Ubuntu: (Multiple Advisories) (CVE-2025-38134): Linux kernel vulnerabilities

In the Linux kernel, the following vulnerability has been resolved:

usb: acpi: Prevent null pointer dereference in usb_acpi_add_usb4_devlink()

As demonstrated by the fix for update_port_device_state,
commit 12783c0b9e2c ("usb: core: Prevent null pointer dereference in update_port_device_state"),
usb_hub_to_struct_hub() can return NULL in certain scenarios,
such as during hub driver unbind or teardown race conditions,
even if the underlying usb_device structure exists.

Plus, all other places that call usb_hub_to_struct_hub() in the same file
do check for NULL return values.

If usb_hub_to_struct_hub() returns NULL, the subsequent access to
hub->ports[udev->portnum - 1] will cause a null pointer dereference.