CVE-2026-80718

Technical 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

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References