(ITS#7167) regression, ldap_result() returns -1

[jvcelak@redhat.com]

Full_Name: Jan Vcelak
Version: 2.4.29
OS: Linux
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (209.132.186.34)


There is a possible regression caused by
06ec9f1db2bb9dc304a4adcd0d0506203cf9e6b6.

SSSD's event loop listens for events on a file descriptor retrieved using
ber_sockbuf_ctrl(sb, LBER_SB_OPT_GET_FD, &ber_fd). If there are some data to be
read, processing using ldap_result is triggered. (Internally, tevent from Samba
project is used, which uses epoll.) But sometimes, ldap_result() returns -1
error code. It seems that the descriptor is marked as readable untimely.

This problem is not present with OpenLDAP 2.4.26, it appears with all future
versions. When the mentioned commit is reverted, everything works well.

Original report in our Bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=771484

It was also reported in Ubuntu:
https://bugs.launchpad.net/ubuntu/+source/openldap/+bug/929888

And i similar report, hopefully with the same cause:
https://bugzilla.redhat.com/show_bug.cgi?id=790414