avformat/iff: fix memleak when get st->codecpar->extradata failed in iff_read_header

Reviewed-by: Paul B Mahol <onemda@gmail.com>
Signed-off-by: Steven Liu <lq@chinaffmpeg.org>

libavformat/iff.c

@@ -529,8 +529,11 @@ static int iff_read_header(AVFormatContext *s)
             st->codecpar->extradata      = av_malloc(data_size + IFF_EXTRA_VIDEO_SIZE + AV_INPUT_BUFFER_PADDING_SIZE);
             if (!st->codecpar->extradata)
                 return AVERROR(ENOMEM);
-            if (avio_read(pb, st->codecpar->extradata + IFF_EXTRA_VIDEO_SIZE, data_size) < 0)
+            if (avio_read(pb, st->codecpar->extradata + IFF_EXTRA_VIDEO_SIZE, data_size) < 0) {
+                av_freep(&st->codecpar->extradata);
+                st->codecpar->extradata_size = 0;
                 return AVERROR(EIO);
+            }
             break;
 
         case ID_BMHD: