debug/tst-longjmp_chk3.c

   1 /* Make sure longjmp fortification catches bad signal stacks.
   2    Copyright (C) 2013-2020 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 int do_test (void);
  24 #define TEST_FUNCTION do_test ()
  25 #include "../test-skeleton.c"
  26
  27 static char buf[SIGSTKSZ * 4];
  28 static jmp_buf jb;
  29
  30 static void
  31 handler (int sig)
  32 {
  33   if (sig == SIGUSR1)
  34     {
  35       if (setjmp (jb) != 0)
  36         {
  37           puts ("setjmp should not have been called");
  38           kill (getpid (), SIGTERM);
  39         }
  40     }
  41   else if (sig == SIGABRT)
  42     {
  43       /* Yeah it worked.  */
  44       _exit (0);
  45     }
  46 }
  47
  48 static int
  49 do_test (void)
  50 {
  51   stack_t ss;
  52
  53   set_fortify_handler (handler);
  54
  55   /* Create a valid signal stack and enable it.  */
  56   ss.ss_sp = buf;
  57   ss.ss_size = sizeof (buf);
  58   ss.ss_flags = 0;
  59   if (sigaltstack (&ss, NULL) < 0)
  60     {
  61       printf ("first sigaltstack failed: %m\n");
  62       return 1;
  63     }
  64
  65   /* Trigger the signal handler which will create a jmpbuf that points to the
  66      end of the signal stack.  */
  67   signal (SIGUSR1, handler);
  68   kill (getpid (), SIGUSR1);
  69
  70   /* Shrink the signal stack so the jmpbuf is now invalid.
  71      We adjust the start & end to handle stacks that grow up & down.  */
  72   ss.ss_sp = buf + sizeof (buf) / 2;
  73   ss.ss_size = sizeof (buf) / 4;
  74   if (sigaltstack (&ss, NULL) < 0)
  75     {
  76       printf ("second sigaltstack failed: %m\n");
  77       return 1;
  78     }
  79
  80   /* This should fail.  */
  81   longjmp (jb, 1);
  82
  83   puts ("longjmp returned and shouldn't");
  84   return 1;
  85 }