CVE-2024-56708

What it actually does

Double kfree of kernel memory structures (mci->pvt_info and igen6_pvt) in the EDAC/igen6 driver during module unload creates a use-after-free condition in kernel memory management.

Why it matters to the business

Affected Linux systems risk crashes or privilege escalation during module operations, disrupting stability in servers and embedded devices with high module churn; the bug has been present since publication with stable EPSS and no known ransomware use.

How an attack unfolds

An attacker loads the EDAC/igen6 module, triggers mci registration to link pvt_info pointers, then unloads the module so that mci_release and igen6_remove both free the same memory, enabling memory corruption that can be leveraged for kernel code execution.

How to fix it

Apply the upstream fix by updating to a kernel containing commit 029ac07bb92d2f7502d47a4916f197a8445d83bf; rebuild and deploy the patched kernel across all affected systems.

How to confirm the fix worked

Inspect the igen6_remove function in edac/igen6.c to confirm mci->pvt_info is set to NULL before kfree(igen6_pvt); verify the commit hash is present in the running kernel source tree.

Typical attack path

1. Obtain ability to load and unload the EDAC/igen6 kernel module
2. Execute modprobe to allocate igen6_pvt and link mci->pvt_info
3. Trigger mci_release during rmmod to free the pointer
4. Execute igen6_remove to free the same memory a second time
5. Reuse the freed memory region for arbitrary kernel code execution

How to detect it

Review dmesg and kernel logs for segmentation faults or use-after-free warnings triggered during igen6 module unload; correlate with modprobe/rmmod audit events.

What your security team should do

• Immediately update to a kernel containing commit 029ac07bb92d2f7502d47a4916f197a8445d83bf on all production systems
• Restrict unprivileged module loading via kernel module signing and CAP_SYS_MODULE controls
• Monitor kernel logs for EDAC-related oops or double-free warnings during module unload