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alac: Check for bitstream overread 

Fixes Ticket801
Bug found by: Oana Stratulat

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
This commit is contained in:
Michael Niedermayer 2011-12-20 17:51:53 +01:00
parent 65f0f9183b
commit a8469223f6
1 changed files with 12 additions and 2 deletions
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14
libavcodec/alac.c
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@ -112,7 +112,7 @@ static inline int decode_scalar(GetBitContext *gb, int k, int limit, int readsam
return x;
}
static void bastardized_rice_decompress(ALACContext *alac,
static int bastardized_rice_decompress(ALACContext *alac,
int32_t *output_buffer,
int output_size,
int readsamplesize, /* arg_10 */
@ -134,6 +134,9 @@ static void bastardized_rice_decompress(ALACContext *alac,
/* standard rice encoding */
int k; /* size of extra bits */
if(get_bits_left(&alac->gb) <= 0)
return -1;
/* read k, that is bits as is */
k = av_log2((history >> 9) + 3);
x= decode_scalar(&alac->gb, k, rice_kmodifier, readsamplesize);
@ -179,6 +182,7 @@ static void bastardized_rice_decompress(ALACContext *alac,
history = 0;
}
}
return 0;
}
static inline int sign_only(int v)
@ -442,12 +446,14 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
if (alac->extra_bits) {
for (i = 0; i < outputsamples; i++) {
if(get_bits_left(&alac->gb) <= 0)
return -1;
for (ch = 0; ch < channels; ch++)
alac->extra_bits_buffer[ch][i] = get_bits(&alac->gb, alac->extra_bits);
}
}
for (ch = 0; ch < channels; ch++) {
bastardized_rice_decompress(alac,
int ret = bastardized_rice_decompress(alac,
alac->predicterror_buffer[ch],
outputsamples,
readsamplesize,
@ -455,6 +461,8 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
alac->setinfo_rice_kmodifier,
ricemodifier[ch] * alac->setinfo_rice_historymult / 4,
(1 << alac->setinfo_rice_kmodifier) - 1);
if(ret<0)
return ret;
if (prediction_type[ch] == 0) {
/* adaptive fir */
@ -478,6 +486,8 @@ static int alac_decode_frame(AVCodecContext *avctx, void *data,
} else {
/* not compressed, easy case */
for (i = 0; i < outputsamples; i++) {
if(get_bits_left(&alac->gb) <= 0)
return -1;
for (ch = 0; ch < channels; ch++) {
alac->outputsamples_buffer[ch][i] = get_sbits_long(&alac->gb,
alac->setinfo_sample_size);