FKIE_CVE-2026-63892

Vulnerability from fkie_nvd - Published: 2026-07-19 16:17 - Updated: 2026-07-27 17:44
Severity
Summary
In the Linux kernel, the following vulnerability has been resolved: thunderbolt: property: Reject dir_len < 4 to prevent size_t underflow On the non-root path, __tb_property_parse_dir() takes dir_len from entry->length (u16 widened to size_t). Two distinct OOB conditions follow when entry->length < 4: 1. The non-root path begins with kmemdup(&block[dir_offset], sizeof(*dir->uuid), ...) which always reads 4 dwords from dir_offset. tb_property_entry_valid() only enforces dir_offset + entry->length <= block_len, so a crafted entry with dir_offset close to the end of the property block and entry->length in 0..3 passes that gate but lets the UUID copy run off the block (e.g. dir_offset = 497, dir_len = 3 in a 500-dword block reads block[497..501]). 2. After the kmemdup, content_len = dir_len - 4 underflows size_t to ~SIZE_MAX, nentries becomes SIZE_MAX / 4, and the entry walk runs OOB on each iteration until an entry fails validation or the kernel oopses on an unmapped page. Reject dir_len < 4 on the non-root path *before* the UUID kmemdup, which closes both holes. Also move INIT_LIST_HEAD(&dir->properties) up to immediately after the dir allocation so the new error-return path (and the existing uuid-alloc failure path) calling tb_property_free_dir() sees a walkable list rather than the zero-initialized NULL next/prev that list_for_each_entry_safe() would oops on.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/37abc4504fa19d8f9f1e87792e8a2b8fdb308e40
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/3bec49ca55e08fb085cc4318f24b1b37eaab28cb
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/542a13890b742099c461d70920e97b14e568f6ec
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5506c825f14d810f0690b1f4367cb7249ebb387a
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d548179adcc87e1bc66b17e00352a1f536e76065
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/de21b59c29e31c5108ddc04210631bbfab81b997
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/de618299190b418291609e6921557253bd417e25
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/e2d4d51cf5785815fa4e91e0c019e3eb2506a84c
Impacted products
Vendor Product Version
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{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/thunderbolt/property.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "37abc4504fa19d8f9f1e87792e8a2b8fdb308e40",
              "status": "affected",
              "version": "cdae7c07e3e3509eaabc18c1640a55dc5b99c179",
              "versionType": "git"
            },
            {
              "lessThan": "e2d4d51cf5785815fa4e91e0c019e3eb2506a84c",
              "status": "affected",
              "version": "cdae7c07e3e3509eaabc18c1640a55dc5b99c179",
              "versionType": "git"
            },
            {
              "lessThan": "de618299190b418291609e6921557253bd417e25",
              "status": "affected",
              "version": "cdae7c07e3e3509eaabc18c1640a55dc5b99c179",
              "versionType": "git"
            },
            {
              "lessThan": "5506c825f14d810f0690b1f4367cb7249ebb387a",
              "status": "affected",
              "version": "cdae7c07e3e3509eaabc18c1640a55dc5b99c179",
              "versionType": "git"
            },
            {
              "lessThan": "542a13890b742099c461d70920e97b14e568f6ec",
              "status": "affected",
              "version": "cdae7c07e3e3509eaabc18c1640a55dc5b99c179",
              "versionType": "git"
            },
            {
              "lessThan": "d548179adcc87e1bc66b17e00352a1f536e76065",
              "status": "affected",
              "version": "cdae7c07e3e3509eaabc18c1640a55dc5b99c179",
              "versionType": "git"
            },
            {
              "lessThan": "3bec49ca55e08fb085cc4318f24b1b37eaab28cb",
              "status": "affected",
              "version": "cdae7c07e3e3509eaabc18c1640a55dc5b99c179",
              "versionType": "git"
            },
            {
              "lessThan": "de21b59c29e31c5108ddc04210631bbfab81b997",
              "status": "affected",
              "version": "cdae7c07e3e3509eaabc18c1640a55dc5b99c179",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/thunderbolt/property.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.15"
            },
            {
              "lessThan": "4.15",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.10.*",
              "status": "unaffected",
              "version": "5.10.259",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "5.15.*",
              "status": "unaffected",
              "version": "5.15.210",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.1.*",
              "status": "unaffected",
              "version": "6.1.176",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.143",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.93",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.18.*",
              "status": "unaffected",
              "version": "6.18.35",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "7.0.*",
              "status": "unaffected",
              "version": "7.0.12",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.1",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nthunderbolt: property: Reject dir_len \u003c 4 to prevent size_t underflow\n\nOn the non-root path, __tb_property_parse_dir() takes dir_len from\nentry-\u003elength (u16 widened to size_t).  Two distinct OOB conditions\nfollow when entry-\u003elength \u003c 4:\n\n1. The non-root path begins with kmemdup(\u0026block[dir_offset],\n   sizeof(*dir-\u003euuid), ...) which always reads 4 dwords from\n   dir_offset.  tb_property_entry_valid() only enforces\n   dir_offset + entry-\u003elength \u003c= block_len, so a crafted entry\n   with dir_offset close to the end of the property block and\n   entry-\u003elength in 0..3 passes that gate but lets the UUID copy\n   run off the block (e.g. dir_offset = 497, dir_len = 3 in a\n   500-dword block reads block[497..501]).\n\n2. After the kmemdup, content_len = dir_len - 4 underflows size_t\n   to ~SIZE_MAX, nentries becomes SIZE_MAX / 4, and the entry\n   walk runs OOB on each iteration until an entry fails\n   validation or the kernel oopses on an unmapped page.\n\nReject dir_len \u003c 4 on the non-root path *before* the UUID kmemdup,\nwhich closes both holes.\n\nAlso move INIT_LIST_HEAD(\u0026dir-\u003eproperties) up to immediately after\nthe dir allocation so the new error-return path (and the existing\nuuid-alloc failure path) calling tb_property_free_dir() sees a\nwalkable list rather than the zero-initialized NULL next/prev that\nlist_for_each_entry_safe() would oops on."
    }
  ],
  "id": "CVE-2026-63892",
  "lastModified": "2026-07-27T17:44:23.777",
  "metrics": {},
  "published": "2026-07-19T16:17:06.577",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/37abc4504fa19d8f9f1e87792e8a2b8fdb308e40"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/3bec49ca55e08fb085cc4318f24b1b37eaab28cb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/542a13890b742099c461d70920e97b14e568f6ec"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/5506c825f14d810f0690b1f4367cb7249ebb387a"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/d548179adcc87e1bc66b17e00352a1f536e76065"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/de21b59c29e31c5108ddc04210631bbfab81b997"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/de618299190b418291609e6921557253bd417e25"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "url": "https://git.kernel.org/stable/c/e2d4d51cf5785815fa4e91e0c019e3eb2506a84c"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Awaiting Analysis"
}



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