Disable direct write if font count in registry is greater than or equal to threshold (currently 175…

content/common/sandbox_win.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/common/sandbox_win.h"
 
 #include <string>
 
 #include "base/base_switches.h"
 #include "base/command_line.h"
 #include "base/debug/profiler.h"
 #include "base/debug/trace_event.h"
 #include "base/file_util.h"
 #include "base/hash.h"
 #include "base/metrics/field_trial.h"
 #include "base/path_service.h"
 #include "base/process/launch.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/win/iat_patch_function.h"
+#include "base/win/registry.h"
 #include "base/win/scoped_handle.h"
 #include "base/win/scoped_process_information.h"
 #include "base/win/windows_version.h"
 #include "content/public/common/content_client.h"
 #include "content/public/common/content_switches.h"
 #include "content/public/common/sandbox_init.h"
 #include "content/public/common/sandboxed_process_launcher_delegate.h"
 #include "sandbox/win/src/process_mitigations.h"
 #include "sandbox/win/src/sandbox.h"
 #include "sandbox/win/src/sandbox_nt_util.h"
@@ skipping 565 matching lines @@
       *base::CommandLine::ForCurrentProcess();
   if (command_line.HasSwitch(switches::kDisableDirectWrite))
     return false;
 
 #if !defined(NACL_WIN64)
   // Can't use GDI on HiDPI.
   if (gfx::GetDPIScale() > 1.0f)
     return true;
 #endif
 
+  // We have logic in renderer_font_platform_win.cc for falling back to safe
+  // font list if machine has more than 1750 fonts installed. Users have
+  // complained about this as safe font list is usually not sufficient.
+  // We now disable direct write (gdi) if we encounter more number
+  // of fonts than a threshold (currently 1750).
+  // Refer: crbug.com/421305
+  const wchar_t kWindowsFontsRegistryKey[] =
+      L"SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\Fonts";
+  base::win::RegistryValueIterator reg_iterator(HKEY_LOCAL_MACHINE,
+                                                kWindowsFontsRegistryKey);
+  const DWORD kMaxAllowedFontsBeforeFallbackToGDI = 1750;
+  if (reg_iterator.ValueCount() >= kMaxAllowedFontsBeforeFallbackToGDI)
+    return false;
+
   // Otherwise, check the field trial.
   const std::string group_name =
       base::FieldTrialList::FindFullName("DirectWrite");
   return group_name != "Disabled";
 }
 
 base::ProcessHandle StartSandboxedProcess(
     SandboxedProcessLauncherDelegate* delegate,
     base::CommandLine* cmd_line) {
   const base::CommandLine& browser_command_line =
@@ skipping 173 matching lines @@
   }
 
   return false;
 }
 
 bool BrokerAddTargetPeer(HANDLE peer_process) {
   return g_broker_services->AddTargetPeer(peer_process) == sandbox::SBOX_ALL_OK;
 }
 
 }  // namespace content