This bug was fixed in the package systemd - 240-6ubuntu5.8
---------------
systemd (240-6ubuntu5.8) disco; urgency=medium
[ Victor Tapia ]
* d/p/resolved_disable-connection-downgrade-when-DNSSEC-yes.patch
Fix regression introduced by
resolved-Mitigate-DVE-2018-0001-by-retrying-NXDOMAIN-with.patch when
DNSSEC=yes (LP: #1796501)
[ Dan Streetman ]
* d/p/lp1840640-shared-seccomp-add-sync_file_range2.patch:
allow sync_file_range2 in nspawn container (LP: #1840640)
* d/p/lp1847527-journal-remote-do-not-request-Content-Length-if-Tran.patch:
do not request Content-Length if Transfer-Encoding is chunked
(LP: #1847527)
* d/t/storage: fix flaky test
(LP: #1847815)
* d/p/lp1843381-dell_passthrough_skip_rename_retry.patch,
debian/extra/rules/73-usb-net-by-mac.rules:
fix rename delay for systems using "Dell MAC passthrough"
(LP: #1843381)
*
d/p/lp1849733/0001-resolved-if-we-can-t-append-EDNS-OPT-RR-then-indicat.patch,
d/p/lp1849733/0002-resolved-don-t-let-EDNS0-OPT-dgram-size-affect-TCP.patch:
ignore EDNS0 payload limit when responding over TCP (LP: #1849733)
* d/p/lp1849658-resolved-set-stream-type-during-DnsStream-creation.patch:
- Fix bug in refcounting TCP stream types (LP: #1849658)
* d/extra/dhclient-enter-resolved-hook:
- only restart resolved if dhclient conf changed (LP: #1805183)
[ Balint Reczey ]
* d/p/test-execute-Filter-dev-.lxc-in-exec-dynamicuser-statedir.patch:
fix test breakage due to running in nested lxd container
(LP: #1845337)
-- Dan Streetman <ddstr...@canonical.com> Fri, 04 Oct 2019 09:06:58
-0400
** Changed in: systemd (Ubuntu Disco)
Status: Fix Committed => Fix Released
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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 Released
Status in systemd source package in Eoan:
Fix Released
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@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@sf247344-upstream:~$ sudo resolvectl flush-caches
ubuntu@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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