+++ /dev/null
-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.
-
---- a/bit.c
-+++ b/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;
-
---- a/frame.c
-+++ b/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;
- }
---- a/layer12.c
-+++ b/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);
-@@ -133,6 +150,11 @@ 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 (nb == 15) {
-@@ -145,6 +167,11 @@ 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 (nb == 15) {
-@@ -161,6 +188,11 @@ 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 defined(OPT_STRICT)
-@@ -185,8 +217,10 @@ 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;
- }
- }
-
-@@ -194,7 +228,14 @@ 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) {
-+ 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 +321,21 @@ 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 +348,14 @@ 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 +391,9 @@ 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 +460,24 @@ 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 +486,14 @@ 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 +516,11 @@ 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 +531,21 @@ 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 +577,9 @@ 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);
-+ 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 +597,9 @@ 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 (stream->error != 0)
-+ return -1;
-
- for (ch = 0; ch < nch; ++ch) {
- for (s = 0; s < 3; ++s) {
---- a/layer3.c
-+++ b/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);
-@@ -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;
-
-- error = III_huffdecode(ptr, xr[ch], channel, sfbwidth[ch], 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], 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);
-@@ -2645,7 +2725,7 @@ 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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