Resolves: fdo#75307 discard invalid user data

Change-Id: Id39b51c344004e02d3d5a281ba98721b944468c3
(cherry picked from commit f5b9db43080658201caf07cd646bae4f4f2acc95)
Reviewed-on: https://gerrit.libreoffice.org/8815
Tested-by: Michael Stahl <mstahl@redhat.com>
Reviewed-by: Michael Stahl <mstahl@redhat.com>