_stream_wrap: prevent use after free in TLS

Queued write requests should be invoked on handle close, otherwise the
"consumer" might be already destroyed when the write callbacks of the
"consumed" handle will be invoked. Same applies to the shutdown
requests.

Make sure to "move" away socket from server to not break the
`connections` counter in `net.js`. Otherwise it might not call `close`
callback, or call it too early.

Fix: #1696
PR-URL: #1910
Reviewed-By: Trevor Norris <trev.norris@gmail.com>

lib/_stream_wrap.js

@@ -1,18 +1,23 @@
 'use strict';
 
+const assert = require('assert');
 const util = require('util');
 const Socket = require('net').Socket;
 const JSStream = process.binding('js_stream').JSStream;
 const uv = process.binding('uv');
+const debug = util.debuglog('stream_wrap');
 
 function StreamWrap(stream) {
-  var handle = new JSStream();
+  const handle = new JSStream();
 
   this.stream = stream;
 
-  var self = this;
+  this._list = null;
+
+  const self = this;
   handle.close = function(cb) {
-    cb();
+    debug('close');
+    self.doClose(cb);
   };
   handle.isAlive = function() {
     return self.isAlive();
@@ -27,21 +32,25 @@ function StreamWrap(stream) {
     return self.readStop();
   };
   handle.onshutdown = function(req) {
-    return self.shutdown(req);
+    return self.doShutdown(req);
   };
   handle.onwrite = function(req, bufs) {
-    return self.write(req, bufs);
+    return self.doWrite(req, bufs);
   };
 
   this.stream.pause();
+  this.stream.on('error', function(err) {
+    self.emit('error', err);
+  });
   this.stream.on('data', function(chunk) {
-    self._handle.readBuffer(chunk);
+    debug('data', chunk.length);
+    if (self._handle)
+      self._handle.readBuffer(chunk);
   });
   this.stream.once('end', function() {
-    self._handle.emitEOF();
-  });
-  this.stream.on('error', function(err) {
-    self.emit('error', err);
+    debug('end');
+    if (self._handle)
+      self._handle.emitEOF();
   });
 
   Socket.call(this, {
@@ -55,11 +64,11 @@ module.exports = StreamWrap;
 StreamWrap.StreamWrap = StreamWrap;
 
 StreamWrap.prototype.isAlive = function isAlive() {
-  return this.readable && this.writable;
+  return true;
 };
 
 StreamWrap.prototype.isClosing = function isClosing() {
-  return !this.isAlive();
+  return !this.readable || !this.writable;
 };
 
 StreamWrap.prototype.readStart = function readStart() {
@@ -72,21 +81,31 @@ StreamWrap.prototype.readStop = function readStop() {
   return 0;
 };
 
-StreamWrap.prototype.shutdown = function shutdown(req) {
-  var self = this;
+StreamWrap.prototype.doShutdown = function doShutdown(req) {
+  const self = this;
+  const handle = this._handle;
+  const item = this._enqueue('shutdown', req);
 
   this.stream.end(function() {
     // Ensure that write was dispatched
     setImmediate(function() {
-      self._handle.finishShutdown(req, 0);
+      if (!self._dequeue(item))
+        return;
+
+      handle.finishShutdown(req, 0);
     });
   });
   return 0;
 };
 
-StreamWrap.prototype.write = function write(req, bufs) {
+StreamWrap.prototype.doWrite = function doWrite(req, bufs) {
+  const self = this;
+  const handle = self._handle;
+
   var pending = bufs.length;
-  var self = this;
+
+  // Queue the request to be able to cancel it
+  const item = self._enqueue('write', req);
 
   self.stream.cork();
   bufs.forEach(function(buf) {
@@ -103,6 +122,10 @@ StreamWrap.prototype.write = function write(req, bufs) {
 
     // Ensure that write was dispatched
     setImmediate(function() {
+      // Do not invoke callback twice
+      if (!self._dequeue(item))
+        return;
+
       var errCode = 0;
       if (err) {
         if (err.code && uv['UV_' + err.code])
@@ -111,10 +134,83 @@ StreamWrap.prototype.write = function write(req, bufs) {
           errCode = uv.UV_EPIPE;
       }
 
-      self._handle.doAfterWrite(req);
-      self._handle.finishWrite(req, errCode);
+      handle.doAfterWrite(req);
+      handle.finishWrite(req, errCode);
     });
   }
 
   return 0;
 };
+
+function QueueItem(type, req) {
+  this.type = type;
+  this.req = req;
+  this.prev = this;
+  this.next = this;
+}
+
+StreamWrap.prototype._enqueue = function enqueue(type, req) {
+  const item = new QueueItem(type, req);
+  if (this._list === null) {
+    this._list = item;
+    return item;
+  }
+
+  item.next = this._list.next;
+  item.prev = this._list;
+  item.next.prev = item;
+  item.prev.next = item;
+
+  return item;
+};
+
+StreamWrap.prototype._dequeue = function dequeue(item) {
+  assert(item instanceof QueueItem);
+
+  var next = item.next;
+  var prev = item.prev;
+
+  if (next === null && prev === null)
+    return false;
+
+  item.next = null;
+  item.prev = null;
+
+  if (next === item) {
+    prev = null;
+    next = null;
+  } else {
+    prev.next = next;
+    next.prev = prev;
+  }
+
+  if (this._list === item)
+    this._list = next;
+
+  return true;
+};
+
+StreamWrap.prototype.doClose = function doClose(cb) {
+  const self = this;
+  const handle = self._handle;
+
+  setImmediate(function() {
+    while (self._list !== null) {
+      const item = self._list;
+      const req = item.req;
+      self._dequeue(item);
+
+      const errCode = uv.UV_ECANCELED;
+      if (item.type === 'write') {
+        handle.doAfterWrite(req);
+        handle.finishWrite(req, errCode);
+      } else if (item.type === 'shutdown') {
+        handle.finishShutdown(req, errCode);
+      }
+    }
+
+    // Should be already set by net.js
+    assert(self._handle === null);
+    cb();
+  });
+};

lib/_tls_wrap.js

@@ -254,7 +254,7 @@ function TLSSocket(socket, options) {
   this.encrypted = true;
 
   net.Socket.call(this, {
-    handle: this._wrapHandle(wrap && wrap._handle),
+    handle: this._wrapHandle(wrap),
     allowHalfOpen: socket && socket.allowHalfOpen,
     readable: false,
     writable: false
@@ -279,7 +279,7 @@ util.inherits(TLSSocket, net.Socket);
 exports.TLSSocket = TLSSocket;
 
 var proxiedMethods = [
-  'close', 'ref', 'unref', 'open', 'bind', 'listen', 'connect', 'bind6',
+  'ref', 'unref', 'open', 'bind', 'listen', 'connect', 'bind6',
   'connect6', 'getsockname', 'getpeername', 'setNoDelay', 'setKeepAlive',
   'setSimultaneousAccepts', 'setBlocking',
 
@@ -295,8 +295,20 @@ proxiedMethods.forEach(function(name) {
   };
 });
 
-TLSSocket.prototype._wrapHandle = function(handle) {
+tls_wrap.TLSWrap.prototype.close = function closeProxy(cb) {
+  if (this._parentWrap && this._parentWrap._handle === this._parent) {
+    setImmediate(cb);
+    return this._parentWrap.destroy();
+  }
+  return this._parent.close(cb);
+};
+
+TLSSocket.prototype._wrapHandle = function(wrap) {
   var res;
+  var handle;
+
+  if (wrap)
+    handle = wrap._handle;
 
   var options = this._tlsOptions;
   if (!handle) {
@@ -310,6 +322,7 @@ TLSSocket.prototype._wrapHandle = function(handle) {
                 tls.createSecureContext();
   res = tls_wrap.wrap(handle, context.context, options.isServer);
   res._parent = handle;
+  res._parentWrap = wrap;
   res._secureContext = context;
   res.reading = handle.reading;
   Object.defineProperty(handle, 'reading', {
@@ -355,7 +368,13 @@ TLSSocket.prototype._init = function(socket, wrap) {
   // represent real writeQueueSize during regular writes.
   ssl.writeQueueSize = 1;
 
-  this.server = options.server || null;
+  this.server = options.server;
+
+  // Move the server to TLSSocket, otherwise both `socket.destroy()` and
+  // `TLSSocket.destroy()` will decrement number of connections of the TLS
+  // server, leading to misfiring `server.close()` callback
+  if (socket && socket.server === this.server)
+    socket.server = null;
 
   // For clients, we will always have either a given ca list or be using
   // default one
@@ -418,6 +437,7 @@ TLSSocket.prototype._init = function(socket, wrap) {
   // set `.onsniselect` callback.
   if (process.features.tls_sni &&
       options.isServer &&
+      options.SNICallback &&
       options.server &&
       (options.SNICallback !== SNICallback ||
        options.server._contexts.length)) {
@@ -554,6 +574,10 @@ TLSSocket.prototype._start = function() {
     return;
   }
 
+  // Socket was destroyed before the connection was established
+  if (!this._handle)
+    return;
+
   debug('start');
   if (this._tlsOptions.requestOCSP)
     this._handle.requestOCSP();

src/js_stream.cc

@@ -163,7 +163,7 @@ template <class Wrap>
 void JSStream::Finish(const FunctionCallbackInfo<Value>& args) {
   Wrap* w = Unwrap<Wrap>(args[0].As<Object>());
 
-  w->Done(args[0]->Int32Value());
+  w->Done(args[1]->Int32Value());
 }
 
 

src/tls_wrap.cc

@@ -320,6 +320,10 @@ void TLSWrap::EncOutCb(WriteWrap* req_wrap, int status) {
   TLSWrap* wrap = req_wrap->wrap()->Cast<TLSWrap>();
   req_wrap->Dispose();
 
+  // We should not be getting here after `DestroySSL`, because all queued writes
+  // must be invoked with UV_ECANCELED
+  CHECK_NE(wrap->ssl_, nullptr);
+
   // Handle error
   if (status) {
     // Ignore errors after shutdown
@@ -331,9 +335,6 @@ void TLSWrap::EncOutCb(WriteWrap* req_wrap, int status) {
     return;
   }
 
-  if (wrap->ssl_ == nullptr)
-    return;
-
   // Commit
   NodeBIO::FromBIO(wrap->enc_out_)->Read(nullptr, wrap->write_size_);
 

test/parallel/test-stream-wrap.js

@@ -0,0 +1,39 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+
+const StreamWrap = require('_stream_wrap');
+const Duplex = require('stream').Duplex;
+const ShutdownWrap = process.binding('stream_wrap').ShutdownWrap;
+
+var done = false;
+
+function testShutdown(callback) {
+  var stream = new Duplex({
+    read: function() {
+    },
+    write: function() {
+    }
+  });
+
+  var wrap = new StreamWrap(stream);
+
+  var req = new ShutdownWrap();
+  req.oncomplete = function(code) {
+    assert(code < 0);
+    callback();
+  };
+  req.handle = wrap._handle;
+
+  // Close the handle to simulate
+  wrap.destroy();
+  req.handle.shutdown(req);
+}
+
+testShutdown(function() {
+  done = true;
+});
+
+process.on('exit', function() {
+  assert(done);
+});

test/parallel/test-tls-connect-given-socket.js

@@ -43,16 +43,33 @@ var server = tls.createServer(options, function(socket) {
     });
     assert(client.readable);
     assert(client.writable);
+
+    return client;
   }
 
-  // Already connected socket
-  var connected = net.connect(common.PORT, function() {
-    establish(connected);
+  // Immediate death socket
+  var immediateDeath = net.connect(common.PORT);
+  establish(immediateDeath).destroy();
+
+  // Outliving
+  var outlivingTCP = net.connect(common.PORT);
+  outlivingTCP.on('connect', function() {
+    outlivingTLS.destroy();
+    next();
   });
+  var outlivingTLS = establish(outlivingTCP);
+
+  function next() {
+    // Already connected socket
+    var connected = net.connect(common.PORT, function() {
+      establish(connected);
+    });
+
+    // Connecting socket
+    var connecting = net.connect(common.PORT);
+    establish(connecting);
 
-  // Connecting socket
-  var connecting = net.connect(common.PORT);
-  establish(connecting);
+  }
 });
 
 process.on('exit', function() {