Circular Locking Dependency in Xilinx UARTPS Driver for Linux Kernel

CVE-2025-21820

Summary

A vulnerability in the Xilinx UARTPS driver of the Linux kernel has been identified, stemming from a circular locking dependency during sysrq handling. The issue occurs when the cdns_uart_console_write function attempts to acquire the port lock without the proper state check on port->sysrq, leading to potential deadlocks. The fix introduces a split in sysrq processing to ensure that the port lock is only acquired when necessary, thereby preventing such deadlocks and improving overall system stability.

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