fix potential overflow in memory size calculation

Signed-off-by: zhenweijin <[email protected]>

Author: kylo5aby

core/iwasm/interpreter/wasm_runtime.c

@@ -335,14 +335,14 @@ memory_instantiate(WASMModuleInstance *module_inst, WASMModuleInstance *parent,
             /* If only one page and at most one page, we just append
                the app heap to the end of linear memory, enlarge the
                num_bytes_per_page, and don't change the page count */
-            heap_offset = num_bytes_per_page;
-            num_bytes_per_page += heap_size;
-            if (num_bytes_per_page < heap_size) {
+            if (heap_size > UINT32_MAX - num_bytes_per_page) {
                 set_error_buf(error_buf, error_buf_size,
                               "failed to insert app heap into linear memory, "
                               "try using `--heap-size=0` option");
                 return NULL;
             }
+            heap_offset = num_bytes_per_page;
+            num_bytes_per_page += heap_size;
         }
         else if (heap_size > 0) {
             if (init_page_count == max_page_count && init_page_count == 0) {