[wasm] Decoding the names section should stop if there is a problem with locals.

test/unittests/wasm/module-decoder-unittest.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 "test/unittests/test-utils.h"
 
 #include "src/handles.h"
 #include "src/objects-inl.h"
 #include "src/wasm/module-decoder.h"
 #include "src/wasm/wasm-limits.h"
@@ skipping 1443 matching lines @@
       SECTION_NAMES(1 + 10),
       ENTRY_COUNT(2),  // --
       FOO_STRING,
       NO_LOCAL_NAMES,  // --
       FOO_STRING,
       NO_LOCAL_NAMES,  // --
   };
   EXPECT_VERIFIES(data);
 }
 
+TEST_F(WasmModuleVerifyTest, Regression684855) {
+  static const byte data[] = {
+      SECTION_NAMES(12),
+      0xfb,  // functions count
+      0x27,  // |
+      0x00,  // function name length
+      0xff,  // local names count
+      0xff,  // |
+      0xff,  // |
+      0xff,  // |
+      0xff,  // |
+      0xff,  // error: "varint too large"
+      0xff,  // |
+      0x00,  // --
+      0x00   // --
+  };
+  EXPECT_VERIFIES(data);
+}
+
 #define EXPECT_INIT_EXPR(Type, type, value, ...)                 \
   {                                                              \
     static const byte data[] = {__VA_ARGS__, kExprEnd};          \
     WasmInitExpr expr =                                          \
         DecodeWasmInitExprForTesting(data, data + sizeof(data)); \
     EXPECT_EQ(WasmInitExpr::k##Type##Const, expr.kind);          \
     EXPECT_EQ(value, expr.val.type##_const);                     \
   }
 
 TEST_F(WasmModuleVerifyTest, InitExpr_i32) {
@@ skipping 122 matching lines @@
       {19, 20, 1, 21, 2, 4},  // --
       {29, 30, 5, 35, 2, 8},  // --
   };
 
   CheckSections(data, data + sizeof(data), expected, arraysize(expected));
 }
 
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8