Bug 2493733 (CVE-2026-53313)

Summary: CVE-2026-53313 kernel: drm/amd/display: Avoid NULL dereference in dc_dmub_srv error paths
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
Status: NEW --- QA Contact:
Severity: low Docs Contact:
Priority: low    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: Doc Type: ---
Doc Text:
A flaw was found in the Linux kernel's drm/amd/display module. This vulnerability allows for a denial of service (DoS) due to a NULL pointer dereference. Specifically, the dc_dmub_srv_log_diagnostic_data() and dc_dmub_srv_enable_dpia_trace() functions do not correctly handle a NULL dc_dmub_srv pointer before attempting to log an error, which can lead to a system crash.
 Story Points: ---
Clone Of: Environment:
Last Closed: Type: ---
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-06-26 21:03:55 UTC 
In the Linux kernel, the following vulnerability has been resolved:

drm/amd/display: Avoid NULL dereference in dc_dmub_srv error paths

In dc_dmub_srv_log_diagnostic_data() and
dc_dmub_srv_enable_dpia_trace().

Both functions check:

  if (!dc_dmub_srv || !dc_dmub_srv->dmub)

and then call DC_LOG_ERROR() inside that block.

DC_LOG_ERROR() uses dc_dmub_srv->ctx internally. So if
dc_dmub_srv is NULL, the logging itself can dereference a
NULL pointer and cause a crash.

Fix this by splitting the checks.

First check if dc_dmub_srv is NULL and return immediately.
Then check dc_dmub_srv->dmub and log the error only when
dc_dmub_srv is valid.

Fixes the below:
../display/dc/dc_dmub_srv.c:962 dc_dmub_srv_log_diagnostic_data() error: we previously assumed 'dc_dmub_srv' could be null (see line 961)
../display/dc/dc_dmub_srv.c:1167 dc_dmub_srv_enable_dpia_trace() error: we previously assumed 'dc_dmub_srv' could be null (see line 1166)
Comment 1 Mauro Matteo Cascella 2026-06-29 09:25:42 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026062621-CVE-2026-53313-4106@gregkh/T