Re: [PATCH] KVM: x86: remove bogus user-triggerable WARN_ON

From: Thomas Gleixner
Date: Fri Mar 20 2020 - 11:23:01 EST


Paolo Bonzini <pbonzini@xxxxxxxxxx> 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.

Thanks,

tglx