CVE-2024-36015

What it actually does

Unchecked return value from ida_simple_get in ppdev register_device allows an invalid (negative) index to be used for device registration, bypassing intended error handling for resource allocation failures.

Why it matters to the business

Kernel modules handling parallel port devices may register devices incorrectly, leading to instability, failed device operations, or crashes on affected Linux systems; the issue is limited to systems using the ppdev driver.

How an attack unfolds

An attacker triggers the ppdev register_device path (typically via user-space interaction with /dev/parport) under conditions where ida_simple_get returns an error; the invalid index is then used without validation, resulting in improper port handling or memory corruption.

How to fix it

Update the Linux kernel to the fixed commit a351e9b9fc24e982ec2f0e76379a49826036da12 or later; rebuild and deploy the updated kernel image across affected systems.

How to confirm the fix worked

Verify the presence of the fix commit in the running kernel source or binary; test device registration paths to confirm error checking now occurs and abnormal indices are rejected with warnings.

Typical attack path

1. Identify system using ppdev driver
2. Interact with parallel port device interface to invoke register_device
3. Force ida_simple_get to return error condition
4. Observe or exploit resulting invalid index usage

How to detect it

Review kernel logs for ppdev registration failures or warnings mentioning ida_simple_get or invalid indices; inspect dmesg or syslog around device initialization events for signs of dropped ports without proper error paths.

What your security team should do

• Apply the kernel patch containing commit a351e9b9fc24e982ec2f0e76379a49826036da12 immediately on systems exposing ppdev
• Audit for custom or out-of-tree ppdev usage and rebuild modules against the fixed kernel
• Monitor kernel logs for ida_simple_get related warnings post-update