[Bug 1795764] Re: systemd: core: Fix edge case when processing /proc/self/mountinfo

[Łukasz Zemczak]

Hello Joshua, or anyone else affected,

Accepted systemd into xenial-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/systemd/229-4ubuntu21.11 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.

** Changed in: systemd (Ubuntu Xenial)
       Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-xenial

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https://bugs.launchpad.net/bugs/1795764

Title:
  systemd: core: Fix edge case when processing /proc/self/mountinfo

Status in systemd package in Ubuntu:
  Fix Released
Status in systemd source package in Xenial:
  Fix Committed

Bug description:
  [Impact]

  kubernetes loaded inactive dead transient mount points grows
  https://github.com/kubernetes/kubernetes/issues/57345

  [Test Case]

  # cd /tmp
  # mkdir -p bind-test/abc
  # mount --bind bind-test bind-test
  # mount -t tmpfs tmpfs bind-test/abc
  # umount bind-test/abc
  # systemctl list-units --all | grep bind-test
  tmp-bind\x2dtest-abc.mount loaded inactive dead /tmp/bind-test/abc
  tmp-bind\x2dtest.mount loaded active mounted /tmp/bind-test

  Expected outcome (w/ the fix) :

  # cd /tmp
  # mkdir -p bind-test/abc
  # mount --bind bind-test bind-test
  # mount -t tmpfs tmpfs bind-test/abc
  # umount bind-test/abc
  # systemctl list-units --all | grep bind-test
  tmp-bind\x2dtest.mount loaded active mounted /tmp/bind-test

  [Regression Potential]

  This is a adapted version of 2 upstream fixes as the original upstream
  commit has been made on top on 2 functions mount_setup_new_unit() &
  mount_setup_existing_unit() that not yet exist systemd 229. It is
  easily adaptable because the current function mount_setup_unit() is
  dealing with both of at the moment instead of being individually
  separate in two distinct function.

  It is an adaptation of commits :
  [65d36b495] core: Fix edge case when processing /proc/self/mountinfo
  [03b8cfede] core: make sure to init mount params before calling mount_is_extrinsic()

  This patch changes mount_setup_unit() to prevent the just_mounted
  mount setup flag from being overwritten if it is set to true. This
  will allow all mount units created from /proc/self/mountinfo entries
  to be initialised properly.

  Additionally, the patch got the blessing of 'xnox' who looked at it
  and mention it looks fine to him.

  [Other Info]

  One line fix in https://github.com/systemd/systemd/pull/7811/files

  Referenced issue: https://github.com/systemd/systemd/issues/7798

  Related kubernetes issue:
  https://github.com/kubernetes/kubernetes/issues/57345

  systemd v237 has this fix, but we'd like to have it fixed in 16.04.

  It only affect systemd for Xenial, later release already has the fix:

  $ git describe --contains 65d36b495
  v237~140

  ==>  systemd | 229-4ubuntu21.4  | xenial-updates
       systemd | 237-3ubuntu10.3  | bionic-updates
       systemd | 239-7ubuntu9     | cosmic

  [Original Description]

  From the PR:
  Currently, if there are two /proc/self/mountinfo entries with the same
  mount point path, the mount setup flags computed for the second of
  these two entries will overwrite the mount setup flags computed for
  the first of these two entries. This is the root cause of issue #7798.
  This patch changes mount_setup_existing_unit to prevent the
  just_mounted mount setup flag from being overwritten if it is set to
  true. This will allow all mount units created from /proc/self/mountinfo
  entries to be initialized properly.

  One line fix in https://github.com/systemd/systemd/pull/7811/files

  Referenced issue: https://github.com/systemd/systemd/issues/7798

  Related kubernetes issue:
  https://github.com/kubernetes/kubernetes/issues/57345

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