FKIE_CVE-2025-38709

Vulnerability from fkie_nvd - Published: 2025-09-04 16:15 - Updated: 2026-10-19 21:10
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: loop: Avoid updating block size under exclusive owner Syzbot came up with a reproducer where a loop device block size is changed underneath a mounted filesystem. This causes a mismatch between the block device block size and the block size stored in the superblock causing confusion in various places such as fs/buffer.c. The particular issue triggered by syzbot was a warning in __getblk_slow() due to requested buffer size not matching block device block size. Fix the problem by getting exclusive hold of the loop device to change its block size. This fails if somebody (such as filesystem) has already an exclusive ownership of the block device and thus prevents modifying the loop device under some exclusive owner which doesn't expect it.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/139a000d20f2f38ce34296feddd641d730fe1c08Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/457d2c5e112fd08dc1039b1ae39a83ec1782360dPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/5d67b30aefeb7a949040bbb1b4e3b84c5d29a624Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/7e49538288e523427beedd26993d446afef1a6fbPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/b928438cc87c0bf7ae078e4b7b6e14261e84c5c5Patch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
linux linux_kernel *
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "drivers/block/loop.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "lessThan": "457d2c5e112fd08dc1039b1ae39a83ec1782360d",
              "status": "affected",
              "version": "89e4fdecb51cf5535867026274bc97de9480ade5",
              "versionType": "git"
            },
            {
              "lessThan": "139a000d20f2f38ce34296feddd641d730fe1c08",
              "status": "affected",
              "version": "89e4fdecb51cf5535867026274bc97de9480ade5",
              "versionType": "git"
            },
            {
              "lessThan": "b928438cc87c0bf7ae078e4b7b6e14261e84c5c5",
              "status": "affected",
              "version": "89e4fdecb51cf5535867026274bc97de9480ade5",
              "versionType": "git"
            },
            {
              "lessThan": "5d67b30aefeb7a949040bbb1b4e3b84c5d29a624",
              "status": "affected",
              "version": "89e4fdecb51cf5535867026274bc97de9480ade5",
              "versionType": "git"
            },
            {
              "lessThan": "7e49538288e523427beedd26993d446afef1a6fb",
              "status": "affected",
              "version": "89e4fdecb51cf5535867026274bc97de9480ade5",
              "versionType": "git"
            }
          ]
        },
        {
          "defaultStatus": "affected",
          "product": "Linux",
          "programFiles": [
            "drivers/block/loop.c"
          ],
          "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
          "vendor": "Linux",
          "versions": [
            {
              "status": "affected",
              "version": "4.14"
            },
            {
              "lessThan": "4.14",
              "status": "unaffected",
              "version": "0",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.6.*",
              "status": "unaffected",
              "version": "6.6.109",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.12.*",
              "status": "unaffected",
              "version": "6.12.43",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.15.*",
              "status": "unaffected",
              "version": "6.15.11",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "6.16.*",
              "status": "unaffected",
              "version": "6.16.2",
              "versionType": "semver"
            },
            {
              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "6.17",
              "versionType": "original_commit_for_fix"
            }
          ]
        }
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "9287A2A2-253D-4FC0-8D89-A750A3B30239",
              "versionEndExcluding": "6.6.109",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "472C5F87-2BF3-4FAB-9B21-DA7513977363",
              "versionEndExcluding": "6.12.43",
              "versionStartIncluding": "6.7",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "BC242347-F722-43AE-B910-BE0B22386977",
              "versionEndExcluding": "6.15.11",
              "versionStartIncluding": "6.13",
              "vulnerable": true
            },
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "matchCriteriaId": "BD7C087D-2415-4521-B624-30003352F899",
              "versionEndExcluding": "6.16.2",
              "versionStartIncluding": "6.16",
              "vulnerable": true
            }
          ],
          "negate": false,
          "operator": "OR"
        }
      ]
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nloop: Avoid updating block size under exclusive owner\n\nSyzbot came up with a reproducer where a loop device block size is\nchanged underneath a mounted filesystem. This causes a mismatch between\nthe block device block size and the block size stored in the superblock\ncausing confusion in various places such as fs/buffer.c. The particular\nissue triggered by syzbot was a warning in __getblk_slow() due to\nrequested buffer size not matching block device block size.\n\nFix the problem by getting exclusive hold of the loop device to change\nits block size. This fails if somebody (such as filesystem) has already\nan exclusive ownership of the block device and thus prevents modifying\nthe loop device under some exclusive owner which doesn\u0027t expect it."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, la siguiente vulnerabilidad ha sido resuelta:\n\nloop: Evitar actualizar el tama\u00f1o de bloque bajo propietario exclusivo\n\nSyzbot encontr\u00f3 un reproductor donde el tama\u00f1o de bloque de un dispositivo loop es cambiado bajo un sistema de archivos montado. Esto causa un desajuste entre el tama\u00f1o de bloque del dispositivo de bloques y el tama\u00f1o de bloque almacenado en el superbloque, causando confusi\u00f3n en varios lugares como fs/buffer.c. El problema particular desencadenado por syzbot fue una advertencia en __getblk_slow() debido a que el tama\u00f1o de b\u00fafer solicitado no coincid\u00eda con el tama\u00f1o de bloque del dispositivo de bloques.\n\nSolucionar el problema adquiriendo un control exclusivo del dispositivo loop para cambiar su tama\u00f1o de bloque. Esto falla si alguien (como un sistema de archivos) ya tiene una propiedad exclusiva del dispositivo de bloques y, por lo tanto, evita modificar el dispositivo loop bajo alg\u00fan propietario exclusivo que no lo espera."
    }
  ],
  "id": "CVE-2025-38709",
  "lastModified": "2026-10-19T21:10:00.160",
  "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": "2025-09-04T16:15:39.997",
  "references": [
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/139a000d20f2f38ce34296feddd641d730fe1c08"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/457d2c5e112fd08dc1039b1ae39a83ec1782360d"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/5d67b30aefeb7a949040bbb1b4e3b84c5d29a624"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/7e49538288e523427beedd26993d446afef1a6fb"
    },
    {
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
        "Patch"
      ],
      "url": "https://git.kernel.org/stable/c/b928438cc87c0bf7ae078e4b7b6e14261e84c5c5"
    }
  ],
  "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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