CVE-2024-57991 is a vulnerability identified in the Linux kernel's wireless driver component, specifically within the Realtek rtw89 WiFi driver. The flaw exists in the function rtw89_entity_recalc_mgnt_roles(), which is responsible for recalculating management roles related to WiFi channel management. The vulnerability arises due to improper loop control during a list normalization process. When the function attempts to reorder a list upon finding an entry matching a target pattern, it uses a 'break' statement intended to exit the loop early. However, this 'break' only exits the inner for-loop, while the outer list_for_each_entry loop continues to iterate. Under typical conditions, only the first entry matches the pattern, so the reordering does not cause issues. In certain special cases, however, this leads to a soft lockup—a state where the CPU becomes unresponsive for an extended period, as evidenced by kernel watchdog logs showing the CPU stuck for over 26 seconds. This soft lockup can cause system instability or hangs, particularly affecting processes like wpa_supplicant that manage WiFi connections. The fix implemented involves replacing the 'break' with a 'goto fill' statement to properly exit the outer loop and prevent the lockup. This vulnerability affects specific Linux kernel versions identified by their commit hashes, and no known exploits are currently reported in the wild. The issue is primarily a denial-of-service (DoS) condition caused by a kernel soft lockup triggered by the WiFi driver malfunction.

For European organizations, this vulnerability could lead to system instability or denial-of-service conditions on Linux-based systems utilizing the affected rtw89 WiFi driver. Since Linux is widely used in servers, embedded devices, and network infrastructure across Europe, organizations relying on affected kernel versions may experience unexpected system hangs or degraded network connectivity, impacting operational continuity. Critical infrastructure sectors such as telecommunications, manufacturing, and public services that depend on stable wireless connectivity could be particularly affected. Additionally, the soft lockup could disrupt WiFi-dependent applications or services, leading to productivity losses. Although no remote code execution or privilege escalation is indicated, the potential for service disruption in environments with high reliance on Linux wireless networking is significant. The lack of known exploits reduces immediate risk, but unpatched systems remain vulnerable to accidental or triggered lockups, which could be exploited in targeted denial-of-service scenarios.

Organizations should promptly identify Linux systems running kernel versions containing the affected rtw89 driver commits and apply the official kernel patches that fix the loop control logic in rtw89_entity_recalc_mgnt_roles(). Since the vulnerability is in the kernel WiFi driver, updating to the latest stable Linux kernel releases that include this fix is the most effective mitigation. For systems where immediate kernel upgrades are not feasible, consider disabling the rtw89 WiFi driver if it is not essential or replacing affected hardware with devices using different drivers. Monitoring system logs for signs of soft lockups or CPU stalls related to the rtw89 driver can help detect attempts to trigger this issue. Network segmentation and limiting access to WiFi management interfaces can reduce the risk of exploitation. Additionally, organizations should maintain robust patch management processes to ensure timely deployment of kernel updates. Testing patches in staging environments before production rollout is recommended to avoid unintended disruptions.