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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 ED4E0C33C9E for ; Sat, 11 Jan 2020 10:33:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C03BF2087F for ; Sat, 11 Jan 2020 10:33:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578738818; bh=cZX9WaJMkEhAVaOZ8IfgV5CsYjAVxPKnk4yiipXnIhw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=gow2Mmx38b8mOdy6QmjqNeiN0ok74eK3hC+zHaod2PkiwJ70oomzNA7nVbk3KHLWs Ge154Xt7Xae7IEij+TVjj8fum/fyBUb77xb1oM2duoWCUmZreCEqHSzkd2fTRIniP5 971re+LpsGdFLKMNNV9RqdULVPgucgSsblPZ2XeI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731615AbgAKKdd (ORCPT ); Sat, 11 Jan 2020 05:33:33 -0500 Received: from mail.kernel.org ([198.145.29.99]:48102 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731419AbgAKKd2 (ORCPT ); Sat, 11 Jan 2020 05:33:28 -0500 Received: from localhost (unknown [62.119.166.9]) (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 E3F0220678; Sat, 11 Jan 2020 10:33:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578738808; bh=cZX9WaJMkEhAVaOZ8IfgV5CsYjAVxPKnk4yiipXnIhw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=l0LaPHlhiFRvN2lVCu5fhELD5zwLZJ8BLrZbWVRHkyEhnt4QUPQKYUznHz4NFpSaj VrpySofapbELLB0kg97yj6VlktlR7YycO+7viQBSRQeXp9rI2XS0Y/cdS7m0J9ZcSJ xfDaR1nWos5axHL59E5txIn9wBQaoPR9nPuVRv84= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Pengcheng Yang , Eric Dumazet , "David S. Miller" Subject: [PATCH 5.4 149/165] tcp: fix "old stuff" D-SACK causing SACK to be treated as D-SACK Date: Sat, 11 Jan 2020 10:51:08 +0100 Message-Id: <20200111094940.253076081@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200111094921.347491861@linuxfoundation.org> References: <20200111094921.347491861@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pengcheng Yang [ Upstream commit c9655008e7845bcfdaac10a1ed8554ec167aea88 ] When we receive a D-SACK, where the sequence number satisfies: undo_marker <= start_seq < end_seq <= prior_snd_una we consider this is a valid D-SACK and tcp_is_sackblock_valid() returns true, then this D-SACK is discarded as "old stuff", but the variable first_sack_index is not marked as negative in tcp_sacktag_write_queue(). If this D-SACK also carries a SACK that needs to be processed (for example, the previous SACK segment was lost), this SACK will be treated as a D-SACK in the following processing of tcp_sacktag_write_queue(), which will eventually lead to incorrect updates of undo_retrans and reordering. Fixes: fd6dad616d4f ("[TCP]: Earlier SACK block verification & simplify access to them") Signed-off-by: Pengcheng Yang Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -1727,8 +1727,11 @@ tcp_sacktag_write_queue(struct sock *sk, } /* Ignore very old stuff early */ - if (!after(sp[used_sacks].end_seq, prior_snd_una)) + if (!after(sp[used_sacks].end_seq, prior_snd_una)) { + if (i == 0) + first_sack_index = -1; continue; + } used_sacks++; }