Bug 1076240

Summary:	scary information leakage
Product:	[Fedora] Fedora	Reporter:	Peter Backes <rtc>
Component:	xorg-x11-drv-nouveau	Assignee:	Ben Skeggs <bskeggs>
Status:	CLOSED EOL	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	high	Docs Contact:
Priority:	unspecified
Version:	20	CC:	airlied, ajax, bskeggs
Target Milestone:	---
Target Release:	---
Hardware:	Unspecified
OS:	Unspecified
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2015-06-29 19:27:12 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Peter Backes 2014-03-13 21:00:56 UTC

Description of problem:
After I boot a machine just turned on (power disconnected before), the lightdm background looks somewhat corrupted, containing mostly black, but some pixels in bright colors.

If I login to a session, then exit the session with a reboot, as soon as lightdm turns up the background now displays fragements of my screen from the session from BEFORE THE REBOOT! How freaking scary is that?

Just think about it, if I enter a password in the terminal in cleartext for some reason, it is now displayed to whoever rebooted the machine!

Version-Release number of selected component (if applicable):
xorg-x11-drv-nouveau-1.0.9-2.fc20.x86_64

How reproducible:
always

Steps to Reproduce:
1. login to a session
2. browse a little bit with firefox
3. from session, reboot
4. after reboot, watch lightdm background

Actual results:
it displays various fragments of the session from before reboot, from firefox as well as from the desktop

Expected results:
it displays /usr/share/backgrounds/default.png as configured in /etc/lightdm/lightdm-gtk-greeter.conf

Additional info:
how is this even theoretically possible given that linux is supposed to zero pages before mapping? http://permalink.gmane.org/gmane.linux.kernel.kernelnewbies/40544 Does a different policy apply to graphics memory?

One would assume it's hard and takes lots of effort to get information from other processes. This keeps the information over a reboot. And conveniently displays it. Scary stuff.

Comment 1 Peter Backes 2015-03-27 20:42:37 UTC

See also
https://hsmr.cc/palinopsia/
http://www.heise.de/newsticker/meldung/Gefaehrliches-Gedaechtnis-der-Grafikkarte-2586875.html

Someone claims at

http://www.heise.de/forum/heise-Security/News-Kommentare/Gefaehrliches-Gedaechtnis-der-Grafikkarte/Fuer-Linuxuser-nichts-Neues/posting-2240457/show/

that this is a longstanding X11 bug?

Comment 2 Fedora End Of Life 2015-05-29 11:14:42 UTC

This message is a reminder that Fedora 20 is nearing its end of life.
Approximately 4 (four) weeks from now Fedora will stop maintaining
and issuing updates for Fedora 20. It is Fedora's policy to close all
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Comment 3 Fedora End Of Life 2015-06-29 19:27:12 UTC

Fedora 20 changed to end-of-life (EOL) status on 2015-06-23. Fedora 20 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.

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