GHSA-WG7V-626P-H26R

Vulnerability from github – Published: 2025-03-12 12:30 – Updated: 2026-05-12 15:30
VLAI
Details

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

acct: perform last write from workqueue

In [1] it was reported that the acct(2) system call can be used to trigger NULL deref in cases where it is set to write to a file that triggers an internal lookup. This can e.g., happen when pointing acc(2) to /sys/power/resume. At the point the where the write to this file happens the calling task has already exited and called exit_fs(). A lookup will thus trigger a NULL-deref when accessing current->fs.

Reorganize the code so that the the final write happens from the workqueue but with the caller's credentials. This preserves the (strange) permission model and has almost no regression risk.

This api should stop to exist though.

Severity
5.5 (Medium)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2025-21846"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-476"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2025-03-12T10:15:16Z",
    "severity": "MODERATE"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nacct: perform last write from workqueue\n\nIn [1] it was reported that the acct(2) system call can be used to\ntrigger NULL deref in cases where it is set to write to a file that\ntriggers an internal lookup. This can e.g., happen when pointing acc(2)\nto /sys/power/resume. At the point the where the write to this file\nhappens the calling task has already exited and called exit_fs(). A\nlookup will thus trigger a NULL-deref when accessing current-\u003efs.\n\nReorganize the code so that the the final write happens from the\nworkqueue but with the caller\u0027s credentials. This preserves the\n(strange) permission model and has almost no regression risk.\n\nThis api should stop to exist though.",
  "id": "GHSA-wg7v-626p-h26r",
  "modified": "2026-05-12T15:30:50Z",
  "published": "2025-03-12T12:30:58Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2025-21846"
    },
    {
      "type": "WEB",
      "url": "https://cert-portal.siemens.com/productcert/html/ssa-265688.html"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/56d5f3eba3f5de0efdd556de4ef381e109b973a9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5a59ced8ffc71973d42c82484a719c8f6ac8f7f7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5c928e14a2ccd99462f2351ead627b58075bb736"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5d5b936cfa4b0d5670ca7420ef165a074bc008eb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/5ee8da9bea70dda492d61f075658939af33d8410"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/8acbf4a88c6a98c8ed00afd1a7d1abcca9b4735e"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a8136afca090412a36429cb6c2543c714d9c0f84"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b03782ae707cc45e65242c7cddd8e28f1c22cde5"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00030.html"
    },
    {
      "type": "WEB",
      "url": "https://lists.debian.org/debian-lts-announce/2025/05/msg00045.html"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ]
}


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