What is the ruling on the fast of one who ate suhoor and slept before Fajr, and did not pray Fajr on time?

Your fasting is valid as long as you did not do anything that invalidates the fast. And if you did not intentionally sleep through the Fajr prayer, and you took the necessary precautions to wake up for it but were overcome by sleep, then there is no sin upon you, according to the Hadith (definition): "There is no negligence in sleep; negligence is only in wakefulness. So, if any of you forgets a prayer or sleeps through it, let him pray it when he remembers it."