CVE-2021-47488
cgroup: Fix memory leak caused by missing cgroup_bpf_offline
Severity Score
Exploit Likelihood
Affected Versions
Public Exploits
0Exploited in Wild
-Decision
Descriptions
In the Linux kernel, the following vulnerability has been resolved:
cgroup: Fix memory leak caused by missing cgroup_bpf_offline
When enabling CONFIG_CGROUP_BPF, kmemleak can be observed by running
the command as below:
$mount -t cgroup -o none,name=foo cgroup cgroup/
$umount cgroup/
unreferenced object 0xc3585c40 (size 64):
comm "mount", pid 425, jiffies 4294959825 (age 31.990s)
hex dump (first 32 bytes):
01 00 00 80 84 8c 28 c0 00 00 00 00 00 00 00 00 ......(.........
00 00 00 00 00 00 00 00 6c 43 a0 c3 00 00 00 00 ........lC......
backtrace:
[<e95a2f9e>] cgroup_bpf_inherit+0x44/0x24c
[<1f03679c>] cgroup_setup_root+0x174/0x37c
[<ed4b0ac5>] cgroup1_get_tree+0x2c0/0x4a0
[<f85b12fd>] vfs_get_tree+0x24/0x108
[<f55aec5c>] path_mount+0x384/0x988
[<e2d5e9cd>] do_mount+0x64/0x9c
[<208c9cfe>] sys_mount+0xfc/0x1f4
[<06dd06e0>] ret_fast_syscall+0x0/0x48
[<a8308cb3>] 0xbeb4daa8
This is because that since the commit 2b0d3d3e4fcf ("percpu_ref: reduce
memory footprint of percpu_ref in fast path") root_cgrp->bpf.refcnt.data
is allocated by the function percpu_ref_init in cgroup_bpf_inherit which
is called by cgroup_setup_root when mounting, but not freed along with
root_cgrp when umounting. Adding cgroup_bpf_offline which calls
percpu_ref_kill to cgroup_kill_sb can free root_cgrp->bpf.refcnt.data in
umount path.
This patch also fixes the commit 4bfc0bb2c60e ("bpf: decouple the lifetime
of cgroup_bpf from cgroup itself"). A cgroup_bpf_offline is needed to do a
cleanup that frees the resources which are allocated by cgroup_bpf_inherit
in cgroup_setup_root.
And inside cgroup_bpf_offline, cgroup_get() is at the beginning and
cgroup_put is at the end of cgroup_bpf_release which is called by
cgroup_bpf_offline. So cgroup_bpf_offline can keep the balance of
cgroup's refcount.
En el kernel de Linux, se resolvió la siguiente vulnerabilidad: cgroup: corrige la pérdida de memoria causada por la falta de cgroup_bpf_offline Al habilitar CONFIG_CGROUP_BPF, se puede observar kmemleak ejecutando el siguiente comando: $mount -t cgroup -o none,name=foo cgroup cgroup / $umount cgroup/ objeto sin referencia 0xc3585c40 (tamaño 64): comm "mount", pid 425, sjiffies 4294959825 (edad 31.990s) volcado hexadecimal (primeros 32 bytes): 01 00 00 80 84 8c 28 c0 00 00 00 00 00 00 00 00 ......(....... 00 00 00 00 00 00 00 00 6c 43 a0 c3 00 00 00 00 ........lC...... retroceso : [] cgroup_bpf_inherit+0x44/0x24c [<1f03679c>] cgroup_setup_root+0x174/0x37c [] cgroup1_get_tree+0x2c0/0x4a0 [] 8 [] ruta_montaje+0x384/ 0x988 [] do_mount+0x64/0x9c [<208c9cfe>] sys_mount+0xfc/0x1f4 [<06dd06e0>] ret_fast_syscall+0x0/0x48 [] 0xbeb4daa8 Esto se debe a que desde El commit 2b0d3d3e4f cf ("percpu_ref: reducir huella de memoria de percpu_ref en la ruta rápida") root_cgrp->bpf.refcnt.data es asignada por la función percpu_ref_init en cgroup_bpf_inherit, que es llamada por cgroup_setup_root al montar, pero no se libera junto con root_cgrp al desmontar. Agregar cgroup_bpf_offline que llama a percpu_ref_kill a cgroup_kill_sb puede liberar root_cgrp->bpf.refcnt.data en la ruta de montaje. Este parche también corrige el commit 4bfc0bb2c60e ("bpf: desacople la vida útil de cgroup_bpf del propio cgroup"). Se necesita cgroup_bpf_offline para realizar una sanitización que libere los recursos asignados por cgroup_bpf_inherit en cgroup_setup_root. Y dentro de cgroup_bpf_offline, cgroup_get() está al principio y cgroup_put está al final de cgroup_bpf_release, que es llamado por cgroup_bpf_offline. Entonces cgroup_bpf_offline puede mantener el saldo del recuento de cgroup.
CVSS Scores
SSVC
- Decision:Track
Timeline
- 2024-05-22 CVE Reserved
- 2024-05-22 CVE Published
- 2024-05-23 EPSS Updated
- 2024-09-11 CVE Updated
- ---------- Exploited in Wild
- ---------- KEV Due Date
- ---------- First Exploit
CWE
CAPEC
References (4)
URL | Tag | Source |
---|---|---|
https://git.kernel.org/stable/c/4bfc0bb2c60e2f4cc8eb60f03cf8dfa72336272a | Vuln. Introduced |
URL | Date | SRC |
---|
URL | Date | SRC |
---|
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" | >= 5.3 < 5.10.77 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.3 < 5.10.77" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.3 < 5.14.16 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.3 < 5.14.16" | en |
Affected
| ||||||
Linux Search vendor "Linux" | Linux Kernel Search vendor "Linux" for product "Linux Kernel" | >= 5.3 < 5.15 Search vendor "Linux" for product "Linux Kernel" and version " >= 5.3 < 5.15" | en |
Affected
|