CVE-2024-46870

What it actually does

Race condition in AMD display controller (DCN35/DMCUB) where extended command processing can lead to attempts to access inaccessible DCN state or NIU port, resulting in system hang or undefined display configuration.

Why it matters to the business

Potential system instability or freezes on affected Linux systems using AMD graphics hardware, leading to downtime and reduced availability; low exploit likelihood limits widespread operational risk.

How an attack unfolds

An attacker with local access triggers display command sequences that exploit the timing window in DMCUB processing, causing the race that hangs the system; no public exploits or named threat actor campaigns are associated with this specific issue.

How to fix it

Update the Linux kernel to a version containing commit 31c254c9cd4b122a10db297124f867107a696d83 or later stable releases that disable the DMCUB timeout for DCN35.

How to confirm the fix worked

Verify the presence of the fix commit in the running kernel source or package; test display initialization and command processing under load to confirm absence of hangs related to DMCUB timing.

Typical attack path

1. Obtain local user access on a vulnerable Linux kernel with AMD DCN35 hardware
2. Perform graphics or display operations that engage DMCUB command processing
3. Trigger the intermittent timing condition leading to attempted access of inaccessible state
4. Cause system hang or undefined display configuration

How to detect it

Examine kernel logs for DMCUB timeout diagnostic errors or NIU-related access failures preceding hangs; no specific post-exploitation artifacts are known.

What your security team should do

• Prioritize kernel updates on systems with AMD DCN35 hardware within standard patching cycles
• Monitor upstream stable kernel releases for backports of the DMCUB timeout disable
• Review system logs for prior DMCUB-related diagnostic errors as indicators of exposure