[PATCH 6/9] gnttab: check handle early in gnttab_get_status_frames()

[Jan Beulich]

Like done in gnttab_setup_table(), check the handle once early in the
function and use the lighter-weight (for PV) copying function in the
loop.

Signed-off-by: Jan Beulich <jbeul...@suse.com>

--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -3261,6 +3261,9 @@ gnttab_get_status_frames(XEN_GUEST_HANDL
         return -EFAULT;
     }
 
+    if ( !guest_handle_okay(op.frame_list, op.nr_frames) )
+        return -EFAULT;
+
     d = rcu_lock_domain_by_any_id(op.dom);
     if ( d == NULL )
     {
@@ -3301,7 +3304,7 @@ gnttab_get_status_frames(XEN_GUEST_HANDL
     for ( i = 0; i < op.nr_frames; i++ )
     {
         gmfn = gfn_x(gnttab_status_gfn(d, gt, i));
-        if ( copy_to_guest_offset(op.frame_list, i, &gmfn, 1) )
+        if ( __copy_to_guest_offset(op.frame_list, i, &gmfn, 1) )
             op.status = GNTST_bad_virt_addr;
     }