[wasm] void is not a valid type for a global.

TEST=unittest WasmModuleVerifyTest.Global_invalid_type2
BUG=chromium:645443
R=titzer@chromium.org

Review-Url: https://codereview.chromium.org/2342593002
Cr-Commit-Position: refs/heads/master@{#39421}

src/wasm/module-decoder.cc

@@ -467,6 +467,9 @@ class ModuleDecoder : public Decoder {
       error("global name is not valid utf8");
     }
     global->type = consume_local_type();
+    if (global->type == kAstStmt) {
+      error("invalid global type");
+    }
     global->offset = 0;
     global->exported = consume_u8("exported") != 0;
   }

test/unittests/wasm/module-decoder-unittest.cc

@@ -213,7 +213,22 @@ TEST_F(WasmModuleVerifyTest, Global_invalid_type) {
       0,    // exported
   };
 
-  ModuleResult result = DecodeModuleNoHeader(data, data + sizeof(data));
+  ModuleResult result = DecodeModule(data, data + sizeof(data));
+  EXPECT_FALSE(result.ok());
+  if (result.val) delete result.val;
+}
+
+TEST_F(WasmModuleVerifyTest, Global_invalid_type2) {
+  static const byte data[] = {
+      SECTION(GLOBALS, 5),  // --
+      1,
+      NAME_LENGTH(1),
+      'g',         // name
+      kLocalVoid,  // invalid memory type
+      0,           // exported
+  };
+
+  ModuleResult result = DecodeModule(data, data + sizeof(data));
   EXPECT_FALSE(result.ok());
   if (result.val) delete result.val;
 }