Fix another really stupid bug - I introduced genl_set_err()
precisely to be able to adjust the group and reject invalid
ones, but then forgot to do so.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
 static inline int genl_set_err(struct genl_family *family, struct net *net,
                               u32 portid, u32 group, int code)
 {
+       if (WARN_ON_ONCE(group >= family->n_mcgrps))
+               return -EINVAL;
+       group = family->mcgrp_offset + group;
        return netlink_set_err(net->genl_sock, portid, group, code);
 }