poly_recv(PG_FUNCTION_ARGS)
{
	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
	POLYGON    *poly;
	int32		npts;
	int32		i;
	int			size;

	npts = pq_getmsgint(buf, sizeof(int32));
	if (npts <= 0 || npts >= (int32) ((INT_MAX - offsetof(POLYGON, p[0])) / sizeof(Point)))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
		  errmsg("invalid number of points in external \"polygon\" value")));

	size = offsetof(POLYGON, p[0]) +sizeof(poly->p[0]) * npts;
	poly = (POLYGON *) palloc0(size);	/* zero any holes */

	SET_VARSIZE(poly, size);
	poly->npts = npts;

	for (i = 0; i < npts; i++)
	{
		poly->p[i].x = pq_getmsgfloat8(buf);
		poly->p[i].y = pq_getmsgfloat8(buf);
	}

	make_bound_box(poly);

	PG_RETURN_POLYGON_P(poly);
}

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