CVE-2021-47443

What it actually does

Failure to release heap-allocated 'params' structure in digital_tg_listen_mdaa() when digital_send_cmd() returns an error, resulting in a kernel memory leak.

Why it matters to the business

Prolonged operation of NFC digital listener paths on affected kernels can gradually exhaust memory, causing performance degradation, reduced availability, or eventual system instability on devices using Linux NFC.

How an attack unfolds

An attacker with local or adjacent access capable of repeatedly invoking NFC digital tag listening operations that trigger digital_send_cmd() failures can accelerate the memory leak; no known threat actors or ransomware campaigns have leveraged this issue.

How to fix it

Update the Linux kernel to a version containing the upstream fix that frees 'params' on digital_send_cmd() failure; apply the patch from the commit resolving the leak if backporting is required.

How to confirm the fix worked

Inspect the digital_tg_listen_mdaa() function in the running kernel source or running kernel binary to confirm 'params' is freed on all digital_send_cmd() error paths; monitor kernel memory statistics for NFC-related allocations after exercising the function.

Typical attack path

1. Obtain local or NFC-adjacent access to the target system
2. Trigger repeated calls to digital_tg_listen_mdaa() under conditions that cause digital_send_cmd() to fail
3. Accumulate unreleased kernel allocations until memory pressure leads to denial of service

How to detect it

Examine kernel logs for repeated NFC digital function failures; monitor process and kernel memory usage trends on systems with NFC enabled; review dmesg or /proc/meminfo for anomalous allocation growth tied to NFC modules.

What your security team should do

• Prioritize kernel updates on systems exposing NFC digital interfaces
• Review kernel configuration to disable unused NFC subsystems where possible
• Incorporate memory-leak regression tests for NFC digital paths into CI pipelines