GHSA-4MM9-H7GJ-362G

Vulnerability from github – Published: 2026-07-24 18:31 – Updated: 2026-07-27 06:30
VLAI
Details

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

pwrseq: core: fix use-after-free in pwrseq_debugfs_seq_next()

pwrseq_debugfs_seq_next() declares 'next' with __free(put_device), which causes put_device() to be called on the returned pointer when the variable goes out of scope. This results in a use-after-free since the seq_file framework receives a pointer whose reference has already been dropped.

Simply removing __free(put_device) would fix the UAF but would leak the reference acquired by bus_find_next_device(), as stop() only calls up_read(&pwrseq_sem) and never releases the device reference.

Fix this by making the reference counting consistent across all seq_file callbacks, matching the standard pattern used by PCI and SCSI:

  • start(): use get_device() so it returns a referenced pointer.
  • next(): explicitly put_device(curr) to release the previous device's reference (no NULL check needed - the seq_file framework only calls next() while the previous return was non-NULL).
  • stop(): put_device(data) to release the last iterated device's reference, with a NULL guard since stop() may be called with NULL when start() returned NULL or next() reached end-of-sequence.
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64251"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-24T16:16:54Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\npwrseq: core: fix use-after-free in pwrseq_debugfs_seq_next()\n\npwrseq_debugfs_seq_next() declares \u0027next\u0027 with __free(put_device),\nwhich causes put_device() to be called on the returned pointer when\nthe variable goes out of scope.  This results in a use-after-free\nsince the seq_file framework receives a pointer whose reference has\nalready been dropped.\n\nSimply removing __free(put_device) would fix the UAF but would leak\nthe reference acquired by bus_find_next_device(), as stop() only\ncalls up_read(\u0026pwrseq_sem) and never releases the device reference.\n\nFix this by making the reference counting consistent across all\nseq_file callbacks, matching the standard pattern used by PCI and\nSCSI:\n\n- start(): use get_device() so it returns a referenced pointer.\n- next(): explicitly put_device(curr) to release the previous\n  device\u0027s reference (no NULL check needed - the seq_file framework\n  only calls next() while the previous return was non-NULL).\n- stop(): put_device(data) to release the last iterated device\u0027s\n  reference, with a NULL guard since stop() may be called with NULL\n  when start() returned NULL or next() reached end-of-sequence.",
  "id": "GHSA-4mm9-h7gj-362g",
  "modified": "2026-07-27T06:30:30Z",
  "published": "2026-07-24T18:31:29Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64251"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/257595adf9dac15ae1edd9d07753fbc576a7583d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/73569a44fca2992f0ca4a4c0104069741b9873a0"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ba0b9f04c7a5f9887b8ce672eaf049502c0548ec"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e91df6d273445c03f5aa302bfe147eda33d45794"
    }
  ],
  "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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