Is this const_cast undefined behavior?

Question

I was wondering whether the following is undefined behavior

// Case 1:
int *p = 0;
int const *q = *const_cast<int const* const*>(&p);

// Case 2: (I think this is the same)
int *p = 0;
int const *const *pp = &p;
int const *q = *pp;

Is this undefined behavior by reading a int* as if it were a int const*? I think it is undefined behavior, but I previously thought that only adding const in general is safe, so I'm unsure.