crypto: fix memory leak in PBKDF2Request

PR-URL: nodejs#2375
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

Author: skomski

src/node_crypto.cc

@@ -4622,6 +4622,7 @@ class PBKDF2Request : public AsyncWrap {
   }
 
   ~PBKDF2Request() override {
+    release();
     persistent().Reset();
   }
 
@@ -4663,10 +4664,15 @@ class PBKDF2Request : public AsyncWrap {
 
   inline void release() {
     free(pass_);
+    pass_ = nullptr;
     passlen_ = 0;
+
     free(salt_);
+    salt_ = nullptr;
     saltlen_ = 0;
+
     free(key_);
+    key_ = nullptr;
     keylen_ = 0;
   }
 
@@ -4737,7 +4743,6 @@ void EIO_PBKDF2After(uv_work_t* work_req, int status) {
   Local<Value> argv[2];
   EIO_PBKDF2After(req, argv);
   req->MakeCallback(env->ondone_string(), ARRAY_SIZE(argv), argv);
-  req->release();
   delete req;
 }
 
@@ -4848,6 +4853,9 @@ void PBKDF2(const FunctionCallbackInfo<Value>& args) {
     Local<Value> argv[2];
     EIO_PBKDF2(req);
     EIO_PBKDF2After(req, argv);
+
+    delete req;
+
     if (argv[0]->IsObject())
       env->isolate()->ThrowException(argv[0]);
     else