CVE-2024-56691

What it actually does

The intel_soc_pmic_bxtwc driver fails to respect per-device IRQ domains when instantiating MFD children for the USB Type-C controller, causing platform_get_irq to receive IRQ 0 (an invalid vIRQ) and triggering kernel warnings plus incorrect IRQ chip hierarchy setup.

Why it matters to the business

On affected Intel platforms, USB Type-C device initialization may produce kernel warnings, delay port functionality, or cause resource allocation problems until the kernel is updated.

How an attack unfolds

An attacker with local access triggers the MFD probe sequence for the intel_soc_pmic_bxtwc driver; the flawed IRQ domain handling supplies an invalid IRQ number, resulting in warnings or misconfigured interrupt resources. No public in-the-wild exploitation is known for this specific flaw.

How to fix it

Update the Linux kernel to commit 0997e77c51330c2866a4f39480e762cca92ad953 or later; rebuild and deploy the updated kernel image on all affected systems.

How to confirm the fix worked

Verify the running kernel contains commit 0997e77c51330c2866a4f39480e762cca92ad953; confirm absence of platform_get_irq WARN messages referencing IRQ 0 during PMIC probe.

Typical attack path

1. Obtain local execution on a system using the intel_soc_pmic_bxtwc driver
2. Trigger or wait for MFD device enumeration for the PMIC/USB Type-C controller
3. Observe platform_get_irq returning IRQ 0 and subsequent kernel WARN
4. Exploit resulting misconfigured interrupt resources for denial-of-service or limited local impact

How to detect it

Search kernel logs for platform_get_irq WARN messages mentioning IRQ 0 or vIRQ during intel_soc_pmic_bxtwc or MFD device probe; review dmesg and journalctl output around PMIC initialization.

• platform_get_irq.*IRQ 0
• WARNING.*intel_soc_pmic_bxtwc
• vIRQ.*supposed to be a Linux IRQ number

What your security team should do

• Prioritize kernel upgrade to the fixed commit on all Intel platforms using the bxtwc PMIC driver
• Add kernel log monitoring for platform_get_irq and IRQ 0 warnings as a temporary detection measure
• Test USB Type-C functionality after patching to confirm correct IRQ assignment