avformat/avidec: fix position overflow in avi_load_index()

Fixes: signed integer overflow: 9223372033098784808 + 4294967072 cannot be represented in type 'long'
Fixes: 29102/clusterfuzz-testcase-minimized-ffmpeg_dem_AVI_fuzzer-6732488912273408

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 2021-04-23 19:11:03 +02:00
parent f034c2e36a
commit 527821a2dd

View File

@ -1776,7 +1776,10 @@ static int avi_load_index(AVFormatContext *s)
size = avio_rl32(pb);
if (avio_feof(pb))
break;
next = avio_tell(pb) + size + (size & 1);
next = avio_tell(pb);
if (next < 0 || next > INT64_MAX - size - (size & 1))
break;
next += size + (size & 1LL);
if (tag == MKTAG('i', 'd', 'x', '1') &&
avi_read_idx1(s, size) >= 0) {