RecursionError error in call_adjusted()

[errors.ubuntu.com bug bridge]

[Impact]

 * Unattended-upgrades may crash and stop installing security updates on users' system due to entering infinite loop.
 * The fix ensures terminating the recursive calls.

[Test Case]

 * TODO / observe the crash not being reported for fixed releases on errors.ubuntu.com.

[Regression Potential]

 * Unattended-upgrades now adjusts package candidates only to lower versions than the one originally offered by apt's resolver. This is a change in behavior which aligns well with the default configuration, i.e. installing packages from -security but not from -updates, since -updates almost always have higher version numbers. This change may cause using different upgrade paths when PPAs are involved and all packages can't be upgraded to the highest versions found in allowed origins, because of Conflicts: for example.
 * Unexpected regressions can cause candidate adjustments not taking place, but please note that autopkgtest now includes applying all outstanding security updates for the release thus the new code is covered, too.

[Original Bug report]

The Ubuntu Error Tracker has been receiving reports about a problem regarding unattended-upgrades. This problem was most recently seen with package version 1.1ubuntu1.18.04.5, the problem page at https://errors.ubuntu.com/problem/fa706afe2f0e04b661fe54da0a59b9fc3da50734 contains more details, including versions of packages affected, stacktrace or traceback, and individual crash reports.
If you do not have access to the Ubuntu Error Tracker and are a software developer, you can request it at http://forms.canonical.com/reports/.

Traceback (most recent call last):
  File "/usr/bin/unattended-upgrade", line 1991, in <module>
    sys.exit(main(options))
  File "/usr/bin/unattended-upgrade", line 1647, in main
    cache, options, allowed_origins, blacklisted_pkgs, whitelisted_pkgs)
  File "/usr/bin/unattended-upgrade", line 1349, in calculate_upgradable_pkgs
    whitelisted_pkgs)
  File "/usr/bin/unattended-upgrade", line 1288, in try_to_upgrade
    cache.mark_upgrade_adjusted(pkg, from_user=not pkg.is_auto_installed)
  File "/usr/bin/unattended-upgrade", line 212, in mark_upgrade_adjusted
    self.call_adjusted(apt.package.Package.mark_upgrade, pkg, **kwargs)
  File "/usr/bin/unattended-upgrade", line 206, in call_adjusted
    self.call_adjusted(function, pkg, **kwargs)
  File "/usr/bin/unattended-upgrade", line 206, in call_adjusted

[Launchpad Janitor (janitor)]

This bug was fixed in the package unattended-upgrades - 1.5ubuntu2

---------------
unattended-upgrades (1.5ubuntu2) cosmic; urgency=medium

  * Reopen Cache after commit() even when frontend locking is supported.
    This fixes build and operation with latest python-apt.

 -- Balint Reczey <email address hidden> Tue, 28 Aug 2018 15:46:25 +0200

[Brian Murray (brian-murray)]

The bucket_id for this crash is ridiculously long and ends causing the Errors site to throw a 414 error. I was able to manually query the database using the bucket_id and discovered the following.

In [10]: cassandra.get_versions_for_bucket(urllib.unquote(bucket2))
Out[10]: OrderedDict([(('Ubuntu 18.04', '1.1ubuntu1.18.04.5'), 16)])

So with that information we should be able to verify that the SRU'ed version of the package is not affected.

[Brian Murray (brian-murray)]

Hello errors.ubuntu.com, or anyone else affected,

Accepted unattended-upgrades into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unattended-upgrades/1.1ubuntu1.18.04.6 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-bionic to verification-done-bionic. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-bionic. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Balint Reczey (rbalint)]

@brian-murray: I'm not observing the crash with 1.1ubuntu1.18.04.6, but if you could check the database manually that would be a better verification, I think.
https://errors.ubuntu.com/?package=unattended-upgrades&period=year&version=1.1ubuntu1.18.04.6

[Brian Murray (brian-murray)]

I've gone ahead and ran the same query as before and we only see 1.1.ubuntu1.18.04.5 in the bucket.

In [6]: cassandra.get_versions_for_bucket(urllib.unquote(bucket2))
Out[6]: OrderedDict([(('Ubuntu 18.04', '1.1ubuntu1.18.04.5'), 41)])

[Balint Reczey (rbalint)]

Marking as verification done based on the crash not appearing with the fixed release.

[Łukasz Zemczak (sil2100)]

The verification of the Stable Release Update for unattended-upgrades has completed successfully and the package has now been released to -updates. Subsequently, the Ubuntu Stable Release Updates Team is being unsubscribed and will not receive messages about this bug report. In the event that you encounter a regression using the package from -updates please report a new bug using ubuntu-bug and tag the bug report regression-update so we can easily find any regressions.

[Launchpad Janitor (janitor)]

This bug was fixed in the package unattended-upgrades - 1.1ubuntu1.18.04.6

---------------
unattended-upgrades (1.1ubuntu1.18.04.6) bionic; urgency=medium

  * Unlock for dpkg operations with apt_pkg.pkgsystem_unlock_inner() when it is
    available. Also stop running when reacquiring the lock fails.
    Thanks to Julian Andres Klode for original partial patch (LP: #1789637)
  * Skip rebuilding python-apt in upgrade autopkgtests.
    Python-apt has a new build dependency making the rebuilding as is failing
    and the reference handling issue is worked around in unattended-upgrades
    already. (LP: #1781586)
  * Stop trying when no adjustment could be made and adjust package candidates
    only to lower versions (LP: #1785093)
  * Skip already adjusted packages from being checked for readjusting.
    This makes it clearer that the recursion ends and can also be a bit quicker.
    (LP: #1785093)

 -- Balint Reczey <email address hidden> Tue, 02 Oct 2018 19:18:02 +0200

[Brian Murray (brian-murray)]

Hello errors.ubuntu.com, or anyone else affected,

Accepted unattended-upgrades into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unattended-upgrades/1.1ubuntu1.18.04.7~16.04.0 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Łukasz Zemczak (sil2100)]

Hello errors.ubuntu.com, or anyone else affected,

Accepted unattended-upgrades into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unattended-upgrades/1.1ubuntu1.18.04.7~16.04.1 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Balint Reczey (rbalint)]

The error is still not appearing on 16.04:

https://errors.ubuntu.com/?release=Ubuntu%2016.04&package=unattended-upgrades&period=year&version=1.1ubuntu1.18.04.7~16.04.1

It is not surprising since the regression was not present in 16.04 without the fix.

[Łukasz Zemczak (sil2100)]

Hello errors.ubuntu.com, or anyone else affected,

Accepted unattended-upgrades into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/unattended-upgrades/1.1ubuntu1.18.04.7~16.04.2 in a few hours, and then in the -proposed repository.

Please help us by testing this new package. See https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how to enable and use -proposed. Your feedback will aid us getting this update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug, mentioning the version of the package you tested and change the tag from verification-needed-xenial to verification-done-xenial. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-xenial. In either case, without details of your testing we will not be able to proceed.

Further information regarding the verification process can be found at https://wiki.ubuntu.com/QATeam/PerformingSRUVerification . Thank you in advance for helping!

N.B. The updated package will be released to -updates after the bug(s) fixed by this package have been verified and the package has been in -proposed for a minimum of 7 days.

[Balint Reczey (rbalint)]

The error is still not appearing on 16.04:

https://errors.ubuntu.com/?release=Ubuntu%2016.04&package=unattended-upgrades&period=year&version=1.1ubuntu1.18.04.7~16.04.2

[Launchpad Janitor (janitor)]

This bug was fixed in the package unattended-upgrades - 1.1ubuntu1.18.04.7~16.04.2

---------------
unattended-upgrades (1.1ubuntu1.18.04.7~16.04.2) xenial; urgency=medium

  * Don't check blacklist too early and report updates from not allowed origins
    as kept back. (LP: #1781176)
  * test/test_blacklisted_wrong_origin.py: Fix and enable test
  * Filter out progress indicator from dpkg log (LP: #1599646)
  * Clear cache when autoremoval fails (LP: #1779157)
  * Find autoremovable kernel packages using the patterns in APT's way
    (LP: #1815494)

unattended-upgrades (1.1ubuntu1.18.04.7~16.04.1) xenial; urgency=medium

  * Start service after systemd-logind.service to be able to take inhibition
    lock (LP: #1806487)
  * Handle gracefully when logind is down (LP: #1806487)

unattended-upgrades (1.1ubuntu1.18.04.7~16.04.0) xenial; urgency=medium

  * Backport to Xenial (LP: #1702793)
  * Revert to build-depending on debhelper (>= 9~) and dh-systemd
  * Revert configuration example changes to avoid triggering a debconf question
  * debian/postinst: Update recovery to be triggered on Xenial's package versions

unattended-upgrades (1.1ubuntu1.18.04.7) bionic; urgency=medium

  * Trigger unattended-upgrade-shutdown actions with PrepareForShutdown()
    Performing upgrades in service's ExecStop did not work when the upgrades
    involved restarting services because systemd blocked other stop/start
    actions making maintainer scripts time out and be killed leaving a broken
    system behind.
    Running unattended-upgrades.service before shutdown.target as a oneshot
    service made it run after unmounting filesystems and scheduling services
    properly on shutdown is a complex problem and adding more services to the
    mix make it even more fragile.
    The solution of monitoring PrepareForShutdown() signal from DBus
    allows Unattended Upgrade to run _before_ the jobs related to shutdown are
    queued thus package upgrades can safely restart services without
    risking causing deadlocks or breaking part of the shutdown actions.
    Also ask running unattended-upgrades to stop when shutdown starts even in
    InstallOnShutdown mode and refactor most of unattended-upgrade-shutdown to
    UnattendedUpgradesShutdown class. (LP: #1778219)
  * Increase logind's InhibitDelayMaxSec to 30s. (LP: #1778219)
    This allows more time for unattended-upgrades to shut down gracefully
    or even install a few packages in InstallOnShutdown mode, but is still a
    big step back from the 30 minutes allowed for InstallOnShutdown previously.
    Users enabling InstallOnShutdown node are advised to increase
    InhibitDelayMaxSec even further possibly to 30 minutes.
    - Add NEWS entry about increasing InhibitDelayMaxSec and InstallOnShutdown
      changes
  * Ignore "W503 line break before binary operator"
    because it will become the best practice and breaks the build
  * Stop using ActionGroups, they interfere with apt.Cache.clear()
    causing all autoremovable packages to be handled as newly autoremovable
    ones and be removed by default. Dropping ActionGroup usage does not slow
    down the most frequent case of not having anything to upgrade a...