foo.c

#define _GNU_SOURCE

#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

static void
handler(int sig)
{
    stack_t another_stack;

    (void) sig;
    another_stack.ss_sp    = malloc(SIGSTKSZ);
    another_stack.ss_size  = SIGSTKSZ;
    another_stack.ss_flags = 0;
    if (sigaltstack(&another_stack, NULL) != 0) {
        perror("sigaltstack in handler"); /* fails with EPERM as expected */
        _exit(1);
    }
}

int
main(void)
{
    struct sigaction sa;
    stack_t          signal_stack;

    signal_stack.ss_sp    = malloc(SIGSTKSZ);
    signal_stack.ss_size  = SIGSTKSZ;
    signal_stack.ss_flags = 0;
    if (sigaltstack(&signal_stack, NULL) != 0) {
        perror("sigaltstack");
    }
    sa.sa_handler = handler;
    sigemptyset(&sa.sa_mask);
    sa.sa_flags = SA_ONSTACK;
    sigaction(SIGALRM, &sa, NULL);
    alarm(1);
    sleep(2);

    return 0;
}