GHSA-6P99-W6F4-QCVQ

Vulnerability from github – Published: 2026-07-23 06:32 – Updated: 2026-08-03 21:31
VLAI
Details

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

xfs: resample the data fork mapping after cycling ILOCK

xfs_reflink_fill_{cow_hole,delalloc} are both presented with an inode, a data fork mapping, and a cow fork mapping. Unfortunately, these two helpers cycle the ILOCK to grab a transaction, which means that the mappings are stale as soon as we reacquire the ILOCK. Currently we refresh the cow fork mapping by re-calling xfs_find_trim_cow_extent, but we don't refresh the data fork mapping beforehand, which means that the xfs_bmap_trim_cow in that function queries the refcount btree about the wrong physical blocks and returns an inaccurate value in *shared.

If *shared is now false, the directio write proceeds with a stale data fork mapping. Fix this by querying the data fork mapping if the sequence counter changes across the ILOCK cycle.

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-2026-64600"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-362"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-23T06:16:50Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nxfs: resample the data fork mapping after cycling ILOCK\n\nxfs_reflink_fill_{cow_hole,delalloc} are both presented with an inode,\na data fork mapping, and a cow fork mapping.  Unfortunately, these two\nhelpers cycle the ILOCK to grab a transaction, which means that the\nmappings are stale as soon as we reacquire the ILOCK.  Currently we\nrefresh the cow fork mapping by re-calling xfs_find_trim_cow_extent, but\nwe don\u0027t refresh the data fork mapping beforehand, which means that the\nxfs_bmap_trim_cow in that function queries the refcount btree about the\nwrong physical blocks and returns an inaccurate value in *shared.\n\nIf *shared is now false, the directio write proceeds with a stale data\nfork mapping.  Fix this by querying the data fork mapping if the\nsequence counter changes across the ILOCK cycle.",
  "id": "GHSA-6p99-w6f4-qcvq",
  "modified": "2026-08-03T21:31:28Z",
  "published": "2026-07-23T06:32:13Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64600"
    },
    {
      "type": "WEB",
      "url": "https://cdn2.qualys.com/advisory/2026/07/22/RefluXFS.txt"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/206c09b04dc5469c7ff14d8aceff2d47c88078d9"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/2f4acd0fcd862e22eab45690ec2c08c80b6ef2e7"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/44f891bc088958399eec27f7604928694aa35581"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/50f0012da1040f69a4e788cd9aed587c9a04983f"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/b8c9aa832b52680ee40d6cab0efb081f9a69df05"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/dc11be133efca5fe3a2fb02b016dee825cc12f18"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/e705d81a7193dd19e69b8e2bad4696d78a4ea075"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/07/22/14"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/07/22/18"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/07/22/19"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/07/31/3"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/08/03/4"
    },
    {
      "type": "WEB",
      "url": "http://www.openwall.com/lists/oss-security/2026/08/03/8"
    }
  ],
  "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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