Is it ok to mutate objects with std::for_each?

for_each accepts InputIterators :

//from c++ standard
template <class InputIterator, class Function>
   Function for_each (InputIterator first, InputIterator last, Function f);

is it ok to change the object in Function f, like this :

struct AddOne
{
    void operator()(int & x){x = x + 1;}
};

std::vector<int> vec(10);
std::for_each(vec.begin(),vec.end(),AddOne());

This code works in VC++2008 and also with GCC, but is it also portable (legal) code ?
(InputIterators are only guaranteed to be usable as rvalue, in this case they are used as lvalue in AddOne's operator())