CVE request for possible NULL ptr deref in XDM when using crypt() from glibc 2.17+

[Alan Coopersmith]

It's been suggested we get a CVE id assigned for this recent fix to the xdm
display/login manager from X.Org:

http://cgit.freedesktop.org/xorg/app/xdm/commit/?id=8d1eb5c74413e4c9a21f689fc106949b121c0117

Without this fix, if xdm is built to use raw crypt() authentication, instead
of a higher level system such as PAM or BSD Auth, and that crypt() function
can return a NULL pointer (as glibc 2.17+ does for invalid input, such as
when an account is locked by prepending a "!" to the password field), then
attempting to login to such an account via xdm can crash the xdm daemon.

For single user console machines, this generally just means you get the 
text console login prompt instead.   For machines set up to support multiple
seats, remote XDMCP access, or X terminals (such as LTSP setups using xdm),
this may be a denial of service for users on those other seats/terminals
/devices.

-- 
	-Alan Coopersmith-              alan.coopersmith at oracle.com
	 Oracle Solaris Engineering - http://blogs.oracle.com/alanc