a6f66e7 Ticket #47659 - ldbm_usn_init: Valgrind reports Invalid read / SIGSEGV

Authored and Committed by nhosoi 7 years ago
    Ticket #47659 - ldbm_usn_init: Valgrind reports Invalid read / SIGSEGV
    
    Bug description: A suffix mapping tree could exist without the corresponding
    backend.  The existing code did not properly check the backend returned from
    slapi_mapping_tree_find_backend_for_sdn.  When NULL backend is returned, it
    triggers the NULL pointer dereference.
    
    Fix description: This patch added a NULL backend check to usn_get_last_usn,
    and moved a logging to the if clause where the backend is not NULL.
    
    https://fedorahosted.org/389/ticket/47659
    
    Reviewed by rmeggins@redhat.com (Thank you, Rich!!)