[*] lo0 flags BEFORE SIOCSIFDESCR:
  flags=0xffff8041 <UP,RUNNING,MULTICAST,PPROMISC,>
[*] lo0 flags AFTER SIOCSIFDESCR(len=2):
  flags=0xffff8040 <RUNNING,MULTICAST,PPROMISC,>

[!] DF-0273 REPRODUCED: IFF_UP cleared by setting a description (fall-through SIOCSIFDESCR -> SIOCSIFFLAGS).
[!] new_flags was driven by ifr_buffer.length==2 (IFF_BROADCAST), bypassing the SIOCSIFFLAGS intent.
[*] lo0 flags AFTER SIOCSIFDESCR(len=256):
  flags=0xffff8040 <RUNNING,MULTICAST,PPROMISC,>
RUN_EXIT=0