[Bug 1849658] Autopkgtest regression report (systemd/237-3ubuntu10.32)

[Ubuntu SRU Bot]

All autopkgtests for the newly accepted systemd (237-3ubuntu10.32) for bionic have finished running.
The following regressions have been reported in tests triggered by the package:

gvfs/1.36.1-0ubuntu1.3.3 (ppc64el)
linux/unknown (ppc64el)


Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/bionic/update_excuses.html#systemd

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

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https://bugs.launchpad.net/bugs/1849658

Title:
  resolved fallback to TCP fails for truncated UDP replies

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Bionic:
  Fix Committed
Status in systemd source package in Disco:
  Fix Committed
Status in systemd source package in Eoan:
  Fix Committed
Status in systemd source package in Focal:
  Fix Released

Bug description:
  [impact]

  for DNS UDP replies larger than 512 bytes, fallback to TCP is used.
  For example 'host toomany.ddstreet.org'.

  Due to a bug in resolved in refcounting DNS stream types, the refcount
  underflows for type 0 streams (which resolved uses to talk to upstream
  nameservers), resulting in resolved being unable to fallback to TCP to
  handle truncated UDP replies.

  [test case]

  ubuntu at sf247344-upstream:~$ dig +noanswer +noedns toomany.ddstreet.org
  ;; Truncated, retrying in TCP mode.

  ; <<>> DiG 9.11.3-1ubuntu1.9-Ubuntu <<>> +noanswer +noedns toomany.ddstreet.org
  ;; global options: +cmd
  ;; Got answer:
  ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2683
  ;; flags: qr rd ra; QUERY: 1, ANSWER: 40, AUTHORITY: 0, ADDITIONAL: 0

  ;; QUESTION SECTION:
  ;toomany.ddstreet.org.		IN	A

  ;; Query time: 0 msec
  ;; SERVER: 127.0.0.53#53(127.0.0.53)
  ;; WHEN: Thu Oct 24 11:40:29 UTC 2019
  ;; MSG SIZE  rcvd: 678

  ubuntu at sf247344-upstream:~$ sudo resolvectl flush-caches
  ubuntu at sf247344-upstream:~$ dig +noanswer +noedns toomany.ddstreet.org

  ; <<>> DiG 9.11.3-1ubuntu1.9-Ubuntu <<>> +noanswer +noedns toomany.ddstreet.org
  ;; global options: +cmd
  ;; connection timed out; no servers could be reached

  [regression potential]

  very low, as this only properly sets the stream type in the DnsStream
  object; any regression would be a failure to be able to use TCP for
  DNS requests or replies.

  [other info]

  https://github.com/systemd/systemd/pull/13838

  The commit adding stream types is not present in x/b, so this is
  needed only for disco and later.

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