CVE-2022-49006 is a vulnerability in the Linux kernel's tracing subsystem, specifically related to dynamic event handling in the ftrace infrastructure. The vulnerability arises from improper management of dynamic event type identifiers when events are created and removed repeatedly. In Linux kernel tracing, dynamic events such as kprobes are assigned a 16-bit type number that identifies the event's binary blob in the tracing ring buffer. When a dynamic event is removed, its type number becomes available for reuse. However, after creating and removing 65,536 dynamic events, the type number allocation logic reuses previously freed type numbers without properly clearing or segregating the associated parsing logic. This leads to a scenario where a new dynamic event reuses a type number still referenced by the ring buffer entries of a previously removed event. Consequently, the kernel may parse binary blobs with incorrect logic, causing data corruption or kernel crashes. The vulnerability can be triggered by repeatedly adding and removing dynamic events, as demonstrated by a loop that creates 65,536 kprobe events. After this, enabling and disabling probes that interpret parameters differently (e.g., as integers vs. strings) results in corrupted trace output or kernel instability. This indicates a use-after-free or stale pointer condition in the kernel's tracing event handling. The issue affects Linux kernel versions identified by the commit hashes listed, and it is resolved by ensuring that buffers are freed when a dynamic event is removed, preventing reuse conflicts. This vulnerability is significant because it can cause kernel crashes (denial of service) and potentially lead to undefined behavior in kernel tracing, which might be exploitable for privilege escalation or information leakage in certain contexts. However, exploitation requires the ability to create and remove dynamic tracing events, which typically requires elevated privileges or specific kernel capabilities.

For European organizations, the impact of CVE-2022-49006 primarily involves potential denial of service (DoS) conditions on Linux systems that utilize dynamic tracing features such as kprobes. Many enterprise Linux distributions widely deployed in Europe (e.g., Ubuntu, Debian, Red Hat Enterprise Linux, SUSE Linux Enterprise) include kernel tracing capabilities. Systems running workloads that rely on kernel tracing for debugging, performance monitoring, or security auditing could experience instability or crashes if exposed to this vulnerability. While the vulnerability does not appear to be exploited in the wild currently, the ability to cause kernel crashes can disrupt critical infrastructure, cloud services, and enterprise environments. In environments where kernel tracing is enabled and accessible to untrusted users or processes, there is a risk of intentional or accidental triggering of this vulnerability. This could lead to service outages or impact the availability of critical systems. Additionally, if attackers gain sufficient privileges to manipulate kernel tracing events, they might leverage this vulnerability as part of a broader attack chain to destabilize systems or potentially escalate privileges, although no direct exploit for privilege escalation is documented. European organizations with strict uptime and security requirements, such as financial institutions, healthcare providers, and government agencies, should be particularly vigilant.

1. Apply Kernel Updates: The primary mitigation is to update Linux kernels to versions that include the patch resolving this vulnerability. Ensure that all Linux systems, especially those running kernel tracing features, are updated promptly. 2. Restrict Access to Tracing Interfaces: Limit access to /sys/kernel/tracing and related tracing interfaces to trusted administrators only. Use Linux capabilities and access control mechanisms to prevent unprivileged users from creating or removing dynamic tracing events. 3. Disable Unnecessary Tracing Features: If kernel tracing is not required, consider disabling or restricting it to reduce the attack surface. 4. Monitor for Abnormal Tracing Activity: Implement monitoring to detect unusual patterns of dynamic event creation and removal, which could indicate attempts to trigger this vulnerability. 5. Harden System Security: Employ mandatory access controls (e.g., SELinux, AppArmor) to restrict processes that can interact with kernel tracing. 6. Test Kernel Upgrades in Controlled Environments: Before deploying kernel updates, test them to ensure compatibility and stability in your environment. 7. Incident Response Preparedness: Prepare for potential DoS incidents by having recovery procedures and backups in place to minimize downtime.