CVE-2022-50067
Estado: AnalizadaAlta (7.8)—
In the Linux kernel, the following vulnerability has been resolved:
btrfs: unset reloc control if transaction commit fails in prepare_to_relocate()
In btrfs_relocate_block_group(), the rc is allocated. Then btrfs_relocate_block_group() calls
that assigns rc to the variable fs_info->reloc_ctl. When prepare_to_relocate() returns, it calls
which may fail for example (or other errors could happen). When the failure occurs, btrfs_relocate_block_group() detects the error and frees rc and doesn't set fs_info->reloc_ctl to NULL. After that, in btrfs_init_reloc_root(), rc is retrieved from fs_info->reloc_ctl and then used, which may cause a use-after-free bug.
Leer descripción completaMostrar menos
This possible bug can be triggered by calling btrfs_ioctl_balance() before calling btrfs_ioctl_defrag().
To fix this possible bug, in prepare_to_relocate(), check if btrfs_commit_transaction() fails. If the failure occurs, unset_reloc_control() is called to set fs_info->reloc_ctl to NULL.
The error log in our fault-injection testing is shown as follows:
Detalles técnicos trazas, registros y código del informe original
relocate_block_group()
prepare_to_relocate()
set_reloc_control()
btrfs_commit_transaction()
btrfs_start_dirty_block_groups()
btrfs_alloc_path()
kmem_cache_zalloc()
[ 58.751070] BUG: KASAN: use-after-free in btrfs_init_reloc_root+0x7ca/0x920 [btrfs]
...
[ 58.753577] Call Trace:
...
[ 58.755800] kasan_report+0x45/0x60
[ 58.756066] btrfs_init_reloc_root+0x7ca/0x920 [btrfs]
[ 58.757304] record_root_in_trans+0x792/0xa10 [btrfs]
[ 58.757748] btrfs_record_root_in_trans+0x463/0x4f0 [btrfs]
[ 58.758231] start_transaction+0x896/0x2950 [btrfs]
[ 58.758661] btrfs_defrag_root+0x250/0xc00 [btrfs]
[ 58.759083] btrfs_ioctl_defrag+0x467/0xa00 [btrfs]
[ 58.759513] btrfs_ioctl+0x3c95/0x114e0 [btrfs]
...
[ 58.768510] Allocated by task 23683:
[ 58.768777] ____kasan_kmalloc+0xb5/0xf0
[ 58.769069] __kmalloc+0x227/0x3d0
[ 58.769325] alloc_reloc_control+0x10a/0x3d0 [btrfs]
[ 58.769755] btrfs_relocate_block_group+0x7aa/0x1e20 [btrfs]
[ 58.770228] btrfs_relocate_chunk+0xf1/0x760 [btrfs]
[ 58.770655] __btrfs_balance+0x1326/0x1f10 [btrfs]
[ 58.771071] btrfs_balance+0x3150/0x3d30 [btrfs]
[ 58.771472] btrfs_ioctl_balance+0xd84/0x1410 [btrfs]
[ 58.771902] btrfs_ioctl+0x4caa/0x114e0 [btrfs]
...
[ 58.773337] Freed by task 23683:
...
[ 58.774815] kfree+0xda/0x2b0
[ 58.775038] free_reloc_control+0x1d6/0x220 [btrfs]
[ 58.775465] btrfs_relocate_block_group+0x115c/0x1e20 [btrfs]
[ 58.775944] btrfs_relocate_chunk+0xf1/0x760 [btrfs]
[ 58.776369] __btrfs_balance+0x1326/0x1f10 [btrfs]
[ 58.776784] btrfs_balance+0x3150/0x3d30 [btrfs]
[ 58.777185] btrfs_ioctl_balance+0xd84/0x1410 [btrfs]
[ 58.777621] btrfs_ioctl+0x4caa/0x114e0 [btrfs]
...CVSS
- Versión: 3.1
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- Puntuación base: 7.8
Probabilidad de explotación (EPSS)
- Probabilidad de explotación en los próximos 30 días: 0.22%
- Percentil entre todas las CVEs puntuadas: 12
- Fecha de la puntuación: 6/10/2026
EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).
🎯 Técnicas ATT&CK
Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.
- Explotación
T1068Exploitation for Privilege Escalationprivilege escalation85 % - Impacto principal
T1059Command and Scripting Interpreterexecution45 %
Vulnerabilidad de escalada local (AV:L, PR:L) con use-after-free que permite ejecutar código con permisos elevados (C:H I:H A:H). Acceso local sin interacción UI:N descarta T1203.
Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.
🛡️ Mitigaciones ATT&CK que cubren estas técnicas
Tecnologías afectadas (1)
CWE
- CWE-416
Referencias
- https://git.kernel.org/stable/c/5d741afed0bac206640cc64d77b97853283cf719
- https://git.kernel.org/stable/c/78f8c2370e3d33e35f23bdc648653d779aeacb6e
- https://git.kernel.org/stable/c/85f02d6c856b9f3a0acf5219de6e32f58b9778eb
- https://git.kernel.org/stable/c/8e546674031fc1576da501e27a8fd165222e5a37
- https://git.kernel.org/stable/c/b60e862e133f646f19023ece1d476d630a660de1
- https://git.kernel.org/stable/c/dcb11fe0a0a9cca2b7425191b9bf30dc29f2ad0f
- https://git.kernel.org/stable/c/ff0e8ed8dfb584575cffc1561f17a1d094e8565b
JSON original (NVD)
Mostrar
{
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"published": "2025-06-18T11:15:35.490",
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"source": "nvd@nist.gov",
"description": [
{
"lang": "en",
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"descriptions": [
{
"lang": "en",
"value": "In the Linux kernel, the following vulnerability has been resolved:\n\nbtrfs: unset reloc control if transaction commit fails in prepare_to_relocate()\n\nIn btrfs_relocate_block_group(), the rc is allocated. Then\nbtrfs_relocate_block_group() calls\n\nrelocate_block_group()\n prepare_to_relocate()\n set_reloc_control()\n\nthat assigns rc to the variable fs_info->reloc_ctl. When\nprepare_to_relocate() returns, it calls\n\nbtrfs_commit_transaction()\n btrfs_start_dirty_block_groups()\n btrfs_alloc_path()\n kmem_cache_zalloc()\n\nwhich may fail for example (or other errors could happen). When the\nfailure occurs, btrfs_relocate_block_group() detects the error and frees\nrc and doesn't set fs_info->reloc_ctl to NULL. After that, in\nbtrfs_init_reloc_root(), rc is retrieved from fs_info->reloc_ctl and\nthen used, which may cause a use-after-free bug.\n\nThis possible bug can be triggered by calling btrfs_ioctl_balance()\nbefore calling btrfs_ioctl_defrag().\n\nTo fix this possible bug, in prepare_to_relocate(), check if\nbtrfs_commit_transaction() fails. If the failure occurs,\nunset_reloc_control() is called to set fs_info->reloc_ctl to NULL.\n\nThe error log in our fault-injection testing is shown as follows:\n\n [ 58.751070] BUG: KASAN: use-after-free in btrfs_init_reloc_root+0x7ca/0x920 [btrfs]\n ...\n [ 58.753577] Call Trace:\n ...\n [ 58.755800] kasan_report+0x45/0x60\n [ 58.756066] btrfs_init_reloc_root+0x7ca/0x920 [btrfs]\n [ 58.757304] record_root_in_trans+0x792/0xa10 [btrfs]\n [ 58.757748] btrfs_record_root_in_trans+0x463/0x4f0 [btrfs]\n [ 58.758231] start_transaction+0x896/0x2950 [btrfs]\n [ 58.758661] btrfs_defrag_root+0x250/0xc00 [btrfs]\n [ 58.759083] btrfs_ioctl_defrag+0x467/0xa00 [btrfs]\n [ 58.759513] btrfs_ioctl+0x3c95/0x114e0 [btrfs]\n ...\n [ 58.768510] Allocated by task 23683:\n [ 58.768777] ____kasan_kmalloc+0xb5/0xf0\n [ 58.769069] __kmalloc+0x227/0x3d0\n [ 58.769325] alloc_reloc_control+0x10a/0x3d0 [btrfs]\n [ 58.769755] btrfs_relocate_block_group+0x7aa/0x1e20 [btrfs]\n [ 58.770228] btrfs_relocate_chunk+0xf1/0x760 [btrfs]\n [ 58.770655] __btrfs_balance+0x1326/0x1f10 [btrfs]\n [ 58.771071] btrfs_balance+0x3150/0x3d30 [btrfs]\n [ 58.771472] btrfs_ioctl_balance+0xd84/0x1410 [btrfs]\n [ 58.771902] btrfs_ioctl+0x4caa/0x114e0 [btrfs]\n ...\n [ 58.773337] Freed by task 23683:\n ...\n [ 58.774815] kfree+0xda/0x2b0\n [ 58.775038] free_reloc_control+0x1d6/0x220 [btrfs]\n [ 58.775465] btrfs_relocate_block_group+0x115c/0x1e20 [btrfs]\n [ 58.775944] btrfs_relocate_chunk+0xf1/0x760 [btrfs]\n [ 58.776369] __btrfs_balance+0x1326/0x1f10 [btrfs]\n [ 58.776784] btrfs_balance+0x3150/0x3d30 [btrfs]\n [ 58.777185] btrfs_ioctl_balance+0xd84/0x1410 [btrfs]\n [ 58.777621] btrfs_ioctl+0x4caa/0x114e0 [btrfs]\n ..."
},
{
"lang": "es",
"value": "En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: btrfs: anular el control de reubicación si falla el commit de la transacción en prepare_to_relocate(). En btrfs_relocate_block_group(), se asigna el rc. Luego, btrfs_relocate_block_group() llama a relocate_block_group() prepare_to_relocate() set_reloc_control() que asigna rc a la variable fs_info->reloc_ctl. Cuando prepare_to_relocate() retorna, llama a btrfs_commit_transaction() btrfs_start_dirty_block_groups() btrfs_alloc_path() kmem_cache_zalloc() que puede fallar, por ejemplo (o podrían ocurrir otros errores). Cuando ocurre el fallo, btrfs_relocate_block_group() detecta el error y libera rc y no establece fs_info->reloc_ctl en NULL. Posteriormente, en btrfs_init_reloc_root(), se recupera rc de fs_info->reloc_ctl y se utiliza, lo que podría causar un error de Use-After-Free. Este posible error se puede activar llamando a btrfs_ioctl_balance() antes de llamar a btrfs_ioctl_defrag(). Para corregir este posible error, en prepare_to_relocate(), compruebe si btrfs_commit_transaction() falla. Si falla, se llama a unset_reloc_control() para establecer fs_info->reloc_ctl en NULL. El registro de errores en nuestras pruebas de inyección de fallas se muestra a continuación: [ 58.751070] ERROR: KASAN: use-after-free en btrfs_init_reloc_root+0x7ca/0x920 [btrfs] ... [ 58.753577] Seguimiento de llamadas: ... [ 58.755800] kasan_report+0x45/0x60 [ 58.756066] btrfs_init_reloc_root+0x7ca/0x920 [btrfs] [ 58.757304] record_root_in_trans+0x792/0xa10 [btrfs] [ 58.757748] btrfs_record_root_in_trans+0x463/0x4f0 [btrfs] [ 58.758231] start_transaction+0x896/0x2950 [btrfs] [ 58.758661] btrfs_defrag_root+0x250/0xc00 [btrfs] [ 58.759083] btrfs_ioctl_defrag+0x467/0xa00 [btrfs] [ 58.759513] btrfs_ioctl+0x3c95/0x114e0 [btrfs] ... [ 58.768510] Asignado por la tarea 23683: [ 58.768777] ____kasan_kmalloc+0xb5/0xf0 [ 58.769069] __kmalloc+0x227/0x3d0 [ 58.769325] alloc_reloc_control+0x10a/0x3d0 [btrfs] [ 58.769755] btrfs_relocate_block_group+0x7aa/0x1e20 [btrfs] [ 58.770228] btrfs_relocate_chunk+0xf1/0x760 [btrfs] [ 58.770655] __btrfs_balance+0x1326/0x1f10 [btrfs] [ 58.771071] btrfs_balance+0x3150/0x3d30 [btrfs] [ 58.771472] btrfs_ioctl_balance+0xd84/0x1410 [btrfs] [ 58.771902] btrfs_ioctl+0x4caa/0x114e0 [btrfs] ... [ 58.773337] Liberado por la tarea 23683: ... [ 58.774815] kfree+0xda/0x2b0 [ 58.775038] free_reloc_control+0x1d6/0x220 [btrfs] [ 58.775465] btrfs_relocate_block_group+0x115c/0x1e20 [btrfs] [ 58.775944] btrfs_relocate_chunk+0xf1/0x760 [btrfs] [ 58.776369] __btrfs_balance+0x1326/0x1f10 [btrfs] [ 58.776784] btrfs_balance+0x3150/0x3d30 [btrfs] [ 58.777185] btrfs_ioctl_balance+0xd84/0x1410 [btrfs] [ 58.777621] btrfs_ioctl+0x4caa/0x114e0 [btrfs] ..."
}
],
"lastModified": "2026-06-17T05:22:41.310",
"configurations": [
{
"nodes": [
{
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}