HCEnls44MAfINTUPR++ufsDIECOcJDG0hsCYEUfQlk+8 wutA== X-Gm-Message-State: AOAM5331BWscNPWMyVq2baHD6CxfZbh1kb/VVSttRDs8gOFjuyrmPzzn BPaKgywJOV+tDq4y5SvQZFkhJwsl4P8= X-Google-Smtp-Source: ABdhPJzx11z/wO9bOtkouRxSASlYujObu13PzWtD5mUe7KEWY08XL6Clk9UGPlizniiwYVOBvlrfrQ== X-Received: by 2002:a4a:cb0e:: with SMTP id r14mr3561068ooq.70.1627576053889; Thu, 29 Jul 2021 09:27:33 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id y19sm540815ooa.2.2021.07.29.09.27.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 29 Jul 2021 09:27:33 -0700 (PDT) Sender: Guenter Roeck Subject: Re: [PATCH] watchdog: Fix an invalid memory access in 'watchdog_cdev_unregister()' To: Christophe JAILLET , wim@linux-watchdog.org, curtis.klein@hpe.com Cc: linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org References: From: Guenter Roeck Message-ID: Date: Thu, 29 Jul 2021 09:27:31 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/29/21 9:16 AM, Christophe JAILLET wrote: > A few lines before 'watchdog_hrtimer_pretimeout_stop(wdd)', we explicitly > set 'wdd->wd_data' to NULL. > So, it is more than likely than this call will lead to an invalid > memory access. > > Move this call before the 'wdd->wd_data = NULL;' > > Fixes: 7b7d2fdc8c3e ("watchdog: Add hrtimer-based pretimeout feature") > Signed-off-by: Christophe JAILLET > --- > Completely untested! > Not sure at all, that it is the way to fix it. Nice catch. Should be ok. Reviewed-by: Guenter Roeck > --- > drivers/watchdog/watchdog_dev.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/drivers/watchdog/watchdog_dev.c b/drivers/watchdog/watchdog_dev.c > index 3bab32485273..ffd8f1a82355 100644 > --- a/drivers/watchdog/watchdog_dev.c > +++ b/drivers/watchdog/watchdog_dev.c > @@ -1096,6 +1096,8 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd) > watchdog_stop(wdd); > } > > + watchdog_hrtimer_pretimeout_stop(wdd); > + > mutex_lock(&wd_data->lock); > wd_data->wdd = NULL; > wdd->wd_data = NULL; > @@ -1103,7 +1105,6 @@ static void watchdog_cdev_unregister(struct watchdog_device *wdd) > > hrtimer_cancel(&wd_data->timer); > kthread_cancel_work_sync(&wd_data->work); > - watchdog_hrtimer_pretimeout_stop(wdd); > > put_device(&wd_data->dev); > } >