[wasm] Fix bounds check in LoadDataSegments.

src/wasm/wasm-module.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 <memory>
 
 #include "src/base/atomic-utils.h"
 #include "src/code-stubs.h"
 
 #include "src/macro-assembler.h"
@@ skipping 1348 matching lines @@
     }
   }
 
   // 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) {
       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("data segment does not fit into memory");
+          dest_offset > (mem_size - source_size)) {
+        thrower_->RangeError(
+            "data segment (start = %u, size = %u) does not fit into memory "
+            "(size = %zu)",
+            dest_offset, source_size, mem_size);
+        return;
       }
       byte* dest = mem_addr + dest_offset;
       const byte* src = reinterpret_cast<const byte*>(
           module_bytes->GetCharsAddress() + segment.source_offset);
       memcpy(dest, src, source_size);
     }
   }
 
   void WriteGlobalValue(WasmGlobal& global, Handle<Object> value) {
     double num = 0;
@@ skipping 865 matching lines @@
     CHECK_NOT_NULL(result.val);
     module = const_cast<WasmModule*>(result.val);
   }
 
   Handle<WasmModuleWrapper> module_wrapper =
       WasmModuleWrapper::New(isolate, module);
 
   compiled_module->set_module_wrapper(module_wrapper);
   DCHECK(WasmCompiledModule::IsWasmCompiledModule(*compiled_module));
 }