avcodec/mscc: avcodec/mscc: allocate the RLE buffer with av_mallocz to avoid heap disclosure

Fixes: use of uninitialized memory
Fixes: poc.avi
Fixes: ROv3JuiJJEdT
Found-by: Umar Pathan (Umar0x)

libavcodec/mscc.c

@@ -233,7 +233,7 @@ static av_cold int decode_init(AVCodecContext *avctx)
         return AVERROR(ENOMEM);
 
     s->uncomp_size = avctx->height * stride;
-    if (!(s->uncomp_buf = av_malloc(s->uncomp_size)))
+    if (!(s->uncomp_buf = av_mallocz(s->uncomp_size)))
         return AVERROR(ENOMEM);
 
     return ff_inflate_init(&s->zstream, avctx);