CVE-2023-52659

/// Technical description

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

x86/mm: Ensure input to pfn_to_kaddr() is treated as a 64-bit type

On 64-bit platforms, the pfn_to_kaddr() macro requires that the input

value is 64 bits in order to ensure that valid address bits don't get

lost when shifting that input by PAGE_SHIFT to calculate the physical

address to provide a virtual address for.

One such example is in pvalidate_pages() (used by SEV-SNP guests), where

the GFN in the struct used for page-state change requests is a 40-bit

bit-field, so attempts to pass this GFN field directly into

pfn_to_kaddr() ends up causing guest crashes when dealing with addresses

above the 1TB range due to the above.

Fix this issue with SEV-SNP guests, as well as any similar cases that

might cause issues in current/future code, by using an inline function,

instead of a macro, so that the input is implicitly cast to the

expected 64-bit input type prior to performing the shift operation.

While it might be ar

/// 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