CVE-2024-26762: Understanding and Mitigating the RAS Error Handling Vulnerability in Linux Kernel

Published on: 08-03-2024 By Soc Team

Overview of CVE-2024-26762

The Linux kernel version exposed a critical vulnerability identified as CVE-2024-26762. This vulnerability stems from the handling of RAS (Reliability, Availability, and Serviceability) errors when a CXL.mem (Compute Express Link) device is detached. The standard PCI AER (Advanced Error Reporting) method may lead to a memory hotplug event, causing instability and potential crashes in the system.

The primary issue arises because the kernel's error handler attempts to unbind the CXL.mem device driver following an AER event. However, a second AER notification post-unbinding cannot assume the status registers are valid, leading to critical errors such as:

BUG: unable to handle page fault for address: ffa00000195e9100
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
...

Affected Versions

The affected versions include various Linux kernel versions within the specified ranges:

  • Versions based on commit 6ac07883dbb5 but less than 21e5e84f3f63
  • Versions based on commit 6ac07883dbb5 but less than eef5c7b28dbe
  • Linux kernel version 6.7

Notably, any version below 6.7 or version 6.8 and above are unaffected.

Mitigation Strategies

To mitigate this vulnerability effectively, the following steps should be undertaken:

Update to a Secure Version: The primary and most effective mitigation strategy is to update the Linux kernel to versions that are not affected by this vulnerability. Specifically:

  • Kernel versions updated to 21e5e84f3f63 and eef5c7b28dbe
  • Kernel version 6.7.7 and above
  • Kernel version 6.8 and any versions fitting the original commit for the fix

Apply Patches: Developers and system administrators should regularly monitor updates and apply patches provided by the kernel maintainers. The patches addressing this vulnerability can be found in the kernel repository:

Regularly updating and patching systems is critical to safeguard against vulnerabilities like CVE-2024-26762 and to maintain the integrity and stability of the Linux environment.

Conclusion

Understanding the intricacies of kernel vulnerabilities such as CVE-2024-26762 is essential for maintaining secure and reliable systems. By promptly updating to secure versions and applying necessary patches, system administrators can significantly reduce the risk posed by such vulnerabilities.