ghsa-prxc-p2g7-m92v
Vulnerability from github
Published
2025-03-31 21:32
Modified
2025-03-31 21:32
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Details

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

keys: Fix UAF in key_put()

Once a key's reference count has been reduced to 0, the garbage collector thread may destroy it at any time and so key_put() is not allowed to touch the key after that point. The most key_put() is normally allowed to do is to touch key_gc_work as that's a static global variable.

However, in an effort to speed up the reclamation of quota, this is now done in key_put() once the key's usage is reduced to 0 - but now the code is looking at the key after the deadline, which is forbidden.

Fix this by using a flag to indicate that a key can be gc'd now rather than looking at the key's refcount in the garbage collector.

Show details on source website

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{
  "affected": [],
  "aliases": [
    "CVE-2025-21893"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-416"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-03-31T20:15:14Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nkeys: Fix UAF in key_put()\n\nOnce a key\u0027s reference count has been reduced to 0, the garbage collector\nthread may destroy it at any time and so key_put() is not allowed to touch\nthe key after that point.  The most key_put() is normally allowed to do is\nto touch key_gc_work as that\u0027s a static global variable.\n\nHowever, in an effort to speed up the reclamation of quota, this is now\ndone in key_put() once the key\u0027s usage is reduced to 0 - but now the code\nis looking at the key after the deadline, which is forbidden.\n\nFix this by using a flag to indicate that a key can be gc\u0027d now rather than\nlooking at the key\u0027s refcount in the garbage collector.",
  "id": "GHSA-prxc-p2g7-m92v",
  "modified": "2025-03-31T21:32:48Z",
  "published": "2025-03-31T21:32:48Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21893"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6afe2ea2daec156bd94ad2c5a6f4f4c48240dcd3"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/75845c6c1a64483e9985302793dbf0dfa5f71e32"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f6a3cf833188e897c97028cd7b926e3f2cb1a8c0"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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