[SRU][J:linux/J:hwe-6.8][PATCH 0/1] Fix virtualbox regression

[Roxana Nicolescu]

BugLink: https://bugs.launchpad.net/bugs/2073267

SRU Justification:

[Impact]

Commit "randomize_kstack: Improve entropy diffusion" changed the
kernel stack for entropy to 1KiB, limiting the thread kernel stack to
15Kib. This impacts virtualbox 6.1.50 on jammy, that is no longer
maintained upstream. The issue does not persist on version 7.0.20 due to a
code refactoring that probably resulted in less stack usage. Fixing it on
the jammy virtualbox package side is not straightfoward because the fix is
not easy to backport to 6.x and upgrading the jammy package to 7.x breaks
current users machines that run Windows, but not only.
Users need to uninstall the Guest additions drivers, migrate the
virtualbox package to 7.x, boot each VMs and install the Guest additions
drivers in each VM.

This impacts:
1. jammy:linux
2. jammy:linux-hwe-6.8
3. focal:linux-hwe-5.15

[Fix]

Revert commit "randomize_kstack: Improve entropy diffusion"

[Test Plan]

Without this fix, a VM would crash, showing with "VCPU0: Guru
Meditation -2708 (VERR_VMM_SET_JMP_ABORTED_RESUME)".
After the kernel upgrade, all VMs should run with no problem.

[Where problems could occur]
This may have an impact on security. The commit is a fix to improve the
stack entropy.

[Other info]
This is a temporary fix. More investigation is required.

Roxana Nicolescu (1):
  UBUNTU SAUCE: Revert "randomize_kstack: Improve entropy diffusion"

 include/linux/randomize_kstack.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

-- 
2.34.1