From: Timo Heister <timo.heister@gmail.com>
Date: Tue, 13 Aug 2024 03:14:02 +0000 (-0400)
Subject: MGTransferMF: fix nullptr access
X-Git-Url: https://gitweb.dealii.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=4add8678061d6102cb598a52bc11710320b3d02d;p=dealii.git

MGTransferMF: fix nullptr access

transfer[min_level] is never used and okay to be null
---

diff --git a/include/deal.II/multigrid/mg_transfer_global_coarsening.h b/include/deal.II/multigrid/mg_transfer_global_coarsening.h
index 689fd70bef..b03fc8c28f 100644
--- a/include/deal.II/multigrid/mg_transfer_global_coarsening.h
+++ b/include/deal.II/multigrid/mg_transfer_global_coarsening.h
@@ -1454,7 +1454,8 @@ MGTransferMF<dim, Number>::initialize_transfer_references(
 
   this->transfer.resize(min_level, max_level);
 
-  for (unsigned int l = min_level; l <= max_level; ++l)
+  // Note that transfer[min_level] is empty and never used:
+  for (unsigned int l = min_level + 1; l <= max_level; ++l)
     this->transfer[l] = &const_cast<MGTwoLevelTransferBase<VectorType> &>(
       static_cast<const MGTwoLevelTransferBase<VectorType> &>(
         Utilities::get_underlying_value(transfer[l])));