From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:41034 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726700AbeJKXJ5 (ORCPT ); Thu, 11 Oct 2018 19:09:57 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , Yuchung Cheng , Yaogong Wang , "David S. Miller" , Mao Wenan Subject: [PATCH 4.4 22/27] tcp: fix a stale ooo_last_skb after a replace Date: Thu, 11 Oct 2018 17:35:09 +0200 Message-Id: <20181011152535.091804300@linuxfoundation.org> In-Reply-To: <20181011152534.014964888@linuxfoundation.org> References: <20181011152534.014964888@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: 4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 76f0dcbb5ae1a7c3dbeec13dd98233b8e6b0b32a ] When skb replaces another one in ooo queue, I forgot to also update tp->ooo_last_skb as well, if the replaced skb was the last one in the queue. To fix this, we simply can re-use the code that runs after an insertion, trying to merge skbs at the right of current skb. This not only fixes the bug, but also remove all small skbs that might be a subset of the new one. Example: We receive segments 2001:3001, 4001:5001 Then we receive 2001:8001 : We should replace 2001:3001 with the big skb, but also remove 4001:50001 from the queue to save space. packetdrill test demonstrating the bug 0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 setsockopt(3, SOL_SOCKET, SO_REUSEADDR, [1], 4) = 0 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 +0 < S 0:0(0) win 32792 +0 > S. 0:0(0) ack 1 +0.100 < . 1:1(0) ack 1 win 1024 +0 accept(3, ..., ...) = 4 +0.01 < . 1001:2001(1000) ack 1 win 1024 +0 > . 1:1(0) ack 1 +0.01 < . 1001:3001(2000) ack 1 win 1024 +0 > . 1:1(0) ack 1 Fixes: 9f5afeae5152 ("tcp: use an RB tree for ooo receive queue") Signed-off-by: Eric Dumazet Reported-by: Yuchung Cheng Cc: Yaogong Wang Signed-off-by: David S. Miller Signed-off-by: Mao Wenan Signed-off-by: Greg Kroah-Hartman --- net/ipv4/tcp_input.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -4465,7 +4465,7 @@ coalesce_done: NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPOFOMERGE); __kfree_skb(skb1); - goto add_sack; + goto merge_right; } } else if (tcp_try_coalesce(sk, skb1, skb, &fragstolen)) { goto coalesce_done; @@ -4477,6 +4477,7 @@ coalesce_done: rb_link_node(&skb->rbnode, parent, p); rb_insert_color(&skb->rbnode, &tp->out_of_order_queue); +merge_right: /* Remove other segments covered by skb. */ while ((q = rb_next(&skb->rbnode)) != NULL) { skb1 = rb_entry(q, struct sk_buff, rbnode);