CVE-2021-47450

KVM: arm64: Fix host stage-2 PGD refcount

State: Published
Severity: 8.8 High
Published: May 22, 2024
Updated: Aug 5, 2026
Reserved: May 21, 2024

Description

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

KVM: arm64: Fix host stage-2 PGD refcount

The KVM page-table library refcounts the pages of concatenated stage-2 PGDs individually. However, when running KVM in protected mode, the host's stage-2 PGD is currently managed by EL2 as a single high-order compound page, which can cause the refcount of the tail pages to reach 0 when they shouldn't, hence corrupting the page-table.

Fix this by introducing a new hyp_split_page() helper in the EL2 page allocator (matching the kernel's split_page() function), and make use of it from host_s2_zalloc_pages_exact().

Scores

CVSS	Score	Vector	Source
3.1	8.8 High	CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H	Linux

Weaknesses

The record names no weakness.

Affected Products

Product	Versions
LinuxLinux	1025c8c0c6accfcbdc8f52ca1940160f65cd87d6 to before b372264c66ef78f2cab44e877fbd765ad6d24c39Affected 1025c8c0c6accfcbdc8f52ca1940160f65cd87d6 to before 1d58a17ef54599506d44c45ac95be27273a4d2b1Affected
LinuxLinux	5.13Affected before 5.13Not affected 5.14.15 through 5.14.*Not affected 5.15 and laterNot affected

References

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