Flaky qrexec-agent on vchan error

[iacore]

Qubes OS release

r4.1

Brief summary

Sometimes (regular enough), when starting up system, I cannot open any GUI app.

By connecting to console using display DVM, I found the error

> cat ~/.xsession-errors
....
Not in GuiVM or dom0. Exiting.
qrexec-fork-server[xxx]: qrexec-agent-data.c: vchan connect error
qrexec-fork-server[xxx]: qrexec-agent-data.c: vchan connect error
qrexec-fork-server[xxx]: qrexec-agent-data.c:159:handle_just_exec: executed (nowait): QUBESRPC qubes.StartApp+xfce4-terminal dom0 (pid 1262)

One way to "fix" this is to run systemctl restart qubes-gui-agent, and it works immediately. Even the app previous I want to open (Application Finder in dom0) opens without any request. This only worked sometimes.

I read the logs with sudo journalctl -xeu qubes-gui-agent, but I cannot find any error there.

I suspect this is another race condition, when "qubes-guishould start beforeqrexec-fork-server`, or vice versa.

Steps to reproduce

This is difficult.

1. install this modified branch Fix focus handling (attempt 2) qubes-gui-agent-linux#154.
2. install a new version of "qubes-gui-agent.xxxxx.tar.zst" in arch linux AppVM
3. shutdown 0
4. Start any app using Application Finder from dom0

[iacore]

So, when the AppVM is still starting up, if I try to open an app, something seem to be broken until restart.

One thing I realized is that qrexec-fork-server is not running as user user when this bug happens. It's running as root instead.
This maybe due to some logic like "if qrexec-fork-server is not running, start it", but it was started as wrong user.

Again, checking logs is useless, as it has no useful info.

[github-actions]

This issue is being closed because:

• This issue is believed to affect only Qubes OS 4.1 (and possibly earlier).
• Qubes OS 4.1 has reached end-of-life (EOL).

If anyone believes that this issue should be reopened, please leave a comment saying so.
(For example, if a bug still affects Qubes OS 4.2, then the comment "Affects 4.2" will suffice.)