From 3dce2ea873a2568d8d63ce5c3029c28012dfbc50 Mon Sep 17 00:00:00 2001
From: Tobias Melson <tobias.melson@mpcdf.mpg.de>
Date: Fri, 25 Feb 2022 14:39:16 +0100
Subject: [PATCH] Avoid integer overflow when calculating length

It may happen that the product of the two 4-byte integers overflows
before assigning to the 8-byte integer. We need to explicitly convert to
8 bytes first before multiplying.
---
 lib/mpifx_win.fpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/mpifx_win.fpp b/lib/mpifx_win.fpp
index 1bd2d63..f54efd2 100644
--- a/lib/mpifx_win.fpp
+++ b/lib/mpifx_win.fpp
@@ -69,7 +69,7 @@ contains
 
     local_length = 0
     if (mycomm%lead) then
-      local_length = length * disp_unit
+      local_length = int(length, kind=MPI_ADDRESS_KIND) * disp_unit
     end if
 
     call mpi_win_allocate_shared(local_length, disp_unit, MPI_INFO_NULL, mycomm%id, baseptr, self%id, error0)