stackoverflow2.c

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/* Test that stack overflow and SIGSEGV are correctly distinguished.
   Copyright (C) 2002-2006, 2008  Bruno Haible <bruno@clisp.org>
   Copyright (C) 2010 Eric Blake <eblake@redhat.com>

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#ifndef _MSC_VER
# include <config.h>
#endif

#include "sigsegv.h"
#include <stdio.h>
#include <limits.h>

#if HAVE_STACK_OVERFLOW_RECOVERY && HAVE_SIGSEGV_RECOVERY

#if defined _WIN32 && !defined __CYGWIN__
  /* Windows doesn't have sigset_t.  */
  typedef int sigset_t;
# define sigemptyset(set)
# define sigprocmask(how,set,oldset)
#endif

#include "mmaputil.h"
#include <stddef.h> /* needed for NULL on SunOS4 */
#include <stdlib.h> /* for abort, exit */
#include <signal.h>
#include <setjmp.h>
#if HAVE_SETRLIMIT
# include <sys/types.h>
# include <sys/time.h>
# include <sys/resource.h>
#endif
#include "altstack.h"

jmp_buf mainloop;
sigset_t mainsigset;

volatile int pass = 0;
unsigned long page;

static void
stackoverflow_handler_continuation (void *arg1, void *arg2, void *arg3)
{
  int arg = (int) (long) arg1;
  longjmp (mainloop, arg);
}

void
stackoverflow_handler (int emergency, stackoverflow_context_t scp)
{
  pass++;
  if (pass <= 2)
    printf ("Stack overflow %d caught.\n", pass);
  else
    {
      printf ("Segmentation violation misdetected as stack overflow.\n");
      exit (1);
    }
  sigprocmask (SIG_SETMASK, &mainsigset, NULL);
  sigsegv_leave_handler (stackoverflow_handler_continuation,
                         (void *) (long) (emergency ? -1 : pass), NULL, NULL);
}

int
sigsegv_handler (void *address, int emergency)
{
  /* This test is necessary to distinguish stack overflow and SIGSEGV.  */
  if (!emergency)
    return 0;

  pass++;
  if (pass <= 2)
    {
      printf ("Stack overflow %d missed.\n", pass);
      exit (1);
    }
  else
    printf ("Segmentation violation correctly detected.\n");
  sigprocmask (SIG_SETMASK, &mainsigset, NULL);
  return sigsegv_leave_handler (stackoverflow_handler_continuation,
                                (void *) (long) pass, NULL, NULL);
}

volatile int *
recurse_1 (int n, volatile int *p)
{  
  if (n < INT_MAX)
    *recurse_1 (n + 1, p) += n;
  return p;
}

int
recurse (volatile int n)
{
  return *recurse_1 (n, &n);
}

int
main ()
{
  sigset_t emptyset;
  void *p;

#if HAVE_SETRLIMIT && defined RLIMIT_STACK
  /* Before starting the endless recursion, try to be friendly to the user's
     machine.  On some Linux 2.2.x systems, there is no stack limit for user
     processes at all.  We don't want to kill such systems.  */
  struct rlimit rl;
  rl.rlim_cur = rl.rlim_max = 0x100000; /* 1 MB */
  setrlimit (RLIMIT_STACK, &rl);
#endif

  /* Prepare the storage for the alternate stack.  */
  prepare_alternate_stack ();

  /* Install the stack overflow handler.  */
  if (stackoverflow_install_handler (&stackoverflow_handler,
                                     mystack, SIGSTKSZ)
      < 0)
    exit (2);

  /* Preparations.  */
#if !HAVE_MMAP_ANON && !HAVE_MMAP_ANONYMOUS && HAVE_MMAP_DEVZERO
  zero_fd = open ("/dev/zero", O_RDONLY, 0644);
#endif

  /* Setup some mmaped memory.  */
  p = mmap_zeromap ((void *) 0x12340000, 0x4000);
  if (p == (void *)(-1))
    {
      fprintf (stderr, "mmap_zeromap failed.\n");
      exit (2);
    }
  page = (unsigned long) p;

  /* Make it read-only.  */
  if (mprotect ((void *) page, 0x4000, PROT_READ) < 0)
    {
      fprintf (stderr, "mprotect failed.\n");
      exit (2);
    }

  /* Install the SIGSEGV handler.  */
  if (sigsegv_install_handler (&sigsegv_handler) < 0)
    exit (2);

  /* Save the current signal mask.  */
  sigemptyset (&emptyset);
  sigprocmask (SIG_BLOCK, &emptyset, &mainsigset);

  /* Provoke two stack overflows in a row.  */
  switch (setjmp (mainloop))
    {
    case -1:
      printf ("emergency exit\n"); exit (1);
    case 0: case 1:
      printf ("Starting recursion pass %d.\n", pass + 1);
      recurse (0);
      printf ("no endless recursion?!\n"); exit (1);
    case 2:
      *(volatile int *) (page + 0x678) = 42;
      break;
    case 3:
      *(volatile int *) 0 = 42;
      break;
    case 4:
      break;
    default:
      abort ();
    }

  /* Validate that the alternate stack did not overflow.  */
  check_alternate_stack_no_overflow ();

  printf ("Test passed.\n");
  exit (0);
}

#else

int
main ()
{
  return 77;
}

#endif