CVE-2021-47119

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.

CVSS v3 5.5 MEDIUM

5.5^/10

CVSS v3 : MEDIUM

Vector :

Exploitability : 1.8 / Impact : 3.6

Attack Vector LOCAL

Attack Complexity LOW

Privileges Required LOW

User Interaction NONE

Confidentiality Impact NONE

Integrity Impact NONE

Availability Impact HIGH

Scope UNCHANGED

References

Link	Resource
https://git.kernel.org/stable/c/01d349a481f0591230300a9171330136f9159bcd	Patch
https://git.kernel.org/stable/c/1385b23396d511d5233b8b921ac3058b3f86a5e1	Patch
https://git.kernel.org/stable/c/afd09b617db3786b6ef3dc43e28fe728cfea84df	Patch
https://git.kernel.org/stable/c/01d349a481f0591230300a9171330136f9159bcd	Patch
https://git.kernel.org/stable/c/1385b23396d511d5233b8b921ac3058b3f86a5e1	Patch
https://git.kernel.org/stable/c/afd09b617db3786b6ef3dc43e28fe728cfea84df	Patch

Configurations

Configuration 1 (hide)

OR	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel::::::::
	cpe:2.3:o:linux:linux_kernel:5.13:rc1::::::
	cpe:2.3:o:linux:linux_kernel:5.13:rc2::::::
	cpe:2.3:o:linux:linux_kernel:5.13:rc3::::::
	cpe:2.3:o:linux:linux_kernel:5.13:rc4::::::

History

No history.

Information

Published : 2024-03-15 21:15

Updated : 2025-01-07 17:31

NVD link : CVE-2021-47119

Mitre link : CVE-2021-47119

CVE.ORG link : CVE-2021-47119

JSON object : View

Products Affected

linux

linux_kernel

CWE

CWE-401

Missing Release of Memory after Effective Lifetime

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And then super block will be reread\nagain but using correct blocksize this time. sb_set_blocksize() didn't\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 <ext4_on_lvm>.mount, and\n systemctl stop <ext4_on_lvm>.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."}], "lastModified": "2025-01-07T17:31:16.383", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "4FE3AE47-9FE6-4BF7-A39E-A283BD97BE7B", "versionEndExcluding": "5.10.43", "versionStartIncluding": "2.6.19"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "27384800-AB48-4C08-891E-34B66F5FC4AA", "versionEndExcluding": "5.12.10", "versionStartIncluding": "5.11"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.13:rc1:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "0CBAD0FC-C281-4666-AB2F-F8E6E1165DF7"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.13:rc2:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "96AC23B2-D46A-49D9-8203-8E1BEDCA8532"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.13:rc3:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "DA610E30-717C-4700-9F77-A3C9244F3BFD"}, {"criteria": "cpe:2.3:o:linux:linux_kernel:5.13:rc4:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "1ECD33F5-85BE-430B-8F86-8D7BD560311D"}], "operator": "OR"}]}], "sourceIdentifier": "416baaa9-dc9f-4396-8d5f-8c081fb06d67"}