CVE-2023-53851

Technical Description

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

drm/msm/dp: Drop aux devices together with DP controller

Using devres to depopulate the aux bus made sure that upon a probe

deferral the EDP panel device would be destroyed and recreated upon next

attempt.

But the struct device which the devres is tied to is the DPUs

(drm_dev->dev), which may be happen after the DP controller is torn

down.

Indications of this can be seen in the commonly seen EDID-hexdump full

of zeros in the log, or the occasional/rare KASAN fault where the

panel's attempt to read the EDID information causes a use after free on

DP resources.

It's tempting to move the devres to the DP controller's struct device,

but the resources used by the device(s) on the aux bus are explicitly

torn down in the error path. The KASAN-reported use-after-free also

remains, as the DP aux "module" explicitly frees its devres-allocated

memory in this code path.

As such, explicitly depopulate the aux bus in the error

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References