xwayland doesn't let root access the display, even via sudo or pkexec

[Paul]

When running a GUI application as root (apport-bug, gparted, etc.), the command invariably fails, no matter how it's run:

$ sudo xclock
No protocol specified
Error: Can't open display: :0
$ pkexec xclock
Error: Can't open display:

Workaround: root can be granted access via xhost as follows, but this is insecure on multi-user systems.

$ xhost +si:localuser:root
localuser:root being added to access control list

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: xwayland 2:1.19.4-1ubuntu2
ProcVersionSignature: Ubuntu 4.13.0-15.16-generic 4.13.4
Uname: Linux 4.13.0-15-generic x86_64
ApportVersion: 2.20.7-0ubuntu3
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,gnomecompat,grid,imgpng,mousepoll,move,place,regex,resize,session,snap,vpswitch,wall,unitymtgrabhandles,animation,expo,ezoom,staticswitcher,workarounds,fade,scale,unityshell]
CompositorRunning: None
CurrentDesktop: GNOME
Date: Fri Oct 13 10:14:47 2017
DistUpgraded: 2017-10-13 08:53:41,683 DEBUG Running PostInstallScript: './xorg_fix_proprietary.py'
DistroCodename: artful
DistroVariant: ubuntu
ExtraDebuggingInterest: Yes
GraphicsCard:
 Intel Corporation HD Graphics 5500 [8086:1616] (rev 09) (prog-if 00 [VGA controller])
   Subsystem: ASUSTeK Computer Inc. HD Graphics 5500 [1043:183d]
InstallationDate: Installed on 2016-12-02 (313 days ago)
InstallationMedia: Ubuntu-GNOME 16.10 "Yakkety Yak" - Release amd64 (20161012.1)
MachineType: ASUSTeK COMPUTER INC. UX303LAB
ProcKernelCmdLine: BOOT_IMAGE=/@/boot/vmlinuz-4.13.0-15-generic root=UUID=795346fb-c6f2-478b-88c6-363f7317e849 ro rootflags=subvol=@ quiet splash acpi_osi= vt.handoff=7
SourcePackage: xorg-server
UpgradeStatus: Upgraded to artful on 2017-10-12 (0 days ago)
dmi.bios.date: 08/25/2015
dmi.bios.vendor: American Megatrends Inc.
dmi.bios.version: UX303LAB.210
dmi.board.asset.tag: ATN12345678901234567
dmi.board.name: UX303LAB
dmi.board.vendor: ASUSTeK COMPUTER INC.
dmi.board.version: 1.0
dmi.chassis.asset.tag: No Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: ASUSTeK COMPUTER INC.
dmi.chassis.version: 1.0
dmi.modalias: dmi:bvnAmericanMegatrendsInc.:bvrUX303LAB.210:bd08/25/2015:svnASUSTeKCOMPUTERINC.:pnUX303LAB:pvr1.0:rvnASUSTeKCOMPUTERINC.:rnUX303LAB:rvr1.0:cvnASUSTeKCOMPUTERINC.:ct10:cvr1.0:
dmi.product.family: UX
dmi.product.name: UX303LAB
dmi.product.version: 1.0
dmi.sys.vendor: ASUSTeK COMPUTER INC.
version.compiz: compiz N/A
version.libdrm2: libdrm2 2.4.83-1
version.libgl1-mesa-dri: libgl1-mesa-dri 17.2.2-0ubuntu1
version.libgl1-mesa-glx: libgl1-mesa-glx 17.2.2-0ubuntu1
version.xserver-xorg-core: xserver-xorg-core 2:1.19.4-1ubuntu2
version.xserver-xorg-input-evdev: xserver-xorg-input-evdev N/A
version.xserver-xorg-video-ati: xserver-xorg-video-ati 1:7.10.0-1
version.xserver-xorg-video-intel: xserver-xorg-video-intel 2:2.99.917+git20170309-0ubuntu1
version.xserver-xorg-video-nouveau: xserver-xorg-video-nouveau 1:1.0.15-2

[Paul (i41bktob-launchpad-net)]

Marking as duplicate (thanks to @brian-murray for identifying the original).

[Norbert (nrbrtx)]

Thanks for reporting. It's already known - see bug 1713313 and bug 1713311.
Please mark as duplicate (I got timeout issue).

[Paul (i41bktob-launchpad-net)]

I have been trying to mark it as a duplicate of 1713313 since 2017-10-13 ...

Has anyone filed a bug against Launchpad?