GHSA-FW9C-WXJQ-5W67

Vulnerability from github – Published: 2026-08-27 06:31 – Updated: 2026-08-27 06:31
VLAI
Details

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

s390/vfio_ccw: Fix out of bounds check on CCW array

The routine ccwchain_calc_length() counts the number of channel command words (CCWs) that are chained together in a single channel program, and rejects anything larger than CCWCHAIN_LEN_MAX (256) CCWs.

The loop itself is "do..while (count < 257)", and while the logic in is_cpa_within_range() correctly adjusts between the 0-index array of CCWs and the count of CCWs starting at 1, this means it would look at a possible 257th CCW before ending the loop and (correctly) returning an error.

Fix this by restructuring the loop to break as soon as 256 CCWs (thus indexes 0-255) are examined, without looking at memory outside the range.

Severity
7.9 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L
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{
  "affected": [],
  "aliases": [
    "CVE-2026-80550"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-08-26T15:17:09Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\ns390/vfio_ccw: Fix out of bounds check on CCW array\n\nThe routine ccwchain_calc_length() counts the number of channel\ncommand words (CCWs) that are chained together in a single channel\nprogram, and rejects anything larger than CCWCHAIN_LEN_MAX (256) CCWs.\n\nThe loop itself is \"do..while (count \u003c 257)\", and while the logic in\nis_cpa_within_range() correctly adjusts between the 0-index array of\nCCWs and the count of CCWs starting at 1, this means it would look\nat a possible 257th CCW before ending the loop and (correctly)\nreturning an error.\n\nFix this by restructuring the loop to break as soon as 256 CCWs\n(thus indexes 0-255) are examined, without looking at memory\noutside the range.",
  "id": "GHSA-fw9c-wxjq-5w67",
  "modified": "2026-08-27T06:31:32Z",
  "published": "2026-08-27T06:31:32Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-80550"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/0282fb1c4b638eecfe2cc558092c460911d8f7e2"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/499a8a66b1598bfab97182aed15e0f1646074a3d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/4c2e1d359d7a2b82cdf3254e4e480af9417f99fb"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/907adc667d902fafbdb2d740d57b55bd025dc4cd"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/a005b7f1a491ffda61bff0fd0f6548f8986fb977"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/af3f80ca4c8b17f20f9e588def076288fdb49e65"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/d5d096cd9369e986d4e5153baa86b8b35c283e09"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/f20be33d093ce7630c17ff7ed93caf7eaf8ac1a3"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:C/C:H/I:N/A:L",
      "type": "CVSS_V3"
    }
  ]
}



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