PtrCtrl really makes sense for relative pointing device only, absolute
devices such as touch devices do not have any PtrCtrl set.
In some cases, if the client issues a XGetPointerControl() immediatlely
after a ChangeMasterDeviceClasses() copied the touch device to the VCP,
a NULL pointer dereference will occur leading to a crash of Xwayland.
Check whether the PtrCtrl is not NULL in ProcGetPointerControl() and
return the default control values otherwise, to avoid the NULL pointer
dereference.
Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1519533
Reviewed-by: Adam Jackson <ajax@redhat.com>
Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
9f7a9be13d