[Bug 1707172] Re: AES256-GCM emits all-zeros ciphertext on aarch64 with hardware acceleration

[Andy Whitcroft]

Hello Ard, or anyone else affected,

Accepted gnutls28 into zesty-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/gnutls28/3.5.6-4ubuntu4.3 in a few
hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation on how
to enable and use -proposed.Your feedback will aid us getting this
update out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested and change the tag from
verification-needed-zesty to verification-done-zesty. If it does not fix
the bug for you, please add a comment stating that, and change the tag
to verification-failed-zesty. In either case, details of your testing
will help us make a better decision.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance!

** Changed in: gnutls28 (Ubuntu Zesty)
       Status: In Progress => Fix Committed

** Tags added: verification-needed verification-needed-zesty

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https://bugs.launchpad.net/bugs/1707172

Title:
  AES256-GCM emits all-zeros ciphertext on aarch64 with hardware
  acceleration

Status in gnutls28 package in Ubuntu:
  Fix Released
Status in gnutls28 source package in Zesty:
  Fix Committed

Bug description:
  [Impact]
  AES256-GCM ciphertext is all zero on arm64 with hardware acceleration, breaking gnome-terminal and xfce4-terminal which use encrypted scrollback buffers.

  [Test case]
  Compile the program from https://gitlab.com/gnutls/gnutls/issues/204 and make sure the cipher text is not all zeros when running it on an aarch64 machine w/ HW accel.

  [Regression potential]
  Code change is limited to AES256-GCM w/ HW accel on aarch64, so that's the only thing that could possibly break. But given that it's broken already, it does not seem to be a big issue even if it breaks otherwise.

  [Other info]
  Original report:

  The following Debian issue exists in the Ubuntu package as well

  https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=867581

  It breaks gnome-terminal and xfce4-terminal on arm64 machines.

  The issue is fixed upstream in 3.5.13, and the fix was backported to
  Debian stretch as well (3.5.8-5+deb9u2)

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