1/* 2 * Copyright (c) 2015 Dmitry V. Levin <ldv@altlinux.org> 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR 17 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 18 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 19 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 21 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 22 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 23 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 24 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 25 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28#include <string.h> 29#include <unistd.h> 30#include <sys/mman.h> 31 32int 33main(void) 34{ 35 const size_t page_len = sysconf(_SC_PAGESIZE); 36 const size_t tail_len = 257; 37 38 if (tail_len >= page_len) 39 return 77; 40 41 void *p = mmap(NULL, page_len * 2, PROT_READ | PROT_WRITE, 42 MAP_PRIVATE | MAP_ANONYMOUS, -1, 0); 43 if (p == MAP_FAILED || mprotect(p + page_len, page_len, PROT_NONE)) 44 return 77; 45 46 memset(p, 0, page_len); 47 char *addr = p + page_len - tail_len; 48 memset(addr, '/', tail_len - 1); 49 if (chdir(addr)) 50 return 77; 51 52 return 0; 53} 54