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=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 65E00C433FF for ; Tue, 6 Aug 2019 22:10:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 37507218AD for ; Tue, 6 Aug 2019 22:10:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565129423; bh=zr+AC2oEeZiny5+/7E2Ef2eKnar4y55dS3Yozf5SRf0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=d8U1CroXYYWNXCkh+HtWv3XoybhBIXeco90ihV37QkVWfmp+dvpERaC21tT+7xj0i AaECw2tJ9XwzEmFLSweELVv3fun43BNhGf5/AH6jSWbMsW+BNDnV+XUQGF8p7UWns2 j6gtRjrzssBrS9hSK7UObPKemzIGssS49YMVcCKk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726998AbfHFWKW (ORCPT ); Tue, 6 Aug 2019 18:10:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:36420 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726902AbfHFWKW (ORCPT ); Tue, 6 Aug 2019 18:10:22 -0400 Received: from localhost (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 21F7321872; Tue, 6 Aug 2019 22:10:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1565129421; bh=zr+AC2oEeZiny5+/7E2Ef2eKnar4y55dS3Yozf5SRf0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=C1q6ZHQd+3xcKPPxybroeJsXM388dNJ+sdWDyJmDoiNwsymggqT/QzU8Ppkz9C7Fn BT9Xuj4ZNqRKd1hpjUe4pa01V6KIQfmSBTkpcvuJnQ38jOBLJmM6pvd6X8aeV7thmN FcC/mvHcjKeN/7fQaggNcscxo23R0ewYwVO1oBYg= Date: Tue, 6 Aug 2019 18:10:20 -0400 From: Sasha Levin To: Eric Dumazet Cc: Matthieu Baerts , stable@vger.kernel.org, Greg Kroah-Hartman , Andrew Prout , Jonathan Lemon , Michal Kubecek , Neal Cardwell , Yuchung Cheng , Christoph Paasch , Jonathan Looney , "David S . Miller" Subject: Re: [PATCH] tcp: be more careful in tcp_fragment() Message-ID: <20190806221020.GO17747@sasha-vm> References: <20190806150914.8797-1-matthieu.baerts@tessares.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org On Tue, Aug 06, 2019 at 05:25:35PM +0200, Eric Dumazet wrote: >On Tue, Aug 6, 2019 at 5:09 PM Matthieu Baerts > wrote: >> >> From: Eric Dumazet >> >> commit b617158dc096709d8600c53b6052144d12b89fab upstream. >> >> Some applications set tiny SO_SNDBUF values and expect >> TCP to just work. Recent patches to address CVE-2019-11478 >> broke them in case of losses, since retransmits might >> be prevented. >> >> We should allow these flows to make progress. >> >> This patch allows the first and last skb in retransmit queue >> to be split even if memory limits are hit. >> >> It also adds the some room due to the fact that tcp_sendmsg() >> and tcp_sendpage() might overshoot sk_wmem_queued by about one full >> TSO skb (64KB size). Note this allowance was already present >> in stable backports for kernels < 4.15 >> >> Note for < 4.15 backports : >> tcp_rtx_queue_tail() will probably look like : >> >> static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk) >> { >> struct sk_buff *skb = tcp_send_head(sk); >> >> return skb ? tcp_write_queue_prev(sk, skb) : tcp_write_queue_tail(sk); >> } >> >> Fixes: f070ef2ac667 ("tcp: tcp_fragment() should apply sane memory limits") >> Signed-off-by: Eric Dumazet >> Reported-by: Andrew Prout >> Tested-by: Andrew Prout >> Tested-by: Jonathan Lemon >> Tested-by: Michal Kubecek >> Acked-by: Neal Cardwell >> Acked-by: Yuchung Cheng >> Acked-by: Christoph Paasch >> Cc: Jonathan Looney >> Signed-off-by: David S. Miller >> Signed-off-by: Matthieu Baerts >> --- >> >> Notes: >> Hello, >> >> Here is the backport for linux-4.14.y branch simply by implementing >> functions written by Eric here in the commit message and in this email >> thread. It might be valid for older versions, I didn't check. >> >> In my setup with MPTCP, I had the same bug other had where TCP flows >> were stalled. The initial fix b6653b3629e5 (tcp: refine memory limit >> test in tcp_fragment()) from Eric was helping but the backport in >> < 4.15 was not looking safe: 1bc13903773b (tcp: refine memory limit >> test in tcp_fragment()). >> >> I then decided to test the new fix and it is working fine in my test >> environment, no stalled TCP flows in a few hours. >> >> In this email thread I see that Eric will push a patch for v4.14. I >> absolutely do not want to add pressure or steal his work but because I >> have the patch here and it is tested, I was thinking it could be a good >> idea to share it with others. Feel free to ignore this patch if needed. >> But if this patch can reduce a tiny bit Eric's workload, I would be >> very glad if it helps :) >> Because at the end, it is Eric's work, feel free to change my >> "Signed-off-by" by "Tested-By" if it is how it work or nothing if you >> prefer to wait for Eric's patch. > >This patch is fine, I was simply on vacation last week, and wanted to >truly take full advantage of them ;) Queued for 4.14, 4.9, and 4.4. Thanks all! -- Thanks, Sasha