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CVE-2026-63939

KVM: SEV: Compute the correct max length of the in-GHCB scratch area PUBLISHED

Description (CNA)

In the Linux kernel, the following vulnerability has been resolved: KVM: SEV: Compute the correct max length of the in-GHCB scratch area When setting the length of the GHCB scratch area, and the area is in the GHCB shared buffer, set the effective length of the scratch area to the max possible size given the start of the guest-provided pointer, and the end of the shared buffer. The code was "fine" when first introduced, as KVM doesn't consult the length of the buffer when emulating MMIO, because the passed in @len always specifies the *max* size required. But for PSC requests, the incoming @len is just the minimum length (to process the header), and KVM needs to know the full size of the scratch area to avoid buffer overflows (spoiler alert). Opportunistically rename @len => @min_len to better reflect its role.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 9b54e248d2644be71cb394eb85f31ad99e023a05 before 6ca9400d36005ffdca25f80186bea781c7e1dc4c; affected 9b54e248d2644be71cb394eb85f31ad99e023a05 before 9f0a9e780f02c02d025a190f1885e1d1d73b87bd; affected 9b54e248d2644be71cb394eb85f31ad99e023a05 before 6644565527c4c5f507088b1c9ddf72de47790b68; affected 9b54e248d2644be71cb394eb85f31ad99e023a05 before 5867d7e202e09f037cefe77f7af4413c7c0fa088
Linux / Linuxaffected 6.11; unaffected 0 before 6.11; unaffected 6.12.93 through 6.12.*; unaffected 6.18.35 through 6.18.*; unaffected 7.0.12 through 7.0.*; unaffected 7.1 through *

CWE

No CWE identifiers supplied.

References

ADP enrichment

CISA-ADP

No English description supplied.

No references supplied.