prevent multiply with overflow resulting in odd errors/segv

diff --git a/src/macros.rs b/src/macros.rs
index f977b88259c6e47637edc17e00489f3ef6a3ff7a..2eda4980312b65f25fd872a4bff38da5f6935c15 100644 (file)
--- a/src/macros.rs
+++ b/src/macros.rs
@@ -472,7 +472,9 @@ macro_rules! resource_error_call_result {
 
 macro_rules! heap_index {
     ($idx:expr) => {
-        ($idx) * std::mem::size_of::<HeapCellValue>()
+        std::mem::size_of::<HeapCellValue>()
+            .checked_mul($idx)
+            .unwrap()
     };
 }