Re: [Qemu-devel] [PATCH] hw/hyperv: fix NULL dereference with pure-kvm SynIC

[Paolo Bonzini <pbonzini@redhat.com>]

On 26/11/18 22:00, Eduardo Habkost wrote:
> On Mon, Nov 26, 2018 at 06:13:49PM +0100, Paolo Bonzini wrote:
>> On 26/11/18 16:28, Roman Kagan wrote:
>>> When started in compat configuration of SynIC, e.g.
>>>
>>> qemu-system-x86_64 -machine pc-i440fx-2.10,accel=kvm \
>>>  -cpu host,-vmx,hv-relaxed,hv_spinlocks=0x1fff,hv-vpindex,hv-synic
>>>
>>> or explicitly
>>>
>>> qemu-system-x86_64 -enable-kvm -cpu host,hv-synic,x-hv-synic-kvm-only=on
>>>
>>> QEMU crashes in hyperv_synic_reset() trying to access the non-present
>>> qobject for SynIC.
>>>
>>> Add the missing check for NULL.
>>>
>>> Reported-by: Vitaly Kuznetsov <vkuznets@redhat.com>
>>> Reported-by: Igor Mammedov <imammedo@redhat.com>
>>> Fixes: 9b4cf107b09d18ac30f46fd1c4de8585ccba030c
>>> Fixes: 4a93722f9c279184e95b1e1ad775c01deec05065
>>> Signed-off-by: Roman Kagan <rkagan@virtuozzo.com>
>>> ---
>>>  hw/hyperv/hyperv.c | 6 +++++-
>>>  1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/hw/hyperv/hyperv.c b/hw/hyperv/hyperv.c
>>> index a28e7249d8..8758635227 100644
>>> --- a/hw/hyperv/hyperv.c
>>> +++ b/hw/hyperv/hyperv.c
>>> @@ -136,7 +136,11 @@ void hyperv_synic_add(CPUState *cs)
>>>  
>>>  void hyperv_synic_reset(CPUState *cs)
>>>  {
>>> -    device_reset(DEVICE(get_synic(cs)));
>>> +    SynICState *synic = get_synic(cs);
>>> +
>>> +    if (synic) {
>>> +        device_reset(DEVICE(synic));
>>> +    }
>>>  }
>>>  
>>>  static const TypeInfo synic_type_info = {
>>>
>>
>> Queued, thanks.
> 
> Oops, I had queued it earlier today and just submitted a pull
> request.

No big deal, it will be included twice. :)

Paolo