Executive Summary

Name CVE-2024-26909 First vendor Publication 2024-04-17
Vendor Cve Last vendor Modification 2024-04-29

Security-Database Scoring CVSS v3

Cvss vector : CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Overall CVSS Score 5.5
Base Score 5.5 Environmental Score 5.5
impact SubScore 3.6 Temporal Score 5.5
Exploitabality Sub Score 1.8
Attack Vector Local Attack Complexity Low
Privileges Required Low User Interaction None
Scope Unchanged Confidentiality Impact None
Integrity Impact None Availability Impact High
Calculate full CVSS 3.0 Vectors scores

Security-Database Scoring CVSS v2

Cvss vector :
Cvss Base Score N/A Attack Range N/A
Cvss Impact Score N/A Attack Complexity N/A
Cvss Expoit Score N/A Authentication N/A
Calculate full CVSS 2.0 Vectors scores


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

soc: qcom: pmic_glink_altmode: fix drm bridge use-after-free

A recent DRM series purporting to simplify support for "transparent bridges" and handling of probe deferrals ironically exposed a use-after-free issue on pmic_glink_altmode probe deferral.

This has manifested itself as the display subsystem occasionally failing to initialise and NULL-pointer dereferences during boot of machines like the Lenovo ThinkPad X13s.

Specifically, the dp-hpd bridge is currently registered before all resources have been acquired which means that it can also be deregistered on probe deferrals.

In the meantime there is a race window where the new aux bridge driver (or PHY driver previously) may have looked up the dp-hpd bridge and stored a (non-reference-counted) pointer to the bridge which is about to be deallocated.

When the display controller is later initialised, this triggers a use-after-free when attaching the bridges:

dp -> aux -> dp-hpd (freed)

which may, for example, result in the freed bridge failing to attach:

[drm:drm_bridge_attach [drm]] *ERROR* failed to attach bridge /soc@0/phy@88eb000 to encoder TMDS-31: -16

or a NULL-pointer dereference:

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Call trace:
drm_bridge_attach+0x70/0x1a8 [drm]
drm_aux_bridge_attach+0x24/0x38 [aux_bridge]
drm_bridge_attach+0x80/0x1a8 [drm]
dp_bridge_init+0xa8/0x15c [msm]
msm_dp_modeset_init+0x28/0xc4 [msm]

The DRM bridge implementation is clearly fragile and implicitly built on the assumption that bridges may never go away. In this case, the fix is to move the bridge registration in the pmic_glink_altmode driver to after all resources have been looked up.

Incidentally, with the new dp-hpd bridge implementation, which registers child devices, this is also a requirement due to a long-standing issue in driver core that can otherwise lead to a probe deferral loop (see commit fbc35b45f9f6 ("Add documentation on meaning of -EPROBE_DEFER")).

[DB: slightly fixed commit message by adding the word 'commit']

Original Source

Url : http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2024-26909

CWE : Common Weakness Enumeration

% Id Name
100 % CWE-416 Use After Free

CPE : Common Platform Enumeration

Application 8
Os 3561

Sources (Detail)

Source Url

Alert History

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Date Informations
2024-04-30 00:27:34
  • Multiple Updates
2024-04-17 17:28:31
  • First insertion