[Bug 2073372] Comment bridged from LTC Bugzilla

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------- Comment From STLI at de.ibm.com 2024-09-10 07:37 EDT-------
FYI: The testcase is now also upstream with commit:
commit "Enhanced test coverage for strncmp, wcsncmp" (Florian Weimer; 2024-08-01)
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=54252394c25ddf0062e288d4a6ab7a885f8ae009

Note: The testcase is only executed with make xcheck.

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https://bugs.launchpad.net/bugs/2073372

Title:
  [UBUNTU 20.04] s390x: z13 wcsncmp implementation segfaults if n=1

Status in Ubuntu on IBM z Systems:
  In Progress
Status in glibc package in Ubuntu:
  Fix Released
Status in glibc source package in Focal:
  Triaged
Status in glibc source package in Jammy:
  Triaged
Status in glibc source package in Noble:
  Triaged
Status in glibc source package in Oracular:
  Fix Released

Bug description:
  The >=z13 wcsncmp implementation segfaults if n=1 and there is only
  one character (equal on both strings) before the page end. Then it
  loads and compares one character and misses to check n again. The
  following load fails.

  This issue was reported here:
  Bug 31934 - wcsncmp crash on s390x on vlbb instruction
  https://sourceware.org/bugzilla/show_bug.cgi?id=31934

  And fixed upstream (first in glibc 2.40):
  s390x: Fix segfault in wcsncmp [BZ #31934]
  https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=9b7651410375ec8848a1944992d663d514db4ba7

  This Fix was cherry-picked to the current branches glibc 2.32-39:
  - 2.39: commit 5c46e6b66636be0010e9a732d5ba1e65ebd54687
  - 2.38: commit 712453634c8efd71a9b3ff0122145a9e90e9955c
  - 2.37: commit 340ca2d5148371614c234068f430c19293f962dc
  - 2.36: commit a70c55a91b2b361f43e4142aadf86f22af57d406
  - 2.35: commit c7cd62653850135bc880688a78104dbf77cf8121
  - 2.34: commit 87fa7bfb84895bb517beb8aaf92bd45b829daabb
  - 2.33: commit 5f08d1df2c07904c1dc98bdf2b363c65874266f7
  - 2.32: commit 5ad449c398a845a9c84808e4ac603beaa1006909

  In case somebody needs the fix for older glibc releases (issue was
  introduced with glibc 2.23), feel free to just cherry-pick it. Note,
  that the file was moved from sysdeps/s390/multiarch/wcsncmp-vx.S to
  sysdeps/s390/wcsncmp-vx.S with commit
  e9873e1d47c870d707117ada91c9be21e3bf1537 (in glibc 2.29), but the
  implementation does not differ.

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