---
id: CVE-2026-97931
title: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ALSA: us122l: Prevent write upgrades for read mappings

  The hwdep mmap callback rejects read-buffer mappings that are initially
  writable, but leaves VM_MAYWRITE set on …
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  ALSA: us122l: Prevent write upgrades for read mappings

  The hwdep mmap callback rejects read-buffer mappings that are initially
  writable, but leaves VM_MAYWRITE set on …
severity: high
cvss: 7
cvssVector: 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 030a07e441296c372f946cd4065b5d831d8dc40c <
    64a87950239867682cde128020e1a47088295e5c
  - >-
    Linux >= 030a07e441296c372f946cd4065b5d831d8dc40c <
    d9c537b14f4982f17b103e3a2cfeee4bee6bc026
  - >-
    Linux >= 030a07e441296c372f946cd4065b5d831d8dc40c <
    0eb9dd4774af0ac4d1fd105ef2b0a1f6cec06f2f
  - >-
    Linux >= 030a07e441296c372f946cd4065b5d831d8dc40c <
    71c610aeb1770302ac9c9e0b9a4ecd37f1311928
  - Linux 2.6.28
published: '2026-09-25'
updated: '2026-09-25'
sourceUpdated: '2026-09-25T15:18:02.450'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-97931'
references:
  - url: 'https://git.kernel.org/stable/c/0eb9dd4774af0ac4d1fd105ef2b0a1f6cec06f2f'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/64a87950239867682cde128020e1a47088295e5c'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/71c610aeb1770302ac9c9e0b9a4ecd37f1311928'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
  - url: 'https://git.kernel.org/stable/c/d9c537b14f4982f17b103e3a2cfeee4bee6bc026'
    label: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
tags:
  - nvd
  - cve.org
ingestedAt: '2026-09-25T11:06:38.885Z'
---

## Overview

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

ALSA: us122l: Prevent write upgrades for read mappings

The hwdep mmap callback rejects read-buffer mappings that are initially
writable, but leaves VM_MAYWRITE set on mappings created with PROT_READ.
A process that can open the hwdep node O_RDWR can later use mprotect() to
make the mapping writable.

The read allocation begins with struct usb_stream. Its read_size member is
used by the fault handler to decide which pages belong to the read buffer.
The read VMA intentionally remains expandable because pcm_usb_stream uses
mremap() after reading that size. Changing read_size first can therefore
map and access pages beyond the allocation. The same member is also
consumed by usb_stream_free(), where changing it can make
free_pages_exact() release pages outside the allocation.

Clear VM_MAYWRITE for read-buffer mappings after rejecting an initially
writable VMA. This keeps the separate output-buffer mapping writable while
preventing later permission upgrades.

## Remediation

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