From: "Zhang, Xiantao" <xiantao.zhang@intel.com>
To: Roel Kluin <roel.kluin@gmail.com>,
       "kvm-ia64@vger.kernel.org" <kvm-ia64@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>
Date: Fri, 8 Jan 2010 07:28:57 +0800
Subject: RE: [PATCH] KVM: dereference of NULL pointer in set_pal_result()
Thread-Topic: [PATCH] KVM: dereference of NULL pointer in set_pal_result()
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References: <4B465C2D.8030303@gmail.com>
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For the check "(p && p->exit_reason == EXIT_REASON_PAL_CALL", if p is NULL, the reference about "p->exit_reason == EXIT_REASON_PAL_CALL" won't be checked any more, so no issue here. 
Xiantao


Roel Kluin wrote:
> Do not dereference a NULL pointer
> 
> Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
> ---
>  arch/ia64/kvm/kvm_fw.c |    6 ++++--
>  1 files changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/ia64/kvm/kvm_fw.c b/arch/ia64/kvm/kvm_fw.c
> index e4b8231..d28494f 100644
> --- a/arch/ia64/kvm/kvm_fw.c
> +++ b/arch/ia64/kvm/kvm_fw.c
> @@ -75,9 +75,11 @@ static void set_pal_result(struct kvm_vcpu *vcpu,
>  	struct exit_ctl_data *p;
> 
>  	p = kvm_get_exit_data(vcpu);
> -	if (p && p->exit_reason == EXIT_REASON_PAL_CALL) {
> +	if (!p)
> +		return;
> +	if (p->exit_reason == EXIT_REASON_PAL_CALL) {
>  		p->u.pal_data.ret = result;
> -		return ;
> +		return;
>  	}
>  	INIT_PAL_STATUS_UNIMPLEMENTED(p->u.pal_data.ret);
>  }

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