oss-security - Re: CVE request: lightdm-gtk-greeter - local DOS due to NULL pointer dereference

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Message-ID: <20140107133950.GB9302@scapa.corsac.net>
Date: Tue, 7 Jan 2014 14:39:50 +0100
From: Yves-Alexis Perez <corsac@...ian.org>
To: oss-security@...ts.openwall.com
Subject: Re: CVE request: lightdm-gtk-greeter - local DOS due
 to NULL pointer dereference

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On Tue, Jan 07, 2014 at 11:47:31AM +0100, Guido Berhoerster wrote:
> Hi,
> 
> an openSUSE user discovered that it is trivial to crash
> lightdm-gtk-greeter by entering an empty username due to a NULL
> pointer dereference. When a greeter crashes the lightdm daemon
> exits.
> This constitutes a local denial of service which can be triggered
> by any unprivileged attacker requiring the intervention of an
> administrator to restart lightdm. It affects all versions of
> lightdm-gtk-greeter.
> 
> The initial downstream report is at
> https://bugzilla.novell.com/show_bug.cgi?id=857303, the bug has
> been reported upstream at
> https://bugs.launchpad.net/lightdm-gtk-greeter/+bug/1266449 and
> fixes for the 1.1 and 1.3 series are available at
> https://build.opensuse.org/package/view_file/home:gberh:branches:OBS_Maintained:lightdm-gtk-greeter/lightdm-gtk-greeter.openSUSE_12.2_Update/lightdm-gtk-greeter-handle-invalid-user.patch?expand=1
> and
> https://build.opensuse.org/package/view_file/home:gberh:branches:OBS_Maintained:lightdm-gtk-greeter/lightdm-gtk-greeter.openSUSE_13.1_Update/lightdm-gtk-greeter-handle-invalid-user.patch?expand=1
> 
> Could a CVE be assigned to this issue please?

I can confirm the bug on Debian (lightdm-gtk-greeter 1.6.1-4 and
1.7.0-1) as well as that the patch above seems to correctly fix it.

Regards,
- -- 
Yves-Alexis Perez
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