vhost/vdpa: reject overflowing PA map page counts on 32-bit

vhost/vdpa: reject overflowing PA map page counts on 32-bit

vhost_vdpa_pa_map() adds the IOVA page offset to the user-controlled map
size before computing the number of pages to pin. On 32-bit systems,
where unsigned long is narrower than u64, that addition can overflow and
the code can pin and map fewer pages than the requested IOTLB range.

Reject sizes that overflow the unsigned long page-count calculation.

Fixes: 22af48cf91aa ("vdpa: factor out vhost_vdpa_pa_map() and vhost_vdpa_pa_unmap()")
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Yousef Alhouseen <alhouseenyousef@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Message-ID: <CAMuQ4bX-iDvcUOPPY+NLz95tkRJYwWqvzAr=U48uNaub_HZLGw@mail.gmail.com>