GHSA-HVV2-RWWX-6Q3H

Vulnerability from github – Published: 2026-07-27 09:31 – Updated: 2026-07-30 06:32
VLAI
Details

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

fs/ntfs3: validate lcns_follow in log_replay conversion

log_replay() converts DIR_PAGE_ENTRY_32 records into DIR_PAGE_ENTRY records when replaying version 0 restart tables.

During this conversion, the memmove() length is derived directly from the on-disk lcns_follow field:

memmove(&dp->vcn, &dp0->vcn_low,
    2 * sizeof(u64) +
            le32_to_cpu(dp->lcns_follow) * sizeof(u64));

check_rstbl() validates restart table structure, but does not constrain per-entry lcns_follow values relative to the entry size. A malformed filesystem image can provide an oversized lcns_follow value, causing the conversion memmove() to access memory beyond the bounds of the allocated restart table buffer.

The same field is later used to bound iteration over page_lcns[], so validating lcns_follow during conversion also prevents downstream out-of-bounds access from the same malformed metadata.

Compute the maximum valid lcns_follow from the already-validated restart table entry size and reject entries that exceed this bound. Reuse the existing t16/t32 scratch variables already declared in log_replay() to avoid introducing new declarations.

[almaz.alexandrovich@paragon-software.com: fixed the conflicts]

Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
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{
  "affected": [],
  "aliases": [
    "CVE-2026-64533"
  ],
  "database_specific": {
    "cwe_ids": [],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-07-27T08:16:22Z",
    "severity": "HIGH"
  },
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nfs/ntfs3: validate lcns_follow in log_replay conversion\n\nlog_replay() converts DIR_PAGE_ENTRY_32 records into DIR_PAGE_ENTRY\nrecords when replaying version 0 restart tables.\n\nDuring this conversion, the memmove() length is derived directly from\nthe on-disk lcns_follow field:\n\n\tmemmove(\u0026dp-\u003evcn, \u0026dp0-\u003evcn_low,\n\t\t2 * sizeof(u64) +\n\t\t\t\tle32_to_cpu(dp-\u003elcns_follow) * sizeof(u64));\n\ncheck_rstbl() validates restart table structure, but does not constrain\nper-entry lcns_follow values relative to the entry size. A malformed\nfilesystem image can provide an oversized lcns_follow value, causing\nthe conversion memmove() to access memory beyond the bounds of the\nallocated restart table buffer.\n\nThe same field is later used to bound iteration over page_lcns[],\nso validating lcns_follow during conversion also prevents downstream\nout-of-bounds access from the same malformed metadata.\n\nCompute the maximum valid lcns_follow from the already-validated\nrestart table entry size and reject entries that exceed this bound.\nReuse the existing t16/t32 scratch variables already declared in\nlog_replay() to avoid introducing new declarations.\n\n[almaz.alexandrovich@paragon-software.com: fixed the conflicts]",
  "id": "GHSA-hvv2-rwwx-6q3h",
  "modified": "2026-07-30T06:32:32Z",
  "published": "2026-07-27T09:31:26Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64533"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/159f694d682e4215b3822ae31ed3a4631628fe55"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/32b9f8733feb241627fa5f564b1a99b5cae974c5"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/57c071e2c4f30b9c6f5aacb6679aab1269fbae99"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/6a4c53a2e26a865565bd6a460961e8d6fcb32329"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/7adb38279812c9c06b0e3fa7382f4d7887f3fa2d"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ca343a99806b4fc8e27c48f08be3445c5fcd1445"
    },
    {
      "type": "WEB",
      "url": "https://git.kernel.org/stable/c/ddfc8683e1a627dbf1b83bacf8961443dd654258"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ]
}



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