t_impossible_sigaltstack.cc

// clang++ -Wall -Werror t_impossible_sigaltstack.cc -o t_impossible_sigaltstack

#include <err.h>
#include <signal.h>
#include <stdlib.h>
#include <sys/mman.h>

namespace {

void HandleSignal(int sig, siginfo_t* info, void* ucontext) {
  struct sigaction sa;
  sa.sa_handler = SIG_DFL;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = 0;
  if (sigaction(sig, &sa, nullptr) != 0) {
    err(EXIT_FAILURE, "sigaction");
  }
}

}  // namespace

int main(int argc, char* argv[]) {
  stack_t ss;
  ss.ss_flags = 0;
  ss.ss_size = SIGSTKSZ;
  ss.ss_sp = mmap(nullptr, ss.ss_size, PROT_READ | PROT_WRITE,
                  MAP_ANON | MAP_PRIVATE, -1, 0);
  if (!ss.ss_sp) {
    err(EXIT_FAILURE, "mmap");
  }
  if (sigaltstack(&ss, nullptr) != 0) {
    err(EXIT_FAILURE, "sigaltstack");
  } 

  struct sigaction sa;
  sa.sa_sigaction = HandleSignal;
  sigemptyset(&sa.sa_mask);
  sa.sa_flags = SA_SIGINFO | SA_ONSTACK;

  if (sigaction(SIGABRT, &sa, nullptr) != 0) {
    err(EXIT_FAILURE, "sigaction");
  }

  if (mprotect(ss.ss_sp, ss.ss_size, PROT_NONE) != 0) {
    err(EXIT_FAILURE, "mprotect");
  }

  abort();

  return EXIT_SUCCESS;
}