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=-16.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL 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 C44EBC31E5B for ; Mon, 17 Jun 2019 17:04:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E9DD20652 for ; Mon, 17 Jun 2019 17:04:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="p5s7QoBH" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728487AbfFQREm (ORCPT ); Mon, 17 Jun 2019 13:04:42 -0400 Received: from mail-ot1-f74.google.com ([209.85.210.74]:43473 "EHLO mail-ot1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725863AbfFQREm (ORCPT ); Mon, 17 Jun 2019 13:04:42 -0400 Received: by mail-ot1-f74.google.com with SMTP id w110so5169026otb.10 for ; Mon, 17 Jun 2019 10:04:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=PvuXpDexDxPOK/auQF0wWfSUrVmG9Xj+h27GpJM7Sy4=; b=p5s7QoBHhbmOEU0Sfoa60z30RPlpLUnxf1r3uhj7BvtzHRJa16yzK8ztXBMrvzpT9C QwgCbVTVeK8tKzII6Yd5bJMbZPZVvPvTLVx8UZmxc6o8LeY4GCyzge7yztVUR7ZqJQd1 IFtBFu6w2DjCOjIXuTWAw9jjEQda42+KfJIsrMEGVBsb46oVV1j9Oh/3dzt+zx1UTshw eQOhfjdFdXjXe5eA+PvbfRFgqxPPXpJ9k7kGCJaZ85A6QZ7CZxcAEto3B2XsbD9Esfxg BaoFjym8DXI3e9HqguxdpAkTvwKEl1b9cpI9lRzWCD4xS5Q3NSeG5dZbozXDsnUjgrvw XnwA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=PvuXpDexDxPOK/auQF0wWfSUrVmG9Xj+h27GpJM7Sy4=; b=VH7gD1qMw/6lUghbMA4nGY31RPL4hRyPDahhIGRf0RGZ1KequOU06Yw1RzzKkyjZHC Y35fRxRMcfUs23Fv8Jqje0m4L1000HX9wbO2ZZYzGA0zZp/kxrtRIS0fjKnuJODZCkrC W3wGOrGe4nJ11QsSPKydeaPJfmy781gvl+CuBBLnATyOb6n7eDudLWqp1xojqV9ajfUK x26l8kLH1NrX+rLvMx9kALQXRbaDmzZCohS38sQSHFGg1oDX1TiIazWYzdYh815+LvR4 SxV/XppXEyAUcJwMWRSjtzxwq+YkgDiAnzB78AsnPEfxRW3Q4guiH9K/0QKfUbmrruyO p0jA== X-Gm-Message-State: APjAAAXDDNuD4+uO/aUSpKANHaePzQeNjuJ0vcqjgEymEHhyXte+EIq2 SmNpILu/rMypGT5vhIQlWYM5zIhmTgoqUg== X-Google-Smtp-Source: APXvYqzjnCkcb0+fvWRAklbERaImcL+p8gDfyTNonXyRYf3nWm8e+PW/Zf9ObHGpfARU9FD5G1Xm1W3ZKwSmCA== X-Received: by 2002:a9d:61c7:: with SMTP id h7mr2154746otk.357.1560791081576; Mon, 17 Jun 2019 10:04:41 -0700 (PDT) Date: Mon, 17 Jun 2019 10:03:54 -0700 In-Reply-To: <20190617170354.37770-1-edumazet@google.com> Message-Id: <20190617170354.37770-5-edumazet@google.com> Mime-Version: 1.0 References: <20190617170354.37770-1-edumazet@google.com> X-Mailer: git-send-email 2.22.0.410.gd8fdbe21b5-goog Subject: [PATCH net 4/4] tcp: enforce tcp_min_snd_mss in tcp_mtu_probing() From: Eric Dumazet To: "David S . Miller" Cc: netdev , Eric Dumazet , Eric Dumazet , Greg Kroah-Hartman , Jonathan Looney , Neal Cardwell , Tyler Hicks , Yuchung Cheng , Bruce Curtis , Jonathan Lemon Content-Type: text/plain; charset="UTF-8" Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org If mtu probing is enabled tcp_mtu_probing() could very well end up with a too small MSS. Use the new sysctl tcp_min_snd_mss to make sure MSS search is performed in an acceptable range. CVE-2019-11479 -- tcp mss hardcoded to 48 Signed-off-by: Eric Dumazet Reported-by: Jonathan Lemon Cc: Jonathan Looney Acked-by: Neal Cardwell Cc: Yuchung Cheng Cc: Tyler Hicks Cc: Bruce Curtis --- net/ipv4/tcp_timer.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 5bad937ce779ef8dca42a26dcbb5f1d60a571c73..c801cd37cc2a9c11f2dd4b9681137755e501a538 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -155,6 +155,7 @@ static void tcp_mtu_probing(struct inet_connection_sock *icsk, struct sock *sk) mss = tcp_mtu_to_mss(sk, icsk->icsk_mtup.search_low) >> 1; mss = min(net->ipv4.sysctl_tcp_base_mss, mss); mss = max(mss, 68 - tcp_sk(sk)->tcp_header_len); + mss = max(mss, net->ipv4.sysctl_tcp_min_snd_mss); icsk->icsk_mtup.search_low = tcp_mss_to_mtu(sk, mss); } tcp_sync_mss(sk, icsk->icsk_pmtu_cookie); -- 2.22.0.410.gd8fdbe21b5-goog