Re: [Qemu-devel] [PATCH] s390: avoid potential null dereference in s390_pcihost_unplug()

[Cornelia Huck <cohuck@redhat.com>]

On Thu,  3 Jan 2019 06:02:46 -0800
Li Qiang <liq3ea@163.com> wrote:

> When getting the 'pbdev', the if...else has no default branch.
> From Coverity, the 'pbdev' maybe null when the 'dev' is not
> the TYPE_PCI_BRIDGE/TYPE_PCI_DEVICE/TYPE_S390_PCI_DEVICE.
> 
> Spotted by Coverity: CID 1398593
> 
> Signed-off-by: Li Qiang <liq3ea@163.com>
> ---
>  hw/s390x/s390-pci-bus.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/hw/s390x/s390-pci-bus.c b/hw/s390x/s390-pci-bus.c
> index 15759b6514..b3122268a3 100644
> --- a/hw/s390x/s390-pci-bus.c
> +++ b/hw/s390x/s390-pci-bus.c
> @@ -956,6 +956,10 @@ static void s390_pcihost_unplug(HotplugHandler *hotplug_dev, DeviceState *dev,
>      } else if (object_dynamic_cast(OBJECT(dev), TYPE_S390_PCI_DEVICE)) {
>          pbdev = S390_PCI_DEVICE(dev);
>          pci_dev = pbdev->pdev;
> +    } else {
> +        error_setg(errp, "s390: device unplug for not supported device"
> +                   " type: %s", object_get_typename(OBJECT(dev)));
> +        return;

I think that is something that really Should Not Happen. However,
looking at s390_pcihost_plug, we just do nothing if the plugged device
does not match any of the expected three values. Maybe we should also
set an error in that case there?

>      }
>  
>      switch (pbdev->state) {