---
id: CVE-2026-98883
title: 'serial: 8250_port: recognize UPIO_AU'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  serial: 8250_port: recognize UPIO_AU

  My MIPS Alchemy systems generate the following warning during
  probe of the 8250 driver:

  WARNING: drivers/tty/serial/8250/8250_por…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    9f67997353caa29c6a080789a1fb6e01fb50c118
  - >-
    Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <
    49fa670efdfdd27e29145cbd2beef065c08717ef
  - Linux < 6.18.53
  - Linux (all versions)
published: '2026-10-23'
updated: '2026-10-23'
sourceUpdated: '2026-10-23T11:37:38.372Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98883'
references:
  - url: 'https://git.kernel.org/stable/c/9f67997353caa29c6a080789a1fb6e01fb50c118'
  - url: 'https://git.kernel.org/stable/c/49fa670efdfdd27e29145cbd2beef065c08717ef'
tags:
  - cve.org
ingestedAt: '2026-10-23T13:24:55.582Z'
---

## Overview

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

serial: 8250_port: recognize UPIO_AU

My MIPS Alchemy systems generate the following warning during
probe of the 8250 driver:

WARNING: drivers/tty/serial/8250/8250_port.c:462 at set_io_from_upio+0xfc/0x124, CPU#0: swapper/0/1
Unsupported UART type 4
[...]
[<80521d40>] set_io_from_upio+0xfc/0x124
[<80521dfc>] serial8250_set_defaults+0x94/0xe0
[<80520fb4>] serial8250_register_8250_port+0x288/0x51c
[<805214ec>] serial8250_probe+0x160/0x1e8
[<8053b5f0>] platform_probe+0x64/0x90

The least invasive fix is to recognize UPIO_AU (type 4) in set_io_from_upio()
and do nothing, since all parameters have already been set up in
8250_rt288x.c::au_platform_setup().

Run-tested on Alchemy Au1300 platform.

## Affected

- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 9f67997353caa29c6a080789a1fb6e01fb50c118`
- `Linux >= 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 < 49fa670efdfdd27e29145cbd2beef065c08717ef`
- `Linux < 6.18.53`
- `Linux (all versions)`

## Remediation

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