Revert resolved-disable-event-sources-before-unreffing-them.patch

Bug #1943982 reported by Lukas Märdian
6
This bug affects 1 person
Affects Status Importance Assigned to Milestone
systemd (Ubuntu)
Won't Fix
Undecided
Unassigned
Focal
Won't Fix
Undecided
Unassigned

Bug Description

[impact]

The initial patch for LP: #1934221 was not sufficient to fix the root cause of the segfault, but rather moved it to a slightly different location in the code (still inside the on_query_timeout handler).

[test case]

this bug is only to revert the previous patch

For verification we should keep systemd-resolved running for a while and observe that it does not crash, using the relevant configuration in addition to being able to resolve DNS queries as expected, e.g.:
```
root@ff-vm:~# cat /etc/systemd/resolved.conf
[Resolve]
DNS=46.182.19.48#dns2.digitalcourage.de 1.1.1.1#cloudflare-dns.com 9.9.9.9#dns.quad9.net
DNSSEC=yes
DNSOverTLS=opportunistic
MulticastDNS=no
LLMNR=no
Cache=yes
DNSStubListener=yes
Domains=~.
root@ff-vm:~# dmesg | grep segfault
root@ff-vm:~# dmesg | grep "systemd-resolve"
root@ff-vm:~# resolvectl query google.com
google.com: 2a00:1450:4001:809::200e -- link: enp5s0
            172.217.18.110 -- link: enp5s0

-- Information acquired via protocol DNS in 177.4ms.
-- Data is authenticated: no
```

[regression potential]

Any regression could cause crashes in systemd-resolved, making it unresponsive to DNS network name requests to local applications.

[other info]

this only reverts the patch that was added for LP: #1934221, as this patch was detected to still produce (slightly different) segfaults in on_query_timeout (https://errors.ubuntu.com/problem/c4e5be3f1c7af9483993c7e6007b9325ab5b78cd), similar to the original segfaults in on_query_timeout (https://errors.ubuntu.com/problem/bb0ce4ff8e6ef86041cfb5647b792823a20b44f7)

We want to revert the patch in Focal (systemd v245) for now, while we'll try to fix the root cause in Hirsute (systemd v247), adding more relevant patches that were added to systemd-stable v247 (but not systemd-stable v245):
https://github.com/systemd/systemd-stable/commits/v247-stable/src/resolve/resolved-dns-query.c
https://github.com/systemd/systemd-stable/commit/64317106aed94a6fb758ab6b08ba490873fc5227
https://github.com/systemd/systemd-stable/commit/91ba2eac4b6b463026b3a93e5a139923e8f2cfe4
https://github.com/systemd/systemd-stable/commit/ab9f7e1a51005f12d3bac83b86716d9d33048eb7
https://github.com/systemd/systemd-stable/commit/78a43c33c8847ebbc2d3cf530ebe304924c58b32
https://github.com/systemd/systemd-stable/commit/c8d7fab2286384b19ff6328cece107c4c02d7bb8

=> Root-causing this issue will be done in the (re-opened) LP: #1934221

Related branches

Revision history for this message
Lukas Märdian (slyon) wrote :
Changed in systemd (Ubuntu Focal):
status: New → Won't Fix
Changed in systemd (Ubuntu):
status: New → Won't Fix
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