[FFmpeg-cvslog] avcodec/pgssubdec: Check for duplicate display segments

[Michael Niedermayer]

ffmpeg | branch: release/4.1 | Michael Niedermayer <michael at niedermayer.cc> | Tue Jan 29 01:06:01 2019 +0100| [7816497ba081003287557096eea830327281f15d] | committer: Michael Niedermayer

avcodec/pgssubdec: Check for duplicate display segments

In such a duplication the previous gets overwritten and leaks

Fixes: memleak
Fixes: 12510/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_PGSSUB_fuzzer-5694439226343424

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 e35c3d887b3e374c6a091342206a42da48785d70)
Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=7816497ba081003287557096eea830327281f15d
---

 libavcodec/pgssubdec.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/libavcodec/pgssubdec.c b/libavcodec/pgssubdec.c
index b897d72aab..8c10f6d573 100644
--- a/libavcodec/pgssubdec.c
+++ b/libavcodec/pgssubdec.c
@@ -676,6 +676,11 @@ static int decode(AVCodecContext *avctx, void *data, int *data_size,
              */
             break;
         case DISPLAY_SEGMENT:
+            if (*data_size) {
+                av_log(avctx, AV_LOG_ERROR, "Duplicate display segment\n");
+                ret = AVERROR_INVALIDDATA;
+                break;
+            }
             ret = display_end_segment(avctx, data, buf, segment_length);
             if (ret >= 0)
                 *data_size = ret;