CVE-2026-80718 - mm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk()

CVE-2026-80718 - mm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk()

https://cvefeed.io/rssfeed/latest.atom / Fri, 08/28/2026 - 13:28
CVE ID :CVE-2026-80718
Published : Aug. 28, 2026, 8:16 a.m. | 2 hours, 13 minutes ago
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.
Severity: 0.0 | NA
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