CVE-2023-52659: x86/mm: Ensure input to pfn_to_kaddr() is treated as a 64-bit type

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-05-17 · updated 2026-06-17

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 argued that the issue is on the caller side, other archs/macros have taken similar approaches to deal with instances like this, such as ARM explicitly casting the input to phys_addr_t: e48866647b48 ("ARM: 8396/1: use phys_addr_t in pfn_to_kaddr()") A C inline function is even better though. [ mingo: Refined the changelog some more & added __always_inline. ]

Affected products

Linux kernel: from 6.5 before 6.6.23; from 6.7 before 6.7.11; from 6.8 before 6.8.2 — fixed in 6.6.23, 6.7.11, 6.8.2

How to fix

Upgrade to a fixed version: Linux kernel 6.6.23, 6.7.11, 6.8.2. Check the vendor advisory for mitigations.

References

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