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=-2.1 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 6AD81C43603 for ; Mon, 16 Dec 2019 16:55:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3BCBB206EC for ; Mon, 16 Dec 2019 16:55:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="CriwyJW8" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726545AbfLPQzg (ORCPT ); Mon, 16 Dec 2019 11:55:36 -0500 Received: from mail-pj1-f68.google.com ([209.85.216.68]:39998 "EHLO mail-pj1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725805AbfLPQzg (ORCPT ); Mon, 16 Dec 2019 11:55:36 -0500 Received: by mail-pj1-f68.google.com with SMTP id s35so3228389pjb.7 for ; Mon, 16 Dec 2019 08:55:36 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=RZ3FMFMV6y5ZTjXPQGyK71brBjPOnI5E8F5urgggObY=; b=CriwyJW8no61Qqq/BRXcxKIGkQlUFjI8xXuvFz6O6+6SOpG8o1gMxSJmxR8IMnmQaZ kRws9XbP7czyQ1SxhgF0Oa1Tqffg5CI1dUbySTnR5HOETNo6B4QnnnCH23Ve16vASaUq mvGpF1gQDROEF0DdLIPL97Dly+G+kwwJlTyiyHQlEuFJkDnwmhGdyfttAeJJtS79Be9W HwkAK2iCAYWLnoUrlKXv7BrQjFhLX2RMvEHMl/VBG7XHIPrxpZRmZBeafHdLCqmKlGo1 oT+kgWF04uWjsaRCDm6MNttJzyovoqabVr2IMoEDOYWDl1YqdphROAa7SUJ9dQytEnDq Vu6A== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=RZ3FMFMV6y5ZTjXPQGyK71brBjPOnI5E8F5urgggObY=; b=FU2+FLISJI/3zO+VT0H8sTOSDQJnOv7RMEM+ydpU+f6cqbWnn4ImQFN17zvH5brNxt 02IRn9yNbNycwEsuxx3kAszsj/R8GUclltYQyq3tbr/Vmcl+6IUFUCQYNDZkZUImt5uh +y4O5l83lhdYq2B2UGqC0UXdcIWcTwbSt2RobtOigzzoTIrsqvSdMvg34NSGZeOgCooB WPG9lka+MoA0QQnusi8OngEc8Bv+p/sscKg6XNtSFMGQLVq9hw/F3S4z015ruQHNuHmZ lUON7exRIprn5L36FvISyVnYFieyib6pWa4vLOL1LdMwffwROwLnVouxL5VKMQ63aCW7 qnsQ== X-Gm-Message-State: APjAAAVwjmxdffVGgMXgfEXoVcBXX5rIYSnXkZt9oE9IQDJM3W1NeAI8 A/O/vjXS0tWS26zXHttmSlM= X-Google-Smtp-Source: APXvYqybcxiZem2ukWyW+P89sTBBeEPrS1ooYagqg/Azx3xAMDui6ZKy8ywbKfcFWdvcXsMqC1Hz9A== X-Received: by 2002:a17:902:265:: with SMTP id 92mr16850815plc.313.1576515335810; Mon, 16 Dec 2019 08:55:35 -0800 (PST) Received: from ?IPv6:2620:15c:2c1:200:55c7:81e6:c7d8:94b? ([2620:15c:2c1:200:55c7:81e6:c7d8:94b]) by smtp.gmail.com with ESMTPSA id d22sm22891673pgg.52.2019.12.16.08.55.34 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 16 Dec 2019 08:55:35 -0800 (PST) Subject: Re: [MPTCP] Re: [PATCH net-next 09/11] tcp: Check for filled TCP option space before SACK To: Paolo Abeni , Eric Dumazet , Mat Martineau , netdev@vger.kernel.org, mptcp@lists.01.org References: <20191213230022.28144-1-mathew.j.martineau@linux.intel.com> <20191213230022.28144-10-mathew.j.martineau@linux.intel.com> <47545b88-94db-e9cd-2f9f-2c6d665246e2@gmail.com> From: Eric Dumazet Message-ID: Date: Mon, 16 Dec 2019 08:55:34 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On 12/16/19 4:52 AM, Paolo Abeni wrote: > Thank you for the feedback! > > Unfortunatelly, the above commit is not enough when MPTCP is enabled, > as, without this patch, we can reach the following code: > > const unsigned int remaining = MAX_TCP_OPTION_SPACE - size; > opts->num_sack_blocks = > min_t(unsigned int, eff_sacks, > (remaining - TCPOLEN_SACK_BASE_ALIGNED) / > TCPOLEN_SACK_PERBLOCK); > > with 'size == MAX_TCP_OPTION_SPACE' and num_sack_blocks will be > miscalculated. So we need 'fix' but only for MPTCP/when MPTCP is > enabled. Still ok for a -net commit? > Does it means MPTCP flows can not use SACK at all ? That would be very bad. What is the size of MPTCP options ?