FKIE_CVE-2026-45892

Vulnerability from fkie_nvd - Published: 2026-05-27 14:17 - Updated: 2026-06-25 21:11
Severity
5.5 (Medium) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Summary
In the Linux kernel, the following vulnerability has been resolved: ext4: drop extent cache after doing PARTIAL_VALID1 zeroout When splitting an unwritten extent in the middle and converting it to initialized in ext4_split_extent() with the EXT4_EXT_MAY_ZEROOUT and EXT4_EXT_DATA_VALID2 flags set, it could leave a stale unwritten extent. Assume we have an unwritten file and buffered write in the middle of it without dioread_nolock enabled, it will allocate blocks as written extent. 0 A B N [UUUUUUUUUUUU] on-disk extent U: unwritten extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDD--] D: valid data |<- ->| ----> this range needs to be initialized ext4_split_extent() first try to split this extent at B with EXT4_EXT_DATA_PARTIAL_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but ext4_split_extent_at() failed to split this extent due to temporary lack of space. It zeroout B to N and leave the entire extent as unwritten. 0 A B N [UUUUUUUUUUUU] on-disk extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDDZZ] Z: zeroed data ext4_split_extent() then try to split this extent at A with EXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and leave an written extent from A to N. 0 A B N [UUWWWWWWWWWW] on-disk extent W: written extent [UUUUUUUUUUUU] extent status tree [--DDDDDDDDZZ] Finally ext4_map_create_blocks() only insert extent A to B to the extent status tree, and leave an stale unwritten extent in the status tree. 0 A B N [UUWWWWWWWWWW] on-disk extent W: written extent [UUWWWWWWWWUU] extent status tree [--DDDDDDDDZZ] Fix this issue by always cached extent status entry after zeroing out the second part.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/28db4bfc6f82fd20e2aadb7fc162244109a4eb31Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/6d882ea3b0931b43530d44149b79fcd4ffc13030Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/a1b962a821e7a52d48212ae269b45808b4411267Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/c2ee51d684adca7645e4aa74adca13f6750390bcPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/d8ee559fccdef713f058cfe5f2c03dc9b18be3b1Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/f0931a5c17005a0c4fc35bd1a001245effc3354bPatch
Impacted products
Vendor Product Version
linux linux_kernel 6.1.167
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ext4/extents.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "28db4bfc6f82fd20e2aadb7fc162244109a4eb31",
              "status": "affected",
              "version": "ddf854e59166533b0f46ba32cd6cd9aca3197d1b",
              "versionType": "git"
            },
            {
              "lessThan": "f0931a5c17005a0c4fc35bd1a001245effc3354b",
              "status": "affected",
              "version": "58ddae5d77b1db3a27b891c75a8fa120239ac092",
              "versionType": "git"
            },
            {
              "lessThan": "d8ee559fccdef713f058cfe5f2c03dc9b18be3b1",
              "status": "affected",
              "version": "d17857b4fb9ba5745b59be0ef38fd532991fccbf",
              "versionType": "git"
            },
            {
              "lessThan": "c2ee51d684adca7645e4aa74adca13f6750390bc",
              "status": "affected",
              "version": "d67c8ecf3d8fda9b8ef80e6f665d84b6d6ac9d88",
              "versionType": "git"
            },
            {
              "lessThan": "a1b962a821e7a52d48212ae269b45808b4411267",
              "status": "affected",
              "version": "7015fcf473796e1d2d876f241bd9e0c36f3d4eef",
              "versionType": "git"
            },
            {
              "lessThan": "6d882ea3b0931b43530d44149b79fcd4ffc13030",
              "status": "affected",
              "version": "1bf6974822d1dba86cf11b5f05498581cf3488a2",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "fs/ext4/extents.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "6.1.168",
              "status": "affected",
              "version": "6.1.167",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:6.1.167:*:*:*:*:*:*:*",
              "matchCriteriaId": "B898A4FB-4E74-40F7-B523-B71FFB681B6D",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: drop extent cache after doing PARTIAL_VALID1 zeroout\n\nWhen splitting an unwritten extent in the middle and converting it to\ninitialized in ext4_split_extent() with the EXT4_EXT_MAY_ZEROOUT and\nEXT4_EXT_DATA_VALID2 flags set, it could leave a stale unwritten extent.\n\nAssume we have an unwritten file and buffered write in the middle of it\nwithout dioread_nolock enabled, it will allocate blocks as written\nextent.\n\n       0  A      B  N\n       [UUUUUUUUUUUU] on-disk extent      U: unwritten extent\n       [UUUUUUUUUUUU] extent status tree\n       [--DDDDDDDD--]                     D: valid data\n          |\u003c-  -\u003e| ----\u003e this range needs to be initialized\n\next4_split_extent() first try to split this extent at B with\nEXT4_EXT_DATA_PARTIAL_VALID1 and EXT4_EXT_MAY_ZEROOUT flag set, but\next4_split_extent_at() failed to split this extent due to temporary lack\nof space. It zeroout B to N and leave the entire extent as unwritten.\n\n       0  A      B  N\n       [UUUUUUUUUUUU] on-disk extent\n       [UUUUUUUUUUUU] extent status tree\n       [--DDDDDDDDZZ]                     Z: zeroed data\n\next4_split_extent() then try to split this extent at A with\nEXT4_EXT_DATA_VALID2 flag set. This time, it split successfully and\nleave an written extent from A to N.\n\n       0  A      B  N\n       [UUWWWWWWWWWW] on-disk extent      W: written extent\n       [UUUUUUUUUUUU] extent status tree\n       [--DDDDDDDDZZ]\n\nFinally ext4_map_create_blocks() only insert extent A to B to the extent\nstatus tree, and leave an stale unwritten extent in the status tree.\n\n       0  A      B  N\n       [UUWWWWWWWWWW] on-disk extent      W: written extent\n       [UUWWWWWWWWUU] extent status tree\n       [--DDDDDDDDZZ]\n\nFix this issue by always cached extent status entry after zeroing out\nthe second part."
    }
  ],
  "id": "CVE-2026-45892",
  "lastModified": "2026-06-25T21:11:06.653",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 5.5,
          "baseSeverity": "MEDIUM",
          "confidentialityImpact": "NONE",
          "integrityImpact": "NONE",
          "privilegesRequired": "LOW",
          "scope": "UNCHANGED",
          "userInteraction": "NONE",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 3.6,
        "source": "nvd@nist.gov",
        "type": "Primary"
      }
    ]
  },
  "published": "2026-05-27T14:17:03.353",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/28db4bfc6f82fd20e2aadb7fc162244109a4eb31"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/6d882ea3b0931b43530d44149b79fcd4ffc13030"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/a1b962a821e7a52d48212ae269b45808b4411267"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/c2ee51d684adca7645e4aa74adca13f6750390bc"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/d8ee559fccdef713f058cfe5f2c03dc9b18be3b1"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/f0931a5c17005a0c4fc35bd1a001245effc3354b"
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "NVD-CWE-noinfo"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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