// For flags

CVE-2021-46972

ovl: fix leaked dentry

Severity Score

5.5
*CVSS v3.1

Exploit Likelihood

*EPSS

Affected Versions

*CPE

Public Exploits

0
*Multiple Sources

Exploited in Wild

-
*KEV

Decision

Track
*SSVC
Descriptions

In the Linux kernel, the following vulnerability has been resolved:

ovl: fix leaked dentry

Since commit 6815f479ca90 ("ovl: use only uppermetacopy state in
ovl_lookup()"), overlayfs doesn't put temporary dentry when there is a
metacopy error, which leads to dentry leaks when shutting down the related
superblock:

overlayfs: refusing to follow metacopy origin for (/file0)
...
BUG: Dentry (____ptrval____){i=3f33,n=file3} still in use (1) [unmount of overlay overlay]
...
WARNING: CPU: 1 PID: 432 at umount_check.cold+0x107/0x14d
CPU: 1 PID: 432 Comm: unmount-overlay Not tainted 5.12.0-rc5 #1
...
RIP: 0010:umount_check.cold+0x107/0x14d
...
Call Trace:
d_walk+0x28c/0x950
? dentry_lru_isolate+0x2b0/0x2b0
? __kasan_slab_free+0x12/0x20
do_one_tree+0x33/0x60
shrink_dcache_for_umount+0x78/0x1d0
generic_shutdown_super+0x70/0x440
kill_anon_super+0x3e/0x70
deactivate_locked_super+0xc4/0x160
deactivate_super+0xfa/0x140
cleanup_mnt+0x22e/0x370
__cleanup_mnt+0x1a/0x30
task_work_run+0x139/0x210
do_exit+0xb0c/0x2820
? __kasan_check_read+0x1d/0x30
? find_held_lock+0x35/0x160
? lock_release+0x1b6/0x660
? mm_update_next_owner+0xa20/0xa20
? reacquire_held_locks+0x3f0/0x3f0
? __sanitizer_cov_trace_const_cmp4+0x22/0x30
do_group_exit+0x135/0x380
__do_sys_exit_group.isra.0+0x20/0x20
__x64_sys_exit_group+0x3c/0x50
do_syscall_64+0x45/0x70
entry_SYSCALL_64_after_hwframe+0x44/0xae
...
VFS: Busy inodes after unmount of overlay. Self-destruct in 5 seconds. Have a nice day...

This fix has been tested with a syzkaller reproducer.

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: ovl: corrige la dentry filtrada Desde el commit 6815f479ca90 ("ovl: usa solo el estado de metacopia superior en ovl_lookup()"), overlayfs no coloca la dentry temporal cuando hay un error de metacopia, lo que conduce a fugas de dentry al cerrar el superbloque relacionado: overlayfs: se niega a seguir el origen de la metacopia para (/file0)... ERROR: Dentry (____ptrval____){i=3f33,n=file3} todavía está en uso (1) [desmontaje de superposición superpuesta]... ADVERTENCIA: CPU: 1 PID: 432 en umount_check.cold+0x107/0x14d CPU: 1 PID: 432 Comm: unmount-overlay No contaminado 5.12.0-rc5 #1... RIP: 0010:umount_check .cold+0x107/0x14d... Seguimiento de llamadas: d_walk+0x28c/0x950 ? dentry_lru_isolate+0x2b0/0x2b0? __kasan_slab_free+0x12/0x20 do_one_tree+0x33/0x60 encogimiento_dcache_for_umount+0x78/0x1d0 generic_shutdown_super+0x70/0x440 kill_anon_super+0x3e/0x70 deactivate_locked_super+0xc4/0x160 deactivate_super+0xfa/0x140 clean up_mnt+0x22e/0x370 __cleanup_mnt+0x1a/0x30 task_work_run+0x139/0x210 do_exit+0xb0c/0x2820? __kasan_check_read+0x1d/0x30 ? find_held_lock+0x35/0x160? lock_release+0x1b6/0x660? mm_update_next_owner+0xa20/0xa20? ¿reaquirir_held_locks+0x3f0/0x3f0? __sanitizer_cov_trace_const_cmp4+0x22/0x30 do_group_exit+0x135/0x380 __do_sys_exit_group.isra.0+0x20/0x20 __x64_sys_exit_group+0x3c/0x50 do_syscall_64+0x45/0x70 entrada_SYSCALL_64 _after_hwframe+0x44/0xae... VFS: Inodos ocupados después de desmontar la superposición. Autodestrucción en 5 segundos. Que tengas un buen día... Esta solución ha sido probada con un reproductor syzkaller.

*Credits: N/A
CVSS Scores
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None
* Common Vulnerability Scoring System
SSVC
  • Decision:Track
Exploitation
None
Automatable
No
Tech. Impact
Partial
* Organization's Worst-case Scenario
Timeline
  • 2024-02-27 CVE Reserved
  • 2024-02-27 CVE Published
  • 2024-02-28 EPSS Updated
  • 2024-08-04 CVE Updated
  • ---------- Exploited in Wild
  • ---------- KEV Due Date
  • ---------- First Exploit
CWE
  • CWE-402: Transmission of Private Resources into a New Sphere ('Resource Leak')
CAPEC
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"
 >= 5.8 < 5.10.35
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.8 < 5.10.35"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.8 < 5.11.19
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.8 < 5.11.19"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.8 < 5.12.2
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.8 < 5.12.2"
en
Affected
Linux
Search vendor "Linux"
 Linux Kernel
Search vendor "Linux" for product "Linux Kernel"
 >= 5.8 < 5.13
Search vendor "Linux" for product "Linux Kernel" and version " >= 5.8 < 5.13"
en
Affected