fkie_cve-2021-47119
Vulnerability from fkie_nvd
Published
2024-03-15 21:15
Modified
2025-01-07 17:31
Severity ?
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
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 |
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"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."
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"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."
}
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"id": "CVE-2021-47119",
"lastModified": "2025-01-07T17:31:16.383",
"metrics": {
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"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"
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"exploitabilityScore": 1.8,
"impactScore": 3.6,
"source": "nvd@nist.gov",
"type": "Primary"
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"published": "2024-03-15T21:15:07.013",
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"vulnStatus": "Analyzed",
"weaknesses": [
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"value": "CWE-401"
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],
"source": "nvd@nist.gov",
"type": "Primary"
}
]
}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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