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Date: Thu, 19 Jan 2012 17:35:23 -0600
From: Tim Zingelman <>
Subject: Re: Screen locking programs on Xorg 1.11

On Thu, Jan 19, 2012 at 1:18 PM, Florian Weimer <> wrote:
>> I recently found out that it is possible to kill a screensaver/screen
>> locker program on the latest version of Xorg (1.11 shipped with
>> archlinux, debian wheezy..) using the Ctrl+Alt+Multiply key binding.
> This used to be, uhm, common knowledge:
> | Option "AllowDeactivateGrabs" "boolean"
> |     This option enables the use of the Ctrl+Alt+Keypad-Divide key
> |     sequence to deactivate any active keyboard and mouse
> |     grabs. Default: off.
> |
> | Option "AllowClosedownGrabs" "boolean"
> |     This option enables the use of the Ctrl+Alt+Keypad-Multiply key
> |     sequence to kill clients with an active keyboard or mouse grab as
> |     well as killing any application that may have locked the server,
> |     normally using the XGrabServer(3x) Xlib function. Default: off.
> |
> |     Note that the options AllowDeactivateGrabs and AllowClosedownGrabs
> |     will allow users to remove the grab used by screen saver/locker
> |     programs. An API was written to such cases. If you enable this
> |     option, make sure your screen saver/locker is updated.
> <>
> The API in question appears to be XF86MiscSetGrabKeysState:
> <>

Given this additional information isn't this a vulnerability issue in
the various screen lock applications rather than an issue with the
Xorg server?

 - Tim

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