CVE-2021-47151

What it actually does

Missing of_node_put() call in of_bcm_voter_get() causes a device tree node reference count leak in the Qualcomm BCM voter interconnect driver.

Why it matters to the business

Gradual kernel memory resource exhaustion on affected Linux systems can lead to instability, degraded performance, or crashes in network and interconnect subsystems.

How an attack unfolds

An attacker with local access repeatedly triggers paths that call of_bcm_voter_get() without corresponding cleanup, accumulating leaked references until memory pressure enables denial of service or secondary memory corruption exploits.

How to fix it

Apply the upstream kernel commit that adds the missing of_node_put() in of_bcm_voter_get(); rebuild and deploy updated kernel images for all affected distributions.

How to confirm the fix worked

Inspect the interconnect/qcom/bcm-voter.c source for the of_node_put() addition after of_bcm_voter_get(); boot the patched kernel and confirm no reference leaks via kmemleak or similar tools under load.

Typical attack path

1. Obtain local code execution or shell access on target system
2. Invoke interconnect or device tree operations that reach of_bcm_voter_get()
3. Repeat operation to accumulate reference leaks
4. Trigger memory pressure or OOM conditions to surface corruption or crash

How to detect it

Review kernel logs for repeated interconnect voter allocation messages or unexplained memory growth; use kmemleak reports or slabinfo to identify accumulating device_node references.

What your security team should do

• Prioritize kernel updates on systems exposing Qualcomm interconnect drivers
• Monitor for memory pressure indicators on production kernels until patched
• Test patched kernels in staging before broad deployment