Reject overflowing manual ban durations

admin.go

@@ -896,13 +896,16 @@ func (b *Barnard) addManualBan(text string) {
 // manualBanDuration validates user input before it reaches the unsigned
 // protocol duration field.
 func manualBanDuration(text string) (time.Duration, error) {
-	minutes, err := strconv.Atoi(text)
+	minutes, err := strconv.ParseInt(text, 10, 64)
 	if err != nil {
 		return 0, fmt.Errorf("ban minutes must be a number")
 	}
 	if minutes < 0 {
 		return 0, fmt.Errorf("ban minutes must not be negative")
 	}
+	if minutes > int64((1<<63-1)/time.Minute) {
+		return 0, fmt.Errorf("ban duration is too long")
+	}
 	return time.Duration(minutes) * time.Minute, nil
 }