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authorWei Yongjun <yjwei@cn.fujitsu.com>2009-06-24 22:29:31 +0000
committerDavid S. Miller <davem@davemloft.net>2009-06-25 20:03:15 -0700
commit1ac530b3553e0b4dc1e18a32bed57cfa84cd57cb (patch)
treecc0198945aeee7b60ea06c1699fc72268efc26f7 /net/ipv4/tcp_minisocks.c
parentd8146bb23ea045fb75c56b4e3b53f0964eed4076 (diff)
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>
Diffstat (limited to 'net/ipv4/tcp_minisocks.c')
-rw-r--r--net/ipv4/tcp_minisocks.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 43bbba7926ee..f8d67ccc64f3 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;