Commit 7bc7fdf1 for libheif

commit 7bc7fdf1215bbf198361a783e678697ebfa4e633
Author: Dirk Farin <dirk.farin@gmail.com>
Date:   Thu Dec 25 21:34:26 2025 +0100

    check for valid sample_description_index

diff --git a/libheif/sequences/seq_boxes.cc b/libheif/sequences/seq_boxes.cc
index f5bb9905..5f3ff1ac 100644
--- a/libheif/sequences/seq_boxes.cc
+++ b/libheif/sequences/seq_boxes.cc
@@ -885,6 +885,14 @@ Error Box_stsc::parse(BitstreamRange& range, const heif_security_limits* limits)
     entry.first_chunk = range.read32();
     entry.samples_per_chunk = range.read32();
     entry.sample_description_index = range.read32();
+
+    if (entry.sample_description_index == 0) {
+      return {
+      heif_error_Invalid_input,
+      heif_suberror_Unspecified,
+      "'sample_description_index' in 'stsc' must not be 0."};
+    }
+
     m_entries[i] = entry;
   }