CVE-2022-48950

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxca7b0a10287e2733bdafb01ef0d4038536625fe3 < 8bffa95ac19ff27c8261904f89d36c7fcf215d59affected
LinuxLinux078c12ccf1fb943cc18c84894c76113dc89e5975 < 78e1317a174edbfd1182599bf76c092a2877672caffected
LinuxLinuxca6c21327c6af02b7eec31ce4b9a740a18c6c13f < 517e6a301f34613bff24a8e35b5455884f2d83d8affected
LinuxLinux5.15.77 < 5.15.84affected
LinuxLinux6.0.7 < 6.0.14affected

Weaknesses

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References