Crash on assert in decref() qpcache.c:711: REQUIRE(*nlocktypep != isc_rwlocktype_none)

Summary

Resolver with minimal load occasionally crashes with assertion failure in decref() function at qpcache.c:711

qpcache.c:711: REQUIRE(*nlocktypep != isc_rwlocktype_none) failed

BIND version affected

• Affects v9.19: commit f8f0f450

Steps to reproduce

Unknown at the moment, but happens after ~ 20 minutes of runtime while the resolver is serving single laptop.

Relevant configuration files

• named.conf

Backtrace

#3  0x000056fe49a3662f in assertion_failed (file=0x7c25fa2a9878 "qpcache.c", line=711, type=isc_assertiontype_require, cond=0x7c25fa2a9b50 "*nlocktypep != isc_rwlocktype_none") at main.c:234
#4  0x00007c25fa529fbd in isc_assertion_failed (file=0x7c25fa2a9878 "qpcache.c", line=711, type=isc_assertiontype_require, cond=0x7c25fa2a9b50 "*nlocktypep != isc_rwlocktype_none") at assertions.c:48
#5  0x00007c25fa120d2c in decref (qpdb=0x7c25f6199600, node=0x7c25f164fee0, nlocktypep=0x7c25f03fa64c, tlocktypep=0x7c25f03fa650, tryupgrade=true) at qpcache.c:711
#6  0x00007c25fa1217f5 in expireheader (header=0x7c25e225e6c0, nlocktypep=0x7c25f03fa64c, tlocktypep=0x7c25f03fa650, reason=dns_expire_ttl) at qpcache.c:959
#7  0x00007c25fa12d56a in expire_ttl_headers (qpdb=0x7c25f6199600, locknum=1, nlocktypep=0x7c25f03fa650, tlocktypep=0x7c25f03fa64c, now=1714634003, cache_is_overmem=false) at qpcache.c:4418
#8  0x00007c25fa12a8cc in addrdataset (db=0x7c25f6199600, node=0x7c25eb161f00, version=0x0, now=1714634003, rdataset=0x7c25eac12bb0, options=0, addedrdataset=0x7c25ef340f20) at qpcache.c:3566
#9  0x00007c25fa053f04 in dns__db_addrdataset (db=0x7c25f6199600, node=0x7c25eb161f00, version=0x0, now=1714634003, rdataset=0x7c25eac12bb0, options=0, addedrdataset=0x7c25ef340f20) at db.c:703
#10 0x00007c25fa1c82b9 in validated (arg=0x7c25eac31a00) at resolver.c:5356
#11 0x00007c25fa52a468 in isc__async_cb (handle=0x7c25f68fcbe8) at async.c:111

Please note the small cache size.