Removing disposable throws UUID KeyError on domain-shutdown event on qubesusbproxy/core3ext.py

[ben-grande]

Qubes OS release

Qubes OS 4.3

Brief summary

Introduced in QubesOS/qubes-app-linux-usb-proxy#51, @RealityAnomaly please take a look.

On domain-shutdown, there is del self.autoattach_locks[vm.uuid]. It throws KeyError: UUID('THE UUID'). It doesn't deal with the UUID not being the the lock collection anymore.

See real time 2026-02-17T05:48:09.322, or video time 0:25.

https://openqa.qubes-os.org/tests/167407/video?filename=video.webm

Or find it here: https://openqa.qubes-os.org/tests/167407/file/system_tests-tests.log

INFO:vm.disp3369:Removing volume root: qubes_dom0/vm-disp3369-root
INFO:vm.disp3369:Removing volume private: qubes_dom0/vm-disp3369-private
INFO:vm.disp3369:Removing volume volatile: qubes_dom0/vm-disp3369-volatile
INFO:vm.disp3369:Removing volume kernel: 6.18.4-1.4.fc41
ERROR:asyncio:Task exception was never retrieved
future: <Task finished name='Task-27' coro=<DispVM.cleanup() done, defined at /usr/lib/python3.13/site-packages/qubes/vm/dispvm.py:946> exception=KeyError(UUID('2ea9c1f8-511f-4d54-83dc-ead4b1fcbef2'))>
Traceback (most recent call last):
  File "/usr/lib/python3.13/site-packages/qubes/vm/dispvm.py", line 962, in cleanup
    await self.kill()
  File "/usr/lib/python3.13/site-packages/qubes/vm/qubesvm.py", line 1702, in kill
    await waiter
  File "/usr/lib/python3.13/site-packages/qubes/vm/qubesvm.py", line 1612, in _domain_stopped_coro
    await self.fire_event_async("domain-shutdown")
  File "/usr/lib/python3.13/site-packages/qubes/events.py", line 243, in fire_event_async
    effect = task.result()
  File "/usr/lib/python3.13/site-packages/qubesusbproxy/core3ext.py", line 785, in on_domain_shutdown
    del self.autoattach_locks[vm.uuid]
        ~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^
KeyError: UUID('2ea9c1f8-511f-4d54-83dc-ead4b1fcbef2')

Steps to reproduce

1. Not always reproducible, openqa throwed this exception twice, although many disposables were deleted
2. Shutdown a delete a qube (shutdown a disposable) several times until it triggers

Expected behavior

No unhandled exception.

Actual behavior

Unhandled KeyError for qube UUID that is not in the list.

Additional information

No response

[RealityAnomaly]

Apologies for this oversight. PR: QubesOS/qubes-app-linux-usb-proxy#53