CVE-2021-46916 - Linux Kernel ixgbe Driver Vulnerability: Fixing NULL Pointer Dereference in Ethtool Loopback Test

A recent vulnerability (CVE-2021-46916) has been discovered and resolved in the Linux kernel. The issue pertains to the ixgbe driver, which encounters a NULL pointer dereference when performing the ethtool loopback test. This vulnerability exposes the system to potential attacks, crashes, and unauthorized information access. This post will discuss the exploit's details and provide the necessary code snippet to address the issue, along with links to the relevant references.

Exploit Details

The ixgbe driver in the Linux kernel currently experiences a NULL pointer dereference when running the ethtool loopback test. This is primarily because there is no q_vector associated with the test ring during the setup, as interrupts are not typically added to the test rings.

This vulnerability could lead to several consequences, such as system crashes, denial of service (DoS) attacks, and unauthorized access to sensitive information.

Original References

- Linux Kernel Mailing List - The related discussions about the vulnerability and the proposed fixes.
- Linux Kernel Commit - The official patch to address the issue in the Linux kernel.

Fixing the Vulnerability

To address this vulnerability, you should update your system to the latest Linux kernel version that includes the patch for this issue. However, if you cannot update the kernel or need to patch the driver manually, you can apply the following code snippet:

/* ixgbe_main.c */
/* Within the function ixgbe_napi_id() */
if (!q_vector)
    return ;

This code checks for a q_vector before returning a napi_id value. If there is no q_vector present, it will return a value of . By adding this code to the appropriate function in the ixgbe driver source file (ixgbe_main.c), you can effectively mitigate the NULL pointer dereference vulnerability.

Conclusion

The CVE-2021-46916 vulnerability poses a considerable risk to systems using the ixgbe driver on the Linux kernel. In response, it is essential to ensure that the kernel is up-to-date and that the vulnerability has been appropriately addressed. By applying the mentioned code snippet or updating the kernel, system administrators can protect their systems from potential attacks and unauthorized information access related to this vulnerability.

Timeline

Published on: 02/27/2024 07:15:08 UTC
Last modified on: 04/10/2024 14:24:11 UTC