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=-15.3 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=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 68C2CC433ED for ; Tue, 11 May 2021 13:37:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38FB461933 for ; Tue, 11 May 2021 13:37:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231530AbhEKNiW (ORCPT ); Tue, 11 May 2021 09:38:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36744 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231604AbhEKNiT (ORCPT ); Tue, 11 May 2021 09:38:19 -0400 Received: from mail-oi1-x230.google.com (mail-oi1-x230.google.com [IPv6:2607:f8b0:4864:20::230]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 72226C06174A; Tue, 11 May 2021 06:37:12 -0700 (PDT) Received: by mail-oi1-x230.google.com with SMTP id u16so19038315oiu.7; Tue, 11 May 2021 06:37:12 -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=YW82r9Shi+W5Wd4oZFNM7KnqQ1f238S0OR4W4r1hOe4=; b=KRNPPP1YsjgzmYQoA2wjU4Yc9MAF6L9GrsLPQ74696/zZtUJAoXB6w7ZWWtsVK0KQC fg/B4WPFQA5X4pNytJnlrNWJaR+cy3F+K22Bv61hyQbwcU8+rl5q5Vc1f9x6TVtXEKwS 3dgz+Gi2CcVvi8Fv+T9wcQi1ahFSPDzRidEAOoyCD1IBf5mphy1fI2BGhtIWtSLxx24o 3eMBjN4KMJGYfTFGEGohrviqfXfX7g8QHKjciZ1WNexnw2w27g4c2T047qQnv1VonZBs na8t+D1w/JJkwB11azXOqcwKPY3+J3K+tm8L490RhV6lYi34O1hX4GVeIHXUufJqp6It N6Zw== 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=YW82r9Shi+W5Wd4oZFNM7KnqQ1f238S0OR4W4r1hOe4=; b=s6g9XOYa8lfadq/R0gn8dRQcqnlmn2ssr0IvEsq/6Lsc9ApJtemBCRm59sir3+Tf+6 Lc6HSmahioZ4woe7obmuBxxCX+JoQgxwo7ERsyy17cDGolgWigwC/n5Tpvkwvqo+DDT+ MpktfSEUqyD2PdTrnsXLV1XBjyc4AX9PPubK/N93x6FSXK1rN1oPTv88zb0Nhh5gNUpm 9QEBkP9Aslpc76nOtGR+bNnEQXmft4mMmgUY3FPfzh2G16ukk2+auYrx9X9vLKO3wsbR 3UHjPXgryNYAVxp8VKTeDN52fO9rd/qAKVYxxUgFMGKXf6oOs+SNn/DshK607gNDDxuo o/3w== X-Gm-Message-State: AOAM531G1KkhOBz3VIdM2Og7J5B73kIkA52Z2Gnwv7p3FBqHw9D2a6mh cBKk0GNXIX/C1FKIW0oldDLdT/6lFak= X-Google-Smtp-Source: ABdhPJxEPAX2MOhVCejnNBESY76RZEg+jQpWd4eFJG/frHsx2njNXVpqyhVCug9aiiPuBR7CLES/zA== X-Received: by 2002:aca:30cc:: with SMTP id w195mr22380951oiw.78.1620740231267; Tue, 11 May 2021 06:37:11 -0700 (PDT) Received: from server.roeck-us.net ([2600:1700:e321:62f0:329c:23ff:fee3:9d7c]) by smtp.gmail.com with ESMTPSA id c9sm3278256ooq.31.2021.05.11.06.37.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 11 May 2021 06:37:10 -0700 (PDT) Sender: Guenter Roeck Subject: Re: [PATCH -next] watchdog: sc520_wdt: Fix possible use-after-free in wdt_turnoff() To: Zou Wei , wim@linux-watchdog.org Cc: linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org References: <1620716691-108460-1-git-send-email-zou_wei@huawei.com> From: Guenter Roeck Message-ID: <78638328-536d-edf6-f913-38f6d3acb1d3@roeck-us.net> Date: Tue, 11 May 2021 06:37:09 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: <1620716691-108460-1-git-send-email-zou_wei@huawei.com> 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-watchdog@vger.kernel.org On 5/11/21 12:04 AM, Zou Wei wrote: > This module'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 > --- > drivers/watchdog/sc520_wdt.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/watchdog/sc520_wdt.c b/drivers/watchdog/sc520_wdt.c > index e66e6b9..ca65468 100644 > --- a/drivers/watchdog/sc520_wdt.c > +++ b/drivers/watchdog/sc520_wdt.c > @@ -186,7 +186,7 @@ static int wdt_startup(void) > static int wdt_turnoff(void) > { > /* Stop the timer */ > - del_timer(&timer); > + del_timer_sync(&timer); > > /* Stop the watchdog */ > wdt_config(0); >