CVE-2025-21820

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description A deadlock situation can occur in the Linux kernel due to a circular locking dependency. This issue arises when the cdns uart console write function attempts to take the port lock before the port->sysrq flag is set, potentially leading to a deadlock. The problem is caused by the cdns uart isr function and printk function accessing the uart port lock and console lock in a way that creates a circular dependency.

Recommendations To resolve this issue, the sysrq handling should be split into two parts, using the prepare helper under the port lock and deferring handling until the lock is released. This approach avoids the circular locking dependency and prevents the deadlock situation.

At the moment, there is no information about a newer version that contains a fix for this vulnerability.