nexthop: off by one in nexthop_mpath_select()

The nhg->nh_entries[] array is allocated in nexthop_grp_alloc() and it
has nhg->num_nh elements so this check should be >= instead of >.

Fixes: 430a0491 ("nexthop: Add support for nexthop groups")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/nexthop.h

@@ -160,7 +160,7 @@ struct nexthop *nexthop_mpath_select(const struct nexthop *nh, int nhsel)
 	/* for_nexthops macros in fib_semantics.c grabs a pointer to
 	 * the nexthop before checking nhsel
 	 */
-	if (nhsel > nhg->num_nh)
+	if (nhsel >= nhg->num_nh)
 		return NULL;
 
 	return nhg->nh_entries[nhsel].nh;