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avformat/rmdec: Initialize and sanity check offset in ivr_read_header() 

Fixes: signed integer overflow: -9223372036854775808 - 17 cannot be represented in type 'long'
Fixes: 18768/clusterfuzz-testcase-minimized-ffmpeg_DEMUXER_fuzzer-5674385247830016

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 2019-11-15 23:00:51 +01:00
parent 8558c231fb
commit 7e665e4a81
1 changed files with 3 additions and 1 deletions
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4
libavformat/rmdec.c
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@ -1171,7 +1171,7 @@ static int ivr_read_header(AVFormatContext *s)
uint8_t key[256], val[256];
AVIOContext *pb = s->pb;
AVStream *st;
int64_t pos, offset, temp;
int64_t pos, offset=0, temp;
pos = avio_tell(pb);
tag = avio_rl32(pb);
@ -1188,6 +1188,8 @@ static int ivr_read_header(AVFormatContext *s)
offset = temp;
temp = avio_rb64(pb);
}
if (offset <= 0)
return AVERROR_INVALIDDATA;
avio_skip(pb, offset - avio_tell(pb));
if (avio_r8(pb) != 1)
return AVERROR_INVALIDDATA;