In the Linux kernel, a significant vulnerability has been discovered and now resolved by adding a NULL check to "@/kernel-5.13/drivers/platform/x86/acpi.c/acpi_quirk_skip_serdev_enumeration()" function. This rectification increases the safety and stability of the Linux Kernel and prevents possible exploits. This post provides an overview of the issue and the recommended solution, as well as information on implementing the code.

What Is the Linux Kernel Issue?

The vulnerability concerns the ACPI, or Advanced Configuration and Power Interface, which is responsible for kernel-level interactions with hardware devices in a computer system. In this specific case, a NULL check was missing in the acpi_dev_hid_match() function, causing potential dereferencing issues that could lead to unexpected crashes or exploits.

Exploit Details

The acpi_dev_hid_match() function does not check for "adev == NULL" scenario, leading to unconditional dereferencing of adev. This means that if the adev pointer happened to be NULL, the function would attempt to access memory that it shouldn't access, resulting in undefined behavior and possible crashes, or worse, a potential security exploit.

Original References

The original work for this resolution can be found in the Linux kernel source code repository. Links to the specific code changes and discussions include:

- Linux kernel source code changes
- Kernel mailing list discussion
- Kernel.org release notes for 5.13

Code Snippet for the Solution

To resolve this issue, you need to add a NULL check for adev before calling the acpi_dev_hid_match() function. The code snippet below shows the added check for adev being NULL:

static bool acpi_quirk_skip_serdev_enumeration(struct serdev_device *serdev, struct acpi_device *adev)
{
  if (!adev)
    return false;

  /* Add other checks for specific ACPI HID matches here */
  ...

  return false;
}

With this added NULL check, any potential dereferencing issues are now eliminated, ensuring that the kernel will not attempt to access invalid memory locations when working with a NULL adev.

Conclusion

With the discovery and resolution of this vulnerability (CVE-2024-56782), the Linux kernel is now more secure and stable. By adding a simple NULL check to the acpi_quirk_skip_serdev_enumeration() function, potential exploits and crashes have been prevented. If you're involved in Linux kernel development or system administration, make sure to apply the changes outlined above to strengthen your system's security.

Remember, "better safe than sorry" when it comes to software security!

Timeline

Published on: 01/08/2025 18:15:19 UTC
Last modified on: 01/09/2025 21:00:44 UTC