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From: roel kluin <roel.kluin@gmail.com>
Date: Fri, 8 Jan 2010 13:25:29 +0100
Message-ID: <25e057c01001080425q33ea8641ncf940c60700e9410@mail.gmail.com>
Subject: Re: [PATCH] KVM: dereference of NULL pointer in set_pal_result()
To: Gabor Gombas <gombasg@sztaki.hu>
Cc: "Zhang, Xiantao" <xiantao.zhang@intel.com>,
       "kvm-ia64@vger.kernel.org" <kvm-ia64@vger.kernel.org>,
       Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>
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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.

>> >     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);
>
> IMHO it's not the test but the INIT_PAL_STATUS_UNIMPLEMENTED() that does
> the unwanted dereferencing, and that's fixed by the patch.
>
> Gabor

Correct. Thanks,

Roel
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