CVE-2024-50194 addresses a vulnerability in the Linux kernel's uprobes implementation specifically for the arm64 architecture running big-endian kernels. Uprobes is a kernel feature that allows dynamic tracing of user-space applications by inserting probes at specific instruction addresses. The vulnerability arises because the uprobes code incorrectly handles instruction encoding endianness: it assumes the in-memory instruction encoding is in the kernel's native endianness, but in reality, instructions are always stored in little-endian format. For big-endian kernels, this mismatch leads to improper interpretation of instructions. The consequences include the kernel erroneously rejecting probes that are safe to place, permitting unsafe stepping out-of-line of instructions, and incorrectly simulating instructions due to interpreting byte-swapped encodings. These issues stem from the arch_uprobe structure fields (insn, ixol) being typed as arrays of u8 without proper endianness conversion, and the casting between types that bypasses endianness checks. The fix involves changing these fields to __le32 types and adding explicit __le32_to_cpu() conversions before instruction analysis. This correction ensures that instructions are properly recognized and simulated, preventing incorrect behavior during dynamic tracing. The patch also removes redundant constants for clarity and has been tested with a sample function demonstrating correct address resolution before and after the fix. This vulnerability is specific to arm64 big-endian Linux kernels, which are less common than little-endian configurations. No known exploits are reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of this vulnerability is generally limited due to the niche nature of big-endian arm64 Linux kernel deployments. Most Linux systems in Europe run on little-endian architectures (x86_64, little-endian arm64). However, organizations using specialized embedded systems, telecommunications equipment, or industrial control systems that rely on big-endian arm64 Linux kernels could be affected. The incorrect handling of uprobes could lead to unreliable dynamic tracing and debugging, potentially causing system instability or incorrect behavior during kernel-level instrumentation. While this does not directly lead to privilege escalation or remote code execution, it can impair the reliability of monitoring and debugging tools, which are critical for incident response and forensic analysis. This could indirectly affect system integrity and availability if kernel tracing tools malfunction during critical operations. Since uprobes are primarily used by developers and system administrators for debugging and performance monitoring, the impact is more operational than security-critical for most enterprises. Nonetheless, environments relying heavily on kernel tracing for security monitoring or compliance auditing might experience degraded visibility or false negatives in their detection capabilities.

European organizations should first identify whether they run arm64 Linux kernels configured for big-endian operation, which is uncommon but possible in certain embedded or specialized environments. If such systems are present, immediate steps include: 1) Applying the official Linux kernel patch that corrects the endianness handling in uprobes as soon as it is available in their distribution or upstream kernel releases. 2) Testing the patched kernel in staging environments to verify that dynamic tracing and debugging tools function correctly without regressions. 3) Temporarily disabling uprobes-based tracing on affected systems if patching is delayed, to avoid incorrect instruction simulation and potential instability. 4) Reviewing and updating kernel tracing and monitoring configurations to ensure they do not rely on faulty uprobes behavior. 5) Monitoring vendor advisories and Linux kernel mailing lists for updates or backported patches relevant to their kernel versions. 6) For embedded device manufacturers or integrators, ensure that kernel builds for big-endian arm64 include this fix before deployment. These targeted mitigations go beyond generic advice by focusing on architecture-specific configurations and the operational role of uprobes in the environment.