CVE-2022-48663

What it actually does

NULL pointer dereference in the gpio-mockup driver during debugfs cleanup on module exit or driver unbind, triggered because platform devices are unregistered after the global debugfs directory is removed.

Why it matters to the business

Systems using the gpio mockup driver may experience kernel panics or crashes during driver unload or module removal, resulting in unexpected downtime and loss of availability on affected Linux kernels.

How an attack unfolds

An attacker with local access triggers repeated load/unload cycles of the gpio-mockup module or unbinds the driver after debugfs entries have been removed, causing the kernel to dereference a NULL pointer and panic.

How to fix it

Upgrade to a fixed kernel version such as 5.10.146 or apply commit bdea98b98f844bd8a983ca880893e509a8b4162f; ensure gpio-mockup devices are unregistered before global debugfs removal.

How to confirm the fix worked

Verify the running kernel contains the fix by checking git commit history or kernel version against 5.10.146 and later; attempt module load/unload cycles in a test environment to confirm absence of NULL dereference.

Typical attack path

1. Obtain local access to a system running a vulnerable Linux kernel
2. Load the gpio-mockup module and create associated platform devices
3. Trigger driver unbind or module removal sequence
4. Cause the kernel to panic due to NULL dereference during debugfs cleanup

How to detect it

Review kernel logs for oops or panic messages referencing gpio_mockup or debugfs during module unload; correlate with audit logs showing gpio-mockup module load/unload events.

• gpio-mockup:.*NULL pointer dereference
• debugfs.*gpio_mockup
• platform device unregister after debugfs removal

What your security team should do

• Prioritize kernel upgrades on systems exposing gpio-mockup functionality
• Monitor for kernel oops or panic logs related to debugfs and gpio during maintenance windows
• Restrict local module loading privileges where possible until patches are applied