linux-kernel - Re: [PATCH] KVM: x86: remove bogus user-triggerable WARN

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Message-ID: <20200319175259.GE11305@linux.intel.com>
Date:   Thu, 19 Mar 2020 10:52:59 -0700
From:   Sean Christopherson <sean.j.christopherson@...el.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        syzbot+00be5da1d75f1cc95f6b@...kaller.appspotmail.com
Subject: Re: [PATCH] KVM: x86: remove bogus user-triggerable WARN_ON

On Thu, Mar 19, 2020 at 01:43:18PM -0400, Paolo Bonzini wrote:
> 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.
> 
> Reported-by: syzbot+00be5da1d75f1cc95f6b@...kaller.appspotmail.com
> Fixes: 9446e6fce0ab ("KVM: x86: fix WARN_ON check of an unsigned less than zero")
> Cc: Sean Christopherson <sean.j.christopherson@...el.com>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---

Reviewed-by: Sean Christopherson <sean.j.christopherson@...el.com>