From 1e1104a11ccdd807f91b43e1a43635a304272501 Mon Sep 17 00:00:00 2001
From: Matthew Parkinson <mattpark@microsoft.com>
Date: Thu, 17 Mar 2022 09:47:01 +0000
Subject: [PATCH] Fix 32bit external pointer.

For 32bit external pointer it was performing a divide by size, and for
things not managed by snmalloc this was causing a crash.  This checks
for zero, and gives the start of the address range as the start of the
object.
---
 src/mem/sizeclasstable.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/src/mem/sizeclasstable.h b/src/mem/sizeclasstable.h
index 1569bc8..ae55545 100644
--- a/src/mem/sizeclasstable.h
+++ b/src/mem/sizeclasstable.h
@@ -357,6 +357,8 @@ namespace snmalloc
     }
     else
     {
+      if (size == 0)
+        return 0;
       return slab_start + (offset / size) * size;
     }
   }