# CVE-2022-49613: serial: 8250: Fix PM usage_count for console handover

Status: published. Published: 2025-02-26. Updated: 2026-11-05.

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).

## Remediation

No remediation reported in collected sources

## Affected products and versions

- Linux / Linux: ≥ bedb404e91bb2908d9921fc736a518a9d89525fc; < d9cb6fabc90102f9e61fe35bd0160db88f4f53b4 (affected, git); ≥ bedb404e91bb2908d9921fc736a518a9d89525fc; < 190ce5cdc55d1b66ea582ac2be6fd5a72e3cc486 (affected, git); ≥ bedb404e91bb2908d9921fc736a518a9d89525fc; < 5df66302f03f87ae8953785a882d78e911f00c55 (affected, git); ≥ bedb404e91bb2908d9921fc736a518a9d89525fc; < f9b11229b79c0fb2100b5bb4628a101b1d37fbf6 (affected, git). Source: CNA: Linux
- Linux / Linux: 5.7 (affected); ≥ 0; < 5.7 (unaffected, semver); ≥ 5.10.132; ≤ 5.10.* (unaffected, semver); ≥ 5.15.56; ≤ 5.15.* (unaffected, semver); ≥ 5.18.13; ≤ 5.18.* (unaffected, semver); ≥ 5.19; ≤ * (unaffected, original_commit_for_fix). Source: CNA: Linux

## Severity and prioritization

- CISA KEV: No listing in collected sources

- EPSS: 0.26% as of 2026-11-05; percentile 17.96%

- SSVC: exploitation none; automatable no; technical impact partial; source ADP: CISA-ADP

- Weaknesses: Not reported

## Exploit evidence

No exploit evidence in collected sources. This is not proof of no exploitation.

## References

- https://git.kernel.org/stable/c/d9cb6fabc90102f9e61fe35bd0160db88f4f53b4 (CNA: Linux)

- https://git.kernel.org/stable/c/190ce5cdc55d1b66ea582ac2be6fd5a72e3cc486 (CNA: Linux)

- https://git.kernel.org/stable/c/5df66302f03f87ae8953785a882d78e911f00c55 (CNA: Linux)

- https://git.kernel.org/stable/c/f9b11229b79c0fb2100b5bb4628a101b1d37fbf6 (CNA: Linux)

## Provenance

- CNA: Linux: https://www.cve.org/CVERecord?id=CVE-2022-49613; retrieved 2026-11-05; source updated 2026-11-05

- FIRST EPSS: https://api.first.org/data/v1/epss?cve=CVE-2022-49613; retrieved 2026-11-05; source updated Not reported

Revision: aeaed558e20f902cae8c07fa58478e74165f5d09f4328fbdae7658e48246b660

Canonical: https://y2.dev/cve/CVE-2022-49613

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