debug/tst-longjmp_chk3.c

   1 /* Make sure longjmp fortification catches bad signal stacks.
   2    Copyright (C) 2013-2023 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <https://www.gnu.org/licenses/>.  */
  18
  19 #include <setjmp.h>
  20 #include <signal.h>
  21 #include <string.h>
  22
  23 static char buf[SIGSTKSZ * 4];
  24 static jmp_buf jb;
  25
  26 static void
  27 handler (int sig)
  28 {
  29   if (sig == SIGUSR1)
  30     {
  31       if (setjmp (jb) != 0)
  32         {
  33           puts ("setjmp should not have been called");
  34           kill (getpid (), SIGTERM);
  35         }
  36     }
  37   else if (sig == SIGABRT)
  38     {
  39       /* Yeah it worked.  */
  40       _exit (0);
  41     }
  42 }
  43
  44 static int
  45 do_test (void)
  46 {
  47   stack_t ss;
  48
  49   set_fortify_handler (handler);
  50
  51   /* Create a valid signal stack and enable it.  */
  52   ss.ss_sp = buf;
  53   ss.ss_size = sizeof (buf);
  54   ss.ss_flags = 0;
  55   if (sigaltstack (&ss, NULL) < 0)
  56     {
  57       printf ("first sigaltstack failed: %m\n");
  58       return 1;
  59     }
  60
  61   /* Trigger the signal handler which will create a jmpbuf that points to the
  62      end of the signal stack.  */
  63   signal (SIGUSR1, handler);
  64   kill (getpid (), SIGUSR1);
  65
  66   /* Shrink the signal stack so the jmpbuf is now invalid.
  67      We adjust the start & end to handle stacks that grow up & down.  */
  68   ss.ss_sp = buf + sizeof (buf) / 2;
  69   ss.ss_size = sizeof (buf) / 4;
  70   if (sigaltstack (&ss, NULL) < 0)
  71     {
  72       printf ("second sigaltstack failed: %m\n");
  73       return 1;
  74     }
  75
  76   /* This should fail.  */
  77   longjmp (jb, 1);
  78
  79   puts ("longjmp returned and shouldn't");
  80   return 1;
  81 }
  82
  83 #include <support/test-driver.c>