[oss-security] CVE request for possible NULL ptr deref in XDM when using crypt() from glibc 2.17+

Kurt Seifried kseifried at redhat.com
Thu Jun 13 16:57:07 PDT 2013


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On 06/11/2013 05:47 PM, Alan Coopersmith wrote:
> 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.
> 


Please use CVE-2013-2179 for this issue.

- -- 
Kurt Seifried Red Hat Security Response Team (SRT)
PGP: 0x5E267993 A90B F995 7350 148F 66BF 7554 160D 4553 5E26 7993
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