Fix for minimum size check

chrome/browser/process_singleton_win.cc

 // Copyright (c) 2009 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 "chrome/browser/process_singleton.h"
 
 #include "base/base_paths.h"
 #include "base/command_line.h"
 #include "base/process_util.h"
 #include "base/win_util.h"
@@ skipping 151 matching lines @@
     LOG(WARNING) << "Not handling WM_COPYDATA as browser is shutting down";
     return FALSE;
   }
 
   // If locked, it means we are not ready to process this message because
   // we are probably in a first run critical phase.
   if (locked_)
     return TRUE;
 
   // We should have enough room for the shortest command (min_message_size)
-  // and also be a multiple of wchar_t bytes.
+  // and also be a multiple of wchar_t bytes. The shortest command
+  // possible is L"START\0\0" (empty current directory and command line).
   static const int min_message_size = 7;
-  if (cds->cbData < min_message_size || cds->cbData % sizeof(wchar_t) != 0) {
+  if (cds->cbData < min_message_size * sizeof(wchar_t) ||
+      cds->cbData % sizeof(wchar_t) != 0) {
     LOG(WARNING) << "Invalid WM_COPYDATA, length = " << cds->cbData;
     return TRUE;
   }
 
   // We split the string into 4 parts on NULLs.
+  DCHECK(cds->lpData);
   const std::wstring msg(static_cast<wchar_t*>(cds->lpData),
                          cds->cbData / sizeof(wchar_t));
   const std::wstring::size_type first_null = msg.find_first_of(L'\0');
   if (first_null == 0 || first_null == std::wstring::npos) {
     // no NULL byte, don't know what to do
     LOG(WARNING) << "Invalid WM_COPYDATA, length = " << msg.length() <<
       ", first null = " << first_null;
     return TRUE;
   }
 
@@ skipping 57 matching lines @@
   switch (message) {
     case WM_COPYDATA:
       return OnCopyData(reinterpret_cast<HWND>(wparam),
                         reinterpret_cast<COPYDATASTRUCT*>(lparam));
     default:
       break;
   }
 
   return ::DefWindowProc(hwnd, message, wparam, lparam);
 }