compiz crashed with SIGSEGV in unity::switcher::Controller::Impl::GetCurrentSelection()

[Barry Warsaw]

The switcher hung and then this crash occurred.

ProblemType: Crash
DistroRelease: Ubuntu 14.04
Package: unity 7.1.2+14.04.20131106.1-0ubuntu2
ProcVersionSignature: Ubuntu 3.13.0-5.20-generic 3.13.0
Uname: Linux 3.13.0-5-generic x86_64
ApportVersion: 2.13.2-0ubuntu2
Architecture: amd64
CurrentDesktop: Unity
Date: Thu Jan 30 09:30:55 2014
EcryptfsInUse: Yes
ExecutablePath: /usr/bin/compiz
InstallationDate: Installed on 2013-12-06 (54 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
ProcCmdline: compiz
SegvAnalysis:
 Segfault happened at: 0x7f07f56b85f3 <_ZNK5unity8switcher10Controller4Impl19GetCurrentSelectionEv+323>: mov (%rdi),%rbp
 PC (0x7f07f56b85f3) ok
 source "(%rdi)" (0x00000000) not located in a known VMA region (needed readable region)!
 destination "%rbp" ok
SegvReason: reading NULL VMA
Signal: 11
SourcePackage: unity
StacktraceTop:
 unity::switcher::Controller::Impl::GetCurrentSelection() const () from /usr/lib/compiz/libunityshell.so
 unity::switcher::Controller::Impl::Hide(bool) () from /usr/lib/compiz/libunityshell.so
 unity::UnityScreen::altTabTerminateCommon(CompAction*, unsigned int, std::vector<CompOption, std::allocator<CompOption> >&) () from /usr/lib/compiz/libunityshell.so
 compiz::private_screen::EventManager::triggerRelease(CompAction*, unsigned int, std::vector<CompOption, std::allocator<CompOption> >&) () from /usr/lib/libcompiz_core.so.ABI-20130415
 PrivateScreen::triggerStateNotifyBindings(std::vector<CompOption, std::allocator<CompOption> >&, _XkbStateNotifyEvent*, std::vector<CompOption, std::allocator<CompOption> >&) () from /usr/lib/libcompiz_core.so.ABI-20130415
Title: compiz crashed with SIGSEGV in unity::switcher::Controller::Impl::GetCurrentSelection()
UpgradeStatus: No upgrade log present (probably fresh install)
UserGroups: adm autopilot cdrom dip fuse lpadmin plugdev sambashare sbuild sudo

[Apport retracing service (apport)]

StacktraceTop:
 unity::switcher::Controller::Impl::GetCurrentSelection() const () from /tmp/apport_sandbox_HMeUMY/usr/lib/compiz/libunityshell.so
 unity::switcher::Controller::Impl::Hide(bool) () from /tmp/apport_sandbox_HMeUMY/usr/lib/compiz/libunityshell.so
 unity::UnityScreen::altTabTerminateCommon(CompAction*, unsigned int, std::vector<CompOption, std::allocator<CompOption> >&) () from /tmp/apport_sandbox_HMeUMY/usr/lib/compiz/libunityshell.so
 operator() (a2=..., a1=2, a0=0x25cd760, this=0x7fff789847b0) at /usr/include/boost/function/function_template.hpp:767
 compiz::private_screen::EventManager::triggerRelease (this=this@entry=0x2111ef8, action=0x25cd760, state=state@entry=2, arguments=...) at /build/buildd/compiz-0.9.10+13.10.20131011/src/event.cpp:191

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.

[Margarita Manterola (marga-9)]

Still seeing this error on current Trusty, unity version 7.2.2+14.04.20140714-0ubuntu1.1

#0 unity::switcher::Controller::Impl::GetCurrentSelection (this=this@entry=0x1ccc970)
    at /build/buildd/unity-7.2.2+14.04.20140714/launcher/SwitcherController.cpp:691
#1 0x00007f781110e7fa in unity::switcher::Controller::Impl::Hide (this=0x1ccc970,
    accept_state=<optimized out>)
    at /build/buildd/unity-7.2.2+14.04.20140714/launcher/SwitcherController.cpp:477
#2 0x00007f781110eab6 in unity::switcher::Controller::Hide (this=<optimized out>,
    accept_state=accept_state@entry=true)
    at /build/buildd/unity-7.2.2+14.04.20140714/launcher/SwitcherController.cpp:118
#3 0x00007f7810f6f30f in unity::UnityScreen::altTabTerminateCommon (this=0x1707200, action=0x1690340,
    state=8194, options=...)

This is the function that is affected:

Selection Controller::Impl::GetCurrentSelection() const
{
  AbstractLauncherIcon::Ptr application;
  Window window = 0;
  if (model_)
  {
    application = model_->Selection();

    if (application)
    {
      if (model_->detail_selection)
      {
        window = model_->DetailSelectionWindow();
      }
      else if (model_->SelectionIsActive())
      {
        window = model_->DetailXids().front(); // This is line 691
      }
    }
  }
  return {application, window};
}

[Margarita Manterola (marga-9)]

Hi,

I'm able to reproduce this crash by using "Shaded windows" (that don't work properly on Trusty anyway. See: https://bugs.launchpad.net/ubuntu/+source/unity/+bug/1322808), with the following instructions:

1. Log into a fresh new user, running Unity
2. Press Windows key, start unity-tweak-tool
3. Select Window Manager/Additional settings
4. Set Title Bar Actions/Double Click to "Toggle Shade"
5. Start a terminal
6. In the terminal, 'pgrep compiz' to get the current PID
7. Double click on titlebar to shade it; window will become "ghosted"
8. Press Alt-Tab to switch windows; keep holding down Alt and press Tab until the terminal window is selected
9. Release Alt.
10. Compiz crashes and takes a while to restart. Repeat 'pgrep compiz' to see new PID for compiz

[Will Cooke (willcooke)]

As part of the big bug clear up for 16.04 LTS I am marking this bug as Wont Fix. These types of crasher are better handled by errors.ubutnu.com which can collate similar crash reports to help us identify persitent bugs rather than one-off crashes. Sorry we are not able to help with this specific issue. If you are still experiencing this crash, please re-open the bug and add the tag “desktop-bugscrub-reopen”. See https://wiki.ubuntu.com/BigDesktopBugScrub for more information.

Unity Tweak Tool is unsupported.