Ubuntu
initramfs-tools package

panic=-1 is completely ignored by the initrd causing unexpected behaviour

Bug #1831252 reported by Oliver Grawert
8
This bug affects 1 person
Affects Status Importance Assigned to Milestone
initramfs-tools (Ubuntu)
Fix Released
Medium
Unassigned
Xenial
Fix Released
Medium
Unassigned
Bionic
Fix Released
Medium
Unassigned
Disco
Fix Released
Medium
Unassigned
Eoan
Fix Released
Medium
Unassigned

Bug Description

[Impact]
in Ubuntu Core we default to using panic=-1 on the kernel command line (documented at [1]) to speed up the auto-rollback mechanism of the kernel. on a kernel level this works just fine and the system reboots immediately ...

when in the initramfs during boot and a panic occurs, no reboot happens at all, the initrd spawns a shell regardless of the panic= value ...

[Test case]

Before booting change root=$foo to root=x$foo - this will make it panic. Then test that

1) "panic=-1" causes an immediate reboot
2) "panic=5" waits 5 seconds
3) no "panic" drops you to a shell

[Regression potential]
This adds some very specific checks for -1 in places that use ${panic}, as such the regression potential is somewhat limited. If there were a regression, it could be a syntax error (causing boot to fail) or a sleep not working correctly (causing sleep to, well, not sleep) - but that's unrealistic.

[Other info]
this is caused by a filter in /usr/share/initramfs-tools/init

        panic=*)
                panic="${x#panic=}"
                case ${panic} in
                *[![:digit:].]*)
                        panic=
                        ;;
                esac
                ;;

this function only lets positive values through, else panic= simply gets unset

the panic() function itself is also not capable of handling negative values, it has a sleep call that interprets negative values as commandline options instead of simply ignoring a negative sleep time [2] (line 11).

the filter in the init script should allow the -1 value (to comply with the kernel documentation and behaviour) and the panic() function should properly skip the sleep call when a negative value for panic= is set.

[1] https://github.com/torvalds/linux/blob/v4.17/Documentation/admin-guide/kernel-parameters.txt#L2931
[2] https://paste.ubuntu.com/p/mswD8Cd869/

See original description
Revision history for this message
Oliver Grawert (ogra) wrote :

targeting to xenial and bionic since we need this SRUed for Ubuntu Core installs.

description: updated
Dimitri John Ledkov (xnox)
tags: added: rls-ee-incoming
Brian Murray (brian-murray)
Changed in initramfs-tools (Ubuntu):
importance: Undecided → Medium
Changed in initramfs-tools (Ubuntu Xenial):
importance: Undecided → Medium
Changed in initramfs-tools (Ubuntu Bionic):
importance: Undecided → Medium
Steve Langasek (vorlon)
tags: removed: rls-ee-incoming
Francis Ginther (fginther)
tags: added: id-5cf9304627a12b717bdbab7a
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package initramfs-tools - 0.133ubuntu10

---------------
initramfs-tools (0.133ubuntu10) eoan; urgency=medium

  * Add support for panic=-1 value (LP: #1831252)

 -- Julian Andres Klode <email address hidden> Thu, 05 Sep 2019 12:31:43 +0200

Changed in initramfs-tools (Ubuntu Eoan):
status: New → Fix Released
Julian Andres Klode (juliank)
description: updated
Julian Andres Klode (juliank)
Changed in initramfs-tools (Ubuntu Disco):
status: New → In Progress
Revision history for this message
Julian Andres Klode (juliank) wrote :

Uploads ready in unapproved queues.

Changed in initramfs-tools (Ubuntu Bionic):
status: New → In Progress
Changed in initramfs-tools (Ubuntu Xenial):
status: New → In Progress
Revision history for this message
Łukasz Zemczak (sil2100) wrote : Please test proposed package

Hello Oliver, or anyone else affected,

Accepted initramfs-tools into disco-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/initramfs-tools/0.131ubuntu19.2 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-disco to verification-done-disco. If it does not fix the bug for you, please add a comment stating that, and change the tag to verification-failed-disco. 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 initramfs-tools (Ubuntu Disco):
status: In Progress → Fix Committed
tags: added: verification-needed verification-needed-disco
Changed in initramfs-tools (Ubuntu Bionic):
status: In Progress → Fix Committed
tags: added: verification-needed-bionic
Revision history for this message
Łukasz Zemczak (sil2100) wrote :

Hello Oliver, or anyone else affected,

Accepted initramfs-tools into bionic-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/initramfs-tools/0.130ubuntu3.9 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.

Changed in initramfs-tools (Ubuntu Xenial):
status: In Progress → Fix Committed
tags: added: verification-needed-xenial
Revision history for this message
Łukasz Zemczak (sil2100) wrote :

Hello Oliver, or anyone else affected,

Accepted initramfs-tools into xenial-proposed. The package will build now and be available at https://launchpad.net/ubuntu/+source/initramfs-tools/0.122ubuntu8.16 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.

Mathew Hodson (mhodson)
Changed in initramfs-tools (Ubuntu Disco):
importance: Undecided → Medium
Revision history for this message
Tiago Stürmer Daitx (tdaitx) wrote :

I tested the initramfs-tools in xenial-proposed, bionic-proposed, and disco-proposed with all 3 testcases (panic=-1, panic=10, and no panic), everything worked as expected:
- panic=-1 rebooted instantly after the root partition is not found
- panic=10 rebooted after 10 seconds
- no "panic" entry caused to drop into a basic shell

ii initramfs-tools 0.122ubuntu8.16 all generic modular initramfs generator (automation)
ii initramfs-tools 0.130ubuntu3.9 all generic modular initramfs generator (automation)
ii initramfs-tools 0.131ubuntu19.2 all generic modular initramfs generator (automation)

multipass@xenial:~$ apt-cache policy initramfs-tools
initramfs-tools:
  Installed: 0.122ubuntu8.16
  Candidate: 0.122ubuntu8.16
  Version table:
 *** 0.122ubuntu8.16 400
        400 http://archive.ubuntu.com/ubuntu xenial-proposed/main amd64 Packages
        100 /var/lib/dpkg/status
     0.122ubuntu8.15 500
        500 http://archive.ubuntu.com/ubuntu xenial-updates/main amd64 Packages
     0.122ubuntu8.14 500
        500 http://security.ubuntu.com/ubuntu xenial-security/main amd64 Packages
     0.122ubuntu8 500
        500 http://archive.ubuntu.com/ubuntu xenial/main amd64 Packages

multipass@bionic:~$ apt-cache policy initramfs-tools
initramfs-tools:
  Installed: 0.130ubuntu3.9
  Candidate: 0.130ubuntu3.9
  Version table:
 *** 0.130ubuntu3.9 400
        400 http://archive.ubuntu.com/ubuntu bionic-proposed/main amd64 Packages
        100 /var/lib/dpkg/status
     0.130ubuntu3.8 500
        500 http://archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages
     0.130ubuntu3.6 500
        500 http://security.ubuntu.com/ubuntu bionic-security/main amd64 Packages
     0.130ubuntu3 500
        500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages

multipass@disco:~$ apt-cache policy initramfs-tools
initramfs-tools:
  Installed: 0.131ubuntu19.2
  Candidate: 0.131ubuntu19.2
  Version table:
 *** 0.131ubuntu19.2 400
        400 http://archive.ubuntu.com/ubuntu disco-proposed/main amd64 Packages
        100 /var/lib/dpkg/status
     0.131ubuntu19.1 500
        500 http://archive.ubuntu.com/ubuntu disco-updates/main amd64 Packages
     0.131ubuntu19 500
        500 http://archive.ubuntu.com/ubuntu disco/main amd64 Packages

tags: added: verification-done-bionic verification-done-disco verification-done-xenial
removed: verification-needed verification-needed-bionic verification-needed-disco verification-needed-xenial
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package initramfs-tools - 0.131ubuntu19.2

---------------
initramfs-tools (0.131ubuntu19.2) disco; urgency=medium

  * Add support for panic=-1 value (LP: #1831252)

 -- Julian Andres Klode <email address hidden> Mon, 07 Oct 2019 12:46:48 +0200

Changed in initramfs-tools (Ubuntu Disco):
status: Fix Committed → Fix Released
Revision history for this message
Łukasz Zemczak (sil2100) wrote : Update Released

The verification of the Stable Release Update for initramfs-tools has completed successfully and the package is now being 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.

Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package initramfs-tools - 0.130ubuntu3.9

---------------
initramfs-tools (0.130ubuntu3.9) bionic; urgency=medium

  * Add support for panic=-1 value (LP: #1831252)

 -- Julian Andres Klode <email address hidden> Mon, 07 Oct 2019 12:53:35 +0200

Changed in initramfs-tools (Ubuntu Bionic):
status: Fix Committed → Fix Released
Revision history for this message
Launchpad Janitor (janitor) wrote :

This bug was fixed in the package initramfs-tools - 0.122ubuntu8.16

---------------
initramfs-tools (0.122ubuntu8.16) xenial; urgency=medium

  * Add support for panic=-1 value (LP: #1831252)

 -- Julian Andres Klode <email address hidden> Mon, 07 Oct 2019 12:53:35 +0200

Changed in initramfs-tools (Ubuntu Xenial):
status: Fix Committed → Fix Released
To post a comment you must log in.
This report contains Public information  
Everyone can see this information.
Subscribing...

Other bug subscribers

Remote bug watches

Bug watches keep track of this bug in other bug trackers.