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=-3.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS 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 78E8DC4742C for ; Fri, 13 Nov 2020 21:30:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3024E22252 for ; Fri, 13 Nov 2020 21:30:02 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ttaylorr-com.20150623.gappssmtp.com header.i=@ttaylorr-com.20150623.gappssmtp.com header.b="b8qdLa0z" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726113AbgKMVaA (ORCPT ); Fri, 13 Nov 2020 16:30:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40928 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726003AbgKMV37 (ORCPT ); Fri, 13 Nov 2020 16:29:59 -0500 Received: from mail-qv1-xf42.google.com (mail-qv1-xf42.google.com [IPv6:2607:f8b0:4864:20::f42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A0457C08E9AA for ; Fri, 13 Nov 2020 13:29:57 -0800 (PST) Received: by mail-qv1-xf42.google.com with SMTP id x13so5373679qvk.8 for ; Fri, 13 Nov 2020 13:29:57 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ttaylorr-com.20150623.gappssmtp.com; s=20150623; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=rbrjCQjQhn5goPJfYS5Ci6QHV65myp9vDlqrR4bk9fM=; b=b8qdLa0z33FM68D3cZfWrYNk8Gm3t35REBdSFuSnm74z6fmkL8qMCxGTn+BPSdoLqX 0++rZ8RBg/GjGYp6eQHRnJlMD0QRCDZR0tTW/GUGhiWxY1l265QUY+ILGD2LW6UzrXYq 2Zn9aeywlcBU4uy2KOpsyoiM9YTDOOFHik5S4sXhr+VddO+me1VVY5Hvu3NfBwBW37aB 2JDuvWsVCR72SEx7cch4zk/igvEMFT3UatiIVFrKi+3I9CQcavsUw9A2T3wBEELAT9Gp 7MFwb0BK7/KENSMXHEyozI8H6G78/OMfLSSBZalkmRRq1ZsI1R1Ft66zIqRDN8vFChfh 1HhA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=rbrjCQjQhn5goPJfYS5Ci6QHV65myp9vDlqrR4bk9fM=; b=GK6Qz9qnAXk6iQh7Bgwlh8BAJ4hL4taE6uYrGBQlNIrci4TvMYGSRsFfYFBgdcJME9 8064mm93PpavkY5rAfXiHIypZAZ0mtU0reL7vKYF/WfE9hi+D/GoeZ7NPWXaqTffUvKy G1IYSk2l3VIayPhwOLLoYs1tDsTUPWZNcGKVjYoJwTbSFUxGTwTAd8BU/BN/agBkUsVL gKDaEZYhX3nA53z4hrnymJtm/XQ3EAsLYWUSdqtGZxD1Ycdz0uUiPPSRzM/M3drtvcZn +yrv7IbX08jkTVTgW3oUHARgMSyyVh2AjMM0GfFQatH19jNcID5p51ulBe7RrD8Wsohh mIkA== X-Gm-Message-State: AOAM532U2VR6mbGenREhMRkNPzEfKBtBB5JXykAVFjScaqW/OF7rI6Lr zxzUeRp1AdNWUbOahrzDWdEHSA== X-Google-Smtp-Source: ABdhPJwjUQKkN6ugpmyq/VK6kXH0Rrx6kExwtAzsucU9ZxJc5GHChlY66jd8OPboOK5rTV9yfz6GtA== X-Received: by 2002:a0c:b664:: with SMTP id q36mr4367065qvf.6.1605302996809; Fri, 13 Nov 2020 13:29:56 -0800 (PST) Received: from localhost ([2605:9480:22e:ff10:51df:232c:7a24:7fb0]) by smtp.gmail.com with ESMTPSA id 72sm7865157qkn.44.2020.11.13.13.29.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 13 Nov 2020 13:29:56 -0800 (PST) Date: Fri, 13 Nov 2020 16:29:54 -0500 From: Taylor Blau To: Jeff King Cc: Martin =?utf-8?B?w4VncmVu?= , Git Mailing List , Derrick Stolee , Junio C Hamano Subject: Re: [PATCH 03/23] pack-bitmap: bounds-check size of cache extension Message-ID: References: <1573902df00e8a14a9cb68c37f55474388b1dc2e.1605123652.git.me@ttaylorr.com> <20201113045700.GA743619@coredump.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20201113045700.GA743619@coredump.intra.peff.net> Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Thu, Nov 12, 2020 at 11:57:00PM -0500, Jeff King wrote: > On Thu, Nov 12, 2020 at 06:47:09PM +0100, Martin Ågren wrote: > > > The addition should be ok or mmap has failed on us. Do we know that we > > have room for the final hash there so that the subtraction is ok? Yes, > > from the previous commit, we know we have room for the header, which is > > even larger. But that's cheating a bit -- see below. > > Yeah, I agree this ought to be checking the minimum size against the > header _plus_ the trailer. > > I think the previous patch is actually where it goes wrong. The original > was checking for a minimum of: > > if (index->map_size < sizeof(*header) + the_hash_algo->rawsz) > > which is the header plus the trailer. We want to readjust for the > MAX_RAWSZ part of the header, so it should be: > > size_t header_size = sizeof(*header) - GIT_MAX_RAWSZ + the_hash_algo->rawsz; > if (index->map_size < sizeof(*header) + the_hash_algo->rawsz) I'm not sure that I follow. If you apply this to the second patch in this series, the only thing that changes is that it factors out: index->map_pos += ...; into size_t header_size = ...; // ... index->map_pos += header_size; What am I missing here? Thanks, Taylor