Comment 23 for bug 929888

I have a little more information about this.

SSSD's event loop listens on the file descriptor we get from
ber_sockbuf_ctrl(sb, LBER_SB_OPT_GET_FD, &ber_fd);

We call a callback to process results from LDAP when that file descriptor becomes marked as readable by the kernel (assumption: there's data on it to be read).

However, it appears that this file descriptor is now sometimes being set "readable" without data that can be processed by ldap_result().

This is the source of the regression. Downgrading to F16's openldap works properly.

In the case above, it seems like the file descriptor is being marked readable before the response has actually arrived. Additionally, see BZ #790414 for another manifestation of this. In that particular case, we're getting it marked as readable AFTER the response has already been fully processed.