From: Wei Yongjun <yjwei@cn•fujitsu.com>
To: David Miller <davem@davemloft•net>, netdev@vger•kernel.org
Subject: [PATCH] tcp: missing check ACK flag of received segment in FIN-WAIT-2 state
Date: Thu, 25 Jun 2009 16:29:31 +0800 [thread overview]
Message-ID: <4A43356B.7060005@cn.fujitsu.com> (raw)
RFC0793 defined that in FIN-WAIT-2 state if the ACK bit is off drop
the segment and return[Page 72]. But this check is missing in function
tcp_timewait_state_process(). This cause the segment with FIN flag but
no ACK has two diffent action:
Case 1:
Node A Node B
<------------- FIN,ACK
(enter FIN-WAIT-1)
ACK ------------->
(enter FIN-WAIT-2)
FIN -------------> discard
(move sk to tw list)
Case 2:
Node A Node B
<------------- FIN,ACK
(enter FIN-WAIT-1)
ACK ------------->
(enter FIN-WAIT-2)
(move sk to tw list)
FIN ------------->
<------------- ACK
This patch fixed the problem.
Signed-off-by: Wei Yongjun <yjwei@cn•fujitsu.com>
---
net/ipv4/tcp_minisocks.c | 3 ++-
1 files changed, 2 insertions(+), 1 deletions(-)
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 43bbba7..f8d67cc 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -128,7 +128,8 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb,
goto kill_with_rst;
/* Dup ACK? */
- if (!after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) ||
+ if (!th->ack ||
+ !after(TCP_SKB_CB(skb)->end_seq, tcptw->tw_rcv_nxt) ||
TCP_SKB_CB(skb)->end_seq == TCP_SKB_CB(skb)->seq) {
inet_twsk_put(tw);
return TCP_TW_SUCCESS;
--
1.6.2.2
next reply other threads:[~2009-06-25 8:30 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-06-25 8:29 Wei Yongjun [this message]
2009-06-26 3:09 ` [PATCH] tcp: missing check ACK flag of received segment in FIN-WAIT-2 state David Miller
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