$NetBSD: patch-XSA139,v 1.1 2015/08/23 17:02:58 spz Exp $

patch for CVE-2015-5166 aka XSA-139 from
http://xenbits.xen.org/xsa/xsa139-qemuu-4.5.patch

--- qemu-xen/hw/ide/piix.c.orig	2015-06-10 11:43:51.000000000 +0000
+++ qemu-xen/hw/ide/piix.c
@@ -172,6 +172,7 @@ int pci_piix3_xen_ide_unplug(DeviceState
     PCIIDEState *pci_ide;
     DriveInfo *di;
     int i = 0;
+    IDEDevice *idedev;
 
     pci_ide = PCI_IDE(dev);
 
@@ -184,6 +185,12 @@ int pci_piix3_xen_ide_unplug(DeviceState
             }
             bdrv_close(di->bdrv);
             pci_ide->bus[di->bus].ifs[di->unit].bs = NULL;
+            if (!(i % 2)) {
+                idedev = pci_ide->bus[di->bus].master;
+            } else {
+                idedev = pci_ide->bus[di->bus].slave;
+            }
+            idedev->conf.bs = NULL;
             drive_put_ref(di);
         }
     }