Hello LinuxPatch Customers,
Today, we're talking about a recent cybersecurity concern that's critical for anyone using Linux systems, especially in a real-time (RT) configuration. This issue, registered under CVE-2024-40980, holds a medium severity rating with a score of 5.5. Here’s everything you need to know about this vulnerability, including the software it impacts, what the issue is about, and the implications for Linux users.
CVE-2024-40980 is a vulnerability found in the Linux kernel, specifically within a function called trace_drop_common(). This function, under certain conditions, erroneously uses a spin_lock instead of a raw_spin_lock. But before we delve into what this means, let’s understand a bit about where this issue occurs.
The Linux kernel, as you might know, is the fundamental core of any Linux operating system. It handles the communication between hardware and software. Notably, real-time versions of the Linux kernel are optimized to handle operations that require high timing precision.
The issue arises in environments running a real-time patched version of the Linux kernel, where typical spin_locks, used to manage resources among multiple threads, can become problematic. In these RT systems, spin_locks behave as sleeping locks, which means they can put a thread to sleep while waiting for resource availability.
Here's where the problem starts: the function trace_drop_common()—which is invoked with preemption disabled—acquires a spin_lock. However, acquiring a sleeping lock in a context where preemption is disabled leads to a system crash or other unintended behaviors because the operation expects that no sleeping should occur. The specific error thrown is:
"BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:48"
Under the hood, raw_spin_lock functions are designed specifically to avoid these sleeping issues under atomic contexts, which do not expect processes to sleep. Transitioning to raw spin locks in the trace_drop_common() function rectifies this critical flaw and realigns the kernel’s functionality with real-time requirements.
The impact of this vulnerability primarily falls on users and administrators of Linux systems with real-time applications. It’s essential for these stakeholders to understand the potential disruptions such an issue could pose to critical systems operations, particularly those that require uninterrupted services and high reliability.
If left unpatched, this vulnerability could lead to unexpected system behavior during peak operations, potentially causing failures in real-time applications, which could be disastrous in systems requiring high precision and reliability, such as industrial control systems, telecommunications, or healthcare devices.
For LinuxPatch customers, we recommend updating your Linux kernel as soon as patches are available to address CVE-2024-40980. Staying ahead of such vulnerabilities is paramount, especially in environments where timing and system response are critical to operational success.
Stay safe and ensure your systems are always updated. If you have any questions or need further assistance regarding this issue or how it might affect your setup, feel free to reach out to our support team.
Until next time, keep your systems secure and optimized!