Bug 63916 - screensaver "Critical" completely freezes my laptop
Summary: screensaver "Critical" completely freezes my laptop
Alias: None
Product: Red Hat Linux
Classification: Retired
Component: XFree86   
(Show other bugs)
Version: 7.3
Hardware: i686 Linux
Target Milestone: ---
Assignee: Mike A. Harris
QA Contact:
Depends On:
TreeView+ depends on / blocked
Reported: 2002-04-21 21:16 UTC by petrosyan
Modified: 2008-05-01 15:38 UTC (History)
2 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2002-06-20 02:14:44 UTC
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
Patch for xscreensaver's critical (1.42 KB, patch)
2002-04-30 06:32 UTC, windonstewart
no flags Details | Diff
my X server configuration file (3.22 KB, text/plain)
2002-06-20 02:08 UTC, petrosyan
no flags Details
X log file (27.34 KB, text/plain)
2002-06-20 02:11 UTC, petrosyan
no flags Details
"/sbin/lspci" output (871 bytes, text/plain)
2002-06-20 02:13 UTC, petrosyan
no flags Details
"/sbin/lspci -n" output (459 bytes, text/plain)
2002-06-20 02:14 UTC, petrosyan
no flags Details

Description petrosyan 2002-04-21 21:16:08 UTC
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:0.9.9) Gecko/20020408

Description of problem:
the screensaver "Critical" totally freezes my system when I start it from
xscreensaver-demo application.

Version-Release number of selected component (if applicable):

How reproducible:

Steps to Reproduce:
1.run xscreensaver-demo
2. choose the screensaver "Critical"
3. press the button "Demo"

Actual Results:  the system freezes right away

Expected Results:  the demo of a screensaver

Additional info:

I have an IBM Thinkpad T20 2647rr3 laptop.
with default installation of skipjack2 and all updates applied.

the default installation of my RH Linux is not stable since it has "Random
Screensaver" installed by default and when I leave laptop unattended it totally
freezes after some period of time.
so i had do disable my screensaver.

Comment 1 petrosyan 2002-04-21 21:27:11 UTC
i just found out that the "Blaster" screensaver also freezes my laptop.
but it takes about 3 seconds to freeze the laptop as opposed to the "Critical"
screensaver which freezes the laptop immediately.

Comment 2 windonstewart 2002-04-30 06:30:08 UTC
Same results on my Dual Pentium II 233 custom-built desktop with savage4 card.

Original code in critical does not initialize the starting coordinate used in
XDrawLine for each simulation which causes the immediate freeze.  I have created
a patch that not only fixes that problem, but also a misallocation in memory [in
the case of sizeof (int) != sizeof (short)], writing an unused value to an
element beyond the end of allocated memory, and a memory leak growing with each

I have tested the patched code with extreme command parameter values for several
hours without lockup or increase in allocated memory.

Comment 3 windonstewart 2002-04-30 06:32:46 UTC
Created attachment 55844 [details]
Patch for xscreensaver's critical

Comment 4 petrosyan 2002-04-30 23:41:12 UTC
don't you think that this sould be considered an XFree4 bug and not an
xsreensaver bug ?

a computer is not supposed to freeze completely just because some program passed
wrong coordinates to XDrawLine function.

Comment 5 windonstewart 2002-05-01 06:54:03 UTC
I agree with you, XFree has a bug that needs to be fixed.  A server of any 
kind should either report an error condition or handle it somehow without 
crashing.  I'm an X newbie, so I'll dig into the XFree86 source and write some 
test programs for XDrawLine and come up with something to report.

However, even if XDrawLine was working properly; the xscreensaver code would 
start off not looking quite the way the author intended, may crash when 
compiled with short-sized ints, but definitely crash with the memory leak if 
left running.  So it still an xscreensaver bug.

Comment 6 Mike A. Harris 2002-05-25 01:50:44 UTC
Please try disabling 2D acceleration to see if that solves the problem.

Use Option "noaccel" in the device section of your config file.  Report
back if that prevents the problem or not, and we can continue troubleshooting
from there.

Comment 7 petrosyan 2002-05-25 06:15:30 UTC
Option "noaccel" solves  the problem.
both screensavers (critical and blaster) work without freezing the computer.
the X Window System started to work noticeably slower without acceleration.

Comment 8 Mike A. Harris 2002-06-19 17:09:43 UTC
Sorry for the delay in responding.  "noaccel" was just a test to see if
2D acceleration was causing the problem.

In order to fix the problem, and in the mean time find a better workaround
for you, here is what you can do:

Read the XF86Config manpage, and look for the options "XaaNoxxxxxx".
Comment out noaccel, and try the XaaNo options one at a time.  This may take
quite some time to test, but is necessary in order to determine where the bug
is.  Use only one XaaNo option at a time, and restart X and test the
screensavers which trigger this out.  Even if you find one option that fixes
the problem, please continue through the full list one at a time.

Please report back which individual option or options solve the problem on
their own.  Once you've done this, you'll have much faster video in the
mean time, we will be able to default the card to this configuration, and
we also can report the troubled code area to Tim Roberts, the Savage
driver maintainer <timr@probo.com>.

Comment 9 Mike A. Harris 2002-06-19 17:10:58 UTC
Oh, please attach your X server log file and config file to the report
using the link below as well, and the output of "lspci" and also "lspci -n".

Bill, you might want to check out the xscreensaver patch...

Comment 10 petrosyan 2002-06-20 02:06:48 UTC
I tried all the XaaNoxxx one at a time and none of the options fixed the problem.
then I tried looking at multiple XaaNoxxxx options and finally found out two
options that eliminate the problem. these options are:

        Option "XaaNoSolidBresenhamLine"
        Option "XaaNoSolidTwoPointLine"

one should choose _both_ of these options in order to solve the problem.

this is also consistent with what windonstewart@netzero.net found out in the
source code of "Critical" screensaver.

Comment 11 petrosyan 2002-06-20 02:08:10 UTC
Created attachment 61744 [details]
my X server configuration file

Comment 12 petrosyan 2002-06-20 02:11:03 UTC
Created attachment 61745 [details]
X log file

Comment 13 petrosyan 2002-06-20 02:13:52 UTC
Created attachment 61746 [details]
"/sbin/lspci" output

Comment 14 petrosyan 2002-06-20 02:14:39 UTC
Created attachment 61747 [details]
"/sbin/lspci -n" output

Comment 15 petrosyan 2002-08-09 03:06:05 UTC
"Critical" and "Blaster" seem to be working fine in the latest release of Limbo

so i am closing this bug

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