crash on reconfig with duplicated zone name in zone catalog vs. named.conf

Summary

Run-time addition of zone into named.conf causes crash if the same zone is present in a catalog zone.

BIND version used

• Affects v9.16: v9_16_34
• Affects v9.18: 2f808b76
• Affects v9.19: f6f52513

Steps to reproduce

1. Define zone in a catalog, e.g. catalog.db empty.db
2. Start primary with this config: primary.conf
3. Configure secondary with catalog: named.conf
4. Start secondary
5. On the secondary, uncomment duplicate zone definition as non-catalog secondary zone (I did not try other types)
6. On the secondary, run rndc reconfig

What is the current bug behavior?

💥

zt.c:166: REQUIRE((__builtin_expect(!!((zt) != ((void *)0)), 1) && __builtin_expect(!!(((const isc__magic_t *)(zt))->magic == ((('Z') << 24 | ('T') << 16 | ('b') << 8 | ('l')))), 1))) failed, back trace

(gdb) bt
#0  0x00007f808410b8ec in ?? () from /usr/lib/libc.so.6
#1  0x00007f80840bcea8 in raise () from /usr/lib/libc.so.6
#2  0x00007f80840a653d in abort () from /usr/lib/libc.so.6
#3  0x0000556161c1bc0a in assertion_failed[cold] ()
#4  0x0000556161e2c7da in isc_assertion_failed ()
#5  0x0000556161df047a in dns_zt_find ()
#6  0x0000556161ca48bf in dns_catz_zones_merge ()
#7  0x0000556161ca8783 in dns_catz_update_from_db ()
#8  0x0000556161ca8938 in dns_catz_update_taskaction ()
#9  0x0000556161e5cc81 in isc_task_run ()
#10 0x0000556161e4666e in process_netievent ()
#11 0x0000556161e46898 in process_queue ()
#12 0x0000556161e47233 in async_cb ()
#13 0x00007f8084278363 in uv__async_io (loop=0x5561622a1400, 
    w=<optimized out>, events=<optimized out>) at src/unix/async.c:163
#14 0x00007f808428ac23 in uv__io_poll (loop=loop@entry=0x5561622a1400, 
    timeout=-1) at src/unix/epoll.c:374
#15 0x00007f8084278d47 in uv_run (loop=0x5561622a1400, mode=UV_RUN_DEFAULT)
    at src/unix/core.c:406
#16 0x0000556161e46b39 in nm_thread ()
#17 0x0000556161e5efd5 in isc.trampoline_run ()

What is the expected correct behavior?

Good question. I'm not sure which zone definition should win, but at least it should not crash.