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| 1 | +/* lzorle_decompress.h |
| 2 | + * |
| 3 | + * from kernel lib/lzo/lzo1x_decompress_safe.c |
| 4 | + * |
| 5 | + * Copyright (C) 1996-2012 Markus F.X.J. Oberhumer <mar...@oberhumer.com> |
| 6 | + * Copyright (C) 2024 NIO |
| 7 | + * |
| 8 | + * This program is free software; you can redistribute it and/or modify |
| 9 | + * it under the terms of the GNU General Public License as published by |
| 10 | + * the Free Software Foundation; either version 2 of the License, or |
| 11 | + * (at your option) any later version. |
| 12 | + * |
| 13 | + * This program is distributed in the hope that it will be useful, |
| 14 | + * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| 15 | + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| 16 | + * GNU General Public License for more details. |
| 17 | + */ |
| 18 | + |
| 19 | +#include "defs.h" |
| 20 | +#include "lzorle_decompress.h" |
| 21 | + |
| 22 | +/* This MAX_255_COUNT is the maximum number of times we can add 255 to a base |
| 23 | + * count without overflowing an integer. The multiply will overflow when |
| 24 | + * multiplying 255 by more than MAXINT/255. The sum will overflow earlier |
| 25 | + * depending on the base count. Since the base count is taken from a u8 |
| 26 | + * and a few bits, it is safe to assume that it will always be lower than |
| 27 | + * or equal to 2*255, thus we can always prevent any overflow by accepting |
| 28 | + * two less 255 steps. See Documentation/lzo.txt for more information. |
| 29 | + */ |
| 30 | +#define MAX_255_COUNT ((((ulong)~0) / 255) - 2) |
| 31 | + |
| 32 | +static inline uint16_t get_unaligned_le16 (const uint8_t *p) { |
| 33 | + return p[0] | p[1] << 8; |
| 34 | +} |
| 35 | + |
| 36 | +int lzorle_decompress_safe(const unsigned char *in, ulong in_len, |
| 37 | + unsigned char *out, ulong *out_len, void *other/* NOT USED */) { |
| 38 | + unsigned char *op; |
| 39 | + const unsigned char *ip; |
| 40 | + ulong t, next; |
| 41 | + ulong state = 0; |
| 42 | + const unsigned char *m_pos; |
| 43 | + const unsigned char * const ip_end = in + in_len; |
| 44 | + unsigned char * const op_end = out + *out_len; |
| 45 | + |
| 46 | + unsigned char bitstream_version; |
| 47 | + |
| 48 | + static int efficient_unaligned_access = -1; |
| 49 | + |
| 50 | + if (efficient_unaligned_access == -1) { |
| 51 | +#if defined(ARM) || defined(ARM64) || defined(X86) || defined(X86_64) || defined(PPC) || defined(PPC64) || defined(S390)|| defined(S390X) |
| 52 | + efficient_unaligned_access = TRUE; |
| 53 | +#else |
| 54 | + efficient_unaligned_access = FALSE; |
| 55 | +#endif |
| 56 | + |
| 57 | + if ((kt->ikconfig_flags & IKCONFIG_AVAIL) && |
| 58 | + (get_kernel_config("CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS", NULL) == IKCONFIG_Y)) |
| 59 | + efficient_unaligned_access = TRUE; |
| 60 | + } |
| 61 | + |
| 62 | + op = out; |
| 63 | + ip = in; |
| 64 | + |
| 65 | + if (in_len < 3) |
| 66 | + goto input_overrun; |
| 67 | + |
| 68 | + if (in_len >= 5 && *ip == 17) { |
| 69 | + bitstream_version = ip[1]; |
| 70 | + ip += 2; |
| 71 | + } else { |
| 72 | + bitstream_version = 0; |
| 73 | + } |
| 74 | + |
| 75 | + if (*ip > 17) { |
| 76 | + t = *ip++ - 17; |
| 77 | + if (t < 4) { |
| 78 | + next = t; |
| 79 | + goto match_next; |
| 80 | + } |
| 81 | + goto copy_literal_run; |
| 82 | + } |
| 83 | + |
| 84 | + for (;;) { |
| 85 | + t = *ip++; |
| 86 | + if (t < 16) { |
| 87 | + if (state == 0) { |
| 88 | + if (t == 0) { |
| 89 | + ulong offset; |
| 90 | + const unsigned char *ip_last = ip; |
| 91 | + |
| 92 | + while (*ip == 0) { |
| 93 | + ip++; |
| 94 | + NEED_IP(1); |
| 95 | + } |
| 96 | + offset = ip - ip_last; |
| 97 | + if (offset > MAX_255_COUNT) |
| 98 | + return LZO_E_ERROR; |
| 99 | + |
| 100 | + offset = (offset << 8) - offset; |
| 101 | + t += offset + 15 + *ip++; |
| 102 | + } |
| 103 | + t += 3; |
| 104 | +copy_literal_run: |
| 105 | + if (efficient_unaligned_access && |
| 106 | + (HAVE_IP(t + 15) && HAVE_OP(t + 15))) { |
| 107 | + const unsigned char *ie = ip + t; |
| 108 | + unsigned char *oe = op + t; |
| 109 | + do { |
| 110 | + COPY8(op, ip); |
| 111 | + op += 8; |
| 112 | + ip += 8; |
| 113 | + COPY8(op, ip); |
| 114 | + op += 8; |
| 115 | + ip += 8; |
| 116 | + } while (ip < ie); |
| 117 | + ip = ie; |
| 118 | + op = oe; |
| 119 | + } else { |
| 120 | + NEED_OP(t); |
| 121 | + NEED_IP(t + 3); |
| 122 | + do { |
| 123 | + *op++ = *ip++; |
| 124 | + } while (--t > 0); |
| 125 | + } |
| 126 | + state = 4; |
| 127 | + continue; |
| 128 | + } else if (state != 4) { |
| 129 | + next = t & 3; |
| 130 | + m_pos = op - 1; |
| 131 | + m_pos -= t >> 2; |
| 132 | + m_pos -= *ip++ << 2; |
| 133 | + TEST_LB(m_pos); |
| 134 | + NEED_OP(2); |
| 135 | + op[0] = m_pos[0]; |
| 136 | + op[1] = m_pos[1]; |
| 137 | + op += 2; |
| 138 | + goto match_next; |
| 139 | + } else { |
| 140 | + next = t & 3; |
| 141 | + m_pos = op - (1 + M2_MAX_OFFSET); |
| 142 | + m_pos -= t >> 2; |
| 143 | + m_pos -= *ip++ << 2; |
| 144 | + t = 3; |
| 145 | + } |
| 146 | + } else if (t >= 64) { |
| 147 | + next = t & 3; |
| 148 | + m_pos = op - 1; |
| 149 | + m_pos -= (t >> 2) & 7; |
| 150 | + m_pos -= *ip++ << 3; |
| 151 | + t = (t >> 5) - 1 + (3 - 1); |
| 152 | + } else if (t >= 32) { |
| 153 | + t = (t & 31) + (3 - 1); |
| 154 | + if (t == 2) { |
| 155 | + ulong offset; |
| 156 | + const unsigned char *ip_last = ip; |
| 157 | + |
| 158 | + while (*ip == 0) { |
| 159 | + ip++; |
| 160 | + NEED_IP(1); |
| 161 | + } |
| 162 | + offset = ip - ip_last; |
| 163 | + if (offset > MAX_255_COUNT) |
| 164 | + return LZO_E_ERROR; |
| 165 | + |
| 166 | + offset = (offset << 8) - offset; |
| 167 | + t += offset + 31 + *ip++; |
| 168 | + NEED_IP(2); |
| 169 | + } |
| 170 | + m_pos = op - 1; |
| 171 | + |
| 172 | + next = get_unaligned_le16(ip); |
| 173 | + ip += 2; |
| 174 | + m_pos -= next >> 2; |
| 175 | + next &= 3; |
| 176 | + } else { |
| 177 | + NEED_IP(2); |
| 178 | + next = get_unaligned_le16(ip); |
| 179 | + if (((next & 0xfffc) == 0xfffc) && |
| 180 | + ((t & 0xf8) == 0x18) && |
| 181 | + bitstream_version) { |
| 182 | + NEED_IP(3); |
| 183 | + t &= 7; |
| 184 | + t |= ip[2] << 3; |
| 185 | + t += MIN_ZERO_RUN_LENGTH; |
| 186 | + NEED_OP(t); |
| 187 | + memset(op, 0, t); |
| 188 | + op += t; |
| 189 | + next &= 3; |
| 190 | + ip += 3; |
| 191 | + goto match_next; |
| 192 | + } else { |
| 193 | + m_pos = op; |
| 194 | + m_pos -= (t & 8) << 11; |
| 195 | + t = (t & 7) + (3 - 1); |
| 196 | + if (t == 2) { |
| 197 | + ulong offset; |
| 198 | + const unsigned char *ip_last = ip; |
| 199 | + |
| 200 | + while (*ip == 0) { |
| 201 | + ip++; |
| 202 | + NEED_IP(1); |
| 203 | + } |
| 204 | + offset = ip - ip_last; |
| 205 | + if (offset > MAX_255_COUNT) |
| 206 | + return LZO_E_ERROR; |
| 207 | + |
| 208 | + offset = (offset << 8) - offset; |
| 209 | + t += offset + 7 + *ip++; |
| 210 | + NEED_IP(2); |
| 211 | + next = get_unaligned_le16(ip); |
| 212 | + } |
| 213 | + ip += 2; |
| 214 | + m_pos -= next >> 2; |
| 215 | + next &= 3; |
| 216 | + if (m_pos == op) |
| 217 | + goto eof_found; |
| 218 | + m_pos -= 0x4000; |
| 219 | + } |
| 220 | + } |
| 221 | + TEST_LB(m_pos); |
| 222 | + |
| 223 | + if (efficient_unaligned_access && |
| 224 | + (op - m_pos >= 8)) { |
| 225 | + unsigned char *oe = op + t; |
| 226 | + if (HAVE_OP(t + 15)) { |
| 227 | + do { |
| 228 | + COPY8(op, m_pos); |
| 229 | + op += 8; |
| 230 | + m_pos += 8; |
| 231 | + COPY8(op, m_pos); |
| 232 | + op += 8; |
| 233 | + m_pos += 8; |
| 234 | + } while (op < oe); |
| 235 | + op = oe; |
| 236 | + if (HAVE_IP(6)) { |
| 237 | + state = next; |
| 238 | + COPY4(op, ip); |
| 239 | + op += next; |
| 240 | + ip += next; |
| 241 | + continue; |
| 242 | + } |
| 243 | + } else { |
| 244 | + NEED_OP(t); |
| 245 | + do { |
| 246 | + *op++ = *m_pos++; |
| 247 | + } while (op < oe); |
| 248 | + } |
| 249 | + } else { |
| 250 | + unsigned char *oe = op + t; |
| 251 | + NEED_OP(t); |
| 252 | + op[0] = m_pos[0]; |
| 253 | + op[1] = m_pos[1]; |
| 254 | + op += 2; |
| 255 | + m_pos += 2; |
| 256 | + do { |
| 257 | + *op++ = *m_pos++; |
| 258 | + } while (op < oe); |
| 259 | + } |
| 260 | +match_next: |
| 261 | + state = next; |
| 262 | + t = next; |
| 263 | + if (efficient_unaligned_access && |
| 264 | + (HAVE_IP(6) && HAVE_OP(4))) { |
| 265 | + COPY4(op, ip); |
| 266 | + op += t; |
| 267 | + ip += t; |
| 268 | + } else { |
| 269 | + NEED_IP(t + 3); |
| 270 | + NEED_OP(t); |
| 271 | + while (t > 0) { |
| 272 | + *op++ = *ip++; |
| 273 | + t--; |
| 274 | + } |
| 275 | + } |
| 276 | + } |
| 277 | + |
| 278 | +eof_found: |
| 279 | + *out_len = op - out; |
| 280 | + return (t != 3 ? LZO_E_ERROR : |
| 281 | + ip == ip_end ? LZO_E_OK : |
| 282 | + ip < ip_end ? LZO_E_INPUT_NOT_CONSUMED : LZO_E_INPUT_OVERRUN); |
| 283 | + |
| 284 | +input_overrun: |
| 285 | + *out_len = op - out; |
| 286 | + return LZO_E_INPUT_OVERRUN; |
| 287 | + |
| 288 | +output_overrun: |
| 289 | + *out_len = op - out; |
| 290 | + return LZO_E_OUTPUT_OVERRUN; |
| 291 | + |
| 292 | +lookbehind_overrun: |
| 293 | + *out_len = op - out; |
| 294 | + return LZO_E_LOOKBEHIND_OVERRUN; |
| 295 | +} |
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