CVE-2023-53842

What it actually does

MBHC resources remain allocated on component probe failure or removal instead of being released, causing leaks not tied to component device lifetime and leading to subsequent IRQ request failures during reprobes.

Why it matters to the business

Audio subsystems on affected Linux kernels fail to initialize during probe deferrals, resulting in repeated sound card instantiation errors, device boot issues, and loss of audio functionality until resources are manually recovered or the system is restarted.

How an attack unfolds

An attacker with local access can induce repeated sound card probe attempts or component unload/reload sequences to exhaust MBHC interrupt and resource pools, triggering allocation failures and audio subsystem instability without requiring special privileges beyond standard device interaction.

How to fix it

Update the Linux kernel to commit 90ab6446eb522e31421b77bf8f45714f5668f9a3 or later stable releases containing the fix that properly releases MBHC resources on probe failure and component removal.

How to confirm the fix worked

Confirm kernel source contains commit 90ab6446eb522e31421b77bf8f45714f5668f9a3; test sound card probe deferral scenarios to verify clean MBHC resource release and absence of IRQ flags mismatch errors on reprobe.

Typical attack path

1. Interact with sound subsystem to force component probe
2. Trigger probe deferral conditions
3. Force reprobe or removal to leak MBHC resources
4. Repeat until IRQ allocation fails with flags mismatch
5. Observe audio initialization errors and system instability

How to detect it

Search kernel and audio subsystem logs for messages indicating MBHC interrupt request failures, IRQ flags mismatches, or repeated component probe errors during sound card initialization.

• Flags mismatch irq.*mbhc sw intr
• Failed to request mbhc interrupts
• mbhc initialization failed
• ASoC: error at snd_soc_component_probe on audio-codec

What your security team should do

• Prioritize kernel upgrade to the fixed commit on all affected systems
• Monitor boot and audio device logs for repeated mbhc initialization failures
• Restrict unprivileged access to audio device nodes until patched