CVE-2026-68438

A flaw was found in the Linux kernel. When CSD (Call Single Data) lock debugging is enabled, the csd_lock() function's acquisition of the CSD lock is not atomic. This allows multiple central processing units (CPUs) to concurrently access and modify the same CSD data. A local attacker could exploit this race condition, causing the target CPU to become stuck in a loop while processing the call_single_queue. This can lead to soft-lockup warnings or system panics, effectively resulting in a Denial of Service (DoS).

This issue affects SMP cross-call debugging when CONFIG_SMP_CSD_LOCK_WAIT_DEBUG is enabled. Multiple CPUs can concurrently prepare the same destination csd_data, breaking the single-writer assumption in csd_lock(). Default production kernels without this debug option are not affected.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.