[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>

net/ipv4/fib_frontend.c

@@ -493,6 +493,11 @@ static int rtm_to_fib_config(struct sk_buff *skb, struct nlmsghdr *nlh,
 	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:

net/ipv4/fib_semantics.c

@@ -89,7 +89,7 @@ static const struct
 {
 	int	error;
 	u8	scope;
-} fib_props[RTA_MAX + 1] = {
+} fib_props[RTN_MAX + 1] = {
 	{
 		.error	= 0,
 		.scope	= RT_SCOPE_NOWHERE,