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

["Michael S. Tsirkin" <mst@redhat.com>]

On Tue, Aug 22, 2017 at 06:43:43PM -0300, Philippe Mathieu-Daudé wrote:
> 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 <thuth@redhat.com>
> Message-Id: <59a56959-ca12-ea75-33fa-ff07eba1b090@redhat.com>
> Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>

Looks like this is a very old bug, isn't it?
Objections to merging this after the release?

> ---
>  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