CVE-2023-54018

What it actually does

Unchecked return value from alloc_ordered_workqueue allows a NULL pointer to be dereferenced in hdmi_hdcp.c and hdmi_hpd.c, resulting in a kernel NULL pointer dereference.

Why it matters to the business

Systems may experience unexpected crashes or instability when handling HDMI display connections under low-memory conditions, potentially disrupting graphics workloads and requiring reboots.

How an attack unfolds

An attacker with local access triggers the workqueue allocation path in the MSM HDMI driver under memory pressure so that alloc_ordered_workqueue returns NULL, which is then dereferenced without a check, causing a kernel panic.

How to fix it

Update to a fixed kernel containing commit b479485b24da1d572a0ce875537af31b02d2f915 or a newer release; Chainguard Cortex users should upgrade to 1.19.0-r7 or later.

How to confirm the fix worked

Verify the presence of the fix commit in the running kernel source tree or confirm package version 1.19.0-r7 (Chainguard/Wolfi) or equivalent; test HDMI/HDCP functionality under memory-constrained conditions to ensure no NULL dereference occurs.

Typical attack path

1. Obtain local code execution on an affected Linux system
2. Induce memory pressure to force alloc_ordered_workqueue to fail
3. Trigger HDMI hot-plug or HDCP-related initialization paths in drm/msm
4. Cause NULL dereference and kernel panic

How to detect it

Review kernel logs (dmesg, /var/log/kern.log) for NULL pointer dereference oops containing hdmi_hdcp.c or hdmi_hpd.c stack frames; correlate with prior low-memory conditions or HDMI-related events.

What your security team should do

• Prioritize patching systems that expose HDMI/HDCP functionality or run graphics workloads
• Apply the fixed kernel version or backport the alloc_ordered_workqueue check
• Monitor for kernel oops/panic reports referencing hdmi_hdcp or hdmi_hpd after low-memory events