*** longjmp causes uninitialized stack frame ***: nsenter-exec terminated

gistfile1.txt

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <setjmp.h>
#include <sched.h>
#include <signal.h>

struct cr_clone_arg {
        char stack[4096] __attribute__((aligned (8)));
        char stack_ptr[0];
        jmp_buf env;
};

static int child_func(void *_arg)
{
        struct cr_clone_arg *arg = (struct cr_clone_arg *) _arg;
        longjmp(arg->env, 1);
}

int main()
{
        int child;
        struct cr_clone_arg ca;


        if (setjmp(ca.env) == 1) {
                printf("Ok\n");
                return 0;
        }

        child = clone(child_func, ca.stack_ptr, CLONE_PARENT | SIGCHLD, &ca);
        if (child < 0) {
                fprintf(stderr, "Unable to fork: %m");
                exit(1);
        }
        printf("Done\n");

        return 0;
}