CVE-2022-49886

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

x86/tdx: Panic on bad configs that #VE on "private" memory access

All normal kernel memory is "TDX private memory". This includes

everything from kernel stacks to kernel text. Handling

exceptions on arbitrary accesses to kernel memory is essentially

impossible because they can happen in horribly nasty places like

kernel entry/exit. But, TDX hardware can theoretically _deliver_

a virtualization exception (#VE) on any access to private memory.

But, it's not as bad as it sounds. TDX can be configured to never

deliver these exceptions on private memory with a "TD attribute"

called ATTR_SEPT_VE_DISABLE. The guest has no way to *set* this

attribute, but it can check it.

Ensure ATTR_SEPT_VE_DISABLE is set in early boot. panic() if it

is unset. There is no sane way for Linux to run with this

attribute clear so a panic() is appropriate.

There's small window during boot before the check where kernel

has an early #VE

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References