Linux Kernel USB Gadget Function f_ncm Net_Device Lifecycle Management Vulnerability

A vulnerability in the Linux kernel's USB gadget function for NCM (Network Control Model) has been addressed. The issue arose because the network device outlasted its parent gadget device during disconnection, leading to dangling sysfs links and null pointer dereference issues. Previous attempts to resolve this by altering the net_device allocation process introduced new problems, including a regression that caused DHCP failures on certain systems. The latest fix involves using device_move to properly manage the net_device's lifecycle, ensuring it remains correctly linked to the gadget device during bind and unbind cycles. This adjustment allows network interfaces to be preserved across USB reconnections, thereby maintaining DHCP bindings.

Impact

The vulnerability could cause network-related null pointer dereference errors, disrupting normal USB gadget functionality and causing DHCP failures on systems like pmOS.

Remediation

Users can apply the latest patch available in the Linux kernel stable tree to address this vulnerability.