avformat/asfdec_o: Use ff_get_extradata()

Fixes: OOM
Fixes: 27240/clusterfuzz-testcase-minimized-ffmpeg_dem_ASF_O_fuzzer-5937469859823616

Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/asfdec_o.c

@@ -573,7 +573,7 @@ static int asf_read_properties(AVFormatContext *s, const GUIDParseTable *g)
     return 0;
 }
 
-static int parse_video_info(AVIOContext *pb, AVStream *st)
+static int parse_video_info(AVFormatContext *avfmt, AVIOContext *pb, AVStream *st)
 {
     uint16_t size_asf; // ASF-specific Format Data size
     uint32_t size_bmp; // BMP_HEADER-specific Format Data size
@@ -588,19 +588,10 @@ static int parse_video_info(AVIOContext *pb, AVStream *st)
     st->codecpar->codec_id  = ff_codec_get_id(ff_codec_bmp_tags, tag);
     size_bmp = FFMAX(size_asf, size_bmp);
 
-    if (size_bmp > BMP_HEADER_SIZE &&
-        size_bmp < INT_MAX - AV_INPUT_BUFFER_PADDING_SIZE) {
-        int ret;
-        st->codecpar->extradata_size  = size_bmp - BMP_HEADER_SIZE;
-        if (!(st->codecpar->extradata = av_malloc(st->codecpar->extradata_size +
-                                               AV_INPUT_BUFFER_PADDING_SIZE))) {
-            st->codecpar->extradata_size = 0;
-            return AVERROR(ENOMEM);
-        }
-        memset(st->codecpar->extradata + st->codecpar->extradata_size , 0,
-               AV_INPUT_BUFFER_PADDING_SIZE);
-        if ((ret = avio_read(pb, st->codecpar->extradata,
-                             st->codecpar->extradata_size)) < 0)
+    if (size_bmp > BMP_HEADER_SIZE) {
+        int ret = ff_get_extradata(avfmt, st->codecpar, pb, size_bmp - BMP_HEADER_SIZE);
+
+        if (ret < 0)
             return ret;
     }
     return 0;
@@ -683,7 +674,7 @@ static int asf_read_stream_properties(AVFormatContext *s, const GUIDParseTable *
         break;
     case AVMEDIA_TYPE_VIDEO:
         asf_st->type = AVMEDIA_TYPE_VIDEO;
-        if ((ret = parse_video_info(pb, st)) < 0)
+        if ((ret = parse_video_info(s, pb, st)) < 0)
             return ret;
         break;
     default: