How to allow 'finger' command to query Active Directory users using gecos field value in Red Hat Enterprise Linux 6 having sssd backend?

Issue

• In Red Hat Enterprise Linux 5, finger command was capable of searching any user using e.g. the last name (which was set in gecos) through the sssd backend (which in our case is checking again an LDAP backend).
• This seems to have stopped working in RHEL 6. I can lookup users giving their uid, but not e.g. something in their gecos field.
• Is this expected behaviour?