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CVE-2024-47794

Estado: ModificadaMedia (5.5)—

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

bpf: Prevent tailcall infinite loop caused by freplace

There is a potential infinite loop issue that can occur when using a combination of tail calls and freplace.

In an upcoming selftest, the attach target for entry_freplace of tailcall_freplace.c is subprog_tc of tc_bpf2bpf.c, while the tail call in entry_freplace leads to entry_tc. This results in an infinite loop:

entry_tc -> subprog_tc -> entry_freplace --tailcall-> entry_tc.

The problem arises because the tail_call_cnt in entry_freplace resets to zero each time entry_freplace is executed, causing the tail call mechanism to never terminate, eventually leading to a kernel panic.

Leer descripción completaMostrar menos

To fix this issue, the solution is twofold:

This ensures that:

Moreover, an extension program should not be tailcalled. As such, return -EINVAL if the program has a type of BPF_PROG_TYPE_EXT when adding it to a prog_array map.

Additionally, fix a minor code style issue by replacing eight spaces with a tab for proper formatting.

Detalles técnicos trazas, registros y código del informe original
1. Prevent updating a program extended by an freplace program to a
   prog_array map.
2. Prevent extending a program that is already part of a prog_array map
   with an freplace program.

* If a program or its subprogram has been extended by an freplace program,
  it can no longer be updated to a prog_array map.
* If a program has been added to a prog_array map, neither it nor its
  subprograms can be extended by an freplace program.

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-2024-47794",
  "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"
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        "impactScore": 5.9,
        "exploitabilityScore": 1.8
      },
      {
        "type": "Primary",
        "source": "nvd@nist.gov",
        "cvssData": {
          "scope": "UNCHANGED",
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          "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",
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            "kernel/bpf/core.c",
            "kernel/bpf/syscall.c",
            "kernel/bpf/trampoline.c"
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              "version": "5.6"
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              "status": "unaffected",
              "version": "0",
              "lessThan": "5.6",
              "versionType": "semver"
            },
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              "status": "unaffected",
              "version": "6.12.5",
              "versionType": "semver",
              "lessThanOrEqual": "6.12.*"
            },
            {
              "status": "unaffected",
              "version": "6.13",
              "versionType": "original_commit_for_fix",
              "lessThanOrEqual": "*"
            }
          ],
          "programFiles": [
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            "kernel/bpf/arraymap.c",
            "kernel/bpf/core.c",
            "kernel/bpf/syscall.c",
            "kernel/bpf/trampoline.c"
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  "published": "2025-01-11T13:15:22.390",
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      "description": [
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          "lang": "en",
          "value": "CWE-835"
        }
      ]
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  ],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Prevent tailcall infinite loop caused by freplace\n\nThere is a potential infinite loop issue that can occur when using a\ncombination of tail calls and freplace.\n\nIn an upcoming selftest, the attach target for entry_freplace of\ntailcall_freplace.c is subprog_tc of tc_bpf2bpf.c, while the tail call in\nentry_freplace leads to entry_tc. This results in an infinite loop:\n\nentry_tc -> subprog_tc -> entry_freplace --tailcall-> entry_tc.\n\nThe problem arises because the tail_call_cnt in entry_freplace resets to\nzero each time entry_freplace is executed, causing the tail call mechanism\nto never terminate, eventually leading to a kernel panic.\n\nTo fix this issue, the solution is twofold:\n\n1. Prevent updating a program extended by an freplace program to a\n   prog_array map.\n2. Prevent extending a program that is already part of a prog_array map\n   with an freplace program.\n\nThis ensures that:\n\n* If a program or its subprogram has been extended by an freplace program,\n  it can no longer be updated to a prog_array map.\n* If a program has been added to a prog_array map, neither it nor its\n  subprograms can be extended by an freplace program.\n\nMoreover, an extension program should not be tailcalled. As such, return\n-EINVAL if the program has a type of BPF_PROG_TYPE_EXT when adding it to a\nprog_array map.\n\nAdditionally, fix a minor code style issue by replacing eight spaces with a\ntab for proper formatting."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: bpf: Evitar bucle infinito de tailcall causado por freplace Existe un posible problema de bucle infinito que puede ocurrir al usar una combinación de llamadas de cola y freplace. En una próxima autoprueba, el objetivo de conexión para entry_freplace de tailcall_freplace.c es subprog_tc de tc_bpf2bpf.c, mientras que la llamada de cola en entry_freplace conduce a entry_tc. Esto da como resultado un bucle infinito: entry_tc -> subprog_tc -> entry_freplace --tailcall-> entry_tc. El problema surge porque tail_call_cnt en entry_freplace se restablece a cero cada vez que se ejecuta entry_freplace, lo que hace que el mecanismo de llamada de cola nunca finalice, lo que finalmente conduce a un pánico del kernel. Para solucionar este problema, la solución es doble: 1. Evitar actualizar un programa extendido por un programa freplace a un mapa prog_array. 2. Evite extender un programa que ya es parte de un mapa prog_array con un programa freplace. Esto garantiza que: * Si un programa o su subprograma ha sido extendido por un programa freplace, ya no puede actualizarse a un mapa prog_array. * Si un programa ha sido agregado a un mapa prog_array, ni él ni sus subprogramas pueden ser extendidos por un programa freplace. Además, un programa de extensión no debe ser llamado al final. Como tal, devuelva -EINVAL si el programa tiene un tipo de BPF_PROG_TYPE_EXT al agregarlo a un mapa prog_array. Además, solucione un problema menor de estilo de código reemplazando ocho espacios con una tabulación para un formato adecuado."
    }
  ],
  "lastModified": "2026-08-04T11:20:49.140",
  "configurations": [
    {
      "nodes": [
        {
          "negate": false,
          "cpeMatch": [
            {
              "criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*",
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              "matchCriteriaId": "83E30040-8849-4588-B81C-AE479356574C",
              "versionEndExcluding": "6.12.5",
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            }
          ],
          "operator": "OR"
        }
      ]
    }
  ],
  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"
}