Xdmx crashed with SIGSEGV in dmxCreateGC()

[gHeift]

Xdmx crashed with SIGSEGV in dmxCreateGC()

running version 1.5.1-1ubuntu2

How to reproduve:
* start an Xephyr server
* start an Xdmx server. which connects to the Xephyr server

What happend: Xdmx throws a segfault
What I expected: Xdmx should not throw a segfault

There is already a patch in the master branch of xorg-xserver:
http://cgit.freedesktop.org/xorg/xserver/commit/?id=6f1d5147cb394b7c83c4c1447c78890fa2b40a45

But with this one I get an strange behavior when I just want to move the mouse in Xephyr:
...
[mi] EQ overflowing. The server is probably stuck in an infinite loop.
[mi] mieqEnequeue: out-of-order valuator event; dropping.
...

If I connect an xterm to the Xdmx server I get a segfault in miPaintWindow.

ProblemType: Crash
Architecture: amd64
CrashCounter: 1
DistroRelease: Ubuntu 8.10
ExecutablePath: /usr/bin/Xdmx
Package: xdmx 2:1.5.1-1ubuntu2
ProcAttrCurrent: unconfined
ProcCmdline: Xdmx :3 -auth xdmx-xauth-3 -display :1
ProcEnviron:
 SHELL=/bin/bash
 PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games
 LANG=de_DE.UTF-8
Signal: 11
SourcePackage: xorg-server
Stacktrace:
 #0 0x000000000043e51a in dmxCreateGC ()
 #1 0x0000000000516fdd in CreateScratchGC ()
 #2 0x000000000051713e in CreateGCperDepth ()
 #3 0x000000000051c245 in main ()
StacktraceTop:
 dmxCreateGC ()
 CreateScratchGC ()
 CreateGCperDepth ()
 main ()
Title: Xdmx crashed with SIGSEGV in dmxCreateGC()
Uname: Linux 2.6.27-6-generic x86_64
UserGroups: adm admin audio cdrom dialout dip floppy fuse lpadmin plugdev pulse pulse-access pulse-rt sambashare video

[Bryce Harrington (bryce)]

I've reported your issue upstream at https://bugs.freedesktop.org/show_bug.cgi?id=19171. Could you please subscribe to that bug report, in case upstream wishes further information or needs you to test something? Thanks ahead of time!

[pmitros (pmtemp79)]

Just to post a work-around until this is fixed in Ubuntu: Install Xdmx from Debian etch. The package is binary-compatible, and works fine under Ubuntu/Intrepid. Note that versions of Debian more recent than etch share the same bug.

I posted details of setting up Xdmx under Intrepid at http://mitros.org/p/xdmx-setup.html (although only a small part of the document is relevant to the bug).

[Bryce Harrington (bryce)]

This bug seems to be pretty ancient; I'm guessing if it were still relevant we'd have seen more recent comments. In any case the backtraces have bitrotted; they no longer point into the right functions. So presumably code's been changed which has made this bug go away.

If I'm wrong and the bug can be reproduced on Karmic, feel free to reopen and attach a fresh Backtrace. A fresh Xorg.0.log couldn't hurt either.

[Joe Batt (joe-soliddesign)]

It's not too hard to reproduce. Just run 'Xdmx :1 -display :0'.

In an up to date Jaunty install...

battjt@dale:~/workspace/CL$ gdb Xdmx
GNU gdb 6.8-debian
Copyright (C) 2008 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later
<http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "i486-linux-gnu"...
(no debugging symbols found)
(gdb) r :1 -display :0
Starting program: /usr/bin/Xdmx :1 -display :0
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
---Type <return> to continue, or q <return> to quit---
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
(no debugging symbols found)
[Thread debugging using libthread_db enabled]
(no debugging symbols found)
(no debugging symbols found)
(II) dmx: Generation: 1
(II) dmx: DMX version: 1.2.20070424 (DMX Project)
(II) dmx: DMX Build OS: Linux 2.6.24-23-server i686 (Ubuntu)
(II) dmx: DMX Build Compiler: gcc 4.3.3
(II) dmx: DMX Execution OS: Linux 2.6.28-15-generic #49-Ubuntu SMP Tue
Aug 18 18:40:08 UTC 2009
(II) dmx: DMX Execution Host: dale
(II) dmx: MAXSCREENS: 16
(II) dmx: Using configuration from command line
(II) dmx: Added :0 at 0 0
(II) dmx[o0/:0]: No Xdmx server running on backend
(II) dmx[o0/:0]: Name of display: :0.0
(II) dmx[o0/:0]: Version number: 11.0
(II) dmx[o0/:0]: Vendor string: The X.Org Foundation
(II) dmx[o0/:0]: Vendor release: 10600000
(II) dmx[o0/:0]: Dimensions: 1440x900 pixels
(II) dmx[o0/:0]: 7 depths on screen 0: 24,1,4,8,15,16,32
(II) dmx[o0/:0]: Depth of root window: 24 planes (24)
(II) dmx[o0/:0]: Number of colormaps: 1 min, 1 max
(II) dmx[o0/:0]: Options: backing-store no, save-unders no
(II) dmx[o0/:0]: Window Manager running: yes
(**) dmx[o0/:0]: Window manager running -- colormaps not supported
(II) dmx[o0/:0]: 1440x900+0+0 on 1440x900 at depth=24, bpp=32
(II) dmx[o0/:0]: 0x21 TrueColor 24b 8b/rgb 256 0xff0000 0xff00 0x00ff *
(II) dmx[o0/:0]: 0x22 DirectColor 24b 8b/rgb 256 0xff0000 0xff00 0x00ff
(II) dmx[o0/:0]: 0x92 TrueColor 24b 8b/rgb 256 0xff0000 0xff00 0x00ff
(II) dmx[o0/:0]: 0x93 TrueColor 24b 8b/rgb 256 0xff0000 0xff00 0x00ff
(II) dmx[o0/:0]: 0x94 TrueColor 24b 8b/rgb 256 0xff0000 0xff00 0x00ff
(II) dmx[o0/:0]: 0x95 TrueColor 24b 8b/rgb 256 0xff0000 0xff00 0x00ff
(II) dmx[o0/:0]: 0x96 TrueColor 24b 8b/rgb 256 0xff0000 0xff00 0x00ff
(II) dmx[o0/:0]: 0x97 TrueColor 24b 8b/rgb 256 0xff0000 0x...

[Lukas Diduch (lukas-diduch)]

Hi,

i'm working on Ubuntu 9.04. xdmx segfaults as described. Using an older debian bin (as recommended on http://mitros.org/p/xdmx-setup.html) did not solve the problem as well

I've built the xserver-xorg from source using apt-get source, since i've got to know that xdmx is part of xorg since 2004.
Still getting segfaults by using:

xinit -- /usr/local/bin/Xorg
xdmx :1 -display ...:0 display ...:0

If needed i can provide backtraces and info from gdb. In any of the three cases (install, debian-bin, build-bin) the segfaults occur in different places though.

[Mayeul KAUFFMANN (mayeul-kauffmann)]

Apparently same thing on Karmic

 gdb Xdmx
GNU gdb (GDB) 7.0-ubuntu
Copyright (C) 2009 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law. Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from /usr/bin/Xdmx...(no debugging symbols found)...done.
(gdb) r :1 -display :0
Starting program: /usr/bin/Xdmx :1 -display :0
[Thread debugging using libthread_db enabled]
(II) dmx: Generation: 1
(II) dmx: DMX version: 1.2.20070424 (DMX Project)
(II) dmx: DMX Build OS: Linux 2.6.24-23-server x86_64 (Ubuntu)
(II) dmx: DMX Build Compiler: gcc 4.4.1
(II) dmx: DMX Execution OS: Linux 2.6.31-14-generic #48-Ubuntu SMP Fri Oct 16 14:05:01 UTC 2009
(II) dmx: DMX Execution Host: mk-desktop-smh
(II) dmx: MAXSCREENS: 16
(II) dmx: Using configuration from command line
(II) dmx: Added :0 at 0 0
(II) dmx[o0/:0]: Name of display: :0.0
(II) dmx[o0/:0]: Version number: 11.0
(II) dmx[o0/:0]: Vendor string: The X.Org Foundation
(II) dmx[o0/:0]: Vendor release: 10604000
(II) dmx[o0/:0]: Dimensions: 1280x1024 pixels
(II) dmx[o0/:0]: 7 depths on screen 0: 24,1,4,8,15,16,32
(II) dmx[o0/:0]: Depth of root window: 24 planes (24)
(II) dmx[o0/:0]: Number of colormaps: 1 min, 1 max
(II) dmx[o0/:0]: Options: backing-store no, save-unders no
(II) dmx[o0/:0]: Window Manager running: yes
(**) dmx[o0/:0]: Window manager running -- colormaps not supported
(II) dmx[o0/:0]: 1280x1024+0+0 on 1280x1024 at depth=24, bpp=32
(II) dmx[o0/:0]: 0x21 TrueColor 24b 8b/rgb 256 0xff0000 0xff00 0x00ff *
(II) dmx[o0/:0]: 0x22 DirectColor 24b 8b/rgb 256 0xff0000 0xff00 0x00ff
(II) dmx[o0/:0]: 0x24 Tru...

[Lukas Diduch (lukas-diduch)]

I can confirm that on Karmic (9.10), this must be a legacy problem though because after building a quite recent xorg from the xorg modular git rep. xdmx works fine. I do have problems with glx though with the nvidia drivers. Using them on the xorg server works fine, but launching xdmx and then using e.g. glxinfo crashes xdmx.