gdb/testsuite/gdb.arch/amd64-invalid-stack-top.c

   1 /* This testcase is part of GDB, the GNU debugger.
   2
   3    Copyright 2014-2022 Free Software Foundation, Inc.
   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 3 of the License, or
   8    (at your option) 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, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19 #include <sys/mman.h>
  20 #include <unistd.h>
  21 #include <assert.h>
  22
  23 void *global_invalid_ptr = NULL;
  24
  25 void
  26 func2 (void)
  27 {
  28   /* Replace the current stack pointer and frame pointer with the invalid
  29      pointer.  */
  30   asm ("mov %0, %%rsp\n\tmov %0, %%rbp" : : "r" (global_invalid_ptr));
  31
  32   /* Create a label for a breakpoint.  */
  33   asm (".global breakpt\nbreakpt:");
  34 }
  35
  36 void
  37 func1 (void *ptr)
  38 {
  39   global_invalid_ptr = ptr;
  40   func2 ();
  41 }
  42
  43 /* Finds and returns an invalid pointer, mmaps in a page, grabs a pointer
  44    to it then unmaps the page again.  This is almost certainly "undefined"
  45    behaviour, but should be good enough for this small test program.  */
  46
  47 static void *
  48 make_invalid_ptr (void)
  49 {
  50   int page_size, ans;
  51   void *ptr;
  52
  53   page_size = getpagesize ();
  54   ptr =  mmap (0, page_size, PROT_NONE,
  55                MAP_PRIVATE | MAP_ANONYMOUS,
  56                -1, 0);
  57   assert (ptr != MAP_FAILED);
  58   ans = munmap (ptr, page_size);
  59   assert (ans == 0);
  60
  61   return ptr;
  62 }
  63
  64 int
  65 main (void)
  66 {
  67   void *invalid_ptr;
  68
  69   invalid_ptr = make_invalid_ptr ();
  70   func1 (invalid_ptr);
  71
  72   return 0;
  73 }