linux-kernel - Re: [PATCH] KVM: ioapic: fix NULL deref ioapic->lock

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Message-ID: <CANRm+Cy8mdqM-i_MBHxY6=Nbf=wdTN+k_2pcjEZc0BOZQzPwGg@mail.gmail.com>
Date:   Wed, 4 Jan 2017 06:03:52 +0800
From:   Wanpeng Li <kernellwp@...il.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     David Hildenbrand <david@...hat.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        KVM list <kvm@...r.kernel.org>,
        Radim Krčmář <rkrcmar@...hat.com>,
        Wanpeng Li <wanpeng.li@...mail.com>
Subject: Re: [PATCH] KVM: ioapic: fix NULL deref ioapic->lock

2017-01-04 1:23 GMT+08:00 Paolo Bonzini <pbonzini@...hat.com>:
>
>
> On 03/01/2017 13:06, David Hildenbrand wrote:
>>>
>>>      switch (cap->cap) {
>>>      case KVM_CAP_HYPERV_SYNIC:
>>> -        return kvm_hv_activate_synic(vcpu);
>>> +        if (!irqchip_in_kernel(vcpu->kvm))
>>> +            return -EINVAL;
>>> +        else
>>
>> You can simply drop the else and return directly.
>>
>> Can't really say if this is the right fix, my first thought was that
>> a request has been set although it should never have been set for
>> that VCPU. Maybe that is an effect of synic being activated
>> (because synic code unconditionally later on sets the request).
>>
>> Fixing the cause of the request seems better than fixing up the result.
>
> Yes, I agree.  Wanpeng's second patch is fine.

Thanks Paolo, I will send out a formal one soon.

Regards,
Wanpeng Li