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CVE-2025-38220

Estado: AnalizadaMedia (5.5)—

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

ext4: only dirty folios when data journaling regular files

fstest generic/388 occasionally reproduces a crash that looks as follows:

This occurs when processing a symlink inode from the orphan list. The partial block zeroing code in the truncate path calls ext4_dirty_journalled_data() -> folio_mark_dirty(). The latter calls mapping->a_ops->dirty_folio(), but symlink inodes are not assigned an a_ops vector in ext4, hence the crash.

To avoid this problem, update the ext4_dirty_journalled_data() helper to only mark the folio dirty on regular files (for which a_ops is assigned). This also matches the journaling logic in the ext4_symlink() creation path, where ext4_handle_dirty_metadata() is called directly.

Detalles técnicos trazas, registros y código del informe original
BUG: kernel NULL pointer dereference, address: 0000000000000000
...
Call Trace:
 <TASK>
 ext4_block_zero_page_range+0x30c/0x380 [ext4]
 ext4_truncate+0x436/0x440 [ext4]
 ext4_process_orphan+0x5d/0x110 [ext4]
 ext4_orphan_cleanup+0x124/0x4f0 [ext4]
 ext4_fill_super+0x262d/0x3110 [ext4]
 get_tree_bdev_flags+0x132/0x1d0
 vfs_get_tree+0x26/0xd0
 vfs_cmd_create+0x59/0xe0
 __do_sys_fsconfig+0x4ed/0x6b0
 do_syscall_64+0x82/0x170
 ...

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

Tecnologías afectadas (1)

Linux — Linux Kernel

CWE

Referencias

JSON original (NVD)

Mostrar
{
  "id": "CVE-2025-38220",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 5.5,
          "attackVector": "LOCAL",
          "baseSeverity": "MEDIUM",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
          "integrityImpact": "NONE",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "NONE"
        },
        "impactScore": 3.6,
        "exploitabilityScore": 1.8
      }
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              "version": "6.15.4",
              "versionType": "semver",
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            },
            {
              "status": "unaffected",
              "version": "6.16",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/ext4/inode.c"
          ],
          "defaultStatus": "affected"
        }
      ]
    }
  ],
  "published": "2025-07-04T14:15:30.597",
  "references": [
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      "url": "https://git.kernel.org/stable/c/be5f3061a6f904e3674257879e71881ceee5b673",
      "tags": [
        "Patch"
      ],
      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
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  "vulnStatus": "Analyzed",
  "weaknesses": [
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      "type": "Primary",
      "source": "nvd@nist.gov",
      "description": [
        {
          "lang": "en",
          "value": "CWE-476"
        }
      ]
    }
  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: only dirty folios when data journaling regular files\n\nfstest generic/388 occasionally reproduces a crash that looks as\nfollows:\n\nBUG: kernel NULL pointer dereference, address: 0000000000000000\n...\nCall Trace:\n <TASK>\n ext4_block_zero_page_range+0x30c/0x380 [ext4]\n ext4_truncate+0x436/0x440 [ext4]\n ext4_process_orphan+0x5d/0x110 [ext4]\n ext4_orphan_cleanup+0x124/0x4f0 [ext4]\n ext4_fill_super+0x262d/0x3110 [ext4]\n get_tree_bdev_flags+0x132/0x1d0\n vfs_get_tree+0x26/0xd0\n vfs_cmd_create+0x59/0xe0\n __do_sys_fsconfig+0x4ed/0x6b0\n do_syscall_64+0x82/0x170\n ...\n\nThis occurs when processing a symlink inode from the orphan list. The\npartial block zeroing code in the truncate path calls\next4_dirty_journalled_data() -> folio_mark_dirty(). The latter calls\nmapping->a_ops->dirty_folio(), but symlink inodes are not assigned an\na_ops vector in ext4, hence the crash.\n\nTo avoid this problem, update the ext4_dirty_journalled_data() helper to\nonly mark the folio dirty on regular files (for which a_ops is\nassigned). This also matches the journaling logic in the ext4_symlink()\ncreation path, where ext4_handle_dirty_metadata() is called directly."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: solo folios sucios cuando se registran datos de archivos normales fstest generic/388 ocasionalmente reproduce un fallo que se parece a lo siguiente: ERROR: desreferencia de puntero NULL del kernel, dirección: 0000000000000000 ... Seguimiento de llamadas: ext4_block_zero_page_range+0x30c/0x380 [ext4] ext4_truncate+0x436/0x440 [ext4] ext4_process_orphan+0x5d/0x110 [ext4] ext4_orphan_cleanup+0x124/0x4f0 [ext4] ext4_fill_super+0x262d/0x3110 [ext4] get_tree_bdev_flags+0x132/0x1d0 vfs_get_tree+0x26/0xd0 vfs_cmd_create+0x59/0xe0 __do_sys_fsconfig+0x4ed/0x6b0 do_syscall_64+0x82/0x170 ... Esto ocurre al procesar un inodo de enlace simbólico de la lista de huérfanos. El código de puesta a cero parcial de bloques en la ruta de truncamiento llama a ext4_dirty_journalled_data() -&gt; folio_mark_dirty(). Este último llama a mapping-&gt;a_ops-&gt;dirty_folio(), pero los inodos de enlace simbólico no tienen asignado un vector a_ops en ext4, lo que explica el fallo. Para evitar este problema, actualice el asistente ext4_dirty_journalled_data() para que solo marque el folio como sucio en archivos normales (para los que se asigna a_ops). Esto también coincide con la lógica de registro en la ruta de creación de ext4_symlink(), donde se llama directamente a ext4_handle_dirty_metadata()."
    }
  ],
  "lastModified": "2026-06-17T09:16:24.937",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
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              "versionEndExcluding": "6.6.95",
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            },
            {
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              "versionEndExcluding": "6.12.35",
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              "matchCriteriaId": "DFD174C5-1AA2-4671-BDDC-1A9FCC753655",
              "versionEndExcluding": "6.15.4",
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          ],
          "operator": "OR"
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  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}