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avformat/mpc8: Check first keyframe position for overflow

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Fixes: signed integer overflow: 9223372036854775791 + 18 cannot be represented in type 'long'
Fixes: 36307/clusterfuzz-testcase-minimized-ffmpeg_dem_MPC8_fuzzer-4917863877050368

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 2021-08-01 20:25:20 +02:00
parent 9bc32d7c4b
commit 2bbef69b0b
1 changed files with 7 additions and 1 deletions
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8
libavformat/mpc8.c
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@ -177,7 +177,13 @@ static void mpc8_parse_seektable(AVFormatContext *s, int64_t off)
} }
seekd = get_bits(&gb, 4); seekd = get_bits(&gb, 4);
for(i = 0; i < 2; i++){ for(i = 0; i < 2; i++){
pos = gb_get_v(&gb) + c->header_pos; pos = gb_get_v(&gb);
if (av_sat_add64(pos, c->header_pos) != pos + (uint64_t)c->header_pos) {
av_free(buf);
return;
}
pos += c->header_pos;
ppos[1 - i] = pos; ppos[1 - i] = pos;
av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME); av_add_index_entry(s->streams[0], pos, i, 0, 0, AVINDEX_KEYFRAME);
} }