CVE-2024-52332 - Exploiting and Understanding the `igb_init_module` Vulnerability in Linux Kernel

In June 2024, a new Linux kernel vulnerability surfaced under CVE-2024-52332. This bug resided in the igb Ethernet driver, which serves Intel gigabit cards, and was related to improper handling on driver initialization failure in the igb_init_module() function. Not only did this create an instability risk, but also exposed Linux systems to possible invalid memory access—something an attacker could potentially escalate if local code execution is available.

Let’s break down CVE-2024-52332, look at why it occurred, demonstrate the bug, and provide resources for mitigation and further reading.

What is CVE-2024-52332?

This CVE points to a flaw in the Linux kernel (multiple versions), specifically in the igb network driver, affecting how module initialization failures are handled.

2. The PCI driver itself.

If registering the PCI driver via the pci_register_driver() function fails, the DCA notifier was not unregistered. This led the kernel to retain dangling pointers; if the notifier is invoked afterward, this access points to memory that may no longer be valid, escalating to a possible crash or memory corruption (use-after-free or similar invalid memory access).

Here’s a stripped-down version to illustrate the mistake

static int __init igb_init_module(void)
{
    int ret;
    ret = dca_register_notify(&igb_dca_notifier);
    if (ret < )
        return ret;

    ret = pci_register_driver(&igb_driver); // <- May fail!
    if (ret < )
        return ret; // <- DCA notifier wasn’t unregistered here (bug)
    return ;
}

If pci_register_driver() fails, return right away WITHOUT undoing the DCA notifier registration. This results in the kernel still keeping a reference to the notifier, and if triggered, it accesses memory linked to a failed module initialization—a hazardous design.

The fix simply unregisters the notifier before exiting on PCI registration failure

static int __init igb_init_module(void)
{
    int ret;
    ret = dca_register_notify(&igb_dca_notifier);
    if (ret < )
        return ret;

    ret = pci_register_driver(&igb_driver);
    if (ret < ) {
        dca_unregister_notify(&igb_dca_notifier); // Fix: Unregister on error
        return ret;
    }
    return ;
}

Real-world Impact: What Can Go Wrong?

- System Crash: If any DCA event is dispatched after init failure, the handler points to an invalid structure, triggering a kernel crash (Oops).
- Denial of Service: Local users could abuse repeated device insertion/removal or force driver binds to reliably crash the system.
- Memory Corruption: In some rare cases, attacker may win a race to reclaim the freed memory, possibly escalating to local privileges.

Because it requires at least local code execution and favorable timing (it’s not remotely exploitable), it’s only a medium-severity kernel bug, but one that kernel users should not ignore.

Exploit Details

This bug isn’t trivial to exploit for privilege escalation, but you can reliably crash a system if you can:

Load the igb module (with root or loading tools)

- Forcibly cause pci_register_driver to fail (e.g., with a bad hardware/PCI environment or through kernel fuzzing)

Proof of Concept Crash (Pseudo-method)

modprobe igb                       # Load the driver
# Cause pci_register_driver to fail, maybe simulate lack of device
# or temporary kernel condition

# Force a system event: echo, device removal, etc, triggering DCA
# Result: Kernel Oops with stack trace referencing invalid memory-access

Remember: you need root to load/unload kernel modules, but in cloud or containerized environments, getting a root crash is an easy denial of service vector.

Timeline and Patch

The vulnerability was reported and patched in mainline Linux in early June 2024.

- Upstream Commit: c36b26fb08afdd752859865321900f58ec727e2c

Mitigation & What You Should Do

- Patch as soon as possible: If you run servers or VMs with the Intel igb platform, apply security updates.
- Limit module loading: Restrict root access or the ability to load kernel modules via modprobe or insmod.

References

- Kernel.org commit diff: Read the original patch and commit log.
- CVE details for CVE-2024-52332 (MITRE)
- Linux kernel mailing list discussion
- igb driver documentation

Conclusion

CVE-2024-52332 is a classic example of why cleanup code matters in error handling and how even seemingly minor omissions in kernel drivers can ripple into system-wide security bugs. While this vulnerability isn’t world-shattering for the average desktop, it’s a textbook case for system administrators and developers on the importance of correct teardown procedures.

If you operate Linux systems, keep an eye on kernel changelogs, and patch early, patch often.

Stay safe!

Author:
*Your exclusive Linux security source.*

Timeline

Published on: 01/11/2025 13:15:25 UTC
Last modified on: 05/04/2025 09:51:22 UTC