gnttab: correct pin status fixup for copy

Regardless of copy operations only setting GNTPIN_hst*, GNTPIN_dev*
also need to be taken into account when deciding whether to clear
_GTF_{read,writ}ing. At least for consistency with code elsewhere the
read part better doesn't use any mask at all.

This is XSA-230.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>
master commit: 6e2a4c7356
master date: 2017-08-15 15:08:03 +0200

xen/common/grant_table.c

@@ -2122,10 +2122,10 @@ __release_grant_for_copy(
 static void __fixup_status_for_copy_pin(const struct active_grant_entry *act,
                                    uint16_t *status)
 {
-    if ( !(act->pin & GNTPIN_hstw_mask) )
+    if ( !(act->pin & (GNTPIN_hstw_mask | GNTPIN_devw_mask)) )
         gnttab_clear_flag(_GTF_writing, status);
 
-    if ( !(act->pin & GNTPIN_hstr_mask) )
+    if ( !act->pin )
         gnttab_clear_flag(_GTF_reading, status);
 }
 
@@ -2333,7 +2333,7 @@ __acquire_grant_for_copy(
  
  unlock_out_clear:
     if ( !(readonly) &&
-         !(act->pin & GNTPIN_hstw_mask) )
+         !(act->pin & (GNTPIN_hstw_mask | GNTPIN_devw_mask)) )
         gnttab_clear_flag(_GTF_writing, status);
 
     if ( !act->pin )