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avformat/dhav: Check position for overflow

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Fixes: signed integer overflow: 9223372036854775807 + 32768 cannot be represented in type 'long'
Fixes: 27744/clusterfuzz-testcase-minimized-ffmpeg_dem_DHAV_fuzzer-5179319491756032

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 0a0b92b4b2b1288141059684cea741a79cc1e7f2)
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Michael Niedermayer 2020-12-04 00:30:12 +01:00
parent 50ac656fdd
commit ef2e673f8f
1 changed files with 2 additions and 2 deletions
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4
libavformat/dhav.c
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@ -173,12 +173,12 @@ static int read_chunk(AVFormatContext *s)
if (avio_feof(s->pb))
return AVERROR_EOF;
if (avio_rl32(s->pb) != MKTAG('D','H','A','V')) {
if (avio_rl32(s->pb) != MKTAG('D','H','A','V') && dhav->last_good_pos < INT64_MAX - 0x8000) {
dhav->last_good_pos += 0x8000;
avio_seek(s->pb, dhav->last_good_pos, SEEK_SET);
while (avio_rl32(s->pb) != MKTAG('D','H','A','V')) {
if (avio_feof(s->pb))
if (avio_feof(s->pb) || dhav->last_good_pos >= INT64_MAX - 0x8000)
return AVERROR_EOF;
dhav->last_good_pos += 0x8000;
ret = avio_skip(s->pb, 0x8000 - 4);