CVE-2026-80718

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

Published Aug 28, 2026 CVSS 3.1 · 7.8 High EPSS < 1% KEV · Not listed
Description
In 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.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Debian DLA Debian DLA DLA-4777-1 linux security update
Debian DLA Debian DLA DLA-4788-1 linux-6.12 security update
Ubuntu USN Ubuntu USN USN-8875-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8877-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-8878-1 Linux kernel (GCP) vulnerabilities
Ubuntu USN Ubuntu USN USN-8879-1 Linux kernel (Oracle) vulnerabilities
Ubuntu USN Ubuntu USN USN-8875-2 Linux kernel (NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9002-1 Linux kernel (NVIDIA Tegra) vulnerabilities
Ubuntu USN Ubuntu USN USN-9019-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9020-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9022-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9023-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9024-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9025-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-9026-1 Linux kernel (Azure) vulnerabilities
Ubuntu USN Ubuntu USN USN-9029-1 Linux kernel (Raspberry Pi) vulnerabilities
Ubuntu USN Ubuntu USN USN-9039-1 Linux kernel (Azure CVM) vulnerabilities
Ubuntu USN Ubuntu USN USN-9040-1 Linux kernel (Low Latency NVIDIA) vulnerabilities
Ubuntu USN Ubuntu USN USN-9066-1 Linux kernel (HWE) vulnerabilities
History
Type Values Removed Values Added
Weaknesses CWE-682
Type Values Removed Values Added
Weaknesses CWE-682
Type Values Removed Values Added
Weaknesses CWE-119
Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}

Type Values Removed Values Added
Weaknesses CWE-119
Type Values Removed Values Added
Weaknesses CWE-119
CWE-787
Type Values Removed Values Added
Weaknesses CWE-119
CWE-787
Type Values Removed Values Added
Description In 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.
Title mm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References
Weaknesses

Sources

Status
PUBLISHED
Assigner
Linux
Published
Updated
Aug 29, 2026, 6:22 AM
Reserved
Aug 26, 2026, 2:34 PM
Status
Received
Published
Aug 28, 2026, 8:16 AM
Modified
Aug 29, 2026, 7:16 AM
Severity
Moderate
Public date
Aug 28, 2026, 12:00 AM