Mercurial > libpst
annotate src/lzfu.c @ 42:7a97f50c39c5 stable-0-5-12 **FUNKY**
security fix for potential buffer overrun in lz decompress
author | carl |
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date | Tue, 02 Oct 2007 16:10:36 -0700 |
parents | 183ae993b9ad |
children | f6db1f060a95 |
rev | line source |
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16 | 1 /* |
36 | 2 This program is free software; you can redistribute it and/or modify |
3 it under the terms of the GNU General Public License as published by | |
4 the Free Software Foundation; either version 2 of the License, or | |
5 (at your option) any later version. | |
16 | 6 |
36 | 7 You should have received a copy of the GNU General Public License |
8 along with this program; if not, write to the Free Software Foundation, | |
9 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA | |
16 | 10 */ |
11 | |
12 #include "define.h" | |
13 #include "libpst.h" | |
14 #include <sys/types.h> | |
15 #include <string.h> | |
16 #include <stdio.h> | |
17 | |
18 #include "lzfu.h" | |
19 | |
36 | 20 #define LZFU_COMPRESSED 0x75465a4c |
21 #define LZFU_UNCOMPRESSED 0x414c454d | |
16 | 22 |
23 // initital dictionary | |
36 | 24 #define LZFU_INITDICT "{\\rtf1\\ansi\\mac\\deff0\\deftab720{\\fonttbl;}" \ |
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25 "{\\f0\\fnil \\froman \\fswiss \\fmodern \\fscrip" \ |
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26 "t \\fdecor MS Sans SerifSymbolArialTimes Ne" \ |
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27 "w RomanCourier{\\colortbl\\red0\\green0\\blue0" \ |
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28 "\r\n\\par \\pard\\plain\\f0\\fs20\\b\\i\\u\\tab" \ |
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29 "\\tx" |
16 | 30 // initial length of dictionary |
31 #define LZFU_INITLENGTH 207 | |
32 | |
33 // header for compressed rtf | |
34 typedef struct _lzfuheader { | |
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35 u_int32_t cbSize; |
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36 u_int32_t cbRawSize; |
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37 u_int32_t dwMagic; |
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38 u_int32_t dwCRC; |
16 | 39 } lzfuheader; |
40 | |
41 | |
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42 unsigned char* lzfu_decompress (unsigned char* rtfcomp, u_int32_t compsize, size_t *size) { |
36 | 43 // the dictionary buffer |
44 unsigned char dict[4096]; | |
45 // the dictionary pointer | |
46 unsigned int dict_length=0; | |
47 // the header of the lzfu block | |
48 lzfuheader lzfuhdr; | |
49 // container for the data blocks | |
50 unsigned char flags; | |
51 // temp value for determining the bits in the flag | |
52 unsigned char flag_mask; | |
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53 u_int32_t i; |
36 | 54 unsigned char *out_buf; |
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55 u_int32_t out_ptr = 0; |
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56 u_int32_t out_size; |
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57 u_int32_t in_ptr; |
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58 u_int32_t in_size; |
16 | 59 |
36 | 60 memcpy(dict, LZFU_INITDICT, LZFU_INITLENGTH); |
61 dict_length = LZFU_INITLENGTH; | |
62 memcpy(&lzfuhdr, rtfcomp, sizeof(lzfuhdr)); | |
37 | 63 LE32_CPU(lzfuhdr.cbSize); |
64 LE32_CPU(lzfuhdr.cbRawSize); | |
65 LE32_CPU(lzfuhdr.dwMagic); | |
66 LE32_CPU(lzfuhdr.dwCRC); | |
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67 //printf("total size: %d\n", lzfuhdr.cbSize+4); |
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68 //printf("raw size : %d\n", lzfuhdr.cbRawSize); |
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69 //printf("compressed: %s\n", (lzfuhdr.dwMagic == LZFU_COMPRESSED ? "yes" : "no")); |
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70 //printf("CRC : %#x\n", lzfuhdr.dwCRC); |
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71 //printf("\n"); |
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72 out_size = lzfuhdr.cbRawSize + 3; // two braces and a null terminator |
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73 out_buf = (unsigned char*)xmalloc(out_size); |
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74 in_ptr = sizeof(lzfuhdr); |
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75 in_size = (lzfuhdr.cbSize < compsize) ? lzfuhdr.cbSize : compsize; |
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76 while (in_ptr < in_size) { |
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77 flags = rtfcomp[in_ptr++]; |
36 | 78 flag_mask = 1; |
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79 while (flag_mask) { |
36 | 80 if (flag_mask & flags) { |
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81 // two bytes available? |
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82 if (in_ptr+1 < in_size) { |
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83 // read 2 bytes from input |
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84 unsigned short int blkhdr, offset, length; |
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85 memcpy(&blkhdr, rtfcomp+in_ptr, 2); |
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86 LE16_CPU(blkhdr); |
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87 in_ptr += 2; |
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88 /* swap the upper and lower bytes of blkhdr */ |
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89 blkhdr = (((blkhdr&0xFF00)>>8)+ |
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90 ((blkhdr&0x00FF)<<8)); |
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91 /* the offset is the first 12 bits of the 16 bit value */ |
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92 offset = (blkhdr&0xFFF0)>>4; |
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93 /* the length of the dict entry are the last 4 bits */ |
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94 length = (blkhdr&0x000F)+2; |
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95 // add the value we are about to print to the dictionary |
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96 for (i=0; i < length; i++) { |
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97 unsigned char c1; |
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98 c1 = dict[(offset+i)%4096]; |
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99 dict[dict_length]=c1; |
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100 dict_length = (dict_length+1) % 4096; |
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101 if (out_ptr < out_size) out_buf[out_ptr++] = c1; |
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102 } |
36 | 103 } |
104 } else { | |
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105 // one byte available? |
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106 if (in_ptr < in_size) { |
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107 // uncompressed chunk (single byte) |
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108 char c1 = rtfcomp[in_ptr++]; |
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109 dict[dict_length] = c1; |
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110 dict_length = (dict_length+1)%4096; |
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111 if (out_ptr < out_size) out_buf[out_ptr++] = c1; |
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112 } |
36 | 113 } |
114 flag_mask <<= 1; | |
115 } | |
16 | 116 } |
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117 // the compressed version doesn't appear to drop the closing |
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118 // braces onto the doc, so we do that here. |
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119 if (out_ptr < out_size) out_buf[out_ptr++] = '}'; |
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120 if (out_ptr < out_size) out_buf[out_ptr++] = '}'; |
37 | 121 *size = out_ptr; |
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122 if (out_ptr < out_size) out_buf[out_ptr++] = '\0'; |
36 | 123 return out_buf; |
16 | 124 } |