CVE-2023-53684

In the Linux kernel, the following vulnerability has been resolved:

xfrm: Zero padding when dumping algos and encap

When copying data to user-space we should ensure that only valid
data is copied over.  Padding in structures may be filled with
random (possibly sensitve) data and should never be given directly
to user-space.

This patch fixes the copying of xfrm algorithms and the encap
template in xfrm_user so that padding is zeroed.