--- /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.
+
+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);
+@@ -133,6 +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) {
+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);
+@@ -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);
+@@ -2653,7 +2733,7 @@ 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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