CVE-2024-42102 is a vulnerability in the Linux kernel related to the memory management subsystem's dirty throttling logic. Dirty throttling is a mechanism that controls the rate at which dirty pages (pages in memory that have been modified but not yet written to disk) are flushed to storage, to avoid overwhelming the system with writeback operations. The vulnerability arises from an incorrect assumption in the dirty throttling code that the dirty limits, expressed in page units, fit within 32 bits. Specifically, a previous patch (commit 9319b647902cbd5cc884ac08a8a6d54ce111fc78) was reverted because it introduced a multiplication overflow on 32-bit architectures when the product of wb_thresh and bg_thresh exceeded 2^32. This overflow can occur under common configurations, such as systems with 4GB of RAM using default settings. Additionally, the patch used an expensive 64-bit division function (div64_u64) on 32-bit architectures, which is inefficient. The vulnerability is essentially a logic flaw and integer overflow in the dirty throttling mechanism that could lead to incorrect throttling behavior, potentially causing system instability or performance degradation. The patch series aims to ensure that dirty limits fit within 32 bits and to replace expensive operations with safer, more efficient alternatives. However, if dirty thresholds exceed 2^32 pages, the dirty balancing mechanism may fail in other ways, indicating a fundamental limitation in the design. There are no known exploits in the wild for this vulnerability as of the publication date. The vulnerability affects multiple Linux kernel versions identified by specific commit hashes, indicating it is present in various recent kernel builds. No CVSS score has been assigned yet.

For European organizations, the impact of CVE-2024-42102 depends largely on their use of Linux systems, particularly those running on 32-bit architectures or with configurations involving large amounts of RAM and default dirty throttling parameters. The vulnerability could lead to system instability, degraded performance, or unexpected behavior in memory management, which in turn might affect critical services relying on Linux servers, such as web hosting, cloud infrastructure, and enterprise applications. While it does not directly enable remote code execution or privilege escalation, the resulting instability could cause denial of service conditions or data loss if writeback operations are improperly throttled or fail. Organizations with embedded Linux devices or legacy systems using 32-bit kernels may be more susceptible. Given the widespread use of Linux across European industries, including finance, manufacturing, telecommunications, and government, any disruption in kernel stability can have cascading effects on business continuity and data integrity. However, since no active exploits are known and the vulnerability requires specific system configurations, the immediate risk is moderate but warrants prompt patching to prevent future exploitation or accidental system failures.

European organizations should take the following specific mitigation steps: 1) Identify Linux systems running affected kernel versions, especially those on 32-bit architectures or with large RAM configurations. 2) Apply the official Linux kernel patches that revert the problematic commit and implement the corrected dirty throttling logic as soon as they become available from trusted sources or Linux distributions. 3) Review and adjust dirty throttling parameters (wb_thresh and bg_thresh) to ensure they remain within safe limits and do not approach the 32-bit overflow threshold, particularly on systems with large memory. 4) Monitor system logs and performance metrics related to memory management and writeback behavior to detect anomalies that could indicate throttling issues. 5) For embedded or legacy systems where patching the kernel is not immediately feasible, consider limiting RAM or adjusting dirty page thresholds to mitigate overflow risks. 6) Incorporate this vulnerability into vulnerability management and patching workflows to ensure timely updates. 7) Engage with Linux distribution vendors for backported fixes and security advisories relevant to specific enterprise Linux versions used in the environment.