CVE-2021-47532

What it actually does

Reference count leak on OPP structures in the drm/msm/devfreq driver prevents proper cleanup of performance point objects, resulting in resource exhaustion within the Linux kernel graphics subsystem.

Why it matters to the business

Systems using Qualcomm MSM graphics hardware may experience gradual memory pressure during extended operation, reducing stability and availability especially on long-running embedded or mobile deployments with high graphics activity.

How an attack unfolds

An attacker with local access triggers repeated devfreq frequency scaling or display operations that acquire OPP references; the missing decrement leaves references held indefinitely, leading to memory consumption that can culminate in denial of service or secondary corruption conditions.

How to fix it

Apply the upstream kernel commit that resolves the OPP refcnt leak in drm/msm/devfreq; rebuild and deploy updated kernels or obtain distribution packages that include the fix.

How to confirm the fix worked

Confirm the patch is present by inspecting the drm/msm/devfreq.c source for the corrected reference handling logic or verify the running kernel version incorporates the resolution.

Typical attack path

1. Obtain local execution on a target Linux system with MSM DRM hardware
2. Invoke graphics or display workloads that exercise devfreq OPP acquisition paths
3. Repeat operations to accumulate unreleased OPP references
4. Observe kernel memory growth and resulting system degradation

How to detect it

Review kernel logs and dmesg output for devfreq or OPP-related warnings; monitor system memory statistics correlated with graphics driver activity for unexplained growth.

What your security team should do

• Expedite kernel updates on all affected Qualcomm MSM platforms
• Review graphics driver usage patterns for unexpected memory growth
• Incorporate kernel version checks into vulnerability scanning processes