1 /* 2 * Copyright (C) 2012 The Android Open Source Project 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 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #undef _FORTIFY_SOURCE 30 31 #include <string.h> 32 #include <stdlib.h> 33 #include "private/libc_logging.h" 34 35 /* 36 * Runtime implementation of __strlen_chk. 37 * 38 * See 39 * http://gcc.gnu.org/onlinedocs/gcc/Object-Size-Checking.html 40 * http://gcc.gnu.org/ml/gcc-patches/2004-09/msg02055.html 41 * for details. 42 * 43 * This strlen check is called if _FORTIFY_SOURCE is defined and 44 * greater than 0. 45 * 46 * This test is designed to detect code such as: 47 * 48 * int main() { 49 * char buf[10]; 50 * memcpy(buf, "1234567890", sizeof(buf)); 51 * size_t len = strlen(buf); // segfault here with _FORTIFY_SOURCE 52 * printf("%d\n", len); 53 * return 0; 54 * } 55 * 56 * or anytime strlen reads beyond an object boundary. 57 */ 58 extern "C" size_t __strlen_chk(const char* s, size_t s_len) { 59 size_t ret = strlen(s); 60 61 if (__predict_false(ret >= s_len)) { 62 __fortify_chk_fail("strlen: prevented read past end of buffer", 0); 63 } 64 65 return ret; 66 } 67
