CVE-2021-47331

What it actually does

NULL pointer dereference in usb-conn-gpio driver when IDDIG interrupt fires before charger registration during OTG cable power-on.

Why it matters to the business

System instability or crash on affected Linux devices using USB OTG, potentially causing downtime for hardware relying on this kernel component.

How an attack unfolds

An attacker with physical access connects an OTG cable to trigger the IDDIG interrupt before the power supply registration completes, dereferencing a null charger pointer and crashing the kernel.

How to fix it

Update the Linux kernel to a version containing the fix that registers the power supply before requesting IDDIG/VBUS IRQs.

How to confirm the fix worked

Confirm kernel version includes the usb-conn-gpio registration order change; inspect dmesg for absence of charger NULL dereference on OTG connect; test OTG power-on sequence.

Typical attack path

1. Obtain physical access to target Linux device with USB OTG support
2. Connect OTG cable to induce early IDDIG interrupt
3. Trigger race condition before charger registration
4. Cause NULL pointer dereference and kernel panic

How to detect it

Review kernel logs for usb-conn-gpio NULL pointer dereference messages around device boot or USB events; check for unexpected panics on systems with OTG hardware.

What your security team should do

• Prioritize kernel updates on all Linux systems exposing USB OTG functionality
• Monitor for kernel oops or panic logs related to usb-conn-gpio
• Apply vendor-supplied patches as soon as available for embedded or IoT devices