sparc: fix array overrun check in of_device_64.c

Do the array length check and fixup before copying the array.
Signed-off-by: Robert Reif <reif@earthlink.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

arch/sparc/kernel/of_device_64.c

@@ -811,11 +811,7 @@ static struct of_device * __init scan_one_device(struct device_node *dp,
 
 	irq = of_get_property(dp, "interrupts", &len);
 	if (irq) {
-		memcpy(op->irqs, irq, len);
 		op->num_irqs = len / 4;
-	} else {
-		op->num_irqs = 0;
-	}
 
 		/* Prevent overrunning the op->irqs[] array.  */
 		if (op->num_irqs > PROMINTR_MAX) {
@@ -824,6 +820,10 @@ static struct of_device * __init scan_one_device(struct device_node *dp,
 			       dp->full_name, op->num_irqs, PROMINTR_MAX);
 			op->num_irqs = PROMINTR_MAX;
 		}
+		memcpy(op->irqs, irq, op->num_irqs * 4);
+	} else {
+		op->num_irqs = 0;
+	}
 
 	build_device_resources(op, parent);
 	for (i = 0; i < op->num_irqs; i++)