void usb_serial_console_init(int minor)
{
	if (minor == 0) {
		/*
		 * Call register_console() if this is the first device plugged
		 * in.  If we call it earlier, then the callback to
		 * console_setup() will fail, as there is not a device seen by
		 * the USB subsystem yet.
		 */
		/*
		 * Register console.
		 * NOTES:
		 * console_setup() is called (back) immediately (from
		 * register_console). console_write() is called immediately
		 * from register_console iff CON_PRINTBUFFER is set in flags.
		 */
		pr_debug("registering the USB serial console.\n");
		register_console(&usbcons);
	}
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.