CVE-2023-52806

What it actually does

Null pointer dereference in ALSA HDA driver when assigning a COUPLED stream type to a stub substream instance that occurs during code-loading.

Why it matters to the business

Local denial of service through kernel crash on Linux systems, disrupting audio processing and requiring reboots with potential data loss in active sessions.

How an attack unfolds

A local attacker interacts with the ALSA subsystem and requests assignment of a COUPLED stream, which the driver does not reject, causing dereference of a null substream pointer.

How to fix it

Update the Linux kernel to include commit 7de25112de8222fd20564769e6c99dc9f9738a0b or equivalent fixed versions from stable branches.

How to confirm the fix worked

Confirm presence of the fix commit in kernel source, rebuild, and test stream assignment paths with both HOST/LINK and COUPLED types.

Typical attack path

1. Gain local user access on a Linux system
2. Load or interact with ALSA HDA audio drivers
3. Request assignment of a COUPLED stream type during code-loading window
4. Trigger null pointer dereference resulting in kernel panic

How to detect it

Review kernel logs and dmesg output for null pointer dereference traces mentioning ALSA HDA stream assignment or coupled streams.

What your security team should do

• Prioritize kernel updates on all affected systems within standard patching windows
• Monitor kernel logs for ALSA-related oops and panics
• Limit untrusted local code execution where feasible