[IPv4] fib: Fix out of bound access of fib_props[]

Fixes a typo which caused fib_props[] to have the wrong size
and makes sure the value used to index the array which is
provided by userspace via netlink is checked to avoid out of
bound access.

Signed-off-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c
index 1fba643..fc920f6 100644
--- a/net/ipv4/fib_frontend.c
+++ b/net/ipv4/fib_frontend.c
@@ -493,6 +493,11 @@
 	cfg->fc_nlinfo.pid = NETLINK_CB(skb).pid;
 	cfg->fc_nlinfo.nlh = nlh;
 
+	if (cfg->fc_type > RTN_MAX) {
+		err = -EINVAL;
+		goto errout;
+	}
+
 	nlmsg_for_each_attr(attr, nlh, sizeof(struct rtmsg), remaining) {
 		switch (attr->nla_type) {
 		case RTA_DST: