---
id: CVE-2025-38086
title: 'net: ch9200: fix uninitialised access during mii_nway_restart'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net: ch9200: fix uninitialised access during mii_nway_restart

  In mii_nway_restart() the code attempts to call
  mii->mdio_read which is ch9200_mdio_read(). ch9200_mdio_r…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb <
    119766de4930ff40db9f36b960cb53b0c400e81b
  - >-
    Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb <
    33163c68d2e3061fa3935b5f0a1867958b1cdbd2
  - >-
    Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb <
    9da3e442714f7f4393ff01c265c4959c03e88c2f
  - >-
    Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb <
    9a350f30d65197354706b7759b5c89d6c267b1a9
  - >-
    Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb <
    6bd2569d0b2f918e9581f744df0263caf73ee76c
  - >-
    Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb <
    4da7fcc098218ff92b2e83a43f545c02f714cedd
  - >-
    Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb <
    cdaa6d1cb2ff1219c6c822b27655dd170ffb0f72
  - >-
    Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb <
    9ad0452c0277b816a435433cca601304cfac7c21
  - Linux 4.3
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-11-05T20:49:18.243571Z'
published: '2025-06-28'
updated: '2026-11-05'
sourceUpdated: '2026-11-05T20:52:15.111Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2025-38086'
references:
  - url: 'https://git.kernel.org/stable/c/119766de4930ff40db9f36b960cb53b0c400e81b'
  - url: 'https://git.kernel.org/stable/c/33163c68d2e3061fa3935b5f0a1867958b1cdbd2'
  - url: 'https://git.kernel.org/stable/c/9da3e442714f7f4393ff01c265c4959c03e88c2f'
  - url: 'https://git.kernel.org/stable/c/9a350f30d65197354706b7759b5c89d6c267b1a9'
  - url: 'https://git.kernel.org/stable/c/6bd2569d0b2f918e9581f744df0263caf73ee76c'
  - url: 'https://git.kernel.org/stable/c/4da7fcc098218ff92b2e83a43f545c02f714cedd'
  - url: 'https://git.kernel.org/stable/c/cdaa6d1cb2ff1219c6c822b27655dd170ffb0f72'
  - url: 'https://git.kernel.org/stable/c/9ad0452c0277b816a435433cca601304cfac7c21'
tags:
  - cve.org
epss: 0.00206
epssPercentile: 0.10679
ingestedAt: '2026-11-05T22:38:31.916Z'
---

## Overview

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

net: ch9200: fix uninitialised access during mii_nway_restart

In mii_nway_restart() the code attempts to call
mii->mdio_read which is ch9200_mdio_read(). ch9200_mdio_read()
utilises a local buffer called "buff", which is initialised
with control_read(). However "buff" is conditionally
initialised inside control_read():

        if (err == size) {
                memcpy(data, buf, size);
        }

If the condition of "err == size" is not met, then
"buff" remains uninitialised. Once this happens the
uninitialised "buff" is accessed and returned during
ch9200_mdio_read():

        return (buff[0] | buff[1] << 8);

The problem stems from the fact that ch9200_mdio_read()
ignores the return value of control_read(), leading to
uinit-access of "buff".

To fix this we should check the return value of
control_read() and return early on error.

## Affected

- `Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb < 119766de4930ff40db9f36b960cb53b0c400e81b`
- `Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb < 33163c68d2e3061fa3935b5f0a1867958b1cdbd2`
- `Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb < 9da3e442714f7f4393ff01c265c4959c03e88c2f`
- `Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb < 9a350f30d65197354706b7759b5c89d6c267b1a9`
- `Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb < 6bd2569d0b2f918e9581f744df0263caf73ee76c`
- `Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb < 4da7fcc098218ff92b2e83a43f545c02f714cedd`
- `Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb < cdaa6d1cb2ff1219c6c822b27655dd170ffb0f72`
- `Linux >= 4a476bd6d1d923922ec950ddc4c27b279f6901eb < 9ad0452c0277b816a435433cca601304cfac7c21`
- `Linux 4.3`

## Remediation

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