update

src/core/ext/census/trace_context.c

@@ -69,6 +69,7 @@ bool decode_trace_context(google_trace_TraceContext *ctxt, uint8_t *buffer,
   if (!status) {
     gpr_log(GPR_DEBUG, "TraceContext decoding failed: %s",
             PB_GET_ERROR(&stream));
+    return false;
   }
 
   // check fields

test/core/census/trace_context_test.c

@@ -189,7 +189,8 @@ static void test_corrupt() {
   ctxt1.is_sampled = true;
   msg_length = encode_trace_context(&ctxt1, buffer, sizeof(buffer));
 
-  // Corrupt some bytes.
+  /* Corrupt some bytes.  255 (0xFF) should be illegal for the first byte of the
+  proto encoded object. */
   buffer[0] = 255;
 
   bool res = validate_decode_context(&ctxt1, buffer, msg_length);