Petr messaged me and suggested maybe we try using rr to capture the
execution and failure to aid in debugging, unfortunately the cpu
performance events are unavailable on the machine I'm attempting
reproduction on.

I did manage to spend a little time the last two days adding some
additional debug logging into a source build of 2.90 which includes the
patch Brian posted to the dnsmasq mailing list in regards to dhcpv6.

I was still able to reproduce this issue leveraging one of ironic's
combined scenario tests jobs which exercises the dhcp configuration a
number of times. I also turned off inotify updates, and dhcp6 in my
local build, and was also still able to reproduce the failure.

I also tried sending a HUP signal a substantial number of times, and
tried massaging the configuration files which were being loaded for
static entries and I was still unable to reproduce the crash. There *IS*
a distinct possibility I just didn't do it "enough", but reproduced
crashes can barely be running for a long time and end up crashing.

From what I've seen, it appears that it can happen after a dhcp offer
response has been sent back to a v4 client, however at least looking
through the code, it appears netids being set is rather sparing to
configuration loading and do_options in src/rfc2131.c. I unfortunately
don't have the context to understand what and why that is being done in
do_options.

I have also been able to figure out a change to prevent the sigabrt by
only calling free() if a parameter is not null which seems to prevent
crashing, but only masks the root cause and there is no telling how long
and what impact that is having long term.

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https://bugs.launchpad.net/bugs/2026757

Title:
  dnsmasq on Ubuntu Jammy crashes on neutron-dhcp-agent updates

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