Steps:

1) Create an InputField (GameObject - UI - InputField)
2) Go in Play mode then type something inside in either Korean, Japanese or Chinese
3) Select the InputField in the Hierarchy, then change its text through its Inspector
4) Returns the following error in the console:

ArgumentOutOfRangeException: startIndex + length > this.length
Parameter name: length
System.String.Substring (Int32 startIndex, Int32 length) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System/String.cs:356)
UnityEngine.UI.InputField.UpdateLabel () (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/InputField.cs:1656)
UnityEngine.UI.InputField.OnValidate () (at C:/buildslave/unity/build/Extensions/guisystem/UnityEngine.UI/UI/Core/InputField.cs:547)
UnityEngine.GUIUtility:ProcessEvent(Int32, IntPtr)

Expected result: the InputField update along the modifications in the Inspector
Actual result: InputField freezes, no longer update