---
id: CVE-2026-99151
title: 'drm/amd/display: Fix NULL sink dereference in USB4 bandwidth functions'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  drm/amd/display: Fix NULL sink dereference in USB4 bandwidth functions

  allocate_usb4_bandwidth_for_stream() and allocate_usb4_bandwidth() both
  use ASSERT(stream->sink)…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 0b1eebd359685dd681f6e0df5540a5bb985a27bf <
    4c8b5e5b9776ad08138d79b14238c5742b32911b
  - >-
    Linux >= 8fa813b7fd1eccbed13e126166cf764f1f11a7d3 <
    55a67aa89342545b89f469dea6f29bfb6fac6f3d
  - Linux >= 7.2.9 < 7.2.13
published: '2026-10-28'
updated: '2026-10-28'
sourceUpdated: '2026-10-28T10:35:06.866Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-99151'
references:
  - url: 'https://git.kernel.org/stable/c/4c8b5e5b9776ad08138d79b14238c5742b32911b'
  - url: 'https://git.kernel.org/stable/c/55a67aa89342545b89f469dea6f29bfb6fac6f3d'
tags:
  - cve.org
ingestedAt: '2026-10-28T11:09:40.416Z'
---

## Overview

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

drm/amd/display: Fix NULL sink dereference in USB4 bandwidth functions

allocate_usb4_bandwidth_for_stream() and allocate_usb4_bandwidth() both
use ASSERT(stream->sink) before dereferencing stream->sink->link. ASSERT
is compiled out in production builds, so a NULL stream->sink causes a
NULL pointer dereference.

link_set_dpms_off() already guards two earlier accesses to stream->sink
with explicit NULL checks, confirming that stream->sink can legitimately
be NULL. The subsequent call to deallocate_usb4_bandwidth() had no
equivalent guard.

Replace the ASSERT() calls with proper NULL checks that return false
early, and add a matching stream->sink guard at the call site in
link_set_dpms_off() consistent with the surrounding pattern.

v2: Keep the existing ASSERT() calls for diagnostics (to report
    unexpected NULL sink), and add explicit NULL checks that return false
    before dereferencing stream->sink. Also add a matching stream->sink
    guard at the deallocation call site in link_set_dpms_off(). (Alex)

(cherry picked from commit 98029a0ce61feb52c563f65349dd9b25f672e355)

## Affected

- `Linux >= 0b1eebd359685dd681f6e0df5540a5bb985a27bf < 4c8b5e5b9776ad08138d79b14238c5742b32911b`
- `Linux >= 8fa813b7fd1eccbed13e126166cf764f1f11a7d3 < 55a67aa89342545b89f469dea6f29bfb6fac6f3d`
- `Linux >= 7.2.9 < 7.2.13`

## Remediation

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