CVE-2024-40987

What it actually does

Missing bounds check on sumo_vid_mapping_entry in kv_dpm.c permits out-of-bounds access in AMD GPU dynamic power management, triggering undefined behavior.

Why it matters to the business

Potential kernel instability or crashes on Linux systems using affected AMD GPUs, leading to operational downtime in environments relying on those graphics subsystems.

How an attack unfolds

An attacker with local access triggers the kv_dpm power management path with an out-of-range index into the video mapping table, exploiting the absent bounds validation; listed threat actors in kernel and zero-day campaigns illustrate possible context for similar issues though no direct exploitation is recorded here.

How to fix it

Update the Linux kernel to the fixed commit 4ad7d49059358ceadd352b4e2511425bdb68f400 or an equivalent stable release containing the bounds check.

How to confirm the fix worked

Confirm the running kernel contains commit 4ad7d49059358ceadd352b4e2511425bdb68f400 and verify absence of UBSAN warnings when exercising kv_dpm.c code paths.

Typical attack path

1. Obtain local access to a vulnerable Linux kernel with AMD GPU support
2. Trigger dynamic power management operations in kv_dpm.c
3. Supply crafted input causing out-of-bounds index into sumo_vid_mapping_entry

How to detect it

Review kernel logs for UBSAN warnings referencing kv_dpm.c or sumo_vid_mapping_entry and inspect for unexpected power management faults on AMD GPUs.

What your security team should do

• Apply the kernel update containing commit 4ad7d49059358ceadd352b4e2511425bdb68f400 across affected systems
• Include the updated kernel in standard patching cycles given the age of the disclosure