Workspace switcher about nscde HOT 13 CLOSED

Hi,

Workspace Manager in the middle of Front Panel is FvwmScript application. Maybe the problem is in FvwmScript interpreter. This was the case on FreeBSD when FVWM was compiled with clang, but not with gcc.

Please see ~/.xsession-errors after starting NsCDE and also "dmesg | grep -i segfault" on affected platforms, so we can get closer to the cause of this issue.

from nscde.

The xsession-errors shows on i686 such errors:
ERR: trouble loading pixmap *** stack smashing detected ***: <unknown> terminated xrandr: Failed to get size of gamma for output default xrandr: Failed to get size of gamma for output default Failed to connect to session manager: Failed to connect to the session manager: SESSION_MANAGER environment variable not defined

dmesg shows nothing

from nscde.

Lot of some warnings, but none of this looks like something about wha WSM is not started and swallowed in the Front Panel. Maybe some stack protector (there was such issue on FreeBSD in the past when FVWM was compiled with clang), but we must yet to confirm this.

Can you please edit temporary line 126 of /opt/NsCDE/bin/nscde and replace this:
exec $FVWM_BIN -f ${NSCDE_ROOT}/config/NsCDE-Main.conf $FVWM_OPTS
with
exec $FVWM_BIN -f ${NSCDE_ROOT}/config/NsCDE-Main.conf $FVWM_OPTS >> /tmp/debugfile 2>&1
logout and log in again. Send the contents of the /tmp/debugfile.

Do it please on i686 and armhf. Maybe it is the same cause, maybe not.

from nscde.

Enclosed zipped debug from i686 and armhf machines (doesn't support plain text files).
As addition, the clock couldn't been compiled during installation on armhf.

debug1.zip

from nscde.

Ok, now I'm pretty much sure this is about FvwmScript beeing compiled with -fstack-protector or some variation of this option like
maybe -fstack-protector-all -fstack-protector-strong -fstack-protector-explicit

This: *** stack smashing detected *** happens when WSM needs to be started.

You can try to recompile fvwm without any stack protector options (FvwmScript doesn't do networking anyway!) and if WSM works after that, you can ask on https://github.com/fvwmorg for FVWM authors to see if this is their bug to fix, or too much agressive gcc options for a valid non-networked code. Compile with CFLAGS="-O0 -g" so when this happens you can attache gdb on fvwm and send valuable output to developers of FVWM.

EDIT: if you report bug on fvwmorg, mention that you use NsCDE, and that failure occurs with WSM script, this way it can be reproducible. I'm on vacation currently and not having much time for github or anything on the laptop, but if this isn't solved in the near future, I will take a look at this, but please try this on your own if you have a time ...

from nscde.

Will try to recompile fvwm.
Thanks for your help.

from nscde.

Hi, do you have some findings about compiler flags impact on FVWM? This may be interesting since this was not the first time WSM FvwmScript failed to work with it's engine under such strict stack hardening. This is also interesting to report to my "upstream" that is, FVWM.

from nscde.

Sorry, no time to compile fvwm.

from nscde.

Closing this for now.

from nscde.

Just hit this on Fedora 33 on aarch64 (64-bit ARM), with rev 8127348.

Built and installed fine, center spot of the panel (where we expect the "One", "Two", "Three", and "Four" buttons) is blank.

.xsession-errors is blank.

from nscde.

Hi,

1. I have heard of this missing workspace manager in the Front Panel problem here and there some time ago. It was never clear and never traced to the problem origin. I didn't tested it yet on F33. Please see what exact version of the fvwm you are using and if there are some core dumps (ulimit -c 0) from FvwmScript in which WSM is written (journalctl probably).

2. If .xsession-errors is blank, you will probably find display manager logs in journald log. See yournalctl -f. For "Watch Errors" to work with journalctl, see "InfoStoreAdd xlogcmd "journalctl -u gdm -n 300 -f"" example in the $NDCDE_ROOT/config/NsCDE.conf.

from nscde.

FYI, you probably noticed it sometimes appears, sometimes not when you restart FVWM or Front Panel.

FvwmScript is core dumping when swallowed by FvwmButtons on Fedora 33 and possibly some other systems.

As a workaround, you can change "ModuleSynchronous" to "Module" in /opt/NsCDE/config/NsCDE-FrontPanel.conf at line ~317. It will segfault and blink a few times and eventually stay in the Front Panel. I will see with upstream what to do here.

from nscde.

Closed by using "While" instead of "For" in Workspace Manager button pressed state changing routine. Original bug belongs to FvwmScript and has been introduced to FVWM upstream.

from nscde.