Welcome to this detailed analysis of a recent high-severity vulnerability identified in the Linux Kernel, tagged as CVE-2024-38588. This CVE has been given a severity rating of 7.8 which suggests a significant risk requiring immediate attention and action. As users and administrators of Linux systems, understanding and mitigating this vulnerability should be a top priority. Let's dive deeper into the specifics of what this means for your systems and how you can ensure you remain protected.
CVE-2024-38588 is a use-after-free issue found within the ftrace functionality of the Linux kernel, particularly in the ftrace_location() function. The ftrace utility in Linux is used for tracing function calls and events in kernel space, which is pivotal for diagnostics and debugging purposes by developers and system administrators. The issue was detected using Kernel Address Sanitizer (KASAN), a dynamic memory error detector designed to find memory safety issues within the kernel code.
The discovered use-after-free vulnerability arises when a race condition occurs between registering and deleting kernel modules involving ftrace pages. On one CPU, the system might be registering a probe while simultaneously, on another CPU, it could be deleting a module which involves freeing ftrace pages. This simultaneous action leads to a scenario where one process is still accessing ftrace data that has already been freed – a typical use-after-free condition. Such vulnerabilities are particularly dangerous as they can lead to arbitrary code execution, crashes, and unexpected behavior in kernel space, posing a significant security risk.
The bug triggers a use-after-free error in the function ftrace_location()+0x90/0x120 as exemplified in the call trace provided by KASAN. This occurs because the lookup_rec() function in ftrace_location() searches for a record of an address in ftrace pages, but those pages might be being released in ftrace_release_mod() as the associated module is being deleted, leading to the misuse of freed memory.
The resolution involves several critical updates to the handling of ftrace records:
ftrace_location_range().lookup_rec() with ftrace_location_range() in the ftrace_location() function.synchronize_rcu() before releasing any ftrace pages, whether during the process of ftrace handling or module deletion.This patch not only resolves the race condition but also strengthens the reliability of module handling in environments where ftrace is extensively used.
For Linux administrators and users, understanding and applying the fixes for CVE-2024-38588 is crucial to maintain system integrity and security. Regularly updating your system to incorporate the latest security patches and being vigilant about potential vulnerabilities are essential steps in protecting your infrastructure. As always, LinuxPatch is here to provide you with the latest updates and guidance on these critical security issues.
Stay safe and keep your systems secure by staying informed and prepared!