IM
IronMonkey Threat Research

CVE-2024-56672 HIGH

Published: 2024-12-27 | Last Modified: 2026-05-12 | Status: Modified

Description

In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: Fix UAF in blkcg_unpin_online() blkcg_unpin_online() walks up the blkcg hierarchy putting the online pin. To walk up, it uses blkcg_parent(blkcg) but it was calling that after blkcg_destroy_blkgs(blkcg) which could free the blkcg, leading to the following UAF: ================================================================== BUG: KASAN: slab-use-after-free in blkcg_unpin_online+0x15a/0x270 Read of size 8 at addr ffff8881057678c0 by task kworker/9:1/117 CPU: 9 UID: 0 PID: 117 Comm: kworker/9:1 Not tainted 6.13.0-rc1-work-00182-gb8f52214c61a-dirty #48 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 02/02/2022 Workqueue: cgwb_release cgwb_release_workfn Call Trace: <TASK> dump_stack_lvl+0x27/0x80 print_report+0x151/0x710 kasan_report+0xc0/0x100 blkcg_unpin_online+0x15a/0x270 cgwb_release_workfn+0x194/0x480 process_scheduled_works+0x71b/0xe20 worker_thread+0x82a/0xbd0 kthread+0x242/0x2c0 ret_from_fork+0x33/0x70 ret_from_fork_asm+0x1a/0x30 </TASK> ... Freed by task 1944: kasan_save_track+0x2b/0x70 kasan_save_free_info+0x3c/0x50 __kasan_slab_free+0x33/0x50 kfree+0x10c/0x330 css_free_rwork_fn+0xe6/0xb30 process_scheduled_works+0x71b/0xe20 worker_thread+0x82a/0xbd0 kthread+0x242/0x2c0 ret_from_fork+0x33/0x70 ret_from_fork_asm+0x1a/0x30 Note that the UAF is not easy to trigger as the free path is indirected behind a couple RCU grace periods and a work item execution. I could only trigger it with artifical msleep() injected in blkcg_unpin_online(). Fix it by reading the parent pointer before destroying the blkcg's blkg's.

Additional Descriptions (1)

En el kernel de Linux, se ha resuelto la siguiente vulnerabilidad: blk-cgroup: corrige UAF en blkcg_unpin_online() blkcg_unpin_online() sube por la jerarquía blkcg y coloca el pin en línea. Para subir, usa blkcg_parent(blkcg) pero lo estaba llamando después de blkcg_destroy_blkgs(blkcg) que podría liberar el blkcg, lo que lleva al siguiente UAF: ====================================================================== ERROR: KASAN: slab-use-after-free en blkcg_unpin_online+0x15a/0x270 Lectura de tamaño 8 en la dirección ffff8881057678c0 por la tarea kworker/9:1/117 CPU: 9 UID: 0 PID: 117 Comm: kworker/9:1 No contaminado 6.13.0-rc1-work-00182-gb8f52214c61a-dirty #48 Nombre del hardware: PC estándar QEMU (i440FX + PIIX, 1996), BIOS desconocido 02/02/2022 Cola de trabajo: cgwb_release cgwb_release_workfn Seguimiento de llamadas: dump_stack_lvl+0x27/0x80 print_report+0x151/0x710 kasan_report+0xc0/0x100 blkcg_unpin_online+0x15a/0x270 cgwb_release_workfn+0x194/0x480 process_scheduled_works+0x71b/0xe20 worker_thread+0x82a/0xbd0 kthread+0x242/0x2c0 ret_from_fork+0x33/0x70 ret_from_fork_asm+0x1a/0x30 ... Liberado por la tarea 1944: kasan_save_track+0x2b/0x70 kasan_save_free_info+0x3c/0x50 __kasan_slab_free+0x33/0x50 kfree+0x10c/0x330 css_free_rwork_fn+0xe6/0xb30 process_scheduled_works+0x71b/0xe20 worker_thread+0x82a/0xbd0 kthread+0x242/0x2c0 ret_from_fork+0x33/0x70 ret_from_fork_asm+0x1a/0x30 Tenga en cuenta que el UAF no es fácil de activar ya que la ruta libre es Se produjo un error indirecto detrás de un par de períodos de gracia de RCU y una ejecución de elemento de trabajo. Solo pude activarlo con msleep() artificial inyectado en blkcg_unpin_online(). Solucione el problema leyendo el puntero principal antes de destruir los blkg de blkcg.

CVSS Metrics

Base Score: 7.0 (HIGH)

CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H

Attack VectorLOCAL
Attack ComplexityHIGH
Privileges RequiredLOW
User InteractionNONE
ScopeUNCHANGED
Confidentiality ImpactHIGH
Integrity ImpactHIGH
Availability ImpactHIGH

Source: [email protected]

Type: Primary

Exploitability Score: 1.0

Impact Score: 5.9

Weaknesses

Source Type Description
[email protected] Primary
en CWE-416
134c704f-9b21-4f2e-91b3-4a467353bcc0 Secondary
en CWE-416

Affected Products

Vendor Product Version Update Type
linux linux_kernel * <built-in method update of dict object at 0x7fd384dea0c0> Operating System
linux linux_kernel * <built-in method update of dict object at 0x7fd36a02cc80> Operating System
linux linux_kernel * <built-in method update of dict object at 0x7fd36adbc080> Operating System
linux linux_kernel 6.13 <built-in method update of dict object at 0x7fd340a00540> Operating System
linux linux_kernel 6.13 <built-in method update of dict object at 0x7fd384de9580> Operating System

Affected Configurations

Operator: OR

Vulnerable CPE
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:6.13:rc1:*:*:*:*:*:*
Yes cpe:2.3:o:linux:linux_kernel:6.13:rc2:*:*:*:*:*:*

References