---
id: CVE-2022-49613
title: 'serial: 8250: Fix PM usage_count for console handover'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  serial: 8250: Fix PM usage_count for console handover

  When console is enabled, univ8250_console_setup() calls
  serial8250_console_setup() before .dev is set to uart_por…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= bedb404e91bb2908d9921fc736a518a9d89525fc <
    d9cb6fabc90102f9e61fe35bd0160db88f4f53b4
  - >-
    Linux >= bedb404e91bb2908d9921fc736a518a9d89525fc <
    190ce5cdc55d1b66ea582ac2be6fd5a72e3cc486
  - >-
    Linux >= bedb404e91bb2908d9921fc736a518a9d89525fc <
    5df66302f03f87ae8953785a882d78e911f00c55
  - >-
    Linux >= bedb404e91bb2908d9921fc736a518a9d89525fc <
    f9b11229b79c0fb2100b5bb4628a101b1d37fbf6
  - Linux 5.7
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T19:46:23.198072Z'
published: '2025-02-26'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T19:49:41.012Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2022-49613'
references:
  - url: 'https://git.kernel.org/stable/c/d9cb6fabc90102f9e61fe35bd0160db88f4f53b4'
  - url: 'https://git.kernel.org/stable/c/190ce5cdc55d1b66ea582ac2be6fd5a72e3cc486'
  - url: 'https://git.kernel.org/stable/c/5df66302f03f87ae8953785a882d78e911f00c55'
  - url: 'https://git.kernel.org/stable/c/f9b11229b79c0fb2100b5bb4628a101b1d37fbf6'
tags:
  - cve.org
epss: 0.00261
epssPercentile: 0.17959
ingestedAt: '2026-11-05T22:38:31.581Z'
---

## Overview

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

serial: 8250: Fix PM usage_count for console handover

When console is enabled, univ8250_console_setup() calls
serial8250_console_setup() before .dev is set to uart_port. Therefore,
it will not call pm_runtime_get_sync(). Later, when the actual driver
is going to take over univ8250_console_exit() is called. As .dev is
already set, serial8250_console_exit() makes pm_runtime_put_sync() call
with usage count being zero triggering PM usage count warning
(extra debug for univ8250_console_setup(), univ8250_console_exit(), and
serial8250_register_ports()):

[    0.068987] univ8250_console_setup ttyS0 nodev
[    0.499670] printk: console [ttyS0] enabled
[    0.717955] printk: console [ttyS0] printing thread started
[    1.960163] serial8250_register_ports assigned dev for ttyS0
[    1.976830] printk: console [ttyS0] disabled
[    1.976888] printk: console [ttyS0] printing thread stopped
[    1.977073] univ8250_console_exit ttyS0 usage:0
[    1.977075] serial8250 serial8250: Runtime PM usage count underflow!
[    1.977429] dw-apb-uart.6: ttyS0 at MMIO 0x4010006000 (irq = 33, base_baud = 115200) is a 16550A
[    1.977812] univ8250_console_setup ttyS0 usage:2
[    1.978167] printk: console [ttyS0] printing thread started
[    1.978203] printk: console [ttyS0] enabled

To fix the issue, call pm_runtime_get_sync() in
serial8250_register_ports() as soon as .dev is set for an uart_port
if it has console enabled.

This problem became apparent only recently because 82586a721595 ("PM:
runtime: Avoid device usage count underflows") added the warning
printout. I confirmed this problem also occurs with v5.18 (w/o the
warning printout, obviously).

## Affected

- `Linux >= bedb404e91bb2908d9921fc736a518a9d89525fc < d9cb6fabc90102f9e61fe35bd0160db88f4f53b4`
- `Linux >= bedb404e91bb2908d9921fc736a518a9d89525fc < 190ce5cdc55d1b66ea582ac2be6fd5a72e3cc486`
- `Linux >= bedb404e91bb2908d9921fc736a518a9d89525fc < 5df66302f03f87ae8953785a882d78e911f00c55`
- `Linux >= bedb404e91bb2908d9921fc736a518a9d89525fc < f9b11229b79c0fb2100b5bb4628a101b1d37fbf6`
- `Linux 5.7`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.