CVE-2021-47119
ext4: fix memory leak in ext4_fill_super
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
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.
En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ext4: corrige la pérdida de memoria en ext4_fill_super Las referencias del encabezado del búfer deben liberarse antes de llamar a kill_bdev(); de lo contrario, kill_bdev no liberará el encabezado del búfer (y su página a la que hace referencia b_data) y, posteriormente, se filtrará ese bh. Si los tamaños de los bloques difieren, sb_set_blocksize() eliminará los búferes actuales y el caché de la página usando kill_bdev(). Y luego el superbloque se volverá a leer, pero esta vez utilizando el tamaño de bloque correcto. sb_set_blocksize() no liberó completamente la página del superbloque y el encabezado del búfer y, al estar ocupados, no se liberaron y en su lugar se filtraron. Esto se puede reproducir fácilmente 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 más fácilmente.
CVSS Scores
SSVC
- Decision:Track
Timeline
- 2024-03-04 CVE Reserved
- 2024-03-15 CVE Published
- 2024-03-16 EPSS Updated
- 2024-12-19 CVE Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
CAPEC
References (4)
URL | Tag | Source |
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https://git.kernel.org/stable/c/ac27a0ec112a089f1a5102bc8dffc79c8c815571 | Vuln. Introduced |
URL | Date | SRC |
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URL | Date | SRC |
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Affected Vendors, Products, and Versions
Vendor | Product | Version | Other | Status | ||||||
---|---|---|---|---|---|---|---|---|---|---|
Vendor | Product | Version | Other | Status | <-- --> | Vendor | Product | Version | Other | Status |
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 2.6.19 < 5.10.43 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.19 < 5.10.43" | en |
Affected
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Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 2.6.19 < 5.12.10 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.19 < 5.12.10" | en |
Affected
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Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 2.6.19 < 5.13 Search vendor "Linux" for product "Linux Kernel" and version " >= 2.6.19 < 5.13" | en |
Affected
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