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avformat/mov: compute absolute dts difference without overflow in mov_find_next_sample() 

Fixes: signed integer overflow: -9223372036854775808 - 9222726413022000000 cannot be represented in type 'long'
Fixes: 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_MOV_fuzzer-5959420033761280

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2023-09-30 21:04:11 +02:00
parent 51f0ab8b12
commit 3508b496e1
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GPG Key ID: B18E8928B3948D64
1 changed files with 3 additions and 2 deletions
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libavformat/mov.c
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@ -8807,12 +8807,13 @@ static AVIndexEntry *mov_find_next_sample(AVFormatContext *s, AVStream **st)
if (msc->pb && msc->current_sample < avsti->nb_index_entries) {
AVIndexEntry *current_sample = &avsti->index_entries[msc->current_sample];
int64_t dts = av_rescale(current_sample->timestamp, AV_TIME_BASE, msc->time_scale);
uint64_t dtsdiff = best_dts > dts ? best_dts - (uint64_t)dts : ((uint64_t)dts - best_dts);
av_log(s, AV_LOG_TRACE, "stream %d, sample %d, dts %"PRId64"\n", i, msc->current_sample, dts);
if (!sample || (no_interleave && current_sample->pos < sample->pos) ||
((s->pb->seekable & AVIO_SEEKABLE_NORMAL) &&
((msc->pb != s->pb && dts < best_dts) || (msc->pb == s->pb && dts != AV_NOPTS_VALUE &&
((FFABS(best_dts - dts) <= AV_TIME_BASE && current_sample->pos < sample->pos) ||
(FFABS(best_dts - dts) > AV_TIME_BASE && dts < best_dts)))))) {
((dtsdiff <= AV_TIME_BASE && current_sample->pos < sample->pos) ||
(dtsdiff > AV_TIME_BASE && dts < best_dts)))))) {
sample = current_sample;
best_dts = dts;
*st = avst;