Ok, I wasn't sure because the testsaslauthd program woks fine to test the authentication process, it's just were LDAP goes to use it that it doesn't work. Perhaps I'll try the SASL list to see if they have anything.
Your backtrace shows that the crash occurs in libsasldb, so this is either a SASL configuration error (since you say you're not using sasldb) or a SASL bug.