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 3E8EFC33C9E for ; Sat, 11 Jan 2020 10:19:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 080E120848 for ; Sat, 11 Jan 2020 10:19:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578737941; bh=xbjLjqMsyS/r2kCZ+WdQUsx0A7curaXmnYmXfRrP0C0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=MhxcPZ739DgKThMeF7nD/Tr5GTvzcDBe69z57gdbsUVU1jMbLRRMrnBQHWaRcd7zB Ea9wQb3/iFyhxF3UvRhyk4ZdEnktnvkWDvFuNSpj6uhPU1h7kpx7UFzhtPYzNHDoOV Sp3pvBgG64nvYDVgYbe8VooWj5xSpDeza9Qhl/Ss= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730319AbgAKKS7 (ORCPT ); Sat, 11 Jan 2020 05:18:59 -0500 Received: from mail.kernel.org ([198.145.29.99]:37780 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729124AbgAKKS6 (ORCPT ); Sat, 11 Jan 2020 05:18:58 -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 6BD6520848; Sat, 11 Jan 2020 10:18:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578737938; bh=xbjLjqMsyS/r2kCZ+WdQUsx0A7curaXmnYmXfRrP0C0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ySk7VGCzP7/J+Sh+qj+03uTopM8vmo32fzoXuqHL1f3gndAj87EfocZY4J6VaGLz9 KpfMgcfGdY954o0L6dxNncQt+b19Dob4buJGjlwIy0FYPBjGJ3E6lcctfTxeKnuwZi gaZ7G0q89+xrybfICz+RCVUm348os9iSDjzVUAuA= 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 4.19 75/84] tcp: fix "old stuff" D-SACK causing SACK to be treated as D-SACK Date: Sat, 11 Jan 2020 10:50:52 +0100 Message-Id: <20200111094912.008450153@linuxfoundation.org> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200111094845.328046411@linuxfoundation.org> References: <20200111094845.328046411@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 @@ -1716,8 +1716,11 @@ 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++; }