linux-kernel - Re: [PATCH 2/4] KVM: x86: zero base3 of unusable segments

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Message-ID: <30aa71c2-065c-6cd4-298b-a50fbc3d6feb@redhat.com>
Date:   Fri, 19 May 2017 15:30:59 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Radim Krčmář <rkrcmar@...hat.com>,
        linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Paolo Bonzini <pbonzini@...hat.com>,
        Dan Carpenter <dan.carpenter@...cle.com>
Subject: Re: [PATCH 2/4] KVM: x86: zero base3 of unusable segments

On 18.05.2017 19:37, Radim Krčmář wrote:
> Static checker noticed that base3 could be used uninitialized if the
> segment was not present (useable).  Random stack values probably would
> not pass VMCS entry checks.
> 
> Reported-by:  Dan Carpenter <dan.carpenter@...cle.com>
> Fixes: 1aa366163b8b ("KVM: x86 emulator: consolidate segment accessors")
> Signed-off-by: Radim Krčmář <rkrcmar@...hat.com>
> ---
>  arch/x86/kvm/x86.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index b54125b590e8..eed8272dd52e 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -5053,6 +5053,8 @@ static bool emulator_get_segment(struct x86_emulate_ctxt *ctxt, u16 *selector,
>  
>  	if (var.unusable) {
>  		memset(desc, 0, sizeof(*desc));
> +		if (base3)
> +			*base3 = 0;
>  		return false;
>  	}
>  
> 

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 

Thanks,

David