annotate src/lzfu.c @ 42:7a97f50c39c5 stable-0-5-12 **FUNKY**

security fix for potential buffer overrun in lz decompress
author carl
date Tue, 02 Oct 2007 16:10:36 -0700
parents 183ae993b9ad
children f6db1f060a95
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1 /*
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2 This program is free software; you can redistribute it and/or modify
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3 it under the terms of the GNU General Public License as published by
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4 the Free Software Foundation; either version 2 of the License, or
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5 (at your option) any later version.
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6
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7 You should have received a copy of the GNU General Public License
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8 along with this program; if not, write to the Free Software Foundation,
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9 Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
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10 */
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11
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12 #include "define.h"
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13 #include "libpst.h"
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14 #include <sys/types.h>
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15 #include <string.h>
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16 #include <stdio.h>
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17
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18 #include "lzfu.h"
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19
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20 #define LZFU_COMPRESSED 0x75465a4c
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21 #define LZFU_UNCOMPRESSED 0x414c454d
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22
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23 // initital dictionary
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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"
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30 // initial length of dictionary
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31 #define LZFU_INITLENGTH 207
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32
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33 // header for compressed rtf
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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;
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39 } lzfuheader;
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41
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42 unsigned char* lzfu_decompress (unsigned char* rtfcomp, u_int32_t compsize, size_t *size) {
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43 // the dictionary buffer
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44 unsigned char dict[4096];
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45 // the dictionary pointer
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46 unsigned int dict_length=0;
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47 // the header of the lzfu block
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48 lzfuheader lzfuhdr;
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49 // container for the data blocks
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50 unsigned char flags;
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51 // temp value for determining the bits in the flag
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52 unsigned char flag_mask;
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53 u_int32_t i;
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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;
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59
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60 memcpy(dict, LZFU_INITDICT, LZFU_INITLENGTH);
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61 dict_length = LZFU_INITLENGTH;
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62 memcpy(&lzfuhdr, rtfcomp, sizeof(lzfuhdr));
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63 LE32_CPU(lzfuhdr.cbSize);
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64 LE32_CPU(lzfuhdr.cbRawSize);
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65 LE32_CPU(lzfuhdr.dwMagic);
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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++];
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78 flag_mask = 1;
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79 while (flag_mask) {
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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 }
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103 }
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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 }
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113 }
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114 flag_mask <<= 1;
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115 }
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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++] = '}';
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121 *size = out_ptr;
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122 if (out_ptr < out_size) out_buf[out_ptr++] = '\0';
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123 return out_buf;
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124 }