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

[Stefan Bader]

On 01.08.24 15:45, Roxana Nicolescu wrote:
> 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(-)
> 

Applied to jammy:linux/master-next and jammy:linux-hwe-6.8/hwe-6.8-next. 
Thanks.

-Stefan

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