remote x applications crash on xubuntu 16.04 beta

[Kenneth Zadeck]

I have two machines, the one with the console is running xubuntu-14.04 and i am trying to run x applications on my laptop which is running xubuntu-16.04 beta (with all of the latest packages updated as of this morning) they all crash.

i do an ssh -X into the laptop and then run emacs and it crashes with the following stacktrace:
numenor:~(1) emacs
Fatal error 11: Segmentation fault
Backtrace:
emacs[0x503743]
emacs[0x4e9dbe]
emacs[0x5024fe]
emacs[0x502723]
/lib/x86_64-linux-gnu/libpthread.so.0(+0x113d0)[0x7f5f38db43d0]
/lib/x86_64-linux-gnu/libc.so.6(__rawmemchr+0x1f)[0x7f5f38a6fb3f]
/lib/x86_64-linux-gnu/libc.so.6(+0x7cf22)[0x7f5f38a56f22]
/lib/x86_64-linux-gnu/libc.so.6(__isoc99_vsscanf+0x57)[0x7f5f38a45b67]
/lib/x86_64-linux-gnu/libc.so.6(__isoc99_sscanf+0x87)[0x7f5f38a45b07]
/usr/lib/x86_64-linux-gnu/libepoxy.so.0(epoxy_glx_version+0x42)[0x7f5f374cbd22]
/usr/lib/x86_64-linux-gnu/libgdk-3.so.0(+0x5d409)[0x7f5f3da1a409]
/usr/lib/x86_64-linux-gnu/libgdk-3.so.0(+0x5d72a)[0x7f5f3da1a72a]
/usr/lib/x86_64-linux-gnu/libgdk-3.so.0(+0x65e3e)[0x7f5f3da22e3e]
/usr/lib/x86_64-linux-gnu/libgdk-3.so.0(+0x62db6)[0x7f5f3da1fdb6]
/usr/lib/x86_64-linux-gnu/libgdk-3.so.0(+0x55165)[0x7f5f3da12165]
/usr/lib/x86_64-linux-gnu/libgdk-3.so.0(gdk_display_manager_open_display+0xd6)[0x7f5f3d9ec5e6]
/usr/lib/x86_64-linux-gnu/libgtk-3.so.0(gtk_init_check+0x20)[0x7f5f3dea93c0]
/usr/lib/x86_64-linux-gnu/libgtk-3.so.0(gtk_init+0x9)[0x7f5f3dea93f9]
emacs[0x4c81c3]
emacs[0x4ca931]
emacs[0x55d9bd]
emacs[0x593083]
emacs[0x55d44f]
emacs[0x55d7eb]
emacs[0x593083]
emacs[0x55d7eb]
emacs[0x55cefc]
emacs[0x56030e]
emacs[0x59448f]
emacs[0x55d7eb]
emacs[0x593083]
emacs[0x55c798]
emacs[0x55cb41]
emacs[0x560504]
emacs[0x55bc47]
emacs[0x4ea206]
emacs[0x55bb2b]
emacs[0x4ee84f]
emacs[0x4eeba8]
emacs[0x418619]
/lib/x86_64-linux-gnu/libc.so.6(__libc_start_main+0xf0)[0x7f5f389fa830]
...
Segmentation fault (core dumped)

I did install emacs24 debug package, but this appears to be the best that i can get. Maybe that is another bug.

also, if i try to run any remote x application (such as update-manager or synaptic), they also fail. They do bring up the bug report window on the laptop. So i think that this is less of a problem with emacs and more likely a problem with the x libraries on the laptop.

Note that this does not appear to be a security issue where the -X just is not working properly. if i ssh into the laptop without -X it works properly in that it brings up emacs in the terminal window.

I also have no problems at all getting emacs to run remotely for all of my other remote linux machines, so i think that the problem is with the laptop running xubuntu 16.04 beta.

the console machine is
moria:~(1) lsb_release -rd
Description: Ubuntu 14.04.4 LTS
Release: 14.04

and the laptop is
numenor:~(4) lsb_release -rd
Description: Ubuntu 16.04 LTS
Release: 16.04

[Ubuntu Foundations Team Bug Bot (crichton)]

Thank you for taking the time to report this bug and helping to make Ubuntu better. It seems that your bug report is not filed about a specific source package though, rather it is just filed against Ubuntu in general. It is important that bug reports be filed about source packages so that people interested in the package can find the bugs about it. You can find some hints about determining what package your bug might be about at https://wiki.ubuntu.com/Bugs/FindRightPackage. You might also ask for help in the #ubuntu-bugs irc channel on Freenode.

To change the source package that this bug is filed about visit https://bugs.launchpad.net/ubuntu/+bug/1570950/+editstatus and add the package name in the text box next to the word Package.

[This is an automated message. I apologize if it reached you inappropriately; please just reply to this message indicating so.]

[Launchpad Janitor (janitor)]

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

[Kenneth Zadeck (zadeck)]

I should point out that for me, this bug went away as soon as i upgraded to a stable release.

kenny

[Dave (dv1)]

I had this problem on a fresh install of 16.04, displaying back to a 12.04 machine.
I saw the crashes when trying to start either of emacs or synaptic.

An strace of the synaptic run showed it failing to find and load libGLX_indirect.so.0.
apt-file pointed me at this library existing on the system in
/usr/lib/nvidia-361/libGLX_indirect.so.0 (as a symlink to libGLX_nvidia.so.361.42, which definintely does exist.)

So I added /usr/lib/nvidia-361 into the local shell's LD_LIBRARY_PATH and it both emacs and synaptic started working fine.

Moreover, it still worked fine when I unset LD_LIBRARY_PATH. Even after I rebooted. Not sure how it's remembering this. ld.so.cache is still timestamped a few hours before these experiments.

[Martin Daser (m4rt1n-d453r)]

Apparently it's still there on 16.04.1 LTS - I just upgraded from 14.04 LTS.

I'd like to confirm, that Dave's workaround helped me.

Could that be an issue of the dynamic linker settings missing an update during the SW installation?

[Dave (dv1)]

Two additional observations about the workaround I posted in #4:

1) The remote display machine (12.04) I'm using has a bank of monitors configured across three separate X screens. The workaround only works per-screen. I have to export DISPLAY=remote:0.0 then run the workaround script; then export DISPLAY=remote:0.1 and run the workaround again; then export DISPLAY=remote:0.2 ...

2) It doesn't persist across all boots. Since then I've had to do it again occasionally and I now suspect that it's applying certain updates and rebooting that undoes the fix.

[Gianfranco Costamagna (costamagnagianfranco)]

can you please test libepoxy from my ppa?
 https://launchpad.net/~costamagnagianfranco/+archive/ubuntu/locutusofborg-ppa

please report back results on bug: https://bugs.launchpad.net/ubuntu/+source/libepoxy/+bug/1647600

this is a duplicate bug.