avformat/rmdec: rm_read_extradata: add error message for oversized extradata

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/rmdec.c

@@ -86,8 +86,10 @@ static void get_str8(AVIOContext *pb, char *buf, int buf_size)
 
 static int rm_read_extradata(AVIOContext *pb, AVCodecContext *avctx, unsigned size)
 {
-    if (size >= 1<<24)
+    if (size >= 1<<24) {
+        av_log(avctx, AV_LOG_ERROR, "extradata size %u too large\n", size);
         return -1;
+    }
     if (ff_get_extradata(avctx, pb, size) < 0)
         return AVERROR(ENOMEM);
     return 0;