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CVE-2024-56549

Estado: ModificadaMedia (5.5)—

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

cachefiles: Fix NULL pointer dereference in object->file

At present, the object->file has the NULL pointer dereference problem in ondemand-mode. The root cause is that the allocated fd and object->file lifetime are inconsistent, and the user-space invocation to anon_fd uses object->file. Following is the process that triggers the issue:

[write fd] [umount] cachefiles_ondemand_fd_write_iter fscache_cookie_state_machine cachefiles_withdraw_cookie if (!file) return -ENOBUFS cachefiles_clean_up_object cachefiles_unmark_inode_in_use fput(object->file) object->file = NULL // file NULL pointer dereference! __cachefiles_write(..., file, ...)

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Fix this issue by add an additional reference count to the object->file before write/llseek, and decrement after it finished.

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)

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{
  "id": "CVE-2024-56549",
  "cveTags": [],
  "metrics": {
    "cvssMetricV31": [
      {
        "type": "Secondary",
        "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "cvssData": {
          "scope": "UNCHANGED",
          "version": "3.1",
          "baseScore": 7.8,
          "attackVector": "LOCAL",
          "baseSeverity": "HIGH",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
          "integrityImpact": "HIGH",
          "userInteraction": "NONE",
          "attackComplexity": "LOW",
          "availabilityImpact": "HIGH",
          "privilegesRequired": "LOW",
          "confidentialityImpact": "HIGH"
        },
        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      },
      {
        "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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          "vendor": "Linux",
          "product": "Linux",
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          ],
          "programFiles": [
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            "fs/cachefiles/ondemand.c"
          ],
          "defaultStatus": "unaffected"
        },
        {
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          "vendor": "Linux",
          "product": "Linux",
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              "version": "0",
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              "versionType": "semver"
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              "version": "6.1.129",
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            },
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              "version": "6.6.78",
              "versionType": "semver",
              "lessThanOrEqual": "6.6.*"
            },
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              "status": "unaffected",
              "version": "6.11.11",
              "versionType": "semver",
              "lessThanOrEqual": "6.11.*"
            },
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              "status": "unaffected",
              "version": "6.12.2",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.13",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
            "fs/cachefiles/interface.c",
            "fs/cachefiles/ondemand.c"
          ],
          "defaultStatus": "affected"
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  ],
  "published": "2024-12-27T14:15:34.747",
  "references": [
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    {
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      "source": "af854a3a-2127-422b-91ae-364da2661108"
    }
  ],
  "vulnStatus": "Modified",
  "weaknesses": [
    {
      "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\ncachefiles: Fix NULL pointer dereference in object->file\n\nAt present, the object->file has the NULL pointer dereference problem in\nondemand-mode. The root cause is that the allocated fd and object->file\nlifetime are inconsistent, and the user-space invocation to anon_fd uses\nobject->file. Following is the process that triggers the issue:\n\n\t  [write fd]\t\t\t\t[umount]\ncachefiles_ondemand_fd_write_iter\n\t\t\t\t       fscache_cookie_state_machine\n\t\t\t\t\t cachefiles_withdraw_cookie\n  if (!file) return -ENOBUFS\n\t\t\t\t\t   cachefiles_clean_up_object\n\t\t\t\t\t     cachefiles_unmark_inode_in_use\n\t\t\t\t\t     fput(object->file)\n\t\t\t\t\t     object->file = NULL\n  // file NULL pointer dereference!\n  __cachefiles_write(..., file, ...)\n\nFix this issue by add an additional reference count to the object->file\nbefore write/llseek, and decrement after it finished."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: cachefiles: Arreglar la desreferencia de puntero NULL en object->file En la actualidad, object->file tiene el problema de desreferencia de puntero NULL en el modo ondemand. La causa raíz es que el fd asignado y el tiempo de vida de object->file son inconsistentes, y la invocación del espacio de usuario a anon_fd usa object->file. A continuación, se muestra el proceso que desencadena el problema: [write fd] [umount] cachefiles_ondemand_fd_write_iter fscache_cookie_state_machine cachefiles_withdraw_cookie if (!file) return -ENOBUFS cachefiles_clean_up_object cachefiles_unmark_inode_in_use fput(object->file) object->file = NULL // file ¡Desreferencia de puntero NULL! __cachefiles_write(..., file, ...) Solucione este problema agregando un recuento de referencia adicional al objeto->archivo antes de escribir/llseek, y disminuya después de que finalice."
    }
  ],
  "lastModified": "2026-08-04T11:22:09.730",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
              "vulnerable": true,
              "matchCriteriaId": "A482F6D5-4DB0-4611-AF23-1D568CE9F2BF",
              "versionEndExcluding": "6.11.11",
              "versionStartIncluding": "5.19"
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            {
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              "matchCriteriaId": "D8882B1B-2ABC-4838-AC1D-DBDBB5764776",
              "versionEndExcluding": "6.12.2",
              "versionStartIncluding": "6.12"
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          ],
          "operator": "OR"
        }
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  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}