CVE-2021-46985

What it actually does

Memory leak in Linux kernel ACPI device scan error path when acpi_device_set_name fails, leaving acpi_device_bus_id->bus_id unfreed.

Why it matters to the business

Gradual kernel memory exhaustion on Linux systems during repeated ACPI device enumeration errors, risking instability or denial of service over time in servers and embedded devices.

How an attack unfolds

An attacker triggers ACPI device registration errors during kernel boot or hotplug events to induce the leak; repeated local or privileged actions accumulate unreleased memory without remote code execution potential.

How to fix it

Apply the upstream kernel patch resolving the ACPI scan memory leak or upgrade to a fixed kernel release containing the error-path free of bus_id.

How to confirm the fix worked

Inspect ACPI scan source for the added free on acpi_device_set_name failure; boot with error-injecting ACPI tables and monitor /proc/meminfo for leak absence.

Typical attack path

1. Obtain local or privileged access to influence ACPI device scan
2. Force acpi_device_set_name failure condition
3. Repeat to accumulate leaked bus_id memory

How to detect it

Review kernel logs for ACPI scan errors coinciding with unexplained memory growth; use memory profiling tools to trace bus_id allocations without corresponding frees.

What your security team should do

• Prioritize kernel updates on all Linux systems handling ACPI
• Monitor kernel memory usage trends in production workloads
• Test ACPI error paths in staging environments before rollout