src/heur-bc.h

   1 /* Detecting stack overflow.  Version for platforms which supply the
   2    stack pointer and have sigsegv_get_vma.
   3    Copyright (C) 2003  Bruno Haible <bruno@clisp.org>
   4
   5    This program is free software; you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 2, or (at your option)
   8    any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program; if not, write to the Free Software Foundation,
  17    Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */
  18
  19 #if HAVE_GETRLIMIT
  20 # include <sys/types.h>
  21 # include <sys/time.h>
  22 # include <sys/resource.h> /* declares struct rlimit */
  23 #endif
  24
  25 /* Address of the last byte belonging to the stack vma.  */
  26 static unsigned long stack_top = 0;
  27
  28 static int
  29 remember_stack_top (void *some_variable_on_stack)
  30 {
  31   struct vma_struct vma;
  32
  33   if (stack_top)
  34     return 0;
  35
  36   /* Needs to be retrieved once only.  */
  37   if (sigsegv_get_vma ((unsigned long) some_variable_on_stack, &vma) >= 0)
  38     {
  39       stack_top = vma.end - 1;
  40       return 0;
  41     }
  42   else
  43     return -1;
  44 }
  45
  46 #define IS_STACK_OVERFLOW \
  47   is_stk_overflow ((unsigned long) (SIGSEGV_FAULT_STACKPOINTER))
  48
  49 static int
  50 is_stk_overflow (int sp)
  51 {
  52   struct vma_struct vma;
  53
  54   if (sigsegv_get_vma (stack_top, &vma) < 0)
  55     return 0;
  56
  57 #if HAVE_GETRLIMIT && defined RLIMIT_STACK
  58   {
  59     /* Heuristic BC: If the stack size has reached its maximal size,
  60        and sp is near the low end, we consider it a stack
  61        overflow.  */
  62     struct rlimit rl;
  63
  64     if (getrlimit (RLIMIT_STACK, &rl) >= 0)
  65       {
  66         unsigned long current_stack_size = vma.end - vma.start;
  67         unsigned long max_stack_size = rl.rlim_cur;
  68         if (current_stack_size <= max_stack_size - 4096)
  69           return 0;
  70       }
  71   }
  72 #endif
  73
  74     /* Heuristic BC: If we know sp, and it is neither
  75        near the low end, nor in the alternate stack, then
  76        it's probably not a stack overflow.  */
  77     return (sp >= stk_extra_stack
  78             && sp <= stk_extra_stack + stk_extra_stack_size)
  79 #if STACK_DIRECTION < 0
  80            || (sp <= vma.start + 4096 && vma.start <= sp + 4096)
  81 #else
  82            || (sp <= vma.end + 4096 && vma.end <= sp + 4096)
  83 #endif
  84            ;
  85 }