The Linux kernel, which forms the core of the Linux operating system, is a fundamental component that manages the system’s resources and allows hardware and software components to communicate effectively. Keeping this core component secure is crucial as it can affect millions of computers and devices running Linux around the world. Recently, a specific vulnerability was identified, which could potentially disrupt many systems if not addressed appropriately. In this article, we're diving into CVE-2024-49949, discussing its implications and the solutions provided.
This vulnerability has been assigned a medium severity rating with a score of 5.5. It involves an issue in the Linux kernel's network handling capabilities, precisely in a function called qdisc_pkt_len_init() used with UFO (UDP Fragmentation Offload). This issue was introduced due to changes made in previous commits (specifically 7c6d2ecbda83 and cf9acc90c80ec) intended to improve the handling of certain GSO (Generic Segmentation Offload) packets.
The vulnerability arises when a crafted GSO packet, with specific characteristics (like a very small gso_size and matching skb->len), reaches the qdisc_pkt_len_init() function. This function computes the segment length for packets queued in the network scheduler to manage traffic efficiently. Due to the flawed logic update from the mentioned commits, executing this crafted packet causes an underflow which eventually leads to the kernel attempting to access a null pointer, resulting in a system crash.
When the Linux kernel encounters such a scenario, it could lead to a denial-of-service (DoS) attack where the system becomes unresponsive or crashes. This impacts not only individual PCs but could also affect servers and cloud environments where Linux is extensively used, potentially leading to significant downtime and disruption of services.
The patches for CVE-2024-49949 have been rolled out, focusing on correcting the logic that calculates the pkt_len in the qdisc_pkt_len_init() function by adding the necessary sanity checks to prevent the integer underflow. Linux users and administrators are strongly advised to update their systems to the latest kernel release that includes this patch to ensure protection against potential exploits utilizing this vulnerability.
Security vulnerabilities like CVE-2024-49949 underscore the continuous need for rigorous testing and updates of the Linux kernel. For Linux users and system administrators, staying informed about such vulnerabilities and promptly applying updates is crucial to safeguarding their systems. At LinuxPatch, we're committed to helping you understand these vulnerabilities and provide timely updates and support to keep your systems secure.