CVE-2024-42124

What it actually does

Calling smp_processor_id() from preemptible context inside qedf_execute_tmf() triggers BUG_ON() on real-time kernels.

Why it matters to the business

Real-time Linux systems using the qedf Fibre Channel driver may suffer kernel crashes during storage task management, causing unexpected downtime for affected hosts.

How an attack unfolds

An attacker or workload triggers qedf_execute_tmf() while the calling context remains preemptible, causing the kernel to assert and panic when smp_processor_id is invoked.

How to fix it

Upgrade the Linux kernel to a version containing commit 4f314aadeed8cdf42c8cf30769425b5e44702748 or later that makes qedf_execute_tmf non-preemptible.

How to confirm the fix worked

Confirm the patched qedf driver no longer calls smp_processor_id from preemptible paths and that RT kernel BUG messages referencing qedf_execute_tmf are absent.

Typical attack path

1. Initiate SCSI task management function via qedf driver
2. Ensure execution occurs in preemptible process context
3. Kernel executes smp_processor_id() and hits BUG_ON()

How to detect it

Search kernel logs and dmesg for BUG messages containing smp_processor_id, preemptible, and the qedf module stack trace.

What your security team should do

• Apply the referenced kernel commit on all real-time deployments using qedf
• Reboot affected hosts after the update and validate storage paths
• Review kernel logs for prior preemptible-context warnings from the qedf module