powerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-89961
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-16 11:17:06 UTC
Updated2026-09-16 15:18:20 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: powerpc/mm: fix wrong addr_pfn tracking in compound vmemmap population vmemmap_populate_compound_pages() uses addr_pfn to determine the PFN offset within a compound page and to decide whether the current vmemmap slot should be populated as a head page mapping or should reuse a tail page mapping. However, addr_pfn is advanced manually in parallel with addr. The loop itself progresses in vmemmap address space, so each PAGE_SIZE step in addr covers PAGE_SIZE / sizeof(struct page) struct page slots. Since addr_pfn is compared against nr_pages in data-PFN units, it should advance by the same number of PFNs. The existing manual increments do not match that and therefore do not reliably track the PFN corresponding to the current addr. As a result, pfn_offset can be computed from the wrong PFN and the code can make the head/tail decision for the wrong compound-page position. Fix this by deriving addr_pfn directly from the current vmemmap address instead of carrying it as loop state.

Risk And Classification

Primary CVSS: v3.1 7.8 HIGH from 416baaa9-dc9f-4396-8d5f-8c081fb06d67

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

VersionSourceTypeScoreSeverityVector
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED7.8HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected f2b79c0d79683d552369bb9a7282c1f0226fc566 b96be860673f9fbbf12cdadb0b25fc4d6d4d207f git Not specified
CNA Linux Linux affected f2b79c0d79683d552369bb9a7282c1f0226fc566 e163c7184acf36ac20a248498f4a16016057ca01 git Not specified
CNA Linux Linux affected f2b79c0d79683d552369bb9a7282c1f0226fc566 9c914b7a0bd18834505c65f22225ce22c152b2d9 git Not specified
CNA Linux Linux affected f2b79c0d79683d552369bb9a7282c1f0226fc566 7968852a7ca3ce81477ec5b4494a28d612f35a97 git Not specified
CNA Linux Linux affected f2b79c0d79683d552369bb9a7282c1f0226fc566 89a4ae32764172468dea303eb6ae90fe6c859712 git Not specified
CNA Linux Linux affected 6.6 Not specified
CNA Linux Linux unaffected 6.6 semver Not specified
CNA Linux Linux unaffected 6.6.157 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.110 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.51 6.18.* semver Not specified
CNA Linux Linux unaffected 7.2.5 7.2.* semver Not specified
CNA Linux Linux unaffected 7.3-rc1 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/b96be860673f9fbbf12cdadb0b25fc4d6d4d207f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/89a4ae32764172468dea303eb6ae90fe6c859712 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/9c914b7a0bd18834505c65f22225ce22c152b2d9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/e163c7184acf36ac20a248498f4a16016057ca01 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/7968852a7ca3ce81477ec5b4494a28d612f35a97 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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