usb: core: Prevent null pointer dereference in update_port_device_state

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: usb: core: Prevent null pointer dereference in update_port_device_state Currently, the function update_port_device_state gets the usb_hub from udev->parent by calling usb_hub_to_struct_hub. However, in case the actconfig or the maxchild is 0, the usb_hub would be NULL and upon further accessing to get port_dev would result in null pointer dereference. Fix this by introducing an if check after the usb_hub is populated.

References

• https://git.kernel.org/stable/c/ed85777c640cf9e6920bb1b60ed8cd48e1f4d873
• https://git.kernel.org/stable/c/465b545d1d7ef282192ddd4439b08279bdb13f6f
• https://git.kernel.org/stable/c/12783c0b9e2c7915a50d5ec829630ff2da50472c