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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 EBF15C76186 for ; Wed, 24 Jul 2019 02:33:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B80D1227BF for ; Wed, 24 Jul 2019 02:33:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="AAc6uNbr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728938AbfGXCdw (ORCPT ); Tue, 23 Jul 2019 22:33:52 -0400 Received: from mail-pg1-f194.google.com ([209.85.215.194]:34341 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726130AbfGXCdv (ORCPT ); Tue, 23 Jul 2019 22:33:51 -0400 Received: by mail-pg1-f194.google.com with SMTP id n9so14154285pgc.1; Tue, 23 Jul 2019 19:33:51 -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=PG5Fjwwrk0QuD+sTgYEYYGjOti0OiQdq1uV5NO/0c8Y=; b=AAc6uNbrMbXFMcL3MnGZRdvGr23b+I7A8qHl2fitW/UP1nyjy8tBU1FkWAY193tSIY zPRChdZEayDulJTZS+1ewNcZY29Oldm0zo2EoQEO8NAZkwGWSpvAloicBvcrVbFaBVjl RmW2WwT00t4W+QRVAXHTm5SPKx09wyvkMuV/mmjP0/wlKagHVVjK5pDEmRXe92mu6Zfy hr1xJVst4mHX32dPWcAiFRsQNwblgmnnwXP3pg3ycebY3OcxECO3IxFDgRCzFmDccVIB nSA+2sS77AFpvay66K18dlgw4RGp5CrN3/Br4bXRPZ2y30/BBMNoPcaqrl4ZKPHiPFgJ 9R8g== 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=PG5Fjwwrk0QuD+sTgYEYYGjOti0OiQdq1uV5NO/0c8Y=; b=OrJbFxk7CvlqTa1mvISHU4hSZtTJTU1cHpiiNDB/Ej4MvmB83ltP3XFaeCGqv+MDo6 +ddGPFqDbj4LzbrbRgTF+a8eAhR7q2ZIAKpIbGE2dQ06vc/gj87M0eu0ZSsnQ4aBQJMQ zbJXk+Bum0xYPejD4kJrWOdpT7KZK4tfzgC4fZj/ZKlDU9B8fIjFK9I8kiluDYplEqsX wiOXLS4dgdWCpk/DjF+jqdLr9TnSSO20BkuzkQJcVYu3FlKzq1NneQn0JChCI23cJn6B HUBnXBOpht8wdCyIzd3/jS0MSsX8dEJyodiZPxo4Xy3qE5uC/S/fjSCgF9YONvq0zOoD r4jQ== X-Gm-Message-State: APjAAAW4MzhvEkBGrxocNeCJPWN01fQCMts5+QX5hvm2g6T6O28CK2aX 40+GSsFYUp0LV9FxsBNMO+WH0p0m X-Google-Smtp-Source: APXvYqxSqfZOC7vaEUmBkXSL8+tgg9fFUHQDwWkNEhKzUNDpfhkEivfM5Ae4Np1l/uYn+5Ti8d7FVA== X-Received: by 2002:a65:5144:: with SMTP id g4mr26835599pgq.202.1563935630873; Tue, 23 Jul 2019 19:33:50 -0700 (PDT) Received: from ?IPv6:2402:f000:4:72:808::177e? ([2402:f000:4:72:808::177e]) by smtp.gmail.com with ESMTPSA id 23sm48509918pfn.176.2019.07.23.19.33.48 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 23 Jul 2019 19:33:50 -0700 (PDT) Subject: Re: [PATCH] fs: btrfs: Fix a possible null-pointer dereference in insert_inline_extent() To: Qu Wenruo , clm@fb.com, josef@toxicpanda.com, dsterba@suse.com Cc: linux-btrfs@vger.kernel.org, linux-kernel@vger.kernel.org References: <20190724021132.27378-1-baijiaju1990@gmail.com> From: Jia-Ju Bai Message-ID: <800ae777-928f-2969-d4dd-6f358a039e48@gmail.com> Date: Wed, 24 Jul 2019 10:33:51 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2019/7/24 10:21, Qu Wenruo wrote: > > On 2019/7/24 上午10:11, Jia-Ju Bai wrote: >> In insert_inline_extent(), there is an if statement on line 181 to check >> whether compressed_pages is NULL: >> if (compressed_size && compressed_pages) >> >> When compressed_pages is NULL, compressed_pages is used on line 215: >> cpage = compressed_pages[i]; >> >> Thus, a possible null-pointer dereference may occur. >> >> To fix this possible bug, compressed_pages is checked on line 214. > This can only be hit with compressed_size > 0 and compressed_pages != NULL. > > It would be better to have an extra ASSERT() to warn developers about > the impossible case. Thanks for the reply :) So I should add ASSERT(compressed_size > 0 & compressed_pages) at the beginning of the function, and remove "if (compressed_size && compressed_pages)"? Best wishes, Jia-Ju Bai