Compiz crashes instantly if configured for autologin and there is a C920 webcam and a pending crash report in /var/crash

[Alistair Buxton]

Steps to reproduce:

1. Have 14.04 and unity/compiz installed.
2. Configure the system to log in automatically.
3. Plug in a Logitech C920 webcam.
4. Cause some program to generate a crash dump with "kill -11"
5. Restart the computer.

Result: Upon booting, the system automatically logs in and then crashes within 1 second. It happens so fast that it's difficult to tell what happens, and you get dumped back at the login screen.

Deleting the pending crash report from /var/crash causes everything to work again, until some other program crashes.

Removing the webcam from the system or replacing it with a different webcam prevents the crash. Logging in manually prevents the crash too.

A retraced crash file with backtrace is attached.

ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: compiz 1:0.9.11.3+14.04.20150313-0ubuntu1
ProcVersionSignature: Ubuntu 3.13.0-74.118-generic 3.13.11-ckt30
Uname: Linux 3.13.0-74-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.19
Architecture: amd64
CompizPlugins: No value set for `/apps/compiz-1/general/screen0/options/active_plugins'
Date: Mon Dec 28 11:50:12 2015
DistUpgraded: 2014-06-20 17:10:19,429 DEBUG enabling apt cron job
DistroCodename: trusty
DistroVariant: ubuntu
GraphicsCard:
 Intel Corporation Xeon E3-1200 v3/4th Gen Core Processor Integrated Graphics Controller [8086:0412] (rev 06) (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. Device [1043:8534]
InstallationDate: Installed on 2013-12-22 (735 days ago)
InstallationMedia: Ubuntu 13.10 "Saucy Salamander" - Release amd64 (20131016.1)
MachineType: ASUS All Series
PackageArchitecture: all
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-3.13.0-74-generic.efi.signed root=UUID=e1e7d1a7-19e8-4203-ad6a-86a144db61bc ro quiet splash vt.handoff=7
SourcePackage: compiz
UpgradeStatus: Upgraded to trusty on 2014-06-20 (555 days ago)
dmi.bios.date: 04/10/2013
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: 0401
dmi.board.asset.tag: To be filled by O.E.M.
dmi.board.name: H87M-E
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: Rev X.0x
dmi.chassis.asset.tag: Asset-1234567890
dmi.chassis.type: 3
dmi.chassis.vendor: Chassis Manufacture
dmi.chassis.version: Chassis Version
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvr0401:bd04/10/2013:svnASUS:pnAllSeries:pvrSystemVersion:rvnASUSTeKCOMPUTERINC.:rnH87M-E:rvrRevX.0x:cvnChassisManufacture:ct3:cvrChassisVersion:
dmi.product.name: All Series
dmi.product.version: System Version
dmi.sys.vendor: ASUS
version.compiz: compiz 1:0.9.11.3+14.04.20150313-0ubuntu1
version.ia32-libs: ia32-libs N/A
version.libdrm2: libdrm2 2.4.60-2~ubuntu14.04.1
version.libgl1-mesa-dri: libgl1-mesa-dri 10.1.3-0ubuntu0.5
version.libgl1-mesa-dri-experimental: libgl1-mesa-dri-experimental N/A
version.libgl1-mesa-glx: libgl1-mesa-glx 10.1.3-0ubuntu0.5
version.xserver-xorg-core: xserver-xorg-core 2:1.15.1-0ubuntu2.7
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev 1:2.8.2-1ubuntu2
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.3.0-1ubuntu3.1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.910-0ubuntu1.6
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.10-1ubuntu2
xserver.bootTime: Mon Dec 28 11:39:41 2015
xserver.configfile: default
xserver.errors:

xserver.logfile: /var/log/Xorg.0.log
xserver.outputs:
 product id 822
 vendor ACR
xserver.version: 2:1.15.1-0ubuntu2.7