Linux Kernel xHCI NULL Pointer Dereference Vulnerability in Debugfs Port Link Info Files

A NULL pointer dereference vulnerability has been identified in the Linux kernel's xHCI debugfs Port Link Info (PORTLI) files. This issue arises when the number of port registers in 'xhci->max_ports' exceeds those indicated by the Supported Protocol capabilities. Such a discrepancy can occur if 'max_ports' surpasses the maximum port number or if there are gaps between ports of varying speeds, leading to 'port->rhub' being NULL. Consequently, the xHCI information cannot be accessed. The vulnerability has been addressed by implementing a NULL check and modifying the PORTLI output to avoid dereferencing the NULL pointer.

Impact

Exploitation of this vulnerability leads to a NULL pointer dereference, causing a system crash.