CVE-2022-48996 is a vulnerability identified in the Linux kernel specifically within the DAMON (Data Access MONitor) subsystem's sysfs interface. The issue arises from a faulty assumption in the function damon_sysfs_set_schemes(), which is responsible for managing DAMON schemes during online tuning. A recent commit (da87878010e5) introduced a change that caused this function to be called for running DAMON contexts that may already have schemes. However, the code incorrectly assumed that the DAMON context would not have any existing schemes, leading it to create and add new schemes unnecessarily. This results in an unintended increase in memory usage (memory footprint) because multiple schemes accumulate when only updates or removals should occur. Although this does not cause a memory leak since all schemes remain referenced within the DAMON context, it can lead to inefficient memory utilization and potentially degrade system performance under certain workloads. The fix involved removing the incorrect assumption and properly handling the presence of existing schemes during online tuning, ensuring that schemes are updated or removed as intended. This vulnerability affects Linux kernel versions that include the specified commit and is relevant to systems using DAMON for memory access monitoring and tuning. No known exploits are reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2022-48996 is primarily related to resource efficiency and system stability rather than direct security compromise. Systems running Linux kernels with the vulnerable DAMON implementation may experience increased memory consumption when performing online tuning of DAMON schemes. This could lead to degraded performance, especially on servers or embedded devices with limited memory resources. In environments where DAMON is actively used for memory access monitoring—such as high-performance computing, cloud infrastructure, or specialized embedded systems—this inefficiency could reduce operational efficiency or increase operational costs due to higher resource usage. However, since the vulnerability does not cause memory leaks or allow privilege escalation, remote code execution, or data corruption, the confidentiality, integrity, and availability of systems are not directly threatened. The absence of known exploits further reduces immediate risk. Nonetheless, organizations relying on DAMON for performance tuning should consider this vulnerability to maintain optimal system behavior and avoid potential performance degradation.

To mitigate CVE-2022-48996, European organizations should: 1) Apply the official Linux kernel patch that corrects the damon_sysfs_set_schemes() function to properly handle existing schemes during online tuning. This involves updating to a kernel version that includes the fix or backporting the patch if using long-term support kernels. 2) Review and audit the use of DAMON in their environments to determine if online tuning of schemes is actively used and whether the vulnerability could impact performance. 3) Monitor system memory usage and performance metrics on systems running affected kernels to detect unusual increases in memory footprint related to DAMON operations. 4) Limit the use of DAMON online tuning to trusted administrators and processes to reduce the risk of unintended resource consumption. 5) Incorporate this vulnerability into regular vulnerability management and patching cycles to ensure timely remediation. Since no exploit is known, prioritization can be balanced with operational impact, but proactive patching is recommended to maintain system efficiency.