avformat/oggenc: Don't free AVStream's priv_data, fix memleak

For FLAC, Speex, Opus and VP8 the Ogg muxer allocates two buffers
for building the headers: The first for extradata in an Ogg-specific
format and the second contains a Vorbiscomment. These buffers are
reachable via pointers in the corresponding AVStream's priv_data.

If an error happens during building the headers, the AVStream's
priv_data would be freed. This is pointless in general as it would be
freed generically anyway, but here it is actively harmful: If the second
of the aforementioned allocations fails, the first buffer would leak
upon freeing priv_data.

This commit stops freeing priv_data manually, which allows the muxer to
properly clean up in the deinit function.
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>

libavformat/oggenc.c

@@ -546,7 +546,6 @@ static int ogg_init(AVFormatContext *s)
                                              &st->metadata);
             if (err) {
                 av_log(s, AV_LOG_ERROR, "Error writing FLAC headers\n");
-                av_freep(&st->priv_data);
                 return err;
             }
         } else if (st->codecpar->codec_id == AV_CODEC_ID_SPEEX) {
@@ -555,7 +554,6 @@ static int ogg_init(AVFormatContext *s)
                                               &st->metadata);
             if (err) {
                 av_log(s, AV_LOG_ERROR, "Error writing Speex headers\n");
-                av_freep(&st->priv_data);
                 return err;
             }
         } else if (st->codecpar->codec_id == AV_CODEC_ID_OPUS) {
@@ -564,7 +562,6 @@ static int ogg_init(AVFormatContext *s)
                                              &st->metadata, s->chapters, s->nb_chapters);
             if (err) {
                 av_log(s, AV_LOG_ERROR, "Error writing Opus headers\n");
-                av_freep(&st->priv_data);
                 return err;
             }
         } else if (st->codecpar->codec_id == AV_CODEC_ID_VP8) {
@@ -572,7 +569,6 @@ static int ogg_init(AVFormatContext *s)
                                             s->flags & AVFMT_FLAG_BITEXACT);
             if (err) {
                 av_log(s, AV_LOG_ERROR, "Error writing VP8 headers\n");
-                av_freep(&st->priv_data);
                 return err;
             }
         } else {
@@ -585,7 +581,7 @@ static int ogg_init(AVFormatContext *s)
                                       st->codecpar->codec_id == AV_CODEC_ID_VORBIS ? 30 : 42,
                                       (const uint8_t**)oggstream->header, oggstream->header_len) < 0) {
                 av_log(s, AV_LOG_ERROR, "Extradata corrupted\n");
-                av_freep(&st->priv_data);
+                oggstream->header[1] = NULL;
                 return AVERROR_INVALIDDATA;
             }
 
@@ -755,7 +751,6 @@ static void ogg_free(AVFormatContext *s)
             av_freep(&oggstream->header[0]);
         }
         av_freep(&oggstream->header[1]);
-        av_freep(&st->priv_data);
     }
 
     while (p) {