A new vulnerability, labeled as CVE-2023-45871, has been identified in the IGB (Intel Gigabit Ethernet) driver of the Linux kernel. This vulnerability affects the versions of the Linux kernel before 6.5.3. The issue is related to the buffer size inadequacy in the IGB driver, specifically in the drivers/net/ethernet/intel/igb/igb_main.c file. As a result of this vulnerability, frames larger than the Maximum Transmission Unit (MTU) may not be adequately handled, causing unpredictable system behavior or even crashes. In this post, we will explore the details behind this vulnerability, including the code snippet, references to original sources, and potential exploit scenarios.

Code Snippet

Upon analyzing the code in the igb_main.c file, the issue can be traced to the following section of the code:

static int igb_xmit_frame(struct sk_buff *skb, struct net_device *dev)
{
    struct igb_adapter *ad = netdev_priv(dev);
    struct pci_dev *pdev = ad->pdev;
    //...
    if (unlikely(igb_tx_map(ad, tx_ring, skb))) {
      dev_kfree_skb_any(skb);
      return NETDEV_TX_OK;
    }
    //...
}

Original References

The vulnerability was first discovered and reported by a kernel developer, who documented the findings in the following locations:

1. Linux Kernel Mailing List: link
2. Official CVE Database Entry: link
3. Report on Kernel.org Bugzilla: link

Exploit Details

As mentioned earlier, the vulnerability lies in the buffer size, which may not be adequate for frames larger than the MTU. Due to this inadequacy, the following exploit scenarios can arise:

1. Denial of Service (DoS) Attack: An attacker can send packets with sizes larger than the MTU to a device running an affected Linux kernel. These packets might cause memory corruption, leading the system to crash or become unresponsive.

2. Information Disclosure: In specific circumstances, memory contents might not be properly zeroed out before being reused. An attacker could leverage this to gain access to sensitive information previously stored in memory.

Mitigation

A patch has been introduced in the Linux kernel version 6.5.3 to address this vulnerability. Users and system administrators are advised to upgrade their Linux kernel to version 6.5.3 or later. The source code change for the patch can be referenced in the following commit:

- Commit in Linux Kernel Git Repository: link

In cases where upgrading the kernel is not feasible, network administrators should implement workarounds to minimize the risk of exploitation. Some of these workarounds include:

Implementing Access Control Lists (ACLs) to block traffic with suspicious frame sizes.

2. Monitoring network traffic for unusual activity that may indicate an attempt to exploit this vulnerability.

Conclusion

CVE-2023-45871 is a significant vulnerability in the IGB driver of the Linux kernel, which can have severe consequences if exploited by malicious actors. To ensure the highest level of security, it is crucial to keep the Linux kernel up-to-date and apply appropriate patches as they are released. Furthermore, network administrators should remain vigilant about monitoring and securing their network infrastructure to minimize the risk of successful exploitation.

Timeline

Published on: 10/15/2023 01:15:09 UTC
Last modified on: 11/10/2023 18:15:08 UTC