Denial of Service in libkcapi via AIO Handle Reuse

Executive Summary

This vulnerability is a flaw in libkcapi where a local attacker can exploit the Asynchronous Input/Output (AIO) interface. By reusing an AIO-enabled handle after a prior completion error, the _kcapi_aio_read_all() function may enter an infinite wait loop, causing a persistent denial of service. This makes the affected application or thread unresponsive.

Useful 0 Not Useful 0

Detection Guidance

Detecting this vulnerability requires checking for applications using libkcapi with AIO enabled. Monitor for unresponsive threads or high CPU usage in processes linked to libkcapi. Check logs for repeated AIO completion errors or infinite loops in _kcapi_aio_read_all().

Commands to check for affected applications: lsof | grep libkcapi, ps aux | grep -E 'libkcapi|AIO', strace -p <PID> to trace system calls for AIO operations. Look for io_getevents() calls without proper timeout handling.

Useful 0 Not Useful 0

Impact Analysis

This vulnerability can cause a persistent denial of service, making the affected application or thread unresponsive. It may lead to high CPU or memory usage due to the infinite loop, disrupting normal operations of applications using libkcapi's AIO interface.

Useful 0 Not Useful 0

Compliance Impact

This vulnerability primarily causes a denial of service by making applications unresponsive due to an infinite loop. It does not directly impact data confidentiality or integrity, which are key concerns for GDPR and HIPAA. However, prolonged denial of service could indirectly affect compliance by disrupting access to critical systems handling personal or health data.

Useful 0 Not Useful 0

Mitigation Strategies

Immediately stop using AIO in libkcapi if not required. If AIO is necessary, ensure handles are destroyed and reinitialized after any AIO completion error instead of reusing them. Avoid initializing handles with KCAPI_INIT_AIO.

Update libkcapi to a patched version if available. Monitor affected applications for persistent denial of service and restart unresponsive threads or processes.

Useful 0 Not Useful 0