From 532ff7e87a951ae40241833713eae963193e1f2d Mon Sep 17 00:00:00 2001
From: Yi LIU <yi@quantstamp.com>
Date: Wed, 11 Feb 2026 18:27:25 +0800
Subject: [PATCH] Fix crash in interpreter when instantiating modules with
 imported globals

instantiate() iterated all globals without checking imported(), causing
ExpressionIterator to be constructed with a null init expression. This
triggered an assertion failure in PostWalker::walk(). Skip imported
globals during instantiation, matching the pattern used by walkModule().
---
 src/interpreter/interpreter.cpp |  3 +++
 test/gtest/interpreter.cpp      | 48 +++++++++++++++++++++++++++++++++
 2 files changed, 51 insertions(+)

diff --git a/src/interpreter/interpreter.cpp b/src/interpreter/interpreter.cpp
index 8007f011dcc..6c97c82f729 100644
--- a/src/interpreter/interpreter.cpp
+++ b/src/interpreter/interpreter.cpp
@@ -293,6 +293,9 @@ Result<> Interpreter::addInstance(std::shared_ptr<Module> wasm) {
 
 Result<> Interpreter::instantiate(Instance& instance) {
   for (auto& global : instance.wasm->globals) {
+    if (global->imported()) {
+      continue;
+    }
     store.callStack.emplace_back(instance, ExpressionIterator(global->init));
     auto results = run();
     assert(results.size() == 1);
diff --git a/test/gtest/interpreter.cpp b/test/gtest/interpreter.cpp
index ca1beb6c564..9008224ee31 100644
--- a/test/gtest/interpreter.cpp
+++ b/test/gtest/interpreter.cpp
@@ -943,6 +943,54 @@ TEST(InterpreterTest, GlobalI32) {
   EXPECT_EQ(results, expected);
 }
 
+TEST(InterpreterTest, ImportedGlobalI32) {
+  auto wasm = std::make_shared<Module>();
+  Builder builder(*wasm);
+
+  auto importedGlobal =
+    builder.makeGlobal("g", Type::i32, nullptr, Builder::Immutable);
+  importedGlobal->module = "env";
+  importedGlobal->base = "g";
+  wasm->addGlobal(std::move(importedGlobal));
+
+  Interpreter interpreter;
+  auto result = interpreter.addInstance(wasm);
+  EXPECT_FALSE(result.getErr());
+}
+
+TEST(InterpreterTest, MixedImportedAndLocalGlobals) {
+  auto wasm = std::make_shared<Module>();
+  Builder builder(*wasm);
+  IRBuilder irBuilder(*wasm);
+
+  auto importedGlobal =
+    builder.makeGlobal("imported", Type::i32, nullptr, Builder::Immutable);
+  importedGlobal->module = "env";
+  importedGlobal->base = "imported";
+  wasm->addGlobal(std::move(importedGlobal));
+
+  wasm->addGlobal(builder.makeGlobal("local",
+                                     Type::i32,
+                                     builder.makeConst(Literal(int32_t(42))),
+                                     Builder::Mutable));
+
+  ASSERT_FALSE(
+    irBuilder.makeBlock(Name{}, Signature(Type::none, Type::i32)).getErr());
+  ASSERT_FALSE(irBuilder.makeGlobalGet("local").getErr());
+  ASSERT_FALSE(irBuilder.visitEnd().getErr());
+
+  auto expr = irBuilder.build();
+  ASSERT_FALSE(expr.getErr());
+
+  Interpreter interpreter;
+  auto result = interpreter.addInstance(wasm);
+  ASSERT_FALSE(result.getErr());
+
+  auto results = interpreter.runTest(*expr);
+  std::vector<Literal> expected{Literal(int32_t(42))};
+  EXPECT_EQ(results, expected);
+}
+
 TEST(InterpreterTest, GlobalInitI32) {
   auto wasm = std::make_shared<Module>();
   Builder builder(*wasm);