[Bug 2039172] Autopkgtest regression report (grub2/2.12~rc1-10ubuntu4.1)

[Ubuntu SRU Bot]

All autopkgtests for the newly accepted grub2 (2.12~rc1-10ubuntu4.1) for mantic have finished running.
The following regressions have been reported in tests triggered by the package:

ubiquity/23.10.8 (armhf)


Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/mantic/update_excuses.html#grub2

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

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https://bugs.launchpad.net/bugs/2039172

Title:
  grub 2.12~rc1 fails to load files from large directories on XFS

Status in grub2 package in Ubuntu:
  Fix Released
Status in grub2-unsigned package in Ubuntu:
  Fix Released
Status in ubuntu-release-upgrader package in Ubuntu:
  Fix Released
Status in grub2 source package in Mantic:
  Fix Committed
Status in grub2-unsigned source package in Mantic:
  Fix Committed
Status in ubuntu-release-upgrader source package in Mantic:
  Fix Released
Status in grub2 source package in Noble:
  Fix Released
Status in grub2-unsigned source package in Noble:
  Fix Released
Status in ubuntu-release-upgrader source package in Noble:
  Fix Released
Status in grub2 package in Debian:
  Fix Released

Bug description:
  [Impact]
  Multi-extent directories are not parsed correctly by grub's XFS code in 2.12~rc1, preventing it from loading files from directories with too many entries, such as the grub module directory.

  This should only affect BIOS systems as they need to load the core
  grub modules from the module directory, whereas UEFI systems have them
  embedded in the ESP EFI image.

  [Test plan: ubuntu-release-upgrader]
  On systems BIOS systems with XFS /boot, or XFS / and no separate boot partition, the upgrade should be prevented early on with a message linking to this bug report.

  We should also test upgrades on "normal"/unaffected system to make
  sure it is not unnecessarily prevented.

  [Where problems could occur: ubuntu-release-upgrader]
  The two risks here are (1) missing a case where we should block upgrade, and (2) preventing an upgrade in a case where we should not. The unit tests included in the patch attempt to mitigate this risk.

  Any issues would probably come from logic errors in the code that
  parses /proc/mounts.

  [Test plan: grub2, grub2-unsigned]
  We'll do both grub2 on BIOS and UEFI.

  - Install system with separate /boot on ext4.
  - Upgrade to new grub. Run grub-install to actually apply bios-upgrade
  - Reboot (this ensures ext4 still works)
  - Take a backup of /boot
  - Format /boot as xfs and restore backup
  - Reboot (this ensures xfs works)

  [Where problems could occur: grub2, grub2-unsigned]
  We could be introducing other XFS parsing bugs including security vulnerabilities.

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