Linux Kernel 8250 Serial Driver Unloading Vulnerability Causes Kernel Paging Request Error

A vulnerability in the Linux kernel's handling of the 8250 serial driver can lead to a kernel paging request error. This issue arises approximately ten seconds after unloading a hardware-specific 8250 driver, during the uart_hangup() function's call to uart_change_pm(). The problem was traced back to an incomplete fix in a previous commit, which failed to properly reset the port->pm function. As a result, the serial8250_pm() function incorrectly calls the port->pm() instead of the intended serial8250_do_pm() function.

Impact

Unloading a hardware-specific 8250 driver can cause a kernel panic due to an unhandled paging request, disrupting system stability.

Reproduction

To reproduce this issue, unload a hardware-specific 8250 driver. After about ten seconds, a kernel paging request error will occur, indicating that the vulnerability has been triggered.

Remediation

The vulnerability has been addressed in the Linux kernel. Users should upgrade to the latest version where this issue has been fixed.