mm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk()

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-80718
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-28 08:16:57 UTC
Updated2026-08-29 07:16:53 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: mm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk() In pcpu_create_chunk(), nr_pages is the total contiguous backing allocation, i.e., nr_units * pcpu_unit_pages, but pcpu_chunk_populated() uses it to set chunk->populated, whose size is pcpu_unit_pages, bitmap. Since bit N in chunk->populated means page offset N inside every unit is backed. When nr_units > 1, the function writes beyond chunk->populated. Fix it by using chunk->nr_pages. It also fixes the global pcpu_nr_empty_pop_pages accounting, since pcpu_balance_free() only iterates up to chunk->nr_pages. Commit a63d4ac4ab609 ("percpu: make percpu-km set chunk->populated bitmap properly") introduced the bitmap overflow issue. Later, commit b539b87fed37f ("percpu: implmeent pcpu_nr_empty_pop_pages and chunk->nr_populated") added pcpu_nr_empty_pop_pages and caused the accounting issue.

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

EPSS: 0.001640000 probability, percentile 0.058890000 (date 2026-08-28)

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 a63d4ac4ab6094c051a5a240260d16117a7a2f86 5f43d2c1bea280dcdfabaf156c25e7402fb8039f git Not specified
CNA Linux Linux affected a63d4ac4ab6094c051a5a240260d16117a7a2f86 92c43ac3c2b09eb16162e8144e73c00b7c3e29d6 git Not specified
CNA Linux Linux affected a63d4ac4ab6094c051a5a240260d16117a7a2f86 6fc7da2a052f2825fff785e860e67183f5acaaba git Not specified
CNA Linux Linux affected a63d4ac4ab6094c051a5a240260d16117a7a2f86 01504da375f5b19df195cb1cb1cf1dd184318f97 git Not specified
CNA Linux Linux affected a63d4ac4ab6094c051a5a240260d16117a7a2f86 a6940b84c8c035da465b7165fdfcfb005545724e git Not specified
CNA Linux Linux affected a63d4ac4ab6094c051a5a240260d16117a7a2f86 32134cf9211b83bed9076d0739c5906fbea4c763 git Not specified
CNA Linux Linux affected a63d4ac4ab6094c051a5a240260d16117a7a2f86 5c7fc39bf19abb38a996aaad77b3e3a8f48581c3 git Not specified
CNA Linux Linux affected a63d4ac4ab6094c051a5a240260d16117a7a2f86 89b1b79c308818a715e75f28744b70d8940a07c9 git Not specified
CNA Linux Linux affected 3.18 Not specified
CNA Linux Linux unaffected 3.18 semver Not specified
CNA Linux Linux unaffected 5.10.265 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.216 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.183 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.151 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.103 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.44 6.18.* semver Not specified
CNA Linux Linux unaffected 7.1.8 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/a6940b84c8c035da465b7165fdfcfb005545724e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/01504da375f5b19df195cb1cb1cf1dd184318f97 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5f43d2c1bea280dcdfabaf156c25e7402fb8039f 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/89b1b79c308818a715e75f28744b70d8940a07c9 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/32134cf9211b83bed9076d0739c5906fbea4c763 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/6fc7da2a052f2825fff785e860e67183f5acaaba 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/5c7fc39bf19abb38a996aaad77b3e3a8f48581c3 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/92c43ac3c2b09eb16162e8144e73c00b7c3e29d6 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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