lib/lzo/lzo1x_decompress_safe.c

   1 /*
   2  *  LZO1X Decompressor from LZO
   3  *
   4  *  Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <markus@oberhumer.com>
   5  *
   6  *  The full LZO package can be found at:
   7  *  http://www.oberhumer.com/opensource/lzo/
   8  *
   9  *  Changed for Linux kernel use by:
  10  *  Nitin Gupta <nitingupta910@gmail.com>
  11  *  Richard Purdie <rpurdie@openedhand.com>
  12  */
  13
  14 #ifndef STATIC
  15 #include <linux/module.h>
  16 #include <linux/kernel.h>
  17 #endif
  18 #include <asm/unaligned.h>
  19 #include <linux/lzo.h>
  20 #include "lzodefs.h"
  21
  22 #define HAVE_IP(x)      ((size_t)(ip_end - ip) >= (size_t)(x))
  23 #define HAVE_OP(x)      ((size_t)(op_end - op) >= (size_t)(x))
  24 #define NEED_IP(x)      if (!HAVE_IP(x)) goto input_overrun
  25 #define NEED_OP(x)      if (!HAVE_OP(x)) goto output_overrun
  26 #define TEST_LB(m_pos)  if ((m_pos) < out) goto lookbehind_overrun
  27
  28 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
  29                           unsigned char *out, size_t *out_len)
  30 {
  31         unsigned char *op;
  32         const unsigned char *ip;
  33         size_t t, next;
  34         size_t state = 0;
  35         const unsigned char *m_pos;
  36         const unsigned char * const ip_end = in + in_len;
  37         unsigned char * const op_end = out + *out_len;
  38
  39         op = out;
  40         ip = in;
  41
  42         if (unlikely(in_len < 3))
  43                 goto input_overrun;
  44         if (*ip > 17) {
  45                 t = *ip++ - 17;
  46                 if (t < 4) {
  47                         next = t;
  48                         goto match_next;
  49                 }
  50                 goto copy_literal_run;
  51         }
  52
  53         for (;;) {
  54                 t = *ip++;
  55                 if (t < 16) {
  56                         if (likely(state == 0)) {
  57                                 if (unlikely(t == 0)) {
  58                                         while (unlikely(*ip == 0)) {
  59                                                 t += 255;
  60                                                 ip++;
  61                                                 NEED_IP(1);
  62                                         }
  63                                         t += 15 + *ip++;
  64                                 }
  65                                 t += 3;
  66 copy_literal_run:
  67 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
  68                                 if (likely(HAVE_IP(t + 15) && HAVE_OP(t + 15))) {
  69                                         const unsigned char *ie = ip + t;
  70                                         unsigned char *oe = op + t;
  71                                         do {
  72                                                 COPY8(op, ip);
  73                                                 op += 8;
  74                                                 ip += 8;
  75                                                 COPY8(op, ip);
  76                                                 op += 8;
  77                                                 ip += 8;
  78                                         } while (ip < ie);
  79                                         ip = ie;
  80                                         op = oe;
  81                                 } else
  82 #endif
  83                                 {
  84                                         NEED_OP(t);
  85                                         NEED_IP(t + 3);
  86                                         do {
  87                                                 *op++ = *ip++;
  88                                         } while (--t > 0);
  89                                 }
  90                                 state = 4;
  91                                 continue;
  92                         } else if (state != 4) {
  93                                 next = t & 3;
  94                                 m_pos = op - 1;
  95                                 m_pos -= t >> 2;
  96                                 m_pos -= *ip++ << 2;
  97                                 TEST_LB(m_pos);
  98                                 NEED_OP(2);
  99                                 op[0] = m_pos[0];
 100                                 op[1] = m_pos[1];
 101                                 op += 2;
 102                                 goto match_next;
 103                         } else {
 104                                 next = t & 3;
 105                                 m_pos = op - (1 + M2_MAX_OFFSET);
 106                                 m_pos -= t >> 2;
 107                                 m_pos -= *ip++ << 2;
 108                                 t = 3;
 109                         }
 110                 } else if (t >= 64) {
 111                         next = t & 3;
 112                         m_pos = op - 1;
 113                         m_pos -= (t >> 2) & 7;
 114                         m_pos -= *ip++ << 3;
 115                         t = (t >> 5) - 1 + (3 - 1);
 116                 } else if (t >= 32) {
 117                         t = (t & 31) + (3 - 1);
 118                         if (unlikely(t == 2)) {
 119                                 while (unlikely(*ip == 0)) {
 120                                         t += 255;
 121                                         ip++;
 122                                         NEED_IP(1);
 123                                 }
 124                                 t += 31 + *ip++;
 125                                 NEED_IP(2);
 126                         }
 127                         m_pos = op - 1;
 128                         next = get_unaligned_le16(ip);
 129                         ip += 2;
 130                         m_pos -= next >> 2;
 131                         next &= 3;
 132                 } else {
 133                         m_pos = op;
 134                         m_pos -= (t & 8) << 11;
 135                         t = (t & 7) + (3 - 1);
 136                         if (unlikely(t == 2)) {
 137                                 while (unlikely(*ip == 0)) {
 138                                         t += 255;
 139                                         ip++;
 140                                         NEED_IP(1);
 141                                 }
 142                                 t += 7 + *ip++;
 143                                 NEED_IP(2);
 144                         }
 145                         next = get_unaligned_le16(ip);
 146                         ip += 2;
 147                         m_pos -= next >> 2;
 148                         next &= 3;
 149                         if (m_pos == op)
 150                                 goto eof_found;
 151                         m_pos -= 0x4000;
 152                 }
 153                 TEST_LB(m_pos);
 154 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 155                 if (op - m_pos >= 8) {
 156                         unsigned char *oe = op + t;
 157                         if (likely(HAVE_OP(t + 15))) {
 158                                 do {
 159                                         COPY8(op, m_pos);
 160                                         op += 8;
 161                                         m_pos += 8;
 162                                         COPY8(op, m_pos);
 163                                         op += 8;
 164                                         m_pos += 8;
 165                                 } while (op < oe);
 166                                 op = oe;
 167                                 if (HAVE_IP(6)) {
 168                                         state = next;
 169                                         COPY4(op, ip);
 170                                         op += next;
 171                                         ip += next;
 172                                         continue;
 173                                 }
 174                         } else {
 175                                 NEED_OP(t);
 176                                 do {
 177                                         *op++ = *m_pos++;
 178                                 } while (op < oe);
 179                         }
 180                 } else
 181 #endif
 182                 {
 183                         unsigned char *oe = op + t;
 184                         NEED_OP(t);
 185                         op[0] = m_pos[0];
 186                         op[1] = m_pos[1];
 187                         op += 2;
 188                         m_pos += 2;
 189                         do {
 190                                 *op++ = *m_pos++;
 191                         } while (op < oe);
 192                 }
 193 match_next:
 194                 state = next;
 195                 t = next;
 196 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 197                 if (likely(HAVE_IP(6) && HAVE_OP(4))) {
 198                         COPY4(op, ip);
 199                         op += t;
 200                         ip += t;
 201                 } else
 202 #endif
 203                 {
 204                         NEED_IP(t + 3);
 205                         NEED_OP(t);
 206                         while (t > 0) {
 207                                 *op++ = *ip++;
 208                                 t--;
 209                         }
 210                 }
 211         }
 212
 213 eof_found:
 214         *out_len = op - out;
 215         return (t != 3       ? LZO_E_ERROR :
 216                 ip == ip_end ? LZO_E_OK :
 217                 ip <  ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN);
 218
 219 input_overrun:
 220         *out_len = op - out;
 221         return LZO_E_INPUT_OVERRUN;
 222
 223 output_overrun:
 224         *out_len = op - out;
 225         return LZO_E_OUTPUT_OVERRUN;
 226
 227 lookbehind_overrun:
 228         *out_len = op - out;
 229         return LZO_E_LOOKBEHIND_OVERRUN;
 230 }
 231 #ifndef STATIC
 232 EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
 233
 234 MODULE_LICENSE("GPL");
 235 MODULE_DESCRIPTION("LZO1X Decompressor");
 236
 237 #endif