[FFmpeg-cvslog] avformat/wtvdec: Check dir_length

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michael at niedermayer.cc> | Mon Oct 19 17:59:53 2020 +0200| [1868cb731660490beb750389266adb6e68e9123d] | committer: Michael Niedermayer

avformat/wtvdec: Check dir_length

Fixes: Infinite loop
Fixes: 26445/clusterfuzz-testcase-minimized-ffmpeg_dem_WTV_fuzzer-5125558331244544

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Reviewed-by: Peter Ross <pross at xvid.org>
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=1868cb731660490beb750389266adb6e68e9123d
---

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

diff --git a/libavformat/wtvdec.c b/libavformat/wtvdec.c
index 83f510b92f..77908e6392 100644
--- a/libavformat/wtvdec.c
+++ b/libavformat/wtvdec.c
@@ -273,6 +273,11 @@ static AVIOContext * wtvfile_open2(AVFormatContext *s, const uint8_t *buf, int b
                    "bad filename length, remaining directory entries ignored\n");
             break;
         }
+        if (dir_length == 0) {
+            av_log(s, AV_LOG_ERROR,
+                   "bad dir length, remaining directory entries ignored\n");
+            break;
+        }
         if (48 + (int64_t)name_size > buf_end - buf) {
             av_log(s, AV_LOG_ERROR, "filename exceeds buffer size; remaining directory entries ignored\n");
             break;