[Qemu-devel] [PATCH for-2.10-rc4?] acpi: pcihp: fix use-after-free for machines previous pc-1.7 compat

[Philippe Mathieu-Daudé]

9e047b982452 "piix4: add acpi pci hotplug support" introduced a new property
'use_acpi_pci_hotplug' for pc-1.7 and older machines.
c24d5e0b91d1 "convert ACPI PCI hotplug to use hotplug-handler API" added the
qbus hotplug handlers but forgot to check for the 'use_acpi_pci_hotplug'
property.

Check for use_acpi_pci_hotplug before calling acpi_pcihp_device_[un]plug_cb().

If Xen is enabled, piix4_pm_init() disables use_acpi_pci_hotplug.

The following valgrind Trace equivs:

  qdev_device_add( "ich9-ahci" )
   -> device_set_realized()
    -> hotplug_handler_plug()
     -> piix4_device_plug_cb()
      -> acpi_pcihp_device_plug_cb()
       -> acpi_pcihp_get_bsel() "Property ACPI_PCIHP_PROP_BSEL not found"
   -> object_unparent()
     <- "Bus doesn't have property ACPI_PCIHP_PROP_BSEL set"

$ valgrind x86_64-softmmu/qemu-system-x86_64 -M pc-1.2 -nographic -S
(qemu) device_add ich9-ahci,id=ich9-ahci
==6604== Invalid read of size 8
==6604==    at 0x609AB0: object_unparent (object.c:445)
==6604==    by 0x4C4478: device_unparent (qdev.c:1095)
==6604==    by 0x60A364: object_finalize_child_property (object.c:1396)
==6604==    by 0x6092A6: object_property_del_child.isra.7 (object.c:427)
==6604==    by 0x451728: qdev_device_add (qdev-monitor.c:634)
==6604==    by 0x451C82: qmp_device_add (qdev-monitor.c:807)
==6604==    by 0x46B689: hmp_device_add (hmp.c:1925)
==6604==    by 0x364083: handle_hmp_command (monitor.c:3119)
==6604==    by 0x365439: monitor_command_cb (monitor.c:3922)
==6604==    by 0x6E5D27: readline_handle_byte (readline.c:393)
==6604==    by 0x364311: monitor_read (monitor.c:3905)
==6604==    by 0x67C573: mux_chr_read (char-mux.c:216)
==6604==  Address 0x15fc5448 is 30,328 bytes inside a block of size 36,288 
free'd
==6604==    at 0x4C2ACDD: free (vg_replace_malloc.c:530)
==6604==    by 0xA04EBCD: g_free (in /usr/lib64/libglib-2.0.so.0.5000.3)
==6604==    by 0x50100E: pci_ich9_uninit (ich.c:161)
==6604==    by 0x5428AB: pci_qdev_unrealize (pci.c:1083)
==6604==    by 0x4C5EE9: device_set_realized (qdev.c:988)
==6604==    by 0x608DCD: property_set_bool (object.c:1886)
==6604==    by 0x60CEBE: object_property_set_qobject (qom-qobject.c:27)
==6604==    by 0x60AB6F: object_property_set_bool (object.c:1162)
==6604==    by 0x4516F3: qdev_device_add (qdev-monitor.c:630)
==6604==    by 0x451C82: qmp_device_add (qdev-monitor.c:807)
==6604==    by 0x46B689: hmp_device_add (hmp.c:1925)
==6604==    by 0x364083: handle_hmp_command (monitor.c:3119)
==6604==  Block was alloc'd at
==6604==    at 0x4C2B975: calloc (vg_replace_malloc.c:711)
==6604==    by 0xA04EB15: g_malloc0 (in /usr/lib64/libglib-2.0.so.0.5000.3)
==6604==    by 0x50094F: ahci_realize (ahci.c:1468)
==6604==    by 0x501098: pci_ich9_ahci_realize (ich.c:115)
==6604==    by 0x543E6D: pci_qdev_realize (pci.c:2002)
==6604==    by 0x4C5E69: device_set_realized (qdev.c:914)
==6604==    by 0x608DCD: property_set_bool (object.c:1886)
==6604==    by 0x60CEBE: object_property_set_qobject (qom-qobject.c:27)
==6604==    by 0x60AB6F: object_property_set_bool (object.c:1162)
==6604==    by 0x4516F3: qdev_device_add (qdev-monitor.c:630)
==6604==    by 0x451C82: qmp_device_add (qdev-monitor.c:807)
==6604==    by 0x46B689: hmp_device_add (hmp.c:1925)

Reported-by: Thomas Huth <address@hidden>
Message-Id: <address@hidden>
Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
 hw/acpi/piix4.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/hw/acpi/piix4.c b/hw/acpi/piix4.c
index f276967365..d4df209a2e 100644
--- a/hw/acpi/piix4.c
+++ b/hw/acpi/piix4.c
@@ -385,7 +385,7 @@ static void piix4_device_plug_cb(HotplugHandler 
*hotplug_dev,
                                 dev, errp);
         }
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
-        if (!xen_enabled()) {
+        if (s->use_acpi_pci_hotplug) {
             acpi_pcihp_device_plug_cb(hotplug_dev, &s->acpi_pci_hotplug, dev,
                                       errp);
         }
@@ -411,7 +411,7 @@ static void piix4_device_unplug_request_cb(HotplugHandler 
*hotplug_dev,
         acpi_memory_unplug_request_cb(hotplug_dev, &s->acpi_memory_hotplug,
                                       dev, errp);
     } else if (object_dynamic_cast(OBJECT(dev), TYPE_PCI_DEVICE)) {
-        if (!xen_enabled()) {
+        if (s->use_acpi_pci_hotplug) {
             acpi_pcihp_device_unplug_cb(hotplug_dev, &s->acpi_pci_hotplug, dev,
                                         errp);
         }
-- 
2.14.1