[IPVS]: Make sure ip_vs_ftp ports are valid

I'm not entirely sure what happens in the case of a valid port,
at best it'll be silently ignored. This patch ignores them a little
more verbosely.
Signed-Off-By: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/ipvs/ip_vs_ftp.c

@@ -373,6 +373,12 @@ static int __init ip_vs_ftp_init(void)
 	for (i=0; i<IP_VS_APP_MAX_PORTS; i++) {
 		if (!ports[i])
 			continue;
+		if (ports[i] < 0 || ports[i] > 0xffff) {
+			IP_VS_WARNING("ip_vs_ftp: Ignoring invalid "
+				      "configuration port[%d] = %d\n",
+				      i, ports[i]);
+			continue;
+		}
 		ret = register_ip_vs_app_inc(app, app->protocol, ports[i]);
 		if (ret)
 			break;