---
id: CVE-2026-64070
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  powerpc/hv-gpci: fix preempt count leak in sysfs show paths

  Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb)
  (which calls preempt_disable()) but o…
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  powerpc/hv-gpci: fix preempt count leak in sysfs show paths

  Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb)
  (which calls preempt_disable()) but o…
severity: medium
cvss: 5.5
cvssVector: 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'
vendor: linux
product: linux_kernel
affected:
  - 'linux_kernel >= 6.6, < 6.6.156'
  - 'linux_kernel >= 6.7, < 6.12.108'
  - 'linux_kernel >= 6.13, < 6.18.49'
  - 'linux_kernel >= 6.19, < 7.0.11'
  - linux_kernel = 7.1
patched:
  - linux_kernel 7.0.11
published: '2026-07-19'
updated: '2026-09-03'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-64070'
references:
  - url: 'https://git.kernel.org/stable/c/45afabe7f99c5d8746434ee41c86584c01d70147'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/903409000a07ac8e31ffedeb8516f4f8d67150c8'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b300312562fd6e4729697adb9f777f00ca0429f3'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/b61ebb2826ca1852c2bbd92a676fb622c358cab4'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/dbc30a57bd8e026995e9fa8e8c31cffd18542c01'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
epss: 0.00162
epssPercentile: 0.04636
ingestedAt: '2026-09-04T04:14:25.745Z'
---

## Overview

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

powerpc/hv-gpci: fix preempt count leak in sysfs show paths

Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb)
(which calls preempt_disable()) but only call the matching put_cpu_var()
on the error path under the 'out:' label. Every successful read leaks
one preempt_disable():

  processor_bus_topology_show()
  processor_config_show()
  affinity_domain_via_virtual_processor_show()
  affinity_domain_via_domain_show()

(affinity_domain_via_partition_show() was already correct.)

On a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and
eventually return to userspace with preemption still disabled. The
next user-mode page fault then hits faulthandler_disabled() == 1,
gets forced to SIGSEGV, and the resulting coredump trips
'BUG: scheduling while atomic' in call_usermodehelper_exec ->
wait_for_completion_state -> schedule:

  BUG: scheduling while atomic: <task>/<pid>/0x00000004
  ...
  __schedule_bug+0x6c/0x90
  __schedule+0x58c/0x13a0
  schedule+0x48/0x1a0
  schedule_timeout+0x104/0x170
  wait_for_completion_state+0x16c/0x330
  call_usermodehelper_exec+0x254/0x2d0
  vfs_coredump+0x1050/0x2590
  get_signal+0xb9c/0xc80
  do_notify_resume+0xf8/0x470

Add an out_success label that calls put_cpu_var() before returning
the byte count, mirroring affinity_domain_via_partition_show().

## Affected

- `linux_kernel >= 6.6, < 6.6.156`
- `linux_kernel >= 6.7, < 6.12.108`
- `linux_kernel >= 6.13, < 6.18.49`
- `linux_kernel >= 6.19, < 7.0.11`
- `linux_kernel = 7.1`

## Remediation

Upgrade past the affected range:

- `linux_kernel 7.0.11`