[Bug 2002511] Re: zlib 1.2.13 (and patched 1.2.11) breaks libxml2 on s390x

[Launchpad Bug Tracker]

This bug was fixed in the package zlib - 1:1.2.13.dfsg-1ubuntu4

---------------
zlib (1:1.2.13.dfsg-1ubuntu4) lunar; urgency=medium

  * Add d/p/1390.patch to not update strm.adler for raw streams on s390x
    (DFLTCC), otherwise libxml2 gets broken on s390x. LP: #2002511

 -- Frank Heimes <frank.heimes at canonical.com>  Wed, 11 Jan 2023 18:02:34
+0100

** Changed in: zlib (Ubuntu Lunar)
       Status: In Progress => Fix Released

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https://bugs.launchpad.net/bugs/2002511

Title:
  zlib 1.2.13 (and patched 1.2.11) breaks libxml2 on s390x

Status in Ubuntu on IBM z Systems:
  In Progress
Status in zlib:
  Fix Released
Status in zlib package in Ubuntu:
  Fix Released
Status in zlib source package in Focal:
  New
Status in zlib source package in Jammy:
  New
Status in zlib source package in Kinetic:
  New
Status in zlib source package in Lunar:
  Fix Released

Bug description:
  SRU Justification:
  ------------------

  [ Impact ]

   * zlib version 1.2.13, as well as patched zlib versions 1.2.11 with
     the patch from LP#1990379, break libxml2 and lxml on s390x.

   * The problem appears during loading a gzipped XML file.

   * Disabling hw compression with 'export DFLTCC=0' solves this,
     hence it's a problem with the hardware acceleration patches DFLTCC.

   * For more info see:
  https://bugzilla.redhat.com/show_bug.cgi?id=2155328

  [ Test Plan ]

   * Steps to Reproduce:
     1. echo "<a></a>" > file.xml
     2. gzip file.xml
     3. python3
     >>> import libxml2
     >>> libxml2.parseFile("file.xml.gz")

   * Actual results:
     file.xml.gz:1: parser error : Document is empty
     ^
     Traceback (most recent call last):
       File "<stdin>", line 1, in <module>
       File "/usr/lib/python3.11/site-packages/libxml2.py",
       line 1362, in parseFile
         if ret is None:raise parserError('xmlParseFile() failed')
                        ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
     libxml2.parserError: xmlParseFile() failed

   * Expected results:
     Loaded file.

  [ Where problems could occur ]

   * Since this is limited to s390x and DFLTCC / hw acceleration active,
     any possible problems are limited to such environments.

   * Fix can be broken if the state handling (state->wrap),
     or the states mixed.

   * The translation from stream to parameter block could be broken
     (again due to wrong states) and the inflate as well.

  [ Other Info ]

   * The official upstream fix is here:
     https://github.com/zlib-ng/zlib-ng/pull/1390
     but it's for zlib-ng.

   * For zlib this needs to be adjusted and was done by the author here:
     https://launchpadlibrarian.net/641454325/patch-1.2.11

   * And again slightly adjusted by me (renamed, some white-space fixes
     and conversion into a quilt patch with proper dep3 header):
     https://launchpadlibrarian.net/645435847/1390.patch

   * The zlib version in Focal, Jammy, Kinetic and Lunar are affected.
  __________

  It has been reported that 1.2.13 as well as the patch from LP#1990379 breaks libxml2 (and libxml) on s390x:
  (https://bugzilla.redhat.com/show_bug.cgi?id=2155328). The attached patch should fix the issue.

  The upstream author proposed a fix and a new test for zlib-ng
  (https://github.com/zlib-ng/zlib-ng/pull/1390) in order to detect such
  breakages in the future.

  ___

  This was initially reported as part of LP#1990379,
  especially: https://bugs.launchpad.net/ubuntu/+source/zlib/+bug/1990379/comments/12
  but needs a separate LP bug (number) - this one.
  ___

  The proposed patch at https://launchpadlibrarian.net/641454325/patch-1.2.11
  needed some tweaks regarding white-spaces, but then applied fine on focal, jammy, kinetic and also  1.2.13, which is what we currently have in lunar-proposed.

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