Let $x = a$ be an integral root of the cubic function above such that we can write the quadratic function in the parameter $m$:
$m^2 + (a^2 - a)m + (1 - a^3) = 0$;
or $m = \frac{(a - a^2) \pm \sqrt{(a - a^2)^2 - 4(1)(1 - a^3)}}{2}$;
or $m = \frac{(a - a^2) \pm \sqrt{a^4 + 2a^3 + a^2 - 4}}{2}$;
or $m = \frac{(a - a^2) \pm \sqrt{a^2(a + 1)^2 - 4}}{2}$ (i)
In order for $m$ to be integral, the discriminant in (i) needs to be a perfect square, or:
$a^2(a + 1)^2 - 4 = N^2$;
or $a^2(a + 1)^2 - N^2 = 4$;
or $[a(a+1) + N][a(a+1) - N] = 4$ (ii)
Since 4 has the positive divisors 1, 2, and 4, these can be checked against the LHS factors in (ii):
$a(a+1) + N = 4, a(a+1) - N = 1 \Rightarrow 2a(a+1) = 5$ (a contradiction & can be eliminated);
$a(a+1) + N = 2, a(a+1) - N = 2 \Rightarrow 2a(a+1) = 4 \Rightarrow a(a+1) = 2 \Rightarrow a^2 + a - 2 = (a+2)(a-1) = 0 \Rightarrow a = -2, 1$ and $N = 0$.
Finally, we compute the integral values of $m$ in (i) from our integral solutions for $a$ and $N$, which produces:
$m = [(a - a^2) \pm N]/2$;
$m = (1 - 1^2)/2 = 0$ and $(-2 - (-2)^2)/2 = -3$
or $\fbox{m = -3, 0}$.