1 /* 2 * Copyright (C) 2014 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 __builtin____stpncpy_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 stpncpy check is called if _FORTIFY_SOURCE is defined and 44 * greater than 0. 45 */ 46 extern "C" char* __stpncpy_chk(char* __restrict dest, const char* __restrict src, 47 size_t len, size_t dest_len) { 48 if (__predict_false(len > dest_len)) { 49 __fortify_chk_fail("stpncpy: prevented write past end of buffer", 50 BIONIC_EVENT_STPNCPY_BUFFER_OVERFLOW); 51 } 52 53 return stpncpy(dest, src, len); 54 } 55 56 /* 57 * __stpncpy_chk2 58 * 59 * This is a variant of __stpncpy_chk, but it also checks to make 60 * sure we don't read beyond the end of "src". The code for this is 61 * based on the original version of stpncpy, but modified to check 62 * how much we read from "src" at the end of the copy operation. 63 */ 64 extern "C" char* __stpncpy_chk2(char* __restrict dst, const char* __restrict src, 65 size_t n, size_t dest_len, size_t src_len) 66 { 67 if (__predict_false(n > dest_len)) { 68 __fortify_chk_fail("stpncpy: prevented write past end of buffer", 69 BIONIC_EVENT_STPNCPY_BUFFER_OVERFLOW); 70 } 71 if (n != 0) { 72 char* d = dst; 73 const char* s = src; 74 75 do { 76 if ((*d++ = *s++) == 0) { 77 /* NUL pad the remaining n-1 bytes */ 78 while (--n != 0) { 79 *d++ = 0; 80 } 81 break; 82 } 83 } while (--n != 0); 84 85 size_t s_copy_len = static_cast<size_t>(s - src); 86 if (__predict_false(s_copy_len > src_len)) { 87 __fortify_chk_fail("stpncpy: prevented read past end of buffer", 0); 88 } 89 } 90 91 return dst; 92 } 93
