zmbv: check decompress result

Changing flush type from Z_FINISH is needed since encoder compresses fixed
amount of data and doesn't care about writing end of stream marker.

libavcodec/zmbv.c

@@ -512,7 +512,11 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPac
         c->zstream.avail_in = len;
         c->zstream.next_out = c->decomp_buf;
         c->zstream.avail_out = c->decomp_size;
-        inflate(&c->zstream, Z_FINISH);
+        zret = inflate(&c->zstream, Z_SYNC_FLUSH);
+        if (zret != Z_OK && zret != Z_STREAM_END) {
+            av_log(avctx, AV_LOG_ERROR, "inflate error %d\n", zret);
+            return AVERROR_INVALIDDATA;
+        }
         c->decomp_len = c->zstream.total_out;
     }
     if (c->flags & ZMBV_KEYFRAME) {