STM32f104 usb smoke

hey guys , is there a diode protection circuit somewhere out there to protect your computer from the STM32 5v output ? I was working on my stm chip and forgot the power was on and plugged in my usb by mistake ! wowee.... could you put inline from the 5v power source a schottkey diode maybe ?

USB ports on boards should NOT feed back voltage to the USB port.

Was it a cheap clone STM