static void clear_evtchn_to_irq_row(unsigned row)
{
	unsigned col;

	for (col = 0; col < EVTCHN_PER_ROW; col++)
		WRITE_ONCE(evtchn_to_irq[row][col], -1);
}
Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code.