avformat/rmdec: Fix memleaks upon read_header failure

For both the RealMedia as well as the IVR demuxer (which share the same
context) each AVStream's priv_data contains an AVPacket that might
contain data (even when reading the header) and therefore needs to be
unreferenced. Up until now, this has not always been done:

The RealMedia demuxer didn't do it when allocating a new stream's
priv_data failed although there might be other streams with packets to
unreference. (The reason for this was that until recently rm_read_close()
couldn't handle an AVStream without priv_data, so one had to choose
between a potential crash and a memleak.)

The IVR demuxer meanwhile never ever called read_close so that the data
already contained in packets leaks upon error.

This patch fixes both demuxers by adding the appropriate cleanup code.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
(cherry picked from commit 9a471c5437)

libavformat/rmdec.c

@@ -614,8 +614,10 @@ static int rm_read_header(AVFormatContext *s)
             get_str8(pb, mime, sizeof(mime)); /* mimetype */
             st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
             st->priv_data = ff_rm_alloc_rmstream();
-            if (!st->priv_data)
-                return AVERROR(ENOMEM);
+            if (!st->priv_data) {
+                ret = AVERROR(ENOMEM);
+                goto fail;
+            }
 
             size = avio_rb32(pb);
             codec_pos = avio_tell(pb);
@@ -1249,20 +1251,19 @@ static int ivr_read_header(AVFormatContext *s)
     }
 
     for (n = 0; n < nb_streams; n++) {
-        st = avformat_new_stream(s, NULL);
-        if (!st)
-            return AVERROR(ENOMEM);
-        st->priv_data = ff_rm_alloc_rmstream();
-        if (!st->priv_data)
-            return AVERROR(ENOMEM);
+        if (!(st = avformat_new_stream(s, NULL)) ||
+            !(st->priv_data = ff_rm_alloc_rmstream())) {
+            ret = AVERROR(ENOMEM);
+            goto fail;
+        }
 
         if (avio_r8(pb) != 1)
-            return AVERROR_INVALIDDATA;
+            goto invalid_data;
 
         count = avio_rb32(pb);
         for (i = 0; i < count; i++) {
             if (avio_feof(pb))
-                return AVERROR_INVALIDDATA;
+                goto invalid_data;
 
             type = avio_r8(pb);
             tlen  = avio_rb32(pb);
@@ -1274,25 +1275,25 @@ static int ivr_read_header(AVFormatContext *s)
             } else if (type == 4 && !strncmp(key, "OpaqueData", tlen)) {
                 ret = ffio_ensure_seekback(pb, 4);
                 if (ret < 0)
-                    return ret;
+                    goto fail;
                 if (avio_rb32(pb) == MKBETAG('M', 'L', 'T', 'I')) {
                     ret = rm_read_multi(s, pb, st, NULL);
                 } else {
                     if (avio_feof(pb))
-                        return AVERROR_INVALIDDATA;
+                        goto invalid_data;
                     avio_seek(pb, -4, SEEK_CUR);
                     ret = ff_rm_read_mdpr_codecdata(s, pb, st, st->priv_data, len, NULL);
                 }
 
                 if (ret < 0)
-                    return ret;
+                    goto fail;
             } else if (type == 4) {
                 int j;
 
                 av_log(s, AV_LOG_DEBUG, "%s = '0x", key);
                 for (j = 0; j < len; j++) {
                     if (avio_feof(pb))
-                        return AVERROR_INVALIDDATA;
+                        goto invalid_data;
                     av_log(s, AV_LOG_DEBUG, "%X", avio_r8(pb));
                 }
                 av_log(s, AV_LOG_DEBUG, "'\n");
@@ -1309,14 +1310,19 @@ static int ivr_read_header(AVFormatContext *s)
     }
 
     if (avio_r8(pb) != 6)
-        return AVERROR_INVALIDDATA;
+        goto invalid_data;
     avio_skip(pb, 12);
     avio_skip(pb, avio_rb64(pb) + pos - avio_tell(s->pb));
     if (avio_r8(pb) != 8)
-        return AVERROR_INVALIDDATA;
+        goto invalid_data;
     avio_skip(pb, 8);
 
     return 0;
+invalid_data:
+    ret = AVERROR_INVALIDDATA;
+fail:
+    rm_read_close(s);
+    return ret;
 }
 
 static int ivr_read_packet(AVFormatContext *s, AVPacket *pkt)