From: Thomas Gleixner <tglx@linutronix.de>
To: Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Cc: syzbot+00be5da1d75f1cc95f6b@syzkaller.appspotmail.com,
Sean Christopherson <sean.j.christopherson@intel.com>
Subject: Re: [PATCH] KVM: x86: remove bogus user-triggerable WARN_ON
Date: Fri, 20 Mar 2020 19:18:42 +0100 [thread overview]
Message-ID: <87tv2i7uv1.fsf@nanos.tec.linutronix.de> (raw)
In-Reply-To: <ef15a35b-3e69-7922-ceda-4a4867054a44@redhat.com>
Paolo Bonzini <pbonzini@redhat.com> writes:
> On 20/03/20 16:23, Thomas Gleixner wrote:
>> Thomas Gleixner <tglx@linutronix.de> writes:
>>
>>> Paolo Bonzini <pbonzini@redhat.com> writes:
>>>> The WARN_ON is essentially comparing a user-provided value with 0. It is
>>>> trivial to trigger it just by passing garbage to KVM_SET_CLOCK. Guests
>>>> can break if you do so, but if it hurts when you do like this just do not
>>>> do it.
>>>
>>> Yes, it's a user provided value and it's completely unchecked. If that
>>> value is bogus then the guest will go sideways because timekeeping is
>>> completely busted. At least you should explain WHY you don't care.
>>
>> Or why it does not matter....
>
> I can change the commit message to "Guests can break if you do so, but
> the same applies to every KVM_SET_* ioctl". It's impossible to be sure
> that userspace doesn't ever send a bogus KVM_SET_CLOCK and later
> rectifies it with the right value.
Yes please.
prev parent reply other threads:[~2020-03-20 18:18 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-19 17:43 Paolo Bonzini
2020-03-19 17:52 ` Sean Christopherson
2020-03-20 15:22 ` Thomas Gleixner
2020-03-20 15:23 ` Thomas Gleixner
2020-03-20 17:47 ` Paolo Bonzini
2020-03-20 18:18 ` Thomas Gleixner [this message]
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