CVE-2022-48950 Information

Description

In the Linux kernel the following vulnerability has been resolved:

perf: Fix perf_pending_task() UaF

Per syzbot it is possible for perf_pending_task() to run after the event is free()’d. There are two related but distinct cases:

• the task_work was already queued before destroying the event;
• destroying the event itself queues the task_work.

The first cannot be solved using task_work_cancel() since perf_release() itself might be called from a task_work (____fput) which means the current->task_works list is already empty and task_work_cancel() won’t be able to find the perf_pending_task() entry.

The simplest alternative is extending the perf_event lifetime to cover the task_work.

The second is just silly queueing a task_work while you know the event is going away makes no sense and is easily avoided by re-arranging how the event is marked STATE_DEAD and ensuring it goes through STATE_OFF on the way down.

CVSS Vector

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

Reference

https://git.kernel.org/stable/c/8bffa95ac19ff27c8261904f89d36c7fcf215d59 https://git.kernel.org/stable/c/78e1317a174edbfd1182599bf76c092a2877672c https://git.kernel.org/stable/c/517e6a301f34613bff24a8e35b5455884f2d83d8

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

7.8