Only take basename of default_file_name when starting a File Chooser.

content/browser/renderer_host/render_view_host_impl.cc

 // Copyright (c) 2012 The Chromium 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 "content/browser/renderer_host/render_view_host_impl.h"
 
 #include <set>
 #include <string>
 #include <utility>
 #include <vector>
@@ skipping 1377 matching lines @@
   HostZoomMapImpl* host_zoom_map =
       static_cast<HostZoomMapImpl*>(HostZoomMap::Get(GetSiteInstance()));
 
   host_zoom_map->SetZoomLevelForView(GetProcess()->GetID(),
                                      GetRoutingID(),
                                      zoom_level,
                                      net::GetHostOrSpecFromURL(url));
 }
 
 void RenderViewHostImpl::OnRunFileChooser(const FileChooserParams& params) {
+  // Do not allow messages with absolute paths in them as this can permit a
+  // renderer to coerce the browser to perform I/O on a renderer controlled
+  // path.
+  if (params.default_file_name != params.default_file_name.BaseName()) {
+    GetProcess()->ReceivedBadMessage();
+    return;
+  }
+
   delegate_->RunFileChooser(this, params);
 }
 
 void RenderViewHostImpl::OnFocusedNodeTouched(bool editable) {
 #if defined(OS_WIN)
   if (editable) {
     virtual_keyboard_requested_ = base::win::DisplayVirtualKeyboard();
     delegate_->SetIsVirtualKeyboardRequested(true);
   } else {
     virtual_keyboard_requested_ = false;
@@ skipping 31 matching lines @@
   FrameTree* frame_tree = delegate_->GetFrameTree();
 
   frame_tree->ResetForMainFrameSwap();
 }
 
 void RenderViewHostImpl::SelectWordAroundCaret() {
   Send(new ViewMsg_SelectWordAroundCaret(GetRoutingID()));
 }
 
 }  // namespace content