Welcome to our deep dive into CVE-2024-39474, a notable vulnerability found in the Linux Kernel, particularly in the mm/vmalloc module that deals with memory management. This article is designed to help you, our valued LinuxPatch customers, understand the nature of this issue, how it might affect your systems, and why it's essential to ensure your systems are promptly patched.
The CVE-2024-39474 issue was first identified during an OPLUS KASAN test, revealing a critical flaw in the vmalloc function which is crucial for allocating memory in the Linux kernel. Under specific conditions, this function failed to operate correctly due to conflicting code changes layed in previous updates, leading to potential unexpected behavior in memory allocation.
CVE-2024-39474 targets the kernel memory management process, where the __vmalloc_node_range() function involved in allocating virtual memory nodes, may fail and return NULL if it's called with the flag __GFP_NOFAIL. This flaw is particularly dangerous because the kernel assumes that memory allocations with this flag will always succeed, thus any failure can result in a kernel panic or other unpredictable system behaviors.
The problem arises from an implementation incompatibility between two kernel commits. The first commit allowed allocations not to be strictly required to be from the kernel (GFP_KERNEL), while a later commit intended to manage out-of-memory (OOM) situations more gracefully by backing off if the current task is killed by the OOM killer. However, this led to a scenario where memory demand could occasionally exceed supply, causing the vmalloc function to return NULL despite the use of __GFR_NOFAIL, which theoretically should prevent such a case.
The primary risk associated with this vulnerability is the potential for a system crash if the memory allocation fails when it is not expected to. This can lead to data loss, service unavailability, and in severe cases, can affect multiple applications running on the same kernel. The severity of this CVE has been rated as MEDIUM with a score of 5.5, reflecting significant impacts in terms of system reliability and stability.
The Linux kernel team has addressed this vulnerability by altering the behavior of vm_area_alloc_pages() to not check for fatal signals if the __GFP_NOFAIL flag is set. This change ensures that the kernel maintains its contract that memory allocations requested under this flag will not fail, thereby preventing the errors observed during the OPLUS KASAN test.
Addressing CVE-2024-39474 is critical for maintaining the stability and security of Linux systems. Unpatched systems may experience sporadic failures and crashes, leading to broader security and operational risks. As customers of LinuxPatch, you have direct access to our platform that simplifies the deployment of such critical updates promptly and efficiently.
Keeping your kernel updated is not just best practice; it's a vital part of maintaining the health and integrity of your computing environment. Given the complex nature of kernel-related vulnerabilities and the potential for widespread impact, we encourage all our users to regularly check for and apply updates as they become available.
CVE-2024-39474 serves as a reminder of the intricate and critical nature of kernel memory management in ensuring system stability. By applying the latest patches and keeping your system up to date, you help safeguard your operations against potential downtime and security breaches that could arise from such vulnerabilities.
To manage and apply patches effectively, visit LinuxPatch, our dedicated patch management platform, and ensure your Linux servers are protected against known vulnerabilities like CVE-2024-39474.