Unfortunately this instance of slapd doesn't have debugging symbols
enabled (it's a stock Debian 2.4.25 slapd package), so I didn't think gdb
would be that helpful...But now that you mention it, I could probably get
some basic stack trace info that might yield some clues.
Thanks for the reminder :-)
Debian ships the debugging symbols as a separate package. All you need
to do is install that package, and you can get a full backtrace.
p slapd-dbg - Debugging information for the OpenLDAP server (slapd)