sysdeps/unix/sysv/linux/generic/____longjmp_chk.c

   1 /* Copyright (C) 2011 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
   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, write to the Free
  17    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  18    02111-1307 USA.  */
  19
  20 #include <jmpbuf-offsets.h>
  21 #include <sysdep.h>
  22 #include <setjmp.h>
  23 #include <signal.h>
  24 #include <stdio.h>
  25 #include <stackinfo.h>
  26
  27 #ifdef _STACK_GROWS_DOWN
  28 #define called_from(this, saved) ((this) < (saved))
  29 #else
  30 #define called_from(this, saved) ((this) > (saved))
  31 #endif
  32
  33 extern void ____longjmp_chk (__jmp_buf __env, int __val)
  34   __attribute__ ((__noreturn__));
  35
  36 void ____longjmp_chk (__jmp_buf env, int val)
  37 {
  38   void *this_frame = __builtin_frame_address (0);
  39   void *saved_frame = JB_FRAME_ADDRESS (env);
  40   INTERNAL_SYSCALL_DECL (err);
  41   stack_t ss;
  42
  43   /* If "env" is from a frame that called us, we're all set.  */
  44   if (called_from(this_frame, saved_frame))
  45     __longjmp (env, val);
  46
  47   /* If we can't get the current stack state, give up and do the longjmp. */
  48   if (INTERNAL_SYSCALL (sigaltstack, err, 2, NULL, &ss) != 0)
  49     __longjmp (env, val);
  50
  51   /* If we we are executing on the alternate stack and within the
  52      bounds, do the longjmp.  */
  53   if (ss.ss_flags == SS_ONSTACK &&
  54       (this_frame >= ss.ss_sp && this_frame < (ss.ss_sp + ss.ss_size)))
  55     __longjmp (env, val);
  56
  57   __fortify_fail ("longjmp causes uninitialized stack frame");
  58 }