Patchwork [1.3,2/2] hmp: do not crash on invalid SCSI hotplug

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Submitter Paolo Bonzini
Date Nov. 23, 2012, 3:56 p.m.
Message ID <1353686178-27520-3-git-send-email-pbonzini@redhat.com>
Download mbox | patch
Permalink /patch/201359/
State New
Headers show

Comments

Paolo Bonzini - Nov. 23, 2012, 3:56 p.m.
Commit 0d93692 (qdev: Convert busses to QEMU Object Model, 2012-05-02)
removed a check on the type of the bus where a SCSI disk is hotplugged.
However, hot-plugging to the wrong kind of device now causes a crash
due to either a NULL pointer dereference (avoided by the previous patch)
or a failed QOM cast.

Instead, in this case we need to use object_dynamic_cast and check for
the result, similar to what was done before that commit.

Reported-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
---
 hw/pci-hotplug.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)
Luiz Capitulino - Nov. 26, 2012, 12:50 p.m.
On Fri, 23 Nov 2012 16:56:18 +0100
Paolo Bonzini <pbonzini@redhat.com> wrote:

> Commit 0d93692 (qdev: Convert busses to QEMU Object Model, 2012-05-02)
> removed a check on the type of the bus where a SCSI disk is hotplugged.
> However, hot-plugging to the wrong kind of device now causes a crash
> due to either a NULL pointer dereference (avoided by the previous patch)
> or a failed QOM cast.
> 
> Instead, in this case we need to use object_dynamic_cast and check for
> the result, similar to what was done before that commit.
> 
> Reported-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

As far as HMP is concerned this looks good.

> ---
>  hw/pci-hotplug.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/pci-hotplug.c b/hw/pci-hotplug.c
> index e7fb780..0ca5546 100644
> --- a/hw/pci-hotplug.c
> +++ b/hw/pci-hotplug.c
> @@ -80,7 +80,13 @@ static int scsi_hot_add(Monitor *mon, DeviceState *adapter,
>      SCSIBus *scsibus;
>      SCSIDevice *scsidev;
>  
> -    scsibus = SCSI_BUS(QLIST_FIRST(&adapter->child_bus));
> +    scsibus = (SCSIBus *)
> +        object_dynamic_cast(OBJECT(QLIST_FIRST(&adapter->child_bus)),
> +                            TYPE_SCSI_BUS);
> +    if (!scsibus) {
> +	error_report("Device is not a SCSI adapter");
> +	return -1;
> +    }
>  
>      /*
>       * drive_init() tries to find a default for dinfo->unit.  Doesn't

Patch

diff --git a/hw/pci-hotplug.c b/hw/pci-hotplug.c
index e7fb780..0ca5546 100644
--- a/hw/pci-hotplug.c
+++ b/hw/pci-hotplug.c
@@ -80,7 +80,13 @@  static int scsi_hot_add(Monitor *mon, DeviceState *adapter,
     SCSIBus *scsibus;
     SCSIDevice *scsidev;
 
-    scsibus = SCSI_BUS(QLIST_FIRST(&adapter->child_bus));
+    scsibus = (SCSIBus *)
+        object_dynamic_cast(OBJECT(QLIST_FIRST(&adapter->child_bus)),
+                            TYPE_SCSI_BUS);
+    if (!scsibus) {
+	error_report("Device is not a SCSI adapter");
+	return -1;
+    }
 
     /*
      * drive_init() tries to find a default for dinfo->unit.  Doesn't