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(t, x)                                   \
  23         (((size_t)(ip_end - ip) >= (size_t)(t + x)) &&  \
  24          (((t + x) >= t) && ((t + x) >= x)))
  25
  26 #define HAVE_OP(t, x)                                   \
  27         (((size_t)(op_end - op) >= (size_t)(t + x)) &&  \
  28          (((t + x) >= t) && ((t + x) >= x)))
  29
  30 #define NEED_IP(t, x)                                   \
  31         do {                                            \
  32                 if (!HAVE_IP(t, x))                     \
  33                         goto input_overrun;             \
  34         } while (0)
  35
  36 #define NEED_OP(t, x)                                   \
  37         do {                                            \
  38                 if (!HAVE_OP(t, x))                     \
  39                         goto output_overrun;            \
  40         } while (0)
  41
  42 #define TEST_LB(m_pos)                                  \
  43         do {                                            \
  44                 if ((m_pos) < out)                      \
  45                         goto lookbehind_overrun;        \
  46         } while (0)
  47
  48 int lzo1x_decompress_safe(const unsigned char *in, size_t in_len,
  49                           unsigned char *out, size_t *out_len)
  50 {
  51         unsigned char *op;
  52         const unsigned char *ip;
  53         size_t t, next;
  54         size_t state = 0;
  55         const unsigned char *m_pos;
  56         const unsigned char * const ip_end = in + in_len;
  57         unsigned char * const op_end = out + *out_len;
  58
  59         op = out;
  60         ip = in;
  61
  62         if (unlikely(in_len < 3))
  63                 goto input_overrun;
  64         if (*ip > 17) {
  65                 t = *ip++ - 17;
  66                 if (t < 4) {
  67                         next = t;
  68                         goto match_next;
  69                 }
  70                 goto copy_literal_run;
  71         }
  72
  73         for (;;) {
  74                 t = *ip++;
  75                 if (t < 16) {
  76                         if (likely(state == 0)) {
  77                                 if (unlikely(t == 0)) {
  78                                         while (unlikely(*ip == 0)) {
  79                                                 t += 255;
  80                                                 ip++;
  81                                                 NEED_IP(1, 0);
  82                                         }
  83                                         t += 15 + *ip++;
  84                                 }
  85                                 t += 3;
  86 copy_literal_run:
  87 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
  88                                 if (likely(HAVE_IP(t, 15) && HAVE_OP(t, 15))) {
  89                                         const unsigned char *ie = ip + t;
  90                                         unsigned char *oe = op + t;
  91                                         do {
  92                                                 COPY8(op, ip);
  93                                                 op += 8;
  94                                                 ip += 8;
  95                                                 COPY8(op, ip);
  96                                                 op += 8;
  97                                                 ip += 8;
  98                                         } while (ip < ie);
  99                                         ip = ie;
 100                                         op = oe;
 101                                 } else
 102 #endif
 103                                 {
 104                                         NEED_OP(t, 0);
 105                                         NEED_IP(t, 3);
 106                                         do {
 107                                                 *op++ = *ip++;
 108                                         } while (--t > 0);
 109                                 }
 110                                 state = 4;
 111                                 continue;
 112                         } else if (state != 4) {
 113                                 next = t & 3;
 114                                 m_pos = op - 1;
 115                                 m_pos -= t >> 2;
 116                                 m_pos -= *ip++ << 2;
 117                                 TEST_LB(m_pos);
 118                                 NEED_OP(2, 0);
 119                                 op[0] = m_pos[0];
 120                                 op[1] = m_pos[1];
 121                                 op += 2;
 122                                 goto match_next;
 123                         } else {
 124                                 next = t & 3;
 125                                 m_pos = op - (1 + M2_MAX_OFFSET);
 126                                 m_pos -= t >> 2;
 127                                 m_pos -= *ip++ << 2;
 128                                 t = 3;
 129                         }
 130                 } else if (t >= 64) {
 131                         next = t & 3;
 132                         m_pos = op - 1;
 133                         m_pos -= (t >> 2) & 7;
 134                         m_pos -= *ip++ << 3;
 135                         t = (t >> 5) - 1 + (3 - 1);
 136                 } else if (t >= 32) {
 137                         t = (t & 31) + (3 - 1);
 138                         if (unlikely(t == 2)) {
 139                                 while (unlikely(*ip == 0)) {
 140                                         t += 255;
 141                                         ip++;
 142                                         NEED_IP(1, 0);
 143                                 }
 144                                 t += 31 + *ip++;
 145                                 NEED_IP(2, 0);
 146                         }
 147                         m_pos = op - 1;
 148                         next = get_unaligned_le16(ip);
 149                         ip += 2;
 150                         m_pos -= next >> 2;
 151                         next &= 3;
 152                 } else {
 153                         m_pos = op;
 154                         m_pos -= (t & 8) << 11;
 155                         t = (t & 7) + (3 - 1);
 156                         if (unlikely(t == 2)) {
 157                                 while (unlikely(*ip == 0)) {
 158                                         t += 255;
 159                                         ip++;
 160                                         NEED_IP(1, 0);
 161                                 }
 162                                 t += 7 + *ip++;
 163                                 NEED_IP(2, 0);
 164                         }
 165                         next = get_unaligned_le16(ip);
 166                         ip += 2;
 167                         m_pos -= next >> 2;
 168                         next &= 3;
 169                         if (m_pos == op)
 170                                 goto eof_found;
 171                         m_pos -= 0x4000;
 172                 }
 173                 TEST_LB(m_pos);
 174 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 175                 if (op - m_pos >= 8) {
 176                         unsigned char *oe = op + t;
 177                         if (likely(HAVE_OP(t, 15))) {
 178                                 do {
 179                                         COPY8(op, m_pos);
 180                                         op += 8;
 181                                         m_pos += 8;
 182                                         COPY8(op, m_pos);
 183                                         op += 8;
 184                                         m_pos += 8;
 185                                 } while (op < oe);
 186                                 op = oe;
 187                                 if (HAVE_IP(6, 0)) {
 188                                         state = next;
 189                                         COPY4(op, ip);
 190                                         op += next;
 191                                         ip += next;
 192                                         continue;
 193                                 }
 194                         } else {
 195                                 NEED_OP(t, 0);
 196                                 do {
 197                                         *op++ = *m_pos++;
 198                                 } while (op < oe);
 199                         }
 200                 } else
 201 #endif
 202                 {
 203                         unsigned char *oe = op + t;
 204                         NEED_OP(t, 0);
 205                         op[0] = m_pos[0];
 206                         op[1] = m_pos[1];
 207                         op += 2;
 208                         m_pos += 2;
 209                         do {
 210                                 *op++ = *m_pos++;
 211                         } while (op < oe);
 212                 }
 213 match_next:
 214                 state = next;
 215                 t = next;
 216 #if defined(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS)
 217                 if (likely(HAVE_IP(6, 0) && HAVE_OP(4, 0))) {
 218                         COPY4(op, ip);
 219                         op += t;
 220                         ip += t;
 221                 } else
 222 #endif
 223                 {
 224                         NEED_IP(t, 3);
 225                         NEED_OP(t, 0);
 226                         while (t > 0) {
 227                                 *op++ = *ip++;
 228                                 t--;
 229                         }
 230                 }
 231         }
 232
 233 eof_found:
 234         *out_len = op - out;
 235         return (t != 3       ? LZO_E_ERROR :
 236                 ip == ip_end ? LZO_E_OK :
 237                 ip <  ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN);
 238
 239 input_overrun:
 240         *out_len = op - out;
 241         return LZO_E_INPUT_OVERRUN;
 242
 243 output_overrun:
 244         *out_len = op - out;
 245         return LZO_E_OUTPUT_OVERRUN;
 246
 247 lookbehind_overrun:
 248         *out_len = op - out;
 249         return LZO_E_LOOKBEHIND_OVERRUN;
 250 }
 251 #ifndef STATIC
 252 EXPORT_SYMBOL_GPL(lzo1x_decompress_safe);
 253
 254 MODULE_LICENSE("GPL");
 255 MODULE_DESCRIPTION("LZO1X Decompressor");
 256
 257 #endif