Variable 'len' is never used in zone_set_initname().
The variable 'len' is set by the call to copyinstr() and then never used. In fact, the whole function seems a bit off. The function could probably could look more like zone_set_bootargs() and zone_set_fs_allowed().
This doesn't seem like a very serious bug, just a bit odd.
For reference, here's the function:
zone_set_bootargs() and zone_fs_allowed() are defined just above zone_set_initname()