There are several places (all error-handling) where sss_cmd_done()
is called with no response packet created. As a short-term
solution, we need to check whether the packet is NULL and simply
return EINVAL. client_send() (the consumer) will then forcibly
disconnect the client (which will return PAM_SYSTEM_ERR to the
client).
This is a quick fix for
https://bugzilla.redhat.com/show_bug.cgi?id=748924
We don't have enough information (or steps to reproduce) to trace back
the processing to its origin, so the best thing we can do for the moment
is to simply prevent the crash. The client will receive an error, but
the SSSD will continue to function.