CVE-2021-47473

What it actually does

Incorrect comparison operator (== instead of !=) in qla2x00_process_els causes either leaking fcport structures or freeing unallocated memory in ELS error paths.

Why it matters to the business

Memory exhaustion or kernel instability possible on systems using QLogic Fibre Channel adapters when specific link service requests hit error handling.

How an attack unfolds

An attacker sends crafted or specific ELS frames over Fibre Channel to trigger the error path in qla2x00_process_els, where the wrong condition either leaks memory repeatedly or performs an invalid free.

How to fix it

Update the Linux kernel to a version containing the corrected comparison (changing == to !=) in the qla2x00_process_els error handling logic.

How to confirm the fix worked

Inspect qla2x00_process_els source to verify the condition uses != FC_BSG_RPT_ELS; exercise ELS error paths in testing and confirm no fcport leaks via memory accounting.

Typical attack path

1. Establish Fibre Channel connectivity to target port
2. Send ELS requests that exercise the error path in qla2x00_process_els
3. Repeat to accumulate leaks or trigger invalid free and crash

How to detect it

Review kernel logs for qla2xxx error paths, fcport allocation warnings, or OOM events tied to the driver; inspect memory usage trends on hosts with QLogic adapters.

What your security team should do

• Apply the upstream fix for the qla2xxx ELS processing condition
• Monitor systems with QLogic HBAs for unexplained memory growth or qla2xxx-related oops
• Restrict untrusted Fibre Channel access where feasible until patched