[Bug 1894329] Re: ZFS revert from grub menu not working.

[Launchpad Bug Tracker]

This bug was fixed in the package zfs-linux - 0.8.4-1ubuntu11.1

---------------
zfs-linux (0.8.4-1ubuntu11.1) groovy; urgency=medium

  [ Didier Roche ]
  [ Jean-Baptiste Lallement ]
  * Generate clone uuid without dd which is flagged as having an executable
    stack. Thanks Usarin Heininga for the patch (LP: #1894329)

  [ Andrea Righi ]
  * fix potential user-space double free when running "zfs mount -a"
    (LP: #1902588)
    - 4702-Revert-Let-zfs-mount-all-tolerate-in-progress-mounts.patch

 -- Colin Ian King <colin.king at canonical.com>  Mon, 30 Nov 2020 19:00:00
+0000

** Changed in: zfs-linux (Ubuntu Groovy)
       Status: Fix Committed => Fix Released

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https://bugs.launchpad.net/bugs/1894329

Title:
  ZFS revert from grub menu not working.

Status in coreutils package in Ubuntu:
  Incomplete
Status in zfs-linux package in Ubuntu:
  Fix Released
Status in coreutils source package in Focal:
  Incomplete
Status in zfs-linux source package in Focal:
  Fix Committed
Status in coreutils source package in Groovy:
  Incomplete
Status in zfs-linux source package in Groovy:
  Fix Released

Bug description:
  [Impact]

   * Users can’t revert to previous snapshots when enabling the hw enablement stack kernel on focal or using any more recent version.
   * The option is available on grub and will let you with a broken system, partially cloned.

  [Test Case]

   * Boot on a system, using ZFS and ZSys.
   * In grub, select "History" entry
   * Select one of the "Revert" option: the system should boot after being reverted with an older version.

  
  [Where problems could occur]
   * The code is in the initramfs, where the generated id suffix for all our ZFS datasets was empty due to new coreutils/kernels.
   * We replace dd with another way (more robust and simple) for generating this ID.

  
  ---------------------

  @coreutils maintainers, any idea why dd is being flagged as having an
  executable stack?

  --------------------

  When I try to revert to a previous state from the grub menu, the boot
  fails. The system drops me to a repair modus.

  zfs-mount-generator fails with the message:
  couldn't ensure boot: Mounted clone bootFS dataset created by initramfs doesn't have a valid _suffix (at least .*_<onechar>): \"rpool/ROOT/ubuntu_\"".

  After a reboot I have an extra clone called "rpool/ROOT/ubuntu_", indeed without a suffix.
  After a little investigation I found the problem in /usr/share/initramfs-tools/scripts/zfs at the end in function
  uid()
  {
     dd if=/dev/urandom of=/dev/stdout bs=1 count=100 2>/dev/null | tr -dc 'a-z0-9' | cut -c-6
  }, the dd command fails during boot with the message "process 'dd' started with executable stack.
  After this an empty uid is returned which explains the dataset without a proper suffix.
  Replacing the function  with:
  uid()
  {
     grep -a -m10 -E "\*" /dev/urandom 2>/dev/null | tr -dc 'a-z0-9' | cut -c-6
  }

  fixes the problem.

  Ubuntu version is:
  Description:    Ubuntu Groovy Gorilla (development branch)
  Release:        20.10

  zfs-initramfs version is:
  0.8.4-1ubuntu11

  With regards,

  Usarin Heininga

  ProblemType: Bug
  DistroRelease: Ubuntu 20.10
  Package: zfs-initramfs 0.8.4-1ubuntu11
  ProcVersionSignature: Ubuntu 5.8.0-18.19-generic 5.8.4
  Uname: Linux 5.8.0-18-generic x86_64
  NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
  ApportVersion: 2.20.11-0ubuntu45
  Architecture: amd64
  CasperMD5CheckResult: skip
  CurrentDesktop: KDE
  Date: Fri Sep  4 20:23:44 2020
  InstallationDate: Installed on 2020-09-02 (2 days ago)
  InstallationMedia: Ubuntu 20.10 "Groovy Gorilla" - Alpha amd64 (20200831)
  ProcEnviron:
   LANGUAGE=
   PATH=(custom, no user)
   XDG_RUNTIME_DIR=<set>
   LANG=nl_NL.UTF-8
   SHELL=/bin/bash
  SourcePackage: zfs-linux
  UpgradeStatus: No upgrade log present (probably fresh install)

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