Setting nfheader_len in xfrm_policy.c

header_len += xfrm[i]->props.header_len;
if (xfrm[i]->type->flags & XFRM_TYPE_NON_FRAGMENT)
    nfheader_len += xfrm[i]->props.header_len;
...
xfrm_init_path((struct xfrm_dst *)dst0, dst, nfheader_len);