[wasm] Data section without memory causes a validation error

Another spec issue.

R=titzer@chromium.org, rossberg@chromium.org
TEST=unittests/WasmModuleVerifyTest.DataWithoutMemory

Review-Url: https://codereview.chromium.org/2486973003
Cr-Commit-Position: refs/heads/master@{#40855}

src/wasm/module-decoder.cc

@@ -327,6 +327,7 @@ class ModuleDecoder : public Decoder {
                                      &module->min_mem_pages, &has_max,
                                      WasmModule::kSpecMaxPages,
                                      &module->max_mem_pages);
+            module->has_memory = true;
             break;
           }
           case kExternalGlobal: {
@@ -411,6 +412,7 @@ class ModuleDecoder : public Decoder {
             "memory", "pages", WasmModule::kV8MaxPages, &module->min_mem_pages,
             &has_max, WasmModule::kSpecMaxPages, &module->max_mem_pages);
       }
+      module->has_memory = true;
       section_iter.advance();
     }
 
@@ -594,6 +596,10 @@ class ModuleDecoder : public Decoder {
       uint32_t data_segments_count = consume_u32v("data segments count");
       module->data_segments.reserve(SafeReserve(data_segments_count));
       for (uint32_t i = 0; ok() && i < data_segments_count; ++i) {
+        if (!module->has_memory) {
+          error("cannot load data without memory");
+          break;
+        }
         TRACE("DecodeDataSegment[%d] module+%d\n", i,
               static_cast<int>(pc_ - start_));
         module->data_segments.push_back({

src/wasm/wasm-module.h

@@ -185,6 +185,7 @@ struct V8_EXPORT_PRIVATE WasmModule {
   const byte* module_end = nullptr;    // end address for the module bytes
   uint32_t min_mem_pages = 0;  // minimum size of the memory in 64k pages
   uint32_t max_mem_pages = 0;  // maximum size of the memory in 64k pages
+  bool has_memory = false;     // true if the memory was defined or imported
   bool mem_export = false;     // true if the memory is exported
   // TODO(wasm): reconcile start function index being an int with
   // the fact that we index on uint32_t, so we may technically not be

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

@@ -516,6 +516,20 @@ TEST_F(WasmModuleVerifyTest, TwoDataSegments) {
   EXPECT_OFF_END_FAILURE(data, 14, sizeof(data));
 }
 
+TEST_F(WasmModuleVerifyTest, DataWithoutMemory) {
+  const byte data[] = {
+      SECTION(Data, 11),
+      ENTRY_COUNT(1),
+      LINEAR_MEMORY_INDEX_0,
+      WASM_INIT_EXPR_I32V_3(0x9bbaa),  // dest addr
+      U32V_1(3),                       // source size
+      'a',
+      'b',
+      'c'  // data bytes
+  };
+  EXPECT_FAILURE(data);
+}
+
 TEST_F(WasmModuleVerifyTest, MaxMaximumMemorySize) {
   {
     const byte data[] = {