genetlink: trigger BUG_ON if a group name is too long

Trigger BUG_ON if a group name is longer than GENL_NAMSIZ.
Signed-off-by: Masatake YAMATO <yamato@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netlink/genetlink.c

@@ -142,6 +142,7 @@ int genl_register_mc_group(struct genl_family *family,
 	int err = 0;
 
 	BUG_ON(grp->name[0] == '\0');
+	BUG_ON(memchr(grp->name, '\0', GENL_NAMSIZ) == NULL);
 
 	genl_lock();