CVE-2022-49052 is a vulnerability in the Linux kernel's memory management subsystem, specifically related to the handling of zram swap pages under certain multi-threaded conditions involving CLONE_VM processes. The issue arises when two processes sharing the same memory space (via CLONE_VM) perform swap page operations concurrently on different CPUs. The vulnerability causes a user process to unexpectedly see zeroed (invalid) pages mapped into its address space instead of the correct data. This occurs because the swap_slot_free_notify mechanism, which is supposed to synchronize the freeing of swap slots, does not properly increase the reference count of the swap slot during copy_mm operations for CLONE_VM processes. Consequently, the system may prematurely discard valid data from the backing device (zram), leading to corrupted user-space memory views. The patch removes the swap_slot_free_notify call and relies solely on page table locks to synchronize swap slot freeing, ensuring that the correct data is mapped. While this fix may increase memory consumption due to temporarily retaining both compressed and uncompressed forms of data in zram, typical usage patterns (no readahead and immediate swap_free after do_swap_page) mitigate this overhead. This vulnerability is subtle and involves low-level kernel synchronization and memory management details, affecting systems using zram swap with multi-threaded processes sharing memory. No known exploits are reported in the wild, and no CVSS score has been assigned yet.

For European organizations, the impact of CVE-2022-49052 depends largely on their use of Linux systems with zram swap enabled, particularly in environments running multi-threaded or containerized workloads that utilize CLONE_VM semantics (e.g., certain container runtimes, virtualization, or high-performance computing). The vulnerability can lead to data corruption in user-space processes, potentially causing application crashes, data integrity issues, or unexpected behavior. This could affect critical services relying on Linux servers, including cloud infrastructure, telecommunications, financial services, and industrial control systems prevalent in Europe. Although the vulnerability does not directly enable code execution or privilege escalation, corrupted data can undermine system reliability and trustworthiness, leading to operational disruptions. The increased memory consumption from the patch might also impact resource-constrained environments, requiring careful capacity planning. Since no known exploits exist, the immediate risk is moderate, but the subtlety of the bug means it could be exploited in targeted attacks or cause hard-to-diagnose failures in critical systems.

European organizations should prioritize updating their Linux kernel to versions that include the fix for CVE-2022-49052. Specifically, kernel updates that remove swap_slot_free_notify for CLONE_VM cases and rely on page table locking should be applied promptly. Organizations using zram swap should audit their configurations to confirm if zram is enabled and assess whether workloads involve CLONE_VM processes that might trigger this issue. For environments where immediate patching is challenging, consider disabling zram swap temporarily or limiting the use of CLONE_VM in user-space applications if feasible. Monitoring system logs and application behavior for signs of memory corruption or unexpected zeroed pages can help detect exploitation attempts or manifestation of the bug. Additionally, capacity planning should account for potential increased memory usage due to the patch to avoid performance degradation. Engaging with Linux distribution vendors for backported patches and security advisories is recommended to ensure timely remediation.