fkie_cve-2021-47119
Vulnerability from fkie_nvd
Published
2024-03-15 21:15
Modified
2025-01-07 17:31
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: fix memory leak in ext4_fill_super Buffer head references must be released before calling kill_bdev(); otherwise the buffer head (and its page referenced by b_data) will not be freed by kill_bdev, and subsequently that bh will be leaked. If blocksizes differ, sb_set_blocksize() will kill current buffers and page cache by using kill_bdev(). And then super block will be reread again but using correct blocksize this time. sb_set_blocksize() didn't fully free superblock page and buffer head, and being busy, they were not freed and instead leaked. This can easily be reproduced by calling an infinite loop of: systemctl start <ext4_on_lvm>.mount, and systemctl stop <ext4_on_lvm>.mount ... since systemd creates a cgroup for each slice which it mounts, and the bh leak get amplified by a dying memory cgroup that also never gets freed, and memory consumption is much more easily noticed.
References
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/01d349a481f0591230300a9171330136f9159bcdPatch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/1385b23396d511d5233b8b921ac3058b3f86a5e1Patch
416baaa9-dc9f-4396-8d5f-8c081fb06d67https://git.kernel.org/stable/c/afd09b617db3786b6ef3dc43e28fe728cfea84dfPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/01d349a481f0591230300a9171330136f9159bcdPatch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/1385b23396d511d5233b8b921ac3058b3f86a5e1Patch
af854a3a-2127-422b-91ae-364da2661108https://git.kernel.org/stable/c/afd09b617db3786b6ef3dc43e28fe728cfea84dfPatch
Impacted products
Vendor Product Version
linux linux_kernel *
linux linux_kernel *
linux linux_kernel 5.13
linux linux_kernel 5.13
linux linux_kernel 5.13
linux linux_kernel 5.13


To clipboard 

{
  "configurations": [
    {
      "nodes": [
        {
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              "versionEndExcluding": "5.10.43",
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  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "In the Linux kernel, the following vulnerability has been resolved:\n\next4: fix memory leak in ext4_fill_super\n\nBuffer head references must be released before calling kill_bdev();\notherwise the buffer head (and its page referenced by b_data) will not\nbe freed by kill_bdev, and subsequently that bh will be leaked.\n\nIf blocksizes differ, sb_set_blocksize() will kill current buffers and\npage cache by using kill_bdev(). And then super block will be reread\nagain but using correct blocksize this time. sb_set_blocksize() didn\u0027t\nfully free superblock page and buffer head, and being busy, they were\nnot freed and instead leaked.\n\nThis can easily be reproduced by calling an infinite loop of:\n\n  systemctl start \u003cext4_on_lvm\u003e.mount, and\n  systemctl stop \u003cext4_on_lvm\u003e.mount\n\n... since systemd creates a cgroup for each slice which it mounts, and\nthe bh leak get amplified by a dying memory cgroup that also never\ngets freed, and memory consumption is much more easily noticed."
    },
    {
      "lang": "es",
      "value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: corrige la p\u00e9rdida de memoria en ext4_fill_super Las referencias del encabezado del b\u00fafer deben liberarse antes de llamar a kill_bdev(); de lo contrario, kill_bdev no liberar\u00e1 el encabezado del b\u00fafer (y su p\u00e1gina a la que hace referencia b_data) y, posteriormente, se filtrar\u00e1 ese bh. Si los tama\u00f1os de los bloques difieren, sb_set_blocksize() eliminar\u00e1 los b\u00faferes actuales y el cach\u00e9 de la p\u00e1gina usando kill_bdev(). Y luego el superbloque se volver\u00e1 a leer, pero esta vez utilizando el tama\u00f1o de bloque correcto. sb_set_blocksize() no liber\u00f3 completamente la p\u00e1gina del superbloque y el encabezado del b\u00fafer y, al estar ocupados, no se liberaron y en su lugar se filtraron. Esto se puede reproducir f\u00e1cilmente llamando a un bucle infinito de: systemctl start .mount, y systemctl stop .mount... ya que systemd crea un cgroup para cada segmento que monta, y la fuga de bh se amplifica con un grupo de memoria moribundo que tampoco se libera nunca, y el consumo de memoria se nota mucho m\u00e1s f\u00e1cilmente."
    }
  ],
  "id": "CVE-2021-47119",
  "lastModified": "2025-01-07T17:31:16.383",
  "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": "2024-03-15T21:15:07.013",
  "references": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
      "tags": [
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      "source": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
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    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
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      "url": "https://git.kernel.org/stable/c/01d349a481f0591230300a9171330136f9159bcd"
    },
    {
      "source": "af854a3a-2127-422b-91ae-364da2661108",
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      "url": "https://git.kernel.org/stable/c/1385b23396d511d5233b8b921ac3058b3f86a5e1"
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      "source": "af854a3a-2127-422b-91ae-364da2661108",
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  "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
  "vulnStatus": "Analyzed",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-401"
        }
      ],
      "source": "nvd@nist.gov",
      "type": "Primary"
    }
  ]
}


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