Some stacks apparently send packets with SYN|URG set. Linux accepts
these packets, so TCP conntrack should to.
Pointed out by Martijn Posthuma <posthuma@sangine.com>.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
 static const u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG) + 1] =
 {
        [TH_SYN]                        = 1,
-       [TH_SYN|TH_ACK]                 = 1,
        [TH_SYN|TH_PUSH]                = 1,
+       [TH_SYN|TH_URG]                 = 1,
+       [TH_SYN|TH_PUSH|TH_URG]         = 1,
+       [TH_SYN|TH_ACK]                 = 1,
        [TH_SYN|TH_ACK|TH_PUSH]         = 1,
        [TH_RST]                        = 1,
        [TH_RST|TH_ACK]                 = 1,
 
 static u8 tcp_valid_flags[(TH_FIN|TH_SYN|TH_RST|TH_PUSH|TH_ACK|TH_URG) + 1] =
 {
        [TH_SYN]                        = 1,
-       [TH_SYN|TH_ACK]                 = 1,
        [TH_SYN|TH_PUSH]                = 1,
+       [TH_SYN|TH_URG]                 = 1,
+       [TH_SYN|TH_PUSH|TH_URG]         = 1,
+       [TH_SYN|TH_ACK]                 = 1,
        [TH_SYN|TH_ACK|TH_PUSH]         = 1,
        [TH_RST]                        = 1,
        [TH_RST|TH_ACK]                 = 1,