[FFmpeg-cvslog] avformat/nutdec: Check fields

[Michael Niedermayer]

ffmpeg | branch: release/5.0 | Michael Niedermayer <michael at niedermayer.cc> | Sun Sep 18 14:47:25 2022 +0200| [cdf35ba1d12bd86dc3e66af3c46e82451df5d96e] | committer: Michael Niedermayer

avformat/nutdec: Check fields

Fixes: signed integer overflow: -2147483648 - 1 cannot be represented in type 'int'
Fixes: 50993/clusterfuzz-testcase-minimized-ffmpeg_dem_NUT_fuzzer-6566001610719232

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 2c146406eac06f3d3cd3d981c29e7affd834cb4d)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=cdf35ba1d12bd86dc3e66af3c46e82451df5d96e
---

 libavformat/nutdec.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavformat/nutdec.c b/libavformat/nutdec.c
index c6b9db5cb3..620c54d404 100644
--- a/libavformat/nutdec.c
+++ b/libavformat/nutdec.c
@@ -244,6 +244,11 @@ static int decode_main_header(NUTContext *nut)
     for (i = 0; i < 256;) {
         int tmp_flags  = ffio_read_varlen(bc);
         int tmp_fields = ffio_read_varlen(bc);
+        if (tmp_fields < 0) {
+            av_log(s, AV_LOG_ERROR, "fields %d is invalid\n", tmp_fields);
+            ret = AVERROR_INVALIDDATA;
+            goto fail;
+        }
 
         if (tmp_fields > 0)
             tmp_pts = get_s(bc);