CVE-2022-48831

What it actually does

A reference to a cryptographic key is not released when an unknown algorithm is encountered during asymmetric signature verification in the IMA subsystem, resulting in a kernel resource leak.

Why it matters to the business

Gradual exhaustion of kernel resources on Linux systems performing signature verifications can lead to instability or denial of service, affecting the availability of servers, embedded devices, and Android-based products that rely on the kernel.

How an attack unfolds

An attacker provides input such as a signed file or kernel module using an unrecognized algorithm to the asymmetric_verify function, causing the reference leak without triggering an error path that releases the key. Repeated triggering depletes resources; context from kernel remote code execution campaigns may be used to chain this into broader attacks on Android or Linux environments.

How to fix it

Apply the fix from Linux kernel commit 0838d6d68182f0b28a5434bc6d50727c4757e35b or equivalent stable releases that resolve the reference leak in asymmetric_verify.

How to confirm the fix worked

Verify the presence of commit 0838d6d68182f0b28a5434bc6d50727c4757e35b in the running kernel source; test asymmetric verification paths with unknown algorithms to confirm no reference leaks occur.

Typical attack path

1. Locate Linux kernel systems with IMA asymmetric verification enabled
2. Craft and submit a signature or key using an unknown algorithm to trigger asymmetric_verify
3. Repeat the operation to accumulate leaked key references
4. Monitor for resource exhaustion leading to system instability or crash

How to detect it

Review kernel logs and IMA-related audit events for errors around asymmetric_verify or key handling; track reference count anomalies in cryptographic key structures during signature operations.

What your security team should do

• Upgrade affected Linux kernels to the fixed commit immediately on all production systems
• Audit IMA configurations to ensure only supported algorithms are used where possible
• Monitor kernel resource usage metrics for unexpected growth in key references