[FFmpeg-cvslog] avcodec/mpeg12dec: Fix uninitialized data in fate-sub-cc-scte20

[Limin Wang]

ffmpeg | branch: master | Limin Wang <lance.lmwang at gmail.com> | Sun Jun 28 20:46:19 2020 +0800| [b6f505ce0ae7bcb05a4ad118753407fd7d022829] | committer: Limin Wang

avcodec/mpeg12dec: Fix uninitialized data in fate-sub-cc-scte20

The issue is introduced in a705bcd763e344fa, please tested with below command line:
make V=1 fate-sub-cc-scte20 TARGET_EXEC="valgrind --error-exitcode=1"

Reported-by:   Martin Storsjö <martin at martin.st>
Reviewed-by:   Martin Storsjö <martin at martin.st>
Signed-off-by: Limin Wang <lance.lmwang at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=b6f505ce0ae7bcb05a4ad118753407fd7d022829
---

 libavcodec/mpeg12dec.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/libavcodec/mpeg12dec.c b/libavcodec/mpeg12dec.c
index f0f92accf6..e9bdccc384 100644
--- a/libavcodec/mpeg12dec.c
+++ b/libavcodec/mpeg12dec.c
@@ -2276,6 +2276,8 @@ static int mpeg_decode_a53_cc(AVCodecContext *avctx,
             if (ret >= 0) {
                 uint8_t field, cc1, cc2;
                 uint8_t *cap = s1->a53_buf_ref->data;
+
+                memset(s1->a53_buf_ref->data + old_size, 0, cc_count * 3);
                 for (i = 0; i < cc_count && get_bits_left(&gb) >= 26; i++) {
                     skip_bits(&gb, 2); // priority
                     field = get_bits(&gb, 2);