[Bug 2001975] Autopkgtest regression report (glibc/2.31-0ubuntu9.11)

[Ubuntu SRU Bot]

All autopkgtests for the newly accepted glibc (2.31-0ubuntu9.11) for focal have finished running.
The following regressions have been reported in tests triggered by the package:

dune-common/2.6.0-4build1 (armhf)
khtml/5.68.0-0ubuntu1 (armhf)
kitemmodels/5.68.0-0ubuntu1 (armhf)
kpeople/5.68.0-0ubuntu1 (armhf)
kplotting/5.68.0-0ubuntu1 (armhf)
kpty/5.68.0-0ubuntu1 (armhf)
kxmlgui/5.68.0-0ubuntu2 (armhf)
linux-nvidia-tegra-5.15/5.15.0-1015.15~20.04.1 (arm64)
netplan.io/0.104-0ubuntu2~20.04.2 (s390x)
nfs-utils/1:1.3.4-2.5ubuntu3.4 (amd64)
ruby-stackprof/0.2.15-2 (arm64)
sbd/1.4.1-3 (s390x)
threadweaver/5.68.0-0ubuntu1 (armhf)


Please visit the excuses page listed below and investigate the failures, proceeding afterwards as per the StableReleaseUpdates policy regarding autopkgtest regressions [1].

https://people.canonical.com/~ubuntu-archive/proposed-
migration/focal/update_excuses.html#glibc

[1] https://wiki.ubuntu.com/StableReleaseUpdates#Autopkgtest_Regressions

Thank you!

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https://bugs.launchpad.net/bugs/2001975

Title:
  overflow bug in wcsncmp_avx2

Status in GLibC:
  Fix Released
Status in glibc package in Ubuntu:
  Fix Released
Status in glibc source package in Focal:
  Fix Committed

Bug description:
  [Impact]

  See https://sourceware.org/bugzilla/show_bug.cgi?id=28755

  Note that we're only impacted by the avx2 issue, the evex-optimized
  version isn't present in the 2.31 branch.

  [Test case]

  > test_wcsncmp.c cat <<EOF
  #include <wchar.h>
  #include <assert.h>

  int
  main(int argc, char ** argv) {
      assert(__wcsncmp_avx2(L"abc", L"abd", (1UL << 62)) != 0);
  }
  EOF
  gcc -static -o test_wcsncmp test_wcsncmp.c
  ./test_scsncmp

  [Regression potential]

  The patch is contained within the AVX-2 optimized routine, but it
  could still cause introduce a new bug there. In addition, we could see
  performance regressions.

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