[DECNet] fib: Fix out of bound access of dn_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/decnet/dn_fib.c

@@ -63,7 +63,7 @@ static struct
 {
 	int error;
 	u8 scope;
-} dn_fib_props[RTA_MAX+1] = {
+} dn_fib_props[RTN_MAX+1] = {
 	[RTN_UNSPEC] =      { .error = 0,       .scope = RT_SCOPE_NOWHERE },
 	[RTN_UNICAST] =     { .error = 0,       .scope = RT_SCOPE_UNIVERSE },
 	[RTN_LOCAL] =       { .error = 0,       .scope = RT_SCOPE_HOST },
@@ -276,6 +276,9 @@ struct dn_fib_info *dn_fib_create_info(const struct rtmsg *r, struct dn_kern_rta
 	struct dn_fib_info *ofi;
 	int nhs = 1;
 
+	if (r->rtm_type > RTN_MAX)
+		goto err_inval;
+
 	if (dn_fib_props[r->rtm_type].scope > r->rtm_scope)
 		goto err_inval;