systemd-resolved segfault in hashmap_iterate_entry

[frigo]

installed libnss-resolve that put "resolve" in nsswitch.conf.

$ lsb_release -rd
Description: Ubuntu 20.04.3 LTS
Release: 20.04
$ dpkg -l systemd | grep systemd
ii systemd 245.4-4ubuntu3.13 amd64 system and service manager
$ grep ^hosts /etc/nsswitch.conf
hosts: files libvirt mdns4_minimal resolve [NOTFOUND=return] dns mymachines

systemd-resolved crashed once with segmentation fault.

(gdb) bt
#0 0x00007f119c67693a in hashmap_iterate_entry (h=h@entry=0x706f746b73656465, i=i@entry=0x7ffc4ef515d0) at ../src/basic/hashmap.c:705
#1 0x00007f119c6789d6 in internal_hashmap_iterate (h=0x706f746b73656465, i=i@entry=0x7ffc4ef515d0, value=value@entry=0x7ffc4ef515c8, key=key@entry=0x0)
    at ../src/basic/hashmap.c:714
#2 0x00007f119c678a8b in set_iterate (s=<optimised out>, i=i@entry=0x7ffc4ef515d0, value=value@entry=0x7ffc4ef515c8) at ../src/basic/hashmap.c:735
#3 0x000055ba5e0ea917 in dns_query_candidate_go (c=c@entry=0x55ba5f353180) at ../src/resolve/resolved-dns-query.c:152
#4 0x000055ba5e0e9f0c in dns_query_candidate_notify (c=c@entry=0x55ba5f353180) at ../src/resolve/resolved-dns-query.c:312
#5 0x000055ba5e0ea178 in dns_transaction_complete (t=0x55ba5f37a9d0, state=<optimised out>) at ../src/resolve/resolved-dns-transaction.c:351
#6 0x000055ba5e0e27cd in dns_transaction_process_dnssec (t=t@entry=0x55ba5f37a9d0) at ../src/resolve/resolved-dns-transaction.c:838
#7 0x000055ba5e0e3649 in dns_transaction_process_reply (t=t@entry=0x55ba5f37a9d0, p=p@entry=0x55ba5f39dce0)
    at ../src/resolve/resolved-dns-transaction.c:1210
#8 0x000055ba5e0e40ab in on_dns_packet (s=<optimised out>, fd=<optimised out>, revents=<optimised out>, userdata=0x55ba5f37a9d0)
    at ../src/resolve/resolved-dns-transaction.c:1264
#9 0x00007f119c5e6c77 in source_dispatch (s=s@entry=0x55ba5f346780) at ../src/libsystemd/sd-event/sd-event.c:3193
#10 0x00007f119c5e6f11 in sd_event_dispatch (e=e@entry=0x55ba5f320430) at ../src/libsystemd/sd-event/sd-event.c:3634
#11 0x00007f119c5e8948 in sd_event_run (e=e@entry=0x55ba5f320430, timeout=timeout@entry=18446744073709551615) at ../src/libsystemd/sd-event/sd-event.c:3692
#12 0x00007f119c5e8b6f in sd_event_loop (e=0x55ba5f320430) at ../src/libsystemd/sd-event/sd-event.c:3714
#13 0x000055ba5e0c326a in run (argv=<optimised out>, argc=<optimised out>) at ../src/resolve/resolved.c:84
#14 main (argc=<optimised out>, argv=<optimised out>) at ../src/resolve/resolved.c:91

This seems to have been reported upstream
https://github.com/systemd/systemd/issues/16168

[Nick Rosbrook (enr0n)]

The mentioned fix in the upstream report has been in systemd since 2021.