pdns crashes on recursive queries (CVE-2011-4313 perhaps?)

[anon]

CentOS 5.7 using PDNS with MySQL backend.

Linux server 2.6.18-274.3.1.el5 #1 SMP Tue Sep 6 20:14:03 EDT 2011 i686 i686 i386 GNU/Linux

pdns_server --version

Version: 2.9.22, compiled on Jan 26 2009, 12:00:34 with gcc version 4.1.2 20080704 (Red Hat 4.1.2-44)

Last night I had one of my servers (using MySQL backend) crashing repeatedly after receiving a very large number of recursion requests. Few log entries in pdns_crash_log_extras.gz I haven't restarted yet, currently there's a pdns-server-instance listening, but stuck, not responding any queries. gdb backtrace in pdns_crash_backtrace.gz

[anon]

backtrace

[anon]

pdns log entries

[peter]

As far as I can tell from the logs, the issue seems to be that MySQL is being overloaded, and PowerDNS is crashing during reconnect. If you can reproduce the issue with 3.0 or current SVN, I would be happy to investigate, as it is likely this bug has been fixed after 2.9.22.

[peter]

Note that it is highly unlikely that this is related to CVE-2011-4313 :)

[anon]

Peter, thanks for checking it out. Are you saying that there is a bug which could match with the description in 2.9.22 that's been fixed in 3.0? Unfortunately I don't have the time right now to set up a 3.0 installation in a test environment and start working on replicating it. But I'll keep an eye on the affected server, haven't seen it crashing again since then.

[peter]

MySQL overload is handled badly in 2.9.22; semi-reasonably in 3.0.

[ahu]

We're not doing 2.9.22 maintenance anymore..