lclenc: allocate FF_INPUT_BUFFER_PADDING_SIZE for extradata

Also check return value.
Signed-off-by: Paul B Mahol <onemda@gmail.com>

libavcodec/lclenc.c

@@ -137,7 +137,9 @@ static av_cold int encode_init(AVCodecContext *avctx)
 
     av_assert0(avctx->width && avctx->height);
 
-    avctx->extradata= av_mallocz(8);
+    avctx->extradata = av_mallocz(8 + FF_INPUT_BUFFER_PADDING_SIZE);
+    if (!avctx->extradata)
+        return AVERROR(ENOMEM);
     avctx->coded_frame= &c->pic;
 
     c->compression = avctx->compression_level == FF_COMPRESSION_DEFAULT ?