[Bug 1459872] Re: using progress mod w/ net files crashes

[Chris J Arges]

Hello dann, or anyone else affected,

Accepted grub2 into vivid-proposed. The package will build now and be
available at
https://launchpad.net/ubuntu/+source/grub2/2.02~beta2-22ubuntu1.5 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 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 to verification-done. If it does not fix the
bug for you, please add a comment stating that, and change the tag to
verification-failed.  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!

** Tags removed: verification-done

** Tags added: verification-needed

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https://bugs.launchpad.net/bugs/1459872

Title:
  using progress mod w/ net files crashes

Status in grub2 package in Ubuntu:
  Fix Released
Status in grub2 source package in Trusty:
  Fix Released
Status in grub2 source package in Vivid:
  Fix Committed
Status in grub2 source package in Wily:
  Fix Released

Bug description:
  [Impact]
  If the progress module is loaded, GRUB will crash when loading files over the network. A common scenario where this occurs is when building a GRUB image for EFI netbooting w/ all modules included. MAAS does this when generating it's grubnet EFI binary. MAAS currently works around this by explicitly blacklisting the progress module - but only on arm64 (we'd only observed this on arm64 at the time, and didn't yet know the root cause).

  While the easy workaround is to just omit the progress module, it
  isn't at all obvious from the crash that progress.mod is the cause.

  [Test Case]
  The simple case is to create a grub image with *just* the progress module and netboot it. For arm64:

  $ grub-mkimage -v -o grubaa64.efi -O arm64-efi -d
  /home/dannf/x/usr/lib/grub/arm64-efi progress

  Booting the resulting image:

  [1] PXE
  [2] ubuntu
  [3] Shell
  [4] Boot Manager
  Start: 1
  ..

  Synchronous Exception at 0x0000000FF7C3DDC8

  Synchronous Exception at 0x0000000FF7C3DDC8

  Synchronous Exception at 0x0000000FF7C3DDC8

  Synchronous Exception at 0x0000000FF7C3DDC8
  [...]

  [Regression Risk]
  The upstream fix for this is a pretty surgical fix to check for NULL before dereferencing a pointer.

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