Unfortunately, the reported did not provide logs from the time of crash.
The backtrace only says that it occurred in nsupdate_child_handler() but
I'm very confident that the root cause was that the dyndns update
reached timeout.
The first patch fixes dyndns unit tests to actually reveal the crash.
Cooler solution would be to use tevent_loop_wait(), but it contains an
issue due to which it is not possible. This issue was reported on Samba
mailing list:
https://lists.samba.org/archive/samba-technical/2013-June/093457.html
Second patch will fix the crash.
What is the difference between child_sig_handler() which uses context
suffixed with _old and sss_sigchld_init()? Would it make sense to update
the code to the new sigchld handler?