[Bug 1809438] Re: systemd-resolved segfaults

[Tim Riker]

How should I persistently bypass systemd-resolved ? The DNS failures are
causes other applications to fail. I'd like resolv.conf to update with
dhcp returned data for DNS servers, but, for the time being, I'd like
applications to talk to the upstream DNS servers until this issue is
resolved.

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Title:
  systemd-resolved segfaults

Status in systemd package in Ubuntu:
  Confirmed

Bug description:
  I regularly (once almost every hour) get segfaults resported in
  systemd-resolved. The syslog is not always the same:

  Dec 21 06:59:21 marshall kernel: [988042.071003] systemd-resolve[15794]: segfault at e60e8ad514 ip 000000e60e8ad514 sp 00007ffe0376e748 error 14 in systemd-resolved[556f74bcf000+59000]
  Dec 21 06:59:21 marshall systemd[1]: systemd-resolved.service: Main process exited, code=dumped, status=11/SEGV
  Dec 21 06:59:21 marshall systemd[1]: systemd-resolved.service: Failed with result 'core-dump'.

  Dec 21 08:17:47 marshall kernel: [992748.334333] systemd-resolve[16943]: segfault at 2a11d9b0 ip 00007f4810f5ad26 sp 00007fff544db0f0 error 4 in libsystemd-shared-237.so[7f4810e1f000+1b5000]
  Dec 21 08:17:47 marshall systemd[1]: systemd-resolved.service: Main process exited, code=dumped, status=11/SEGV
  Dec 21 08:17:47 marshall systemd[1]: systemd-resolved.service: Failed with result 'core-dump'.

  Dec 21 06:22:45 marshall systemd-resolved[15727]: Assertion 'p->n_ref > 0' failed at ../src/resolve/resolved-dns-packet.c:210, function dns_packet_unref(). Aborting.
  Dec 21 06:22:45 marshall systemd[1]: systemd-resolved.service: Main process exited, code=dumped, status=6/ABRT
  Dec 21 06:22:45 marshall systemd[1]: systemd-resolved.service: Failed with result 'core-dump'.

  Dec 21 06:17:46 marshall systemd-resolved[15662]: Assertion 'DNS_TRANSACTION_IS_LIVE(q->state)' failed at ../src/resolve/resolved-dns-query.c:540, function dns_query_complete(). Aborting.
  Dec 21 06:17:46 marshall systemd[1]: systemd-resolved.service: Main process exited, code=dumped, status=6/ABRT
  Dec 21 06:17:46 marshall systemd[1]: systemd-resolved.service: Failed with result 'core-dump'.

  The system in question uses dnsmasq as local DNS server. Logging that is probably unrelated, but often seen (possibly due to the setup with dnsmasq) is:
  dec 21 10:22:00 marshall systemd-resolved[3183]: Server returned error NXDOMAIN, mitigating potential DNS violation DVE-2018-0001, retrying transaction with reduced feature level UDP.
  dec 21 10:17:15 marshall systemd-resolved[3183]: Using degraded feature set (TCP) for DNS server 127.0.0.1.

  
  # dpkg --status systemd
  Package: systemd
  Installed-Size: 12444
  Maintainer: Ubuntu Developers <ubuntu-devel-discuss at lists.ubuntu.com>
  Architecture: amd64
  Multi-Arch: foreign
  Version: 237-3ubuntu10.9

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