In the Linux kernel, the following vulnerability has been resolved:
xhci: Fix NULL pointer dereference when reading portli debugfs files
Michal reported and debgged a NULL pointer dereference bug in the
recently added portli debugfs files
Oops is caused when there are more port registers counted in
xhci->max_ports than ports reported by Supported Protocol capabilities.
This is possible if max_ports is more than maximum port number, or
if there are gaps between ports of different speeds the 'Supported
Protocol' capabilities.
In such cases port->rhub will be NULL so we can't reach xhci behind it.
Add an explicit NULL check for this case, and print portli in hex
without dereferencing port->rhub.