Setting std::function to nullptr from invoked callable target

Is it legal C++ (this means without undefined behavior, etc.) to set a std::function variable to nullptr from the function/lambda expression stored to this variable when it was invoked?

My intention is to omit further invoking the of std::function.

#include <functional>

std::function<void(int)> func;

void setFunc(std::function<void(int)> f) {
    func = f;
}

int main() {
    setFunc([](int status) {
        // do something...
        setFunc(nullptr); // callback shall only be called once
    });

    for(;;) {
        int status = 0;

        // fetch status

        if (func)
            func(status);
    }
}