[wasm] Mutable globals cannot be exported

src/wasm/module-decoder.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/wasm/module-decoder.h"
 
 #include "src/base/functional.h"
 #include "src/base/platform/platform.h"
 #include "src/flags.h"
 #include "src/macro-assembler.h"
@@ skipping 457 matching lines @@
           }
           case kExternalMemory: {
             uint32_t index = consume_u32v("memory index");
             if (index != 0) error("invalid memory index != 0");
             module->mem_export = true;
             break;
           }
           case kExternalGlobal: {
             WasmGlobal* global = nullptr;
             exp->index = consume_global_index(module, &global);
-            if (global) global->exported = true;
+            if (global) {
+              if (global->mutability) {
+                error("mutable globals cannot be exported");
+              }
+              global->exported = true;
+            }
             break;
           }
           default:
             error(pos, pos, "invalid export kind 0x%02x", exp->kind);
             break;
         }
       }
       // Check for duplicate exports.
       if (ok() && module->export_table.size() > 1) {
         std::vector<WasmExport> sorted_exports(module->export_table);
@@ skipping 711 matching lines @@
     table.push_back(std::move(func_asm_offsets));
   }
   if (decoder.more()) decoder.error("unexpected additional bytes");
 
   return decoder.toResult(std::move(table));
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8