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=-3.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 B4F85C35242 for ; Sat, 8 Feb 2020 18:31:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9A7E7217BA for ; Sat, 8 Feb 2020 18:31:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728384AbgBHSby (ORCPT ); Sat, 8 Feb 2020 13:31:54 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:34658 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727950AbgBHS3t (ORCPT ); Sat, 8 Feb 2020 13:29:49 -0500 Received: from [192.168.4.242] (helo=deadeye) by shadbolt.decadent.org.uk with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.89) (envelope-from ) id 1j0UrP-0003jJ-C4; Sat, 08 Feb 2020 18:29:43 +0000 Received: from ben by deadeye with local (Exim 4.93) (envelope-from ) id 1j0UrM-000CX2-UW; Sat, 08 Feb 2020 18:29:40 +0000 Content-Type: text/plain; charset="UTF-8" Content-Disposition: inline Content-Transfer-Encoding: 8bit MIME-Version: 1.0 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org CC: akpm@linux-foundation.org, Denis Kirjanov , "David S. Miller" , "Neal Cardwell" , "Soheil Hassas Yeganeh" , "Eric Dumazet" , "syzbot" Date: Sat, 08 Feb 2020 18:21:19 +0000 Message-ID: X-Mailer: LinuxStableQueue (scripts by bwh) X-Patchwork-Hint: ignore Subject: [PATCH 3.16 140/148] tcp: md5: fix potential overestimation of TCP option space In-Reply-To: X-SA-Exim-Connect-IP: 192.168.4.242 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.16.82-rc1 review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet commit 9424e2e7ad93ffffa88f882c9bc5023570904b55 upstream. Back in 2008, Adam Langley fixed the corner case of packets for flows having all of the following options : MD5 TS SACK Since MD5 needs 20 bytes, and TS needs 12 bytes, no sack block can be cooked from the remaining 8 bytes. tcp_established_options() correctly sets opts->num_sack_blocks to zero, but returns 36 instead of 32. This means TCP cooks packets with 4 extra bytes at the end of options, containing unitialized bytes. Fixes: 33ad798c924b ("tcp: options clean up") Signed-off-by: Eric Dumazet Reported-by: syzbot Acked-by: Neal Cardwell Acked-by: Soheil Hassas Yeganeh Signed-off-by: David S. Miller Signed-off-by: Ben Hutchings --- net/ipv4/tcp_output.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -680,8 +680,9 @@ static unsigned int tcp_established_opti min_t(unsigned int, eff_sacks, (remaining - TCPOLEN_SACK_BASE_ALIGNED) / TCPOLEN_SACK_PERBLOCK); - size += TCPOLEN_SACK_BASE_ALIGNED + - opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; + if (likely(opts->num_sack_blocks)) + size += TCPOLEN_SACK_BASE_ALIGNED + + opts->num_sack_blocks * TCPOLEN_SACK_PERBLOCK; } return size;