angle_between(const fz_point u, const fz_point v)
{
	float det = u.x * v.y - u.y * v.x;
	float sign = (det < 0 ? -1 : 1);
	float magu = u.x * u.x + u.y * u.y;
	float magv = v.x * v.x + v.y * v.y;
	float udotv = u.x * v.x + u.y * v.y;
	float t = udotv / (magu * magv);
	/* guard against rounding errors when near |1| (where acos will return NaN) */
	if (t < -1) t = -1;
	if (t > 1) t = 1;
	return sign * acosf(t);
}

The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary. This may result in read or write operations on unexpected memory locations that could be linked to other variables, data structures, or internal program data.