avformat/yuv4mpegen: Sanity check input packet frame dimensions

Fixes: out of array access if a filter-graph is used the injects changing dimensions

Found-by: Zhenpeng (Leo) Lin from depthfirst
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavformat/yuv4mpegenc.c

@@ -197,6 +197,9 @@ static int yuv4_write_packet(AVFormatContext *s, AVPacket *pkt)
 
     width  = st->codecpar->width;
     height = st->codecpar->height;
+    if (frame->width != width || frame->height != height)
+        return AVERROR(EINVAL);
+
     desc   = av_pix_fmt_desc_get(st->codecpar->format);
 
     /* The following code presumes all planes to be non-interleaved. */