From 442e21a69cf4d3afecbba40cd01fa83a8f487a52 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Kacper=20Michaj=C5=82ow?= <kasper93@gmail.com>
Date: Wed, 5 Mar 2025 20:03:14 +0100
Subject: [PATCH] demux_mkv: add missing invalid value check

---
 demux/demux_mkv.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/demux/demux_mkv.c b/demux/demux_mkv.c
index bc7d91d133..8fe4a121c2 100644
--- a/demux/demux_mkv.c
+++ b/demux/demux_mkv.c
@@ -3191,7 +3191,9 @@ static int read_next_block_into_queue(demuxer_t *demuxer)
             }
 
             case MATROSKA_ID_BLOCKGROUP: {
-                int64_t end = ebml_read_length(s);
+                uint64_t end = ebml_read_length(s);
+                if (end == EBML_UINT_INVALID)
+                    goto find_next_cluster;
                 end += stream_tell(s);
                 if (end > mkv_d->cluster_end)
                     goto find_next_cluster;