ghsa-x2pf-v9q2-vj6j
Vulnerability from github
Published
2024-05-03 18:30
Modified
2024-05-03 18:30
Details

In the Linux kernel, the following vulnerability has been resolved:

vfio/type1: Unpin zero pages

There's currently a reference count leak on the zero page. We increment the reference via pin_user_pages_remote(), but the page is later handled as an invalid/reserved page, therefore it's not accounted against the user and not unpinned by our put_pfn().

Introducing special zero page handling in put_pfn() would resolve the leak, but without accounting of the zero page, a single user could still create enough mappings to generate a reference count overflow.

The zero page is always resident, so for our purposes there's no reason to keep it pinned. Therefore, add a loop to walk pages returned from pin_user_pages_remote() and unpin any zero pages.

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{
  "affected": [],
  "aliases": [
    "CVE-2022-48700"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2024-05-03T16:15:08Z",
    "severity": null
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nvfio/type1: Unpin zero pages\n\nThere\u0027s currently a reference count leak on the zero page.  We increment\nthe reference via pin_user_pages_remote(), but the page is later handled\nas an invalid/reserved page, therefore it\u0027s not accounted against the\nuser and not unpinned by our put_pfn().\n\nIntroducing special zero page handling in put_pfn() would resolve the\nleak, but without accounting of the zero page, a single user could\nstill create enough mappings to generate a reference count overflow.\n\nThe zero page is always resident, so for our purposes there\u0027s no reason\nto keep it pinned.  Therefore, add a loop to walk pages returned from\npin_user_pages_remote() and unpin any zero pages.",
  "id": "GHSA-x2pf-v9q2-vj6j",
  "modified": "2024-05-03T18:30:36Z",
  "published": "2024-05-03T18:30:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-48700"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5321908ef74fb593e0dbc8737d25038fc86c9986"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/578d644edc7d2c1ff53f7e4d0a25da473deb4a03"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5d721bf222936f5cf3ee15ced53cc483ecef7e46"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/873aefb376bbc0ed1dd2381ea1d6ec88106fdbd4"
    }
  ],
  "schema_version": "1.4.0",
  "severity": []
}


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