lib: http: poison parser references after freeing

Make it a little harder to slip in use-after-free bugs by nulling out
references to the parser object after handing it off to freeParser().

Reviewed-by: Trevor Norris <trev.norris@gmail.com>

lib/_http_client.js

@@ -257,7 +257,7 @@ function socketCloseListener() {
 
   if (parser) {
     parser.finish();
-    freeParser(parser, req);
+    freeParser(parser, req, socket);
   }
 }
 
@@ -276,7 +276,7 @@ function socketErrorListener(err) {
 
   if (parser) {
     parser.finish();
-    freeParser(parser, req);
+    freeParser(parser, req, socket);
   }
   socket.destroy();
 }
@@ -294,7 +294,7 @@ function socketOnEnd() {
   }
   if (parser) {
     parser.finish();
-    freeParser(parser, req);
+    freeParser(parser, req, socket);
   }
   socket.destroy();
 }
@@ -309,7 +309,7 @@ function socketOnData(d) {
   var ret = parser.execute(d);
   if (ret instanceof Error) {
     debug('parse error');
-    freeParser(parser, req);
+    freeParser(parser, req, socket);
     socket.destroy();
     req.emit('error', ret);
     req.socket._hadError = true;
@@ -344,7 +344,7 @@ function socketOnData(d) {
       // Got Upgrade header or CONNECT method, but have no handler.
       socket.destroy();
     }
-    freeParser(parser, req);
+    freeParser(parser, req, socket);
   } else if (parser.incoming && parser.incoming.complete &&
              // When the status code is 100 (Continue), the server will
              // send a final response after this client sends a request
@@ -352,7 +352,7 @@ function socketOnData(d) {
              parser.incoming.statusCode !== 100) {
     socket.removeListener('data', socketOnData);
     socket.removeListener('end', socketOnEnd);
-    freeParser(parser, req);
+    freeParser(parser, req, socket);
   }
 }
 

lib/_http_common.js

@@ -192,7 +192,7 @@ exports.parsers = parsers;
 // up by doing `parser.data = {}`, which should
 // be done in FreeList.free.  `parsers.free(parser)`
 // should be all that is needed.
-function freeParser(parser, req) {
+function freeParser(parser, req, socket) {
   if (parser) {
     parser._headers = [];
     parser.onIncoming = null;
@@ -207,6 +207,9 @@ function freeParser(parser, req) {
   if (req) {
     req.parser = null;
   }
+  if (socket) {
+    socket.parser = null;
+  }
 }
 exports.freeParser = freeParser;
 

lib/_http_server.js

@@ -285,8 +285,9 @@ function connectionListener(socket) {
   function serverSocketCloseListener() {
     debug('server socket close');
     // mark this parser as reusable
-    if (this.parser)
-      freeParser(this.parser);
+    if (this.parser) {
+      freeParser(this.parser, null, this);
+    }
 
     abortIncoming();
   }
@@ -353,7 +354,8 @@ function connectionListener(socket) {
       socket.removeListener('end', socketOnEnd);
       socket.removeListener('close', serverSocketCloseListener);
       parser.finish();
-      freeParser(parser, req);
+      freeParser(parser, req, null);
+      parser = null;
 
       var eventName = req.method === 'CONNECT' ? 'connect' : 'upgrade';
       if (EventEmitter.listenerCount(self, eventName) > 0) {