sysdeps/unix/sysv/linux/____longjmp_chk.c

   1 /* longjmp fortify implementation.  Linux version.
   2    Copyright (C) 2011-2023 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 <jmpbuf-offsets.h>
  20 #include <sysdep.h>
  21 #include <setjmp.h>
  22 #include <signal.h>
  23 #include <stdio.h>
  24 #include <stackinfo.h>
  25
  26 #ifdef _STACK_GROWS_DOWN
  27 #define called_from(this, saved) ((this) < (saved))
  28 #else
  29 #define called_from(this, saved) ((this) > (saved))
  30 #endif
  31
  32 _Noreturn extern void ____longjmp_chk (__jmp_buf __env, int __val);
  33
  34 void ____longjmp_chk (__jmp_buf env, int val)
  35 {
  36   void *this_frame = __builtin_frame_address (0);
  37   void *saved_frame = JB_FRAME_ADDRESS (env);
  38   stack_t ss;
  39
  40   /* If "env" is from a frame that called us, we're all set.  */
  41   if (called_from(this_frame, saved_frame))
  42     __longjmp (env, val);
  43
  44   /* If we can't get the current stack state, give up and do the longjmp. */
  45   if (INTERNAL_SYSCALL_CALL (sigaltstack, NULL, &ss) != 0)
  46     __longjmp (env, val);
  47
  48   /* If we we are executing on the alternate stack and within the
  49      bounds, do the longjmp.  */
  50   if (ss.ss_flags == SS_ONSTACK
  51       && (this_frame >= ss.ss_sp && this_frame < (ss.ss_sp + ss.ss_size)))
  52     __longjmp (env, val);
  53
  54   __fortify_fail ("longjmp causes uninitialized stack frame");
  55 }