[FFmpeg-cvslog] libavformat/iff: Check for overflow in body_end calculation

[Michael Niedermayer]

ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Mon Aug 22 20:31:32 2022 +0200| [37139adfbfcc5daea7d04be6294c2511c1e1e4e4] | committer: Michael Niedermayer

libavformat/iff: Check for overflow in body_end calculation

Fixes: signed integer overflow: -6322983228386819992 - 5557477266266529857 cannot be represented in type 'long'
Fixes: 50112/clusterfuzz-testcase-minimized-ffmpeg_dem_IFF_fuzzer-6329186221948928

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
(cherry picked from commit bcb46903040e5a5199281f4ad0a1fdaf750ebc37)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=37139adfbfcc5daea7d04be6294c2511c1e1e4e4
---

 libavformat/iff.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/libavformat/iff.c b/libavformat/iff.c
index 1a1c80551a..52bc8c99c9 100644
--- a/libavformat/iff.c
+++ b/libavformat/iff.c
@@ -502,6 +502,9 @@ static int iff_read_header(AVFormatContext *s)
         case ID_DST:
         case ID_MDAT:
             iff->body_pos = avio_tell(pb);
+            if (iff->body_pos < 0 || iff->body_pos + data_size > INT64_MAX)
+                return AVERROR_INVALIDDATA;
+
             iff->body_end = iff->body_pos + data_size;
             iff->body_size = data_size;
             if (chunk_id == ID_DST) {