---
id: CVE-2026-98786
title: 'drm/amd/display: guard dc_sink dereferences in MST mode validation'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  drm/amd/display: guard dc_sink dereferences in MST mode validation

  dm_dp_mst_is_port_support_mode() reads
  aconnector->dc_sink->dsc_caps... for the DSC branch-throughpu…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= f04d275d94e164d24516c32437c988a323018f63 <
    daa0437fe5e451856aaf8fda602a9fc2105bbd54
  - >-
    Linux >= f04d275d94e164d24516c32437c988a323018f63 <
    217f64f348c90cba62164e7ff38e0ccf78a5ca09
  - Linux 6.0
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:48:22.989Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98786'
references:
  - url: 'https://git.kernel.org/stable/c/daa0437fe5e451856aaf8fda602a9fc2105bbd54'
  - url: 'https://git.kernel.org/stable/c/217f64f348c90cba62164e7ff38e0ccf78a5ca09'
tags:
  - cve.org
ingestedAt: '2026-10-18T16:47:32.487Z'
---

## Overview

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

drm/amd/display: guard dc_sink dereferences in MST mode validation

dm_dp_mst_is_port_support_mode() reads
aconnector->dc_sink->dsc_caps... for the DSC branch-throughput check,
and get_conv_frl_bw()'s HDMI-PCON FRL-bandwidth path reads
aconnector->dc_sink->edid_caps.max_frl_rate, both without a NULL
check. dc_sink is cleared asynchronously on MST unplug, and both
functions run from paths that the driver's own comments document as
racing that teardown: the connector probe worker's ->mode_valid
callback and a compositor's atomic check, neither of which holds the
MST manager lock that the teardown path uses. The former does have an
existing dsc_aux NULL check, but dsc_aux isn't reliably cleared in
every path that clears dc_sink, so it doesn't cover this.

Fail the port-support check and skip the FRL conversion path when the
sink is already gone.

(cherry picked from commit 7c3db8da4e039698ae198c870712428644e965c7)

## Affected

- `Linux >= f04d275d94e164d24516c32437c988a323018f63 < daa0437fe5e451856aaf8fda602a9fc2105bbd54`
- `Linux >= f04d275d94e164d24516c32437c988a323018f63 < 217f64f348c90cba62164e7ff38e0ccf78a5ca09`
- `Linux 6.0`

## Remediation

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