[Bug 2011421] Re: TDX azure instances crash during boot because of glibc bug

[Dexuan Cui]

The segfault no longer repros after I upgraded my glibc:

cat <<EOF >/etc/apt/sources.list.d/ubuntu-$(lsb_release -cs)-proposed.list
# Enable Ubuntu proposed archive
deb http://archive.ubuntu.com/ubuntu/ $(lsb_release -cs)-proposed restricted main multiverse universe
EOF

apt update

dpkg -l |grep libc6
ii  libc6:amd64                         2.35-0ubuntu3.2                         amd64        GNU C Library: Shared libraries

apt install libc6

root at ubuntu:~# dpkg -l |grep libc6
ii  libc6:amd64                         2.35-0ubuntu3.3                         amd64        GNU C Library: Shared libraries

update-initramfs -u

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https://bugs.launchpad.net/bugs/2011421

Title:
  TDX azure instances crash during boot because of glibc bug

Status in glibc package in Ubuntu:
  Fix Released
Status in linux-azure package in Ubuntu:
  Fix Released
Status in glibc source package in Jammy:
  Fix Committed
Status in linux-azure source package in Jammy:
  Invalid
Status in glibc source package in Kinetic:
  Won't Fix
Status in linux-azure source package in Kinetic:
  In Progress
Status in glibc source package in Lunar:
  Fix Released
Status in linux-azure source package in Lunar:
  New

Bug description:
  [IMPACT]

  Glibc in jammy and kinetic is affected by the following bug :
  https://sourceware.org/bugzilla/show_bug.cgi?id=29953

  When cpuid reports no information on a shared cache, the
  x86_non_temporal_threshold will be set to zero, causing memcpy/memset to
  behave wrong for mid-sized operations. sysdeps/x86/dl-cacheinfo.h indicates
  that the minimum value must be 0x4040, but this is not enforced for the
  default value.

  The issue was reported because jammy tdx instances are failing to boot
  (crashing) on azure. The bug has been resolved upstream in
  https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=48b74865c63840b288bd85b4d8743533b73b339b

  [TEST CASE]

  Test case requires an azure tdx instance.
  Microsoft has tested a test package with the above commit and
  confirmed that instances boot successfully.

  [REGRESSION POTENTIAL]

  The patches have been accepted upstream. They modify code for x86 architecture, so any
  potential regression would affect x86.

  [OTHER]

  Bug upstream: https://sourceware.org/bugzilla/show_bug.cgi?id=29953
  Duplicate bug: https://sourceware.org/bugzilla/show_bug.cgi?id=30037

  In jammy we need 2 commits :
  https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=b446822b6ae4e8149902a78cdd4a886634ad6321
  https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=48b74865c63840b288bd85b4d8743533b73b339b

  In kinetic we just need :
  https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=48b74865c63840b288bd85b4d8743533b73b339b

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