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avcodec/snowdec: Avoid integer overflow with huge qlog 

Fixes: integer overflow
Fixes: 22285/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SNOW_fuzzer-5682428762128384

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
(cherry picked from commit 38fbf33c72)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2020-06-06 17:45:39 +02:00
parent 361416218a
commit 4dec5b22ac
1 changed files with 2 additions and 2 deletions
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4
libavcodec/snowdec.c
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@ -117,7 +117,7 @@ static av_always_inline void predict_slice_buffered(SnowContext *s, slice_buffer
static inline void decode_subband_slice_buffered(SnowContext *s, SubBand *b, slice_buffer * sb, int start_y, int h, int save_state[1]){
const int w= b->width;
int y;
const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
const int qlog= av_clip(s->qlog + (int64_t)b->qlog, 0, QROOT*16);
int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
int new_index = 0;
@ -224,7 +224,7 @@ static int decode_q_branch(SnowContext *s, int level, int x, int y){
static void dequantize_slice_buffered(SnowContext *s, slice_buffer * sb, SubBand *b, IDWTELEM *src, int stride, int start_y, int end_y){
const int w= b->width;
const int qlog= av_clip(s->qlog + b->qlog, 0, QROOT*16);
const int qlog= av_clip(s->qlog + (int64_t)b->qlog, 0, QROOT*16);
const int qmul= ff_qexp[qlog&(QROOT-1)]<<(qlog>>QSHIFT);
const int qadd= (s->qbias*qmul)>>QBIAS_SHIFT;
int x,y;