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>