DescriptionIn 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. ]
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
linux (PTS)buster4.19.249-2fixed
buster (security)4.19.304-1fixed
bullseye (security)5.10.218-1fixed
bookworm (security)6.1.90-1fixed
sid, trixie6.8.12-1fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
linuxsourcebuster(not affected)
linuxsourcebullseye(not affected)
linuxsourcebookworm(not affected)


[bookworm] - linux <not-affected> (Vulnerable code not present)
[bullseye] - linux <not-affected> (Vulnerable code not present)
[buster] - linux <not-affected> (Vulnerable code not present) (6.9-rc1)

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