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libmad
length-check.patch
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File length-check.patch of Package libmad
From: Kurt Roeckx <kurt@roeckx.be> Date: Sun, 28 Jan 2018 19:26:36 +0100 Subject: Check the size before reading with mad_bit_read There are various cases where it attemps to read past the end of the buffer using mad_bit_read(). Most functions didn't even know the size of the buffer they were reading from. Index: libmad-0.15.1b/bit.c =================================================================== --- libmad-0.15.1b.orig/bit.c +++ libmad-0.15.1b/bit.c @@ -138,6 +138,9 @@ unsigned long mad_bit_read(struct mad_bi { register unsigned long value; + if (len == 0) + return 0; + if (bitptr->left == CHAR_BIT) bitptr->cache = *bitptr->byte; Index: libmad-0.15.1b/frame.c =================================================================== --- libmad-0.15.1b.orig/frame.c +++ libmad-0.15.1b/frame.c @@ -120,11 +120,18 @@ static int decode_header(struct mad_header *header, struct mad_stream *stream) { unsigned int index; + struct mad_bitptr bufend_ptr; header->flags = 0; header->private_bits = 0; + mad_bit_init(&bufend_ptr, stream->bufend); + /* header() */ + if (mad_bit_length(&stream->ptr, &bufend_ptr) < 32) { + stream->error = MAD_ERROR_BUFLEN; + return -1; + } /* syncword */ mad_bit_skip(&stream->ptr, 11); @@ -225,8 +232,13 @@ int decode_header(struct mad_header *hea /* error_check() */ /* crc_check */ - if (header->flags & MAD_FLAG_PROTECTION) + if (header->flags & MAD_FLAG_PROTECTION) { + if (mad_bit_length(&stream->ptr, &bufend_ptr) < 16) { + stream->error = MAD_ERROR_BUFLEN; + return -1; + } header->crc_target = mad_bit_read(&stream->ptr, 16); + } return 0; } @@ -338,7 +350,7 @@ int mad_header_decode(struct mad_header stream->error = MAD_ERROR_BUFLEN; goto fail; } - else if (!(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0)) { + else if ((end - ptr >= 2) && !(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0)) { /* mark point where frame sync word was expected */ stream->this_frame = ptr; stream->next_frame = ptr + 1; @@ -361,6 +373,8 @@ int mad_header_decode(struct mad_header ptr = mad_bit_nextbyte(&stream->ptr); } + stream->error = MAD_ERROR_NONE; + /* begin processing */ stream->this_frame = ptr; stream->next_frame = ptr + 1; /* possibly bogus sync word */ @@ -413,7 +427,7 @@ int mad_header_decode(struct mad_header /* check that a valid frame header follows this frame */ ptr = stream->next_frame; - if (!(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0)) { + if ((end - ptr >= 2) && !(ptr[0] == 0xff && (ptr[1] & 0xe0) == 0xe0)) { ptr = stream->next_frame = stream->this_frame + 1; goto sync; } Index: libmad-0.15.1b/layer12.c =================================================================== --- libmad-0.15.1b.orig/layer12.c +++ libmad-0.15.1b/layer12.c @@ -72,10 +72,18 @@ mad_fixed_t const linear_table[14] = { * DESCRIPTION: decode one requantized Layer I sample from a bitstream */ static -mad_fixed_t I_sample(struct mad_bitptr *ptr, unsigned int nb) +mad_fixed_t I_sample(struct mad_bitptr *ptr, unsigned int nb, struct mad_stream *stream) { mad_fixed_t sample; + struct mad_bitptr frameend_ptr; + mad_bit_init(&frameend_ptr, stream->next_frame); + + if (mad_bit_length(ptr, &frameend_ptr) < nb) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return 0; + } sample = mad_bit_read(ptr, nb); /* invert most significant bit, extend sign, then scale to fixed format */ @@ -106,6 +114,10 @@ int mad_layer_I(struct mad_stream *strea struct mad_header *header = &frame->header; unsigned int nch, bound, ch, s, sb, nb; unsigned char allocation[2][32], scalefactor[2][32]; + struct mad_bitptr bufend_ptr, frameend_ptr; + + mad_bit_init(&bufend_ptr, stream->bufend); + mad_bit_init(&frameend_ptr, stream->next_frame); nch = MAD_NCHANNELS(header); @@ -118,6 +130,11 @@ int mad_layer_I(struct mad_stream *strea /* check CRC word */ if (header->flags & MAD_FLAG_PROTECTION) { + if (mad_bit_length(&stream->ptr, &bufend_ptr) + < 4 * (bound * nch + (32 - bound))) { + stream->error = MAD_ERROR_BADCRC; + return -1; + } header->crc_check = mad_bit_crc(stream->ptr, 4 * (bound * nch + (32 - bound)), header->crc_check); @@ -133,7 +150,17 @@ int mad_layer_I(struct mad_stream *strea for (sb = 0; sb < bound; ++sb) { for (ch = 0; ch < nch; ++ch) { + if (mad_bit_length(&stream->ptr, &frameend_ptr) < 4) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } nb = mad_bit_read(&stream->ptr, 4); + if (mad_bit_nextbyte(&stream->ptr) > stream->next_frame) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; +} if (nb == 15) { stream->error = MAD_ERROR_BADBITALLOC; @@ -145,7 +172,17 @@ int mad_layer_I(struct mad_stream *strea } for (sb = bound; sb < 32; ++sb) { + if (mad_bit_length(&stream->ptr, &frameend_ptr) < 4) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } nb = mad_bit_read(&stream->ptr, 4); + if (mad_bit_nextbyte(&stream->ptr) > stream->next_frame) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } if (nb == 15) { stream->error = MAD_ERROR_BADBITALLOC; @@ -161,7 +198,17 @@ int mad_layer_I(struct mad_stream *strea for (sb = 0; sb < 32; ++sb) { for (ch = 0; ch < nch; ++ch) { if (allocation[ch][sb]) { + if (mad_bit_length(&stream->ptr, &frameend_ptr) < 6) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } scalefactor[ch][sb] = mad_bit_read(&stream->ptr, 6); + if (mad_bit_nextbyte(&stream->ptr) > stream->next_frame) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } # if defined(OPT_STRICT) /* @@ -185,8 +232,15 @@ int mad_layer_I(struct mad_stream *strea for (ch = 0; ch < nch; ++ch) { nb = allocation[ch][sb]; frame->sbsample[ch][s][sb] = nb ? - mad_f_mul(I_sample(&stream->ptr, nb), + mad_f_mul(I_sample(&stream->ptr, nb, stream), sf_table[scalefactor[ch][sb]]) : 0; + if (stream->error != 0) + return -1; + if (mad_bit_nextbyte(&stream->ptr) > stream->next_frame) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } } } @@ -194,7 +248,14 @@ int mad_layer_I(struct mad_stream *strea if ((nb = allocation[0][sb])) { mad_fixed_t sample; - sample = I_sample(&stream->ptr, nb); + if (mad_bit_length(&stream->ptr, &frameend_ptr) < nb || mad_bit_nextbyte(&stream->ptr) > stream->next_frame) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } + sample = I_sample(&stream->ptr, nb, stream); + if (stream->error != 0) + return -1; for (ch = 0; ch < nch; ++ch) { frame->sbsample[ch][s][sb] = @@ -280,13 +341,21 @@ struct quantclass { static void II_samples(struct mad_bitptr *ptr, struct quantclass const *quantclass, - mad_fixed_t output[3]) + mad_fixed_t output[3], struct mad_stream *stream) { unsigned int nb, s, sample[3]; + struct mad_bitptr frameend_ptr; + + mad_bit_init(&frameend_ptr, stream->next_frame); if ((nb = quantclass->group)) { unsigned int c, nlevels; + if (mad_bit_length(ptr, &frameend_ptr) < quantclass->bits) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return; + } /* degrouping */ c = mad_bit_read(ptr, quantclass->bits); nlevels = quantclass->nlevels; @@ -299,8 +368,14 @@ void II_samples(struct mad_bitptr *ptr, else { nb = quantclass->bits; - for (s = 0; s < 3; ++s) + for (s = 0; s < 3; ++s) { + if (mad_bit_length(ptr, &frameend_ptr) < nb) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return; + } sample[s] = mad_bit_read(ptr, nb); + } } for (s = 0; s < 3; ++s) { @@ -336,6 +411,9 @@ int mad_layer_II(struct mad_stream *stre unsigned char const *offsets; unsigned char allocation[2][32], scfsi[2][32], scalefactor[2][32][3]; mad_fixed_t samples[3]; + struct mad_bitptr frameend_ptr; + + mad_bit_init(&frameend_ptr, stream->next_frame); nch = MAD_NCHANNELS(header); @@ -402,13 +480,24 @@ int mad_layer_II(struct mad_stream *stre for (sb = 0; sb < bound; ++sb) { nbal = bitalloc_table[offsets[sb]].nbal; - for (ch = 0; ch < nch; ++ch) + for (ch = 0; ch < nch; ++ch) { + if (mad_bit_length(&stream->ptr, &frameend_ptr) < nbal) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } allocation[ch][sb] = mad_bit_read(&stream->ptr, nbal); + } } for (sb = bound; sb < sblimit; ++sb) { nbal = bitalloc_table[offsets[sb]].nbal; + if (mad_bit_length(&stream->ptr, &frameend_ptr) < nbal) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } allocation[0][sb] = allocation[1][sb] = mad_bit_read(&stream->ptr, nbal); } @@ -417,8 +506,14 @@ int mad_layer_II(struct mad_stream *stre for (sb = 0; sb < sblimit; ++sb) { for (ch = 0; ch < nch; ++ch) { - if (allocation[ch][sb]) + if (allocation[ch][sb]) { + if (mad_bit_length(&stream->ptr, &frameend_ptr) < 2) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } scfsi[ch][sb] = mad_bit_read(&stream->ptr, 2); + } } } @@ -441,6 +536,11 @@ int mad_layer_II(struct mad_stream *stre for (sb = 0; sb < sblimit; ++sb) { for (ch = 0; ch < nch; ++ch) { if (allocation[ch][sb]) { + if (mad_bit_length(&stream->ptr, &frameend_ptr) < 6) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } scalefactor[ch][sb][0] = mad_bit_read(&stream->ptr, 6); switch (scfsi[ch][sb]) { @@ -451,11 +551,21 @@ int mad_layer_II(struct mad_stream *stre break; case 0: + if (mad_bit_length(&stream->ptr, &frameend_ptr) < 6) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } scalefactor[ch][sb][1] = mad_bit_read(&stream->ptr, 6); /* fall through */ case 1: case 3: + if (mad_bit_length(&stream->ptr, &frameend_ptr) < 6) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } scalefactor[ch][sb][2] = mad_bit_read(&stream->ptr, 6); } @@ -487,7 +597,17 @@ int mad_layer_II(struct mad_stream *stre if ((index = allocation[ch][sb])) { index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1]; - II_samples(&stream->ptr, &qc_table[index], samples); + if (mad_bit_nextbyte(&stream->ptr) > stream->next_frame) + { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } + + + II_samples(&stream->ptr, &qc_table[index], samples, stream); + if (stream->error != 0) + return -1; for (s = 0; s < 3; ++s) { frame->sbsample[ch][3 * gr + s][sb] = @@ -505,7 +625,15 @@ int mad_layer_II(struct mad_stream *stre if ((index = allocation[0][sb])) { index = offset_table[bitalloc_table[offsets[sb]].offset][index - 1]; - II_samples(&stream->ptr, &qc_table[index], samples); + II_samples(&stream->ptr, &qc_table[index], samples, stream); + if (mad_bit_nextbyte(&stream->ptr) > stream->next_frame) + { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } + if (stream->error != 0) + return -1; for (ch = 0; ch < nch; ++ch) { for (s = 0; s < 3; ++s) { Index: libmad-0.15.1b/layer3.c =================================================================== --- libmad-0.15.1b.orig/layer3.c +++ libmad-0.15.1b/layer3.c @@ -598,7 +598,8 @@ enum mad_error III_sideinfo(struct mad_b static unsigned int III_scalefactors_lsf(struct mad_bitptr *ptr, struct channel *channel, - struct channel *gr1ch, int mode_extension) + struct channel *gr1ch, int mode_extension, + unsigned int bits_left, unsigned int *part2_length) { struct mad_bitptr start; unsigned int scalefac_compress, index, slen[4], part, n, i; @@ -644,8 +645,12 @@ unsigned int III_scalefactors_lsf(struct n = 0; for (part = 0; part < 4; ++part) { - for (i = 0; i < nsfb[part]; ++i) + for (i = 0; i < nsfb[part]; ++i) { + if (bits_left < slen[part]) + return MAD_ERROR_BADSCFSI; channel->scalefac[n++] = mad_bit_read(ptr, slen[part]); + bits_left -= slen[part]; + } } while (n < 39) @@ -690,7 +695,10 @@ unsigned int III_scalefactors_lsf(struct max = (1 << slen[part]) - 1; for (i = 0; i < nsfb[part]; ++i) { + if (bits_left < slen[part]) + return MAD_ERROR_BADSCFSI; is_pos = mad_bit_read(ptr, slen[part]); + bits_left -= slen[part]; channel->scalefac[n] = is_pos; gr1ch->scalefac[n++] = (is_pos == max); @@ -703,7 +711,8 @@ unsigned int III_scalefactors_lsf(struct } } - return mad_bit_length(&start, ptr); + *part2_length = mad_bit_length(&start, ptr); + return MAD_ERROR_NONE; } /* @@ -712,7 +721,8 @@ unsigned int III_scalefactors_lsf(struct */ static unsigned int III_scalefactors(struct mad_bitptr *ptr, struct channel *channel, - struct channel const *gr0ch, unsigned int scfsi) + struct channel const *gr0ch, unsigned int scfsi, + unsigned int bits_left, unsigned int *part2_length) { struct mad_bitptr start; unsigned int slen1, slen2, sfbi; @@ -728,12 +738,20 @@ unsigned int III_scalefactors(struct mad sfbi = 0; nsfb = (channel->flags & mixed_block_flag) ? 8 + 3 * 3 : 6 * 3; - while (nsfb--) + while (nsfb--) { + if (bits_left < slen1) + return MAD_ERROR_BADSCFSI; channel->scalefac[sfbi++] = mad_bit_read(ptr, slen1); + bits_left -= slen1; + } nsfb = 6 * 3; - while (nsfb--) + while (nsfb--) { + if (bits_left < slen2) + return MAD_ERROR_BADSCFSI; channel->scalefac[sfbi++] = mad_bit_read(ptr, slen2); + bits_left -= slen2; + } nsfb = 1 * 3; while (nsfb--) @@ -745,8 +763,12 @@ unsigned int III_scalefactors(struct mad channel->scalefac[sfbi] = gr0ch->scalefac[sfbi]; } else { - for (sfbi = 0; sfbi < 6; ++sfbi) + for (sfbi = 0; sfbi < 6; ++sfbi) { + if (bits_left < slen1) + return MAD_ERROR_BADSCFSI; channel->scalefac[sfbi] = mad_bit_read(ptr, slen1); + bits_left -= slen1; + } } if (scfsi & 0x4) { @@ -754,8 +776,12 @@ unsigned int III_scalefactors(struct mad channel->scalefac[sfbi] = gr0ch->scalefac[sfbi]; } else { - for (sfbi = 6; sfbi < 11; ++sfbi) + for (sfbi = 6; sfbi < 11; ++sfbi) { + if (bits_left < slen1) + return MAD_ERROR_BADSCFSI; channel->scalefac[sfbi] = mad_bit_read(ptr, slen1); + bits_left -= slen1; + } } if (scfsi & 0x2) { @@ -763,8 +789,12 @@ unsigned int III_scalefactors(struct mad channel->scalefac[sfbi] = gr0ch->scalefac[sfbi]; } else { - for (sfbi = 11; sfbi < 16; ++sfbi) + for (sfbi = 11; sfbi < 16; ++sfbi) { + if (bits_left < slen2) + return MAD_ERROR_BADSCFSI; channel->scalefac[sfbi] = mad_bit_read(ptr, slen2); + bits_left -= slen2; + } } if (scfsi & 0x1) { @@ -772,14 +802,19 @@ unsigned int III_scalefactors(struct mad channel->scalefac[sfbi] = gr0ch->scalefac[sfbi]; } else { - for (sfbi = 16; sfbi < 21; ++sfbi) + for (sfbi = 16; sfbi < 21; ++sfbi) { + if (bits_left < slen2) + return MAD_ERROR_BADSCFSI; channel->scalefac[sfbi] = mad_bit_read(ptr, slen2); + bits_left -= slen2; + } } channel->scalefac[21] = 0; } - return mad_bit_length(&start, ptr); + *part2_length = mad_bit_length(&start, ptr); + return MAD_ERROR_NONE; } /* @@ -933,19 +968,17 @@ static enum mad_error III_huffdecode(struct mad_bitptr *ptr, mad_fixed_t xr[576], struct channel *channel, unsigned char const *sfbwidth, - unsigned int part2_length) + signed int part3_length) { signed int exponents[39], exp; signed int const *expptr; struct mad_bitptr peek; - signed int bits_left, cachesz; + signed int bits_left, cachesz, fakebits; register mad_fixed_t *xrptr; mad_fixed_t const *sfbound; register unsigned long bitcache; - bits_left = (signed) channel->part2_3_length - (signed) part2_length; - if (bits_left < 0) - return MAD_ERROR_BADPART3LEN; + bits_left = part3_length; III_exponents(channel, sfbwidth, exponents); @@ -956,8 +989,12 @@ enum mad_error III_huffdecode(struct mad cachesz = mad_bit_bitsleft(&peek); cachesz += ((32 - 1 - 24) + (24 - cachesz)) & ~7; + if (bits_left < cachesz) { + cachesz = bits_left; + } bitcache = mad_bit_read(&peek, cachesz); bits_left -= cachesz; + fakebits = 0; xrptr = &xr[0]; @@ -986,7 +1023,7 @@ enum mad_error III_huffdecode(struct mad big_values = channel->big_values; - while (big_values-- && cachesz + bits_left > 0) { + while (big_values-- && cachesz + bits_left - fakebits > 0) { union huffpair const *pair; unsigned int clumpsz, value; register mad_fixed_t requantized; @@ -1023,10 +1060,19 @@ enum mad_error III_huffdecode(struct mad unsigned int bits; bits = ((32 - 1 - 21) + (21 - cachesz)) & ~7; + if (bits_left < bits) { + bits = bits_left; + } bitcache = (bitcache << bits) | mad_bit_read(&peek, bits); cachesz += bits; bits_left -= bits; } + if (cachesz < 21) { + unsigned int bits = 21 - cachesz; + bitcache <<= bits; + cachesz += bits; + fakebits += bits; + } /* hcod (0..19) */ @@ -1041,6 +1087,8 @@ enum mad_error III_huffdecode(struct mad } cachesz -= pair->value.hlen; + if (cachesz < fakebits) + return MAD_ERROR_BADHUFFDATA; if (linbits) { /* x (0..14) */ @@ -1054,10 +1102,15 @@ enum mad_error III_huffdecode(struct mad case 15: if (cachesz < linbits + 2) { - bitcache = (bitcache << 16) | mad_bit_read(&peek, 16); - cachesz += 16; - bits_left -= 16; + unsigned int bits = 16; + if (bits_left < 16) + bits = bits_left; + bitcache = (bitcache << bits) | mad_bit_read(&peek, bits); + cachesz += bits; + bits_left -= bits; } + if (cachesz - fakebits < linbits) + return MAD_ERROR_BADHUFFDATA; value += MASK(bitcache, cachesz, linbits); cachesz -= linbits; @@ -1074,6 +1127,8 @@ enum mad_error III_huffdecode(struct mad } x_final: + if (cachesz - fakebits < 1) + return MAD_ERROR_BADHUFFDATA; xrptr[0] = MASK1BIT(bitcache, cachesz--) ? -requantized : requantized; } @@ -1089,10 +1144,15 @@ enum mad_error III_huffdecode(struct mad case 15: if (cachesz < linbits + 1) { - bitcache = (bitcache << 16) | mad_bit_read(&peek, 16); - cachesz += 16; - bits_left -= 16; + unsigned int bits = 16; + if (bits_left < 16) + bits = bits_left; + bitcache = (bitcache << bits) | mad_bit_read(&peek, bits); + cachesz += bits; + bits_left -= bits; } + if (cachesz - fakebits < linbits) + return MAD_ERROR_BADHUFFDATA; value += MASK(bitcache, cachesz, linbits); cachesz -= linbits; @@ -1109,6 +1169,8 @@ enum mad_error III_huffdecode(struct mad } y_final: + if (cachesz - fakebits < 1) + return MAD_ERROR_BADHUFFDATA; xrptr[1] = MASK1BIT(bitcache, cachesz--) ? -requantized : requantized; } @@ -1128,6 +1190,8 @@ enum mad_error III_huffdecode(struct mad requantized = reqcache[value] = III_requantize(value, exp); } + if (cachesz - fakebits < 1) + return MAD_ERROR_BADHUFFDATA; xrptr[0] = MASK1BIT(bitcache, cachesz--) ? -requantized : requantized; } @@ -1146,6 +1210,8 @@ enum mad_error III_huffdecode(struct mad requantized = reqcache[value] = III_requantize(value, exp); } + if (cachesz - fakebits < 1) + return MAD_ERROR_BADHUFFDATA; xrptr[1] = MASK1BIT(bitcache, cachesz--) ? -requantized : requantized; } @@ -1155,9 +1221,6 @@ enum mad_error III_huffdecode(struct mad } } - if (cachesz + bits_left < 0) - return MAD_ERROR_BADHUFFDATA; /* big_values overrun */ - /* count1 */ { union huffquad const *table; @@ -1167,15 +1230,24 @@ enum mad_error III_huffdecode(struct mad requantized = III_requantize(1, exp); - while (cachesz + bits_left > 0 && xrptr <= &xr[572]) { + while (cachesz + bits_left - fakebits > 0 && xrptr <= &xr[572]) { union huffquad const *quad; /* hcod (1..6) */ if (cachesz < 10) { - bitcache = (bitcache << 16) | mad_bit_read(&peek, 16); - cachesz += 16; - bits_left -= 16; + unsigned int bits = 16; + if (bits_left < 16) + bits = bits_left; + bitcache = (bitcache << bits) | mad_bit_read(&peek, bits); + cachesz += bits; + bits_left -= bits; + } + if (cachesz < 10) { + unsigned int bits = 10 - cachesz; + bitcache <<= bits; + cachesz += bits; + fakebits += bits; } quad = &table[MASK(bitcache, cachesz, 4)]; @@ -1188,6 +1260,11 @@ enum mad_error III_huffdecode(struct mad MASK(bitcache, cachesz, quad->ptr.bits)]; } + if (cachesz - fakebits < quad->value.hlen + quad->value.v + + quad->value.w + quad->value.x + quad->value.y) + /* We don't have enough bits to read one more entry, consider them + * stuffing bits. */ + break; cachesz -= quad->value.hlen; if (xrptr == sfbound) { @@ -1236,22 +1313,8 @@ enum mad_error III_huffdecode(struct mad xrptr += 2; } - - if (cachesz + bits_left < 0) { -# if 0 && defined(DEBUG) - fprintf(stderr, "huffman count1 overrun (%d bits)\n", - -(cachesz + bits_left)); -# endif - - /* technically the bitstream is misformatted, but apparently - some encoders are just a bit sloppy with stuffing bits */ - - xrptr -= 4; - } } - assert(-bits_left <= MAD_BUFFER_GUARD * CHAR_BIT); - # if 0 && defined(DEBUG) if (bits_left < 0) fprintf(stderr, "read %d bits too many\n", -bits_left); @@ -1577,7 +1640,7 @@ void III_imdct_l(mad_fixed_t const [18], # else # if 1 static -void fastsdct(mad_fixed_t const x[9], mad_fixed_t y[18]) +void fastsdct(mad_fixed_t const x[9], mad_fixed_t y[17]) { mad_fixed_t a0, a1, a2, a3, a4, a5, a6, a7, a8, a9, a10, a11, a12; mad_fixed_t a13, a14, a15, a16, a17, a18, a19, a20, a21, a22, a23, a24, a25; @@ -2348,10 +2411,11 @@ void III_freqinver(mad_fixed_t sample[18 */ static enum mad_error III_decode(struct mad_bitptr *ptr, struct mad_frame *frame, - struct sideinfo *si, unsigned int nch) + struct sideinfo *si, unsigned int nch, unsigned int md_len) { struct mad_header *header = &frame->header; unsigned int sfreqi, ngr, gr; + int bits_left = md_len * CHAR_BIT; { unsigned int sfreq; @@ -2383,6 +2447,7 @@ enum mad_error III_decode(struct mad_bit for (ch = 0; ch < nch; ++ch) { struct channel *channel = &granule->ch[ch]; unsigned int part2_length; + unsigned int part3_length; sfbwidth[ch] = sfbwidth_table[sfreqi].l; if (channel->block_type == 2) { @@ -2391,18 +2456,30 @@ enum mad_error III_decode(struct mad_bit } if (header->flags & MAD_FLAG_LSF_EXT) { - part2_length = III_scalefactors_lsf(ptr, channel, + error = III_scalefactors_lsf(ptr, channel, ch == 0 ? 0 : &si->gr[1].ch[1], - header->mode_extension); + header->mode_extension, bits_left, &part2_length); } else { - part2_length = III_scalefactors(ptr, channel, &si->gr[0].ch[ch], - gr == 0 ? 0 : si->scfsi[ch]); + error = III_scalefactors(ptr, channel, &si->gr[0].ch[ch], + gr == 0 ? 0 : si->scfsi[ch], bits_left, &part2_length); } + if (error) + return error; + + bits_left -= part2_length; + + if (part2_length > channel->part2_3_length) + return MAD_ERROR_BADPART3LEN; + + part3_length = channel->part2_3_length - part2_length; + if (part3_length > bits_left) + return MAD_ERROR_BADPART3LEN; - error = III_huffdecode(ptr, xr[ch], channel, sfbwidth[ch], part2_length); + error = III_huffdecode(ptr, xr[ch], channel, sfbwidth[ch], part3_length); if (error) return error; + bits_left -= part3_length; } /* joint stereo processing */ @@ -2519,11 +2596,13 @@ int mad_layer_III(struct mad_stream *str unsigned int nch, priv_bitlen, next_md_begin = 0; unsigned int si_len, data_bitlen, md_len; unsigned int frame_space, frame_used, frame_free; - struct mad_bitptr ptr; + struct mad_bitptr ptr, bufend_ptr; struct sideinfo si; enum mad_error error; int result = 0; + mad_bit_init(&bufend_ptr, stream->bufend); + /* allocate Layer III dynamic structures */ if (stream->main_data == 0) { @@ -2587,14 +2666,15 @@ int mad_layer_III(struct mad_stream *str unsigned long header; mad_bit_init(&peek, stream->next_frame); + if (mad_bit_length(&peek, &bufend_ptr) >= 57) { + header = mad_bit_read(&peek, 32); + if ((header & 0xffe60000L) /* syncword | layer */ == 0xffe20000L) { + if (!(header & 0x00010000L)) /* protection_bit */ + mad_bit_skip(&peek, 16); /* crc_check */ - header = mad_bit_read(&peek, 32); - if ((header & 0xffe60000L) /* syncword | layer */ == 0xffe20000L) { - if (!(header & 0x00010000L)) /* protection_bit */ - mad_bit_skip(&peek, 16); /* crc_check */ - - next_md_begin = - mad_bit_read(&peek, (header & 0x00080000L) /* ID */ ? 9 : 8); + next_md_begin = + mad_bit_read(&peek, (header & 0x00080000L) /* ID */ ? 9 : 8); + } } mad_bit_finish(&peek); @@ -2608,6 +2688,11 @@ int mad_layer_III(struct mad_stream *str next_md_begin = 0; md_len = si.main_data_begin + frame_space - next_md_begin; + if (md_len + MAD_BUFFER_GUARD > MAD_BUFFER_MDLEN) { + stream->error = MAD_ERROR_LOSTSYNC; + stream->sync = 0; + return -1; + } frame_used = 0; @@ -2645,7 +2730,7 @@ int mad_layer_III(struct mad_stream *str /* decode main_data */ if (result == 0) { - error = III_decode(&ptr, frame, &si, nch); + error = III_decode(&ptr, frame, &si, nch, md_len); if (error) { stream->error = error; result = -1;
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