CVE-2021-47052

What it actually does

Two error return paths in the sa2ul crypto driver fail to free the rxd structure, resulting in a kernel memory leak.

Why it matters to the business

Repeated triggering of the affected error paths can gradually exhaust kernel memory, leading to performance degradation or system instability on affected Linux systems over time.

How an attack unfolds

An attacker with local access or the ability to induce specific error conditions in the sa2ul driver can cause repeated allocation without corresponding frees, slowly consuming kernel memory until the system becomes unresponsive.

How to fix it

Update to a Linux kernel version that includes the fix for the rxd memory leak in the sa2ul driver.

How to confirm the fix worked

Confirm the presence of the upstream commit that adds the missing kfree calls on the two error paths; monitor kernel memory usage under load that exercises the driver.

Typical attack path

1. Obtain local access or control over inputs that reach the sa2ul driver error paths
2. Repeatedly trigger the error conditions that bypass rxd deallocation
3. Observe gradual kernel memory consumption until denial of service occurs

How to detect it

Look for unexplained increases in kernel memory usage correlated with sa2ul driver activity; examine kernel logs for repeated error paths in the driver.

What your security team should do

• Prioritize kernel updates for systems using the sa2ul crypto accelerator
• Review workloads that may repeatedly hit the error paths for temporary mitigations such as process limits
• Monitor kernel memory statistics for unexpected growth on affected systems