[wasm] Check data segments for zero-sized memory.

src/wasm/wasm-module.cc

Index: src/wasm/wasm-module.cc
diff --git a/src/wasm/wasm-module.cc b/src/wasm/wasm-module.cc
index 179af57ac6d626c06d0fc315d2aa38826b37892b..9e76c2005b750311dc23c933d0efc40fb78842fc 100644
--- a/src/wasm/wasm-module.cc
+++ b/src/wasm/wasm-module.cc
@@ -1149,6 +1149,8 @@ class WasmInstanceBuilder {
       RelocateMemoryReferencesInCode(code_table, old_mem_start, mem_start,
                                      old_mem_size, mem_size);
       compiled_module_->set_memory(memory_);
+    } else if (!CheckDataSegmentsAreEmpty()) {

[titzer, 2016/11/09 17:20:31]

Why not just call LoadDataSegments(nullptr, 0)?

[ahaas, 2016/11/10 10:26:25]

Done. I also fixed another issue with non-empty memory an out-of-bounds empty
segments.

+      thrower_->TypeError("data segment does not fit");
     }
 
     //--------------------------------------------------------------------------
@@ -1345,7 +1347,7 @@ class WasmInstanceBuilder {
     return result;
   }
 
-  uint32_t EvalUint32InitExpr(WasmInitExpr& expr) {
+  uint32_t EvalUint32InitExpr(const WasmInitExpr& expr) {
     switch (expr.kind) {
       case WasmInitExpr::kI32Const:
         return expr.val.i32_const;
@@ -1362,12 +1364,12 @@ class WasmInstanceBuilder {
   // Load data segments into the memory.
   void LoadDataSegments(Address mem_addr, size_t mem_size) {
     Handle<SeqOneByteString> module_bytes = compiled_module_->module_bytes();
-    for (auto segment : module_->data_segments) {
+    for (const WasmDataSegment& segment : module_->data_segments) {
       uint32_t dest_offset = EvalUint32InitExpr(segment.dest_addr);
       uint32_t source_size = segment.source_size;
       if (dest_offset >= mem_size || source_size >= mem_size ||
           dest_offset > (mem_size - source_size)) {
-        thrower_->RangeError(
+        thrower_->TypeError(
             "data segment (start = %u, size = %u) does not fit into memory "
             "(size = %zu)",
             dest_offset, source_size, mem_size);
@@ -1380,6 +1382,16 @@ class WasmInstanceBuilder {
     }
   }
 
+  // Returns true if all segments are empty and write to address 0.
+  bool CheckDataSegmentsAreEmpty() {
+    for (const WasmDataSegment& segment : module_->data_segments) {
+      if (segment.source_size > 0) {
+        return false;
+      }
+    }
+    return true;
+  }
+
   void WriteGlobalValue(WasmGlobal& global, Handle<Object> value) {
     double num = 0;
     if (value->IsSmi()) {