From: Wei Yongjun <yjwei@cn.fujitsu.com>
Date: Wed, 24 Jun 2009 22:29:31 +0000 (+0000)
Subject: tcp: missing check ACK flag of received segment in FIN-WAIT-2 state
X-Git-Tag: v2.6.31-rc2~72^2~13
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1ac530b3553e0b4dc1e18a32bed57cfa84cd57cb;p=pandora-kernel.git

tcp: missing check ACK flag of received segment in FIN-WAIT-2 state

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>
Signed-off-by: David S. Miller <davem@davemloft.net>
---

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