fix security issue
fix security issue

Change-Id: If5425a3caf4b80097e20a5686acd1d036fcb1cd2
Reviewed-on: http://cr.qtquick.me/498
Tested-by: http://ci.qtquick.me/
Reviewed-by: Tasuku Suzuki <42980d970444f9101663582e70cd53623b3238b4@gmail.com>
Tested-by: Tasuku Suzuki <42980d970444f9101663582e70cd53623b3238b4@gmail.com>

yatsek/silk,yatsek/silk,qt-users-jp/silk,yatsek/silk,qt-users-jp/silk,qt-users-jp/silk,yatsek/silk,qt-users-jp/silk