[Pkg-utopia-maintainers] Bug#989934: flatpak-portal fd leak when apps run flatpak-spawn --env=...

[Simon McVittie]

Package: flatpak
Version: 1.8.5-1
Severity: important
Tags: upstream fixed-upstream
Control: found -1 1.2.5-0+deb10u2

The flatpak-portal service in flatpak >= 1.8.5-1 leaks a file descriptor
every time a Flatpak app launches a subsandbox (a separate container for
part of itself, perhaps with more restrictions or a different runtime
library stack) using flatpak-spawn --env=... or equivalent D-Bus calls.

Minimal reproducer: in one terminal run

    /usr/libexec/flatpak-portal -vr

and in another, run

    flatpak run --command=bash org.gnome.Weather -euxc \
    'while flatpak-spawn --env=FOO=bar sh -euxc "$1"; do :; done' \
    sh \
    'test "$FOO" = bar'

(org.gnome.Weather is just an example, it can be any app). Terminate
the flatpak run loop with Ctrl+C after a few seconds.

Ignore lines of output that say "F: ioctl(0, TIOCSCTTY, 0) failed:
Operation not permitted"; these are harmless.

Good result: in the flatpak-portal -vr output, you see the same --env-fd=
every time.

Bad result: the number after --env-fd= keeps going up.

The real-world impact is that if Flatpak apps launch enough subsandboxes,
the subsandbox interface will stop working for the rest of the login
session, causing other Flatpak apps to fail to work. Chromium is a notable
example of a Flatpak app that uses subsandboxes.

    smcv