CVE-2024-56634

What it actually does

The vulnerability is a missing NULL check on the return value of devm_kasprintf() inside grgpio_probe, allowing a kernel NULL pointer dereference when memory allocation fails.

Why it matters to the business

Systems using the GRGPIO driver may experience kernel crashes or denial of service under low-memory conditions during device initialization, disrupting hardware control and overall system availability.

How an attack unfolds

An attacker with local access induces memory pressure to force devm_kasprintf to return NULL during grgpio_probe execution, triggering an immediate kernel NULL pointer dereference and potential panic.

How to fix it

Upgrade the affected qemu package on Ubuntu 14.04 LTS to version 2.0.0+dfsg-2ubuntu1.24 or later to include the added NULL check.

How to confirm the fix worked

Confirm the installed package version meets or exceeds 2.0.0+dfsg-2ubuntu1.24 and inspect the grgpio_probe function for the presence of a NULL check after devm_kasprintf.

Typical attack path

1. Obtain local access on a system exposing the grgpio driver
2. Trigger device probe or module load while causing allocation failure
3. Trigger NULL pointer dereference in grgpio_probe

How to detect it

Review kernel logs and dmesg output for NULL pointer dereference or oops entries mentioning grgpio_probe around device initialization time.

What your security team should do

• Apply the fixed package version 2.0.0+dfsg-2ubuntu1.24 immediately on all affected systems
• Reboot or reload the driver after upgrade to ensure the patched probe path is active
• Monitor kernel logs for oops or panic messages referencing grgpio