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.
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Linux
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Linux Kernel
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Solution
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Workaround
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Fri, 28 Aug 2026 17:45:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-119 |
Fri, 28 Aug 2026 14:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-119 CWE-787 |
Fri, 28 Aug 2026 11:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-119 CWE-787 |
Fri, 28 Aug 2026 07:30:00 +0000
| 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 |
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| References |
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-08-28T06:53:15.490Z
Reserved: 2026-08-26T14:34:25.788Z
Link: CVE-2026-80718
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-08-28T08:16:57.563
Modified: 2026-08-28T08:16:57.563
Link: CVE-2026-80718
Redhat
No data.
OpenCVE Enrichment
Updated: 2026-08-28T17:30:08Z