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=-4.2 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 500B1C4338F for ; Tue, 3 Aug 2021 02:46:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 31F1560F94 for ; Tue, 3 Aug 2021 02:46:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233654AbhHCCqn (ORCPT ); Mon, 2 Aug 2021 22:46:43 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58620 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233356AbhHCCqm (ORCPT ); Mon, 2 Aug 2021 22:46:42 -0400 Received: from mail-pj1-x102c.google.com (mail-pj1-x102c.google.com [IPv6:2607:f8b0:4864:20::102c]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C5A01C06175F for ; Mon, 2 Aug 2021 19:46:31 -0700 (PDT) Received: by mail-pj1-x102c.google.com with SMTP id ca5so27788700pjb.5 for ; Mon, 02 Aug 2021 19:46:31 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-transfer-encoding:content-language; bh=Yk5HA+RCKHucxQd1hb4X8opTplCmtw5uKcxcakFiF0U=; b=MaG58TNhD4YNzQyT3/dmEVsU7r4gkAb1PD/HMSjheFBh4SDFSb6bqqYXazBNxJpdeV XPjGsWWDDpw7GC3r7Ib63O6iufdA0E29ko7akAMpPlUjf2zZfDn7iA4F20oW4i/8MOW9 ujSt5aPdaCeNwfSFK2nXXUj4WZqEg3Jhcq3PK5WRGPFeK3aFcwrXHRWLhfQ3P686HHa8 VyRGtD+H0g5LuK2Kotp9ubmv9UIAMBntG5ekjsscAgsygd0X1523gfP+kkf9FKTxdE/E vc4klUtLOYq9cEByFZSO2AmuRh4QX/hZbLIPO9eC3sP6Trs7zXqoHVt1gU7BgxMcUEYn QPqw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-transfer-encoding :content-language; bh=Yk5HA+RCKHucxQd1hb4X8opTplCmtw5uKcxcakFiF0U=; b=a7/dE2NlKcnxuz7wLdROK6lEPwQk9Wl+ec+hEV2vBQTVnvNa9GXEh5JmvY+mXjdgo2 /gTGY6pnRHvI53egxzzZp7Mtfms1dFwhEvjI9bgBpS0xhfmXtxK/DCYgiSg9Lj9PLRfj +5gD2J/hidAG2Fdv0jN/w01G3VthLVlZH3LKkmsRQdRaYEu4l1s3zcb/GYBEqGDQcSpD +rpgDcQ+a9t8p4BpYOllZRMMlbBu43wcR3jlLkzEp0jccdXq2UShB3y4w9QwYK0+iGM3 n8+kROq48YTuoKnsBvlmxwcRz8K5WaKxhnZi1kU5SLg36GFa+PmcnNp8tonz4wa1nmo1 1p/Q== X-Gm-Message-State: AOAM530h7+laUOxLt+704e/l+ipHmT0dEJ5X1jm17OyKl4VF0jgMXbsH fuaaalBY5Pd5IPfKRVpa5BQ= X-Google-Smtp-Source: ABdhPJwZS5jd92KVmGgS4zUDIGxaEMC8bTGpcCpTB+MRGs/Z5typsAOun/fc/bi5Awfz1SP4o/kvHA== X-Received: by 2002:a05:6a00:1305:b029:347:676:d38f with SMTP id j5-20020a056a001305b02903470676d38fmr19626430pfu.39.1627958791419; Mon, 02 Aug 2021 19:46:31 -0700 (PDT) Received: from [10.58.0.94] ([45.135.186.121]) by smtp.gmail.com with ESMTPSA id j19sm13396893pfr.82.2021.08.02.19.46.30 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Aug 2021 19:46:31 -0700 (PDT) Subject: Re: [BUG] jfs: possible uninitialized-variable access in xtSplitUp() To: Dave Kleikamp Cc: jfs-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org, baijiaju1990@gmail.com References: <6b3b3a56-b77c-aff7-c9f1-94a99d4929d2@gmail.com> From: Li Tuo Message-ID: <09905e41-c450-df22-45bb-746be314ecc5@gmail.com> Date: Tue, 3 Aug 2021 10:46:28 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thanks for your feedback, and any feedback about the further check would be appreciated! Best wishes, Tuo Li On 2021/8/3 3:04, Dave Kleikamp wrote: > On 7/31/21 1:31 AM, Li Tuo wrote: >> Hello, >> >> Our static analysis tool finds a possible uninitialized-variable >> access in the jfs driver in Linux 5.14.0-rc3: >> >> At the beginning of the function xtSplitUp(), the variable rbn is not >> initialized. >> If sp->header.flag & BT_ROOT is true, >> 780:    rc = (sp->header.flag & BT_ROOT) ? xtSplitRoot(tid, ip, >> split, &rmp) : xtSplitPage(tid, ip, split, &rmp, &rbn); >> >> the varialbe rbn will remain uninitialized. >> However, it is accessed through: >> 814:    rcbn = rbn; >> >> I am not quite sure whether this possible uninitialized-variable >> access is real and how to fix it if it is real. >> Any feedback would be appreciated, thanks! > > I think the logic that protects us is that in the case where rbn is > uninitialized, sp->header.flag & BT_ROOT, which means it SHOULD BE the > last entry in btstack, so we shouldn't enter the loop: >     while ((parent = BT_POP(btstack)) != NULL) { > > It does seem that some type of sanity check is warranted. I'll take a > closer look and see if I can add some kind of error path if things are > out of sync. > >> >> Reported-by: TOTE Robot >> >> Best wishes, >> Tuo Li