---
id: CVE-2025-39724
title: 'serial: 8250: fix panic due to PSLVERR'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  serial: 8250: fix panic due to PSLVERR

  When the PSLVERR_RESP_EN parameter is set to 1, the device generates
  an error response if an attempt is made to read an empty RB…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d <
    0b882f00655afefbc7729c6b5aec86f7a5473a3d
  - >-
    Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d <
    b8ca8e3f75ede308b4d49a6ca5081460be01bdb5
  - >-
    Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d <
    68c4613e89f000e8198f9ace643082c697921c9f
  - >-
    Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d <
    c826943abf473a3f7260fbadfad65e44db475460
  - >-
    Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d <
    cb7b3633ed749db8e56f475f43c960652cbd6882
  - >-
    Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d <
    8e2739478c164147d0774802008528d9e03fb802
  - >-
    Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d <
    38c0ea484dedb58cb3a4391229933e16be0d1031
  - >-
    Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d <
    7f8fdd4dbffc05982b96caf586f77a014b2a9353
  - Linux 6d5e79331417886196cb3a733bdb6645ba85bc42
  - Linux 2401577586898b3590db80f8b97a26f81f0f6d4e
  - Linux >= 3.10.48 < 3.11
  - Linux >= 3.12.24 < 3.13
  - Linux 3.13
published: '2025-09-05'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T01:08:07.062Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-39724'
references:
  - url: 'https://git.kernel.org/stable/c/0b882f00655afefbc7729c6b5aec86f7a5473a3d'
  - url: 'https://git.kernel.org/stable/c/b8ca8e3f75ede308b4d49a6ca5081460be01bdb5'
  - url: 'https://git.kernel.org/stable/c/68c4613e89f000e8198f9ace643082c697921c9f'
  - url: 'https://git.kernel.org/stable/c/c826943abf473a3f7260fbadfad65e44db475460'
  - url: 'https://git.kernel.org/stable/c/cb7b3633ed749db8e56f475f43c960652cbd6882'
  - url: 'https://git.kernel.org/stable/c/8e2739478c164147d0774802008528d9e03fb802'
  - url: 'https://git.kernel.org/stable/c/38c0ea484dedb58cb3a4391229933e16be0d1031'
  - url: 'https://git.kernel.org/stable/c/7f8fdd4dbffc05982b96caf586f77a014b2a9353'
tags:
  - cve.org
epss: 0.00174
epssPercentile: 0.06814
ingestedAt: '2026-10-15T05:52:46.079Z'
---

## Overview

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

serial: 8250: fix panic due to PSLVERR

When the PSLVERR_RESP_EN parameter is set to 1, the device generates
an error response if an attempt is made to read an empty RBR (Receive
Buffer Register) while the FIFO is enabled.

In serial8250_do_startup(), calling serial_port_out(port, UART_LCR,
UART_LCR_WLEN8) triggers dw8250_check_lcr(), which invokes
dw8250_force_idle() and serial8250_clear_and_reinit_fifos(). The latter
function enables the FIFO via serial_out(p, UART_FCR, p->fcr).
Execution proceeds to the serial_port_in(port, UART_RX).
This satisfies the PSLVERR trigger condition.

When another CPU (e.g., using printk()) is accessing the UART (UART
is busy), the current CPU fails the check (value & ~UART_LCR_SPAR) ==
(lcr & ~UART_LCR_SPAR) in dw8250_check_lcr(), causing it to enter
dw8250_force_idle().

Put serial_port_out(port, UART_LCR, UART_LCR_WLEN8) under the port->lock
to fix this issue.

Panic backtrace:
[    0.442336] Oops - unknown exception [#1]
[    0.442343] epc : dw8250_serial_in32+0x1e/0x4a
[    0.442351]  ra : serial8250_do_startup+0x2c8/0x88e
...
[    0.442416] console_on_rootfs+0x26/0x70

## Affected

- `Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d < 0b882f00655afefbc7729c6b5aec86f7a5473a3d`
- `Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d < b8ca8e3f75ede308b4d49a6ca5081460be01bdb5`
- `Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d < 68c4613e89f000e8198f9ace643082c697921c9f`
- `Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d < c826943abf473a3f7260fbadfad65e44db475460`
- `Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d < cb7b3633ed749db8e56f475f43c960652cbd6882`
- `Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d < 8e2739478c164147d0774802008528d9e03fb802`
- `Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d < 38c0ea484dedb58cb3a4391229933e16be0d1031`
- `Linux >= c49436b657d0a56a6ad90d14a7c3041add7cf64d < 7f8fdd4dbffc05982b96caf586f77a014b2a9353`
- `Linux 6d5e79331417886196cb3a733bdb6645ba85bc42`
- `Linux 2401577586898b3590db80f8b97a26f81f0f6d4e`
- `Linux >= 3.10.48 < 3.11`
- `Linux >= 3.12.24 < 3.13`
- `Linux 3.13`

## Remediation

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