[wasm] improve handling of malformed input

test/unittests/wasm/loop-assignment-analysis-unittest.cc

 // Copyright 2016 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/v8.h"
 
 #include "test/cctest/wasm/test-signatures.h"
 
@@ skipping 162 matching lines @@
       WASM_STORE_MEM(MachineType::Float32(), WASM_ZERO, WASM_GET_LOCAL(kSum)),
       WASM_GET_LOCAL(kIter))};
 
   BitVector* assigned = Analyze(code + 1, code + arraysize(code));
   for (int j = 0; j < assigned->length(); j++) {
     bool expected = j == kIter || j == kSum;
     CHECK_EQ(expected, assigned->Contains(j));
   }
 }
 
+TEST_F(WasmLoopAssignmentAnalyzerTest, Malformed) {
+  byte code[] = {kExprLoop, kExprF32Neg, kExprBrTable, 0x0e, 'h', 'e',
+                 'l',       'l',         'o',          ',',  ' ', 'w',
+                 'o',       'r',         'l',          'd',  '!'};
+  BitVector* assigned = Analyze(code, code + arraysize(code));
+  CHECK_NULL(assigned);
+}
+
 }  // namespace wasm
 }  // namespace internal
 }  // namespace v8