From mboxrd@z Thu Jan  1 00:00:00 1970
From: Diego Ongaro <diego.ongaro@citrix.com>
Subject: [PATCH] gnttab_setup_table error case
Date: Wed, 30 Jul 2008 14:17:39 +0100
Message-ID: <489069F3.7070200@citrix.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Return-path: <xen-devel-bounces@lists.xensource.com>
List-Unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
List-Post: <mailto:xen-devel@lists.xensource.com>
List-Help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-Subscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>,
	<mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
Sender: xen-devel-bounces@lists.xensource.com
Errors-To: xen-devel-bounces@lists.xensource.com
To: xen-devel@lists.xensource.com
List-Id: xen-devel@lists.xenproject.org

gnttab_setup_table should set an error status code if the gmfn it gets
for a grant table page is invalid.

I ran into this issue when I tried to set up the grant table during hvm
domain creation, and it caused a BUG_ON later down the line. With this
patch, the hypercall will gracefully fail instead.

Signed-off-by: Diego Ongaro <diego.ongaro@citrix.com>
---
diff --git a/xen/common/grant_table.c b/xen/common/grant_table.c
--- a/xen/common/grant_table.c
+++ b/xen/common/grant_table.c
@@ -913,8 +913,15 @@ gnttab_setup_table(
     op.status = GNTST_okay;
     for ( i = 0; i < op.nr_frames; i++ )
     {
         gmfn = gnttab_shared_gmfn(d, d->grant_table, i);
+        if ( gmfn == -1 )
+        {
+            gdprintk(XENLOG_INFO,
+                    "grant table gmfn unavailable\n");
+            op.status = GNTST_general_error;
+            goto out3;
+        }
         (void)copy_to_guest_offset(op.frame_list, i, &gmfn, 1);
     }
 
  out3: