GHSA-WV7W-Q623-9GWQ

Vulnerability from github – Published: 2026-08-28 09:31 – Updated: 2026-08-28 09:31
VLAI
Details

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.

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{
  "affected": [],
  "aliases": [
    "CVE-2026-80718"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-28T08:16:57Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nmm/percpu-km: fix bitmap overflow and accounting in pcpu_create_chunk()\n\nIn pcpu_create_chunk(), nr_pages is the total contiguous backing\nallocation, i.e., nr_units * pcpu_unit_pages, but pcpu_chunk_populated()\nuses it to set chunk-\u003epopulated, whose size is pcpu_unit_pages, bitmap. \nSince bit N in chunk-\u003epopulated means page offset N inside every unit is\nbacked.  When nr_units \u003e 1, the function writes beyond chunk-\u003epopulated. \nFix it by using chunk-\u003enr_pages.\n\nIt also fixes the global pcpu_nr_empty_pop_pages accounting, since\npcpu_balance_free() only iterates up to chunk-\u003enr_pages.\n\nCommit a63d4ac4ab609 (\"percpu: make percpu-km set chunk-\u003epopulated bitmap\nproperly\") introduced the bitmap overflow issue.  Later, commit\nb539b87fed37f (\"percpu: implmeent pcpu_nr_empty_pop_pages and\nchunk-\u003enr_populated\") added pcpu_nr_empty_pop_pages and caused the\naccounting issue.",
  "id": "GHSA-wv7w-q623-9gwq",
  "modified": "2026-08-28T09:31:50Z",
  "published": "2026-08-28T09:31:50Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80718"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/01504da375f5b19df195cb1cb1cf1dd184318f97"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/32134cf9211b83bed9076d0739c5906fbea4c763"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5c7fc39bf19abb38a996aaad77b3e3a8f48581c3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5f43d2c1bea280dcdfabaf156c25e7402fb8039f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6fc7da2a052f2825fff785e860e67183f5acaaba"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/89b1b79c308818a715e75f28744b70d8940a07c9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/92c43ac3c2b09eb16162e8144e73c00b7c3e29d6"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a6940b84c8c035da465b7165fdfcfb005545724e"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}



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