void GfxSubpath::curveTo(double x1, double y1, double x2, double y2,
			 double x3, double y3) {
  if (n+3 > size) {
    size += 16;
    x = (double *)greallocn(x, size, sizeof(double));
    y = (double *)greallocn(y, size, sizeof(double));
    curve = (GBool *)greallocn(curve, size, sizeof(GBool));
  }
  x[n] = x1;
  y[n] = y1;
  x[n+1] = x2;
  y[n+1] = y2;
  x[n+2] = x3;
  y[n+2] = y3;
  curve[n] = curve[n+1] = gTrue;
  curve[n+2] = gFalse;
  n += 3;
}

This weakness involves numeric computation errors, such as integer overflows, underflows, or precision losses, which can lead to miscalculations and exploitable behaviors in software.