[NETFILTER]: TCP conntrack: accept RST|PSH as valid

This combination has been encountered on an IBM AS/400 in response
to packets sent to a closed session. There is no particular reason
to mark it invalid.
Signed-off-by: NWilly Tarreau <w@1wt.eu>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/netfilter/nf_conntrack_proto_tcp.c

@@ -774,6 +774,7 @@ static u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG) + 1] =
 	[TH_SYN|TH_ACK]			= 1,
 	[TH_SYN|TH_ACK|TH_PUSH]		= 1,
 	[TH_RST]			= 1,
+	[TH_RST|TH_PUSH]		= 1,
 	[TH_RST|TH_ACK]			= 1,
 	[TH_RST|TH_ACK|TH_PUSH]		= 1,
 	[TH_FIN|TH_ACK]			= 1,