xfwm4 crashed with SIGSEGV in XUnmapWindow()

[Peter Brille]

xscreensaver crashes under xubuntu 14.04.
This happens quite often.

Since my screensaver also should keep people from using my machine I think this is quite an important issue, because when I leave my machine unattended people can get full access to my profile.

Jan 27 17:36:20 pc001-ac kernel: [550190.538995] xfwm4[3335]: segfault at 968 ip 00007ff35644cd1c sp 00007fff89a81870 error 4 in libX11.so.6.3.0[7ff356413000+130000]

ProblemType: Crash
DistroRelease: Ubuntu 14.04
Package: xfwm4 4.11.1-2ubuntu2
ProcVersionSignature: Ubuntu 3.13.0-44.73-generic 3.13.11-ckt12
Uname: Linux 3.13.0-44-generic x86_64
NonfreeKernelModules: nvidia
ApportVersion: 2.14.1-0ubuntu3.6
Architecture: amd64
CurrentDesktop: XFCE
Date: Tue Jan 27 17:36:21 2015
ExecutablePath: /usr/bin/xfwm4
ExecutableTimestamp: 1397040366
InstallationDate: Installed on 2014-05-20 (252 days ago)
InstallationMedia: Xubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140416.2)
ProcCmdline: xfwm4 --display :0.0 --sm-client-id 203f5d3fc-d8a1-4fa3-ada7-6a28ce895cb5
ProcCwd: /home/demmer
ProcEnviron:
 LANGUAGE=de_DE:en
 PATH=(custom, no user)
 XDG_RUNTIME_DIR=<set>
 LANG=de_DE.UTF-8
 SHELL=/bin/bash
SegvAnalysis:
 Segfault happened at: 0x7ff35644cd1c <XUnmapWindow+12>: mov 0x968(%rdi),%rax
 PC (0x7ff35644cd1c) ok
 source "0x968(%rdi)" (0x00000968) not located in a known VMA region (needed readable region)!
 destination "%rax" ok
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: xfwm4
StacktraceTop:
 XUnmapWindow () from /usr/lib/x86_64-linux-gnu/libX11.so.6
 ?? ()
 ?? ()
 ?? ()
 ?? () from /usr/lib/x86_64-linux-gnu/libgdk-x11-2.0.so.0
Title: xfwm4 crashed with SIGSEGV in XUnmapWindow()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: Domain Users adm cdrom dip lpadmin plugdev sambashare sudo

[Apport retracing service (apport)]

Thank you for taking the time to report this crash and helping to make this software better. This particular crash has already been reported and is a duplicate of bug #1157311, so is being marked as such. Please look at the other bug report to see if there is any missing information that you can provide, or to see if there is a workaround for the bug. Additionally, any further discussion regarding the bug should occur in the other report. Please continue to report any other bugs you may find.