[Bug 1974109] [NEW] [UBUNTU 22.04] zipl segfaults when "parameters=" is missing

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You have been subscribed to a public bug by Frank Heimes (fheimes):

SRU Justification:
------------------

[Impact]

 * The zipl boot-loader tool segfaults if a section doesn't contain
   a "parameters =" line.

 * Adding a "parameters =" line makes the problem go away.

 * This is especially problematic when secure execution is set up,
   since the parameter is provided in the secure image
   and hence a zipl parameter is not needed.

[Fix]

 * 6ff8202f 6ff8202fa9e172199e995298d336d9dd87ca8180 "zipl: Add missing
check for a nullpointer."

[Test Plan]

 * Setup a default Ubuntu Server for s390x test installation.

 * Backup the existing /etc/zipl.conf:
   cp /etc/zipl.conf ~

 * Edit /etc/zipl.conf and remove (or better comment out)
   'the parameters =' line:
   sudo vi /etc/zipl.conf
   and save the file.

 * Execute the zipl tool to re-write the zipl bootloader
   and it will segfault
   without the patch (like this):
   sudo zipl
   Using config file '/etc/zipl.conf'
   Segmentation fault

 * or complete successfully (like this):
   sudo zipl
   Using config file '/etc/zipl.conf'
   Building bootmap in '/boot'
   Adding IPL section 'ubuntu' (default)
   Preparing boot device: dasda (0101).
   Done.

[Where problems could occur]

 * It's a patch that changes just one line,
   checks the existence of the parmline
   and only then computes it's length,
   and otherwise sets the length to 0.

 * Issues could occur if the compact/short if
   statement is wrong and for example the logic mixed up.

 * Or if somewhere else in the code a length of 0
   for the parameters line is not expected and will
   cause further issues.

 * Both cases can simply be covered by the above test.

[Other Info]

 * The above fix is included in s390-tools v2.23
   and is with that incl. in the kinetic s390-tools version.
__________

ZIPL segfaults if a section doesn't contain a "parameter=" line.
Adding that line makes the problem go away.

This is especially a problem when secure execution is set up since the
parameter is provided in the secure image and hence a zipl parameter is
not needed.

---uname output---
Linux linux6 5.15.0-27-generic #28-Ubuntu SMP Thu Apr 14 04:55:23 UTC 2022 s390x s390x s390x GNU/Linux

Machine Type = z16

---Steps to Reproduce---
Add a section to /etc/zipl.conf that doesn't have a parameter line.

Userspace tool common name: zipl

The userspace tool has the following bit modes: 64-bit

** Affects: ubuntu-z-systems
     Importance: Undecided
     Assignee: Skipper Bug Screeners (skipper-screen-team)
         Status: Incomplete

** Affects: s390-tools (Ubuntu)
     Importance: Undecided
         Status: New

** Affects: s390-tools-signed (Ubuntu)
     Importance: Undecided
         Status: New


** Tags: architecture-s39064 bugnameltc-198062 severity-medium targetmilestone-inin---
-- 
[UBUNTU 22.04] zipl segfaults when "parameters=" is missing
https://bugs.launchpad.net/bugs/1974109
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