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Date:   Tue, 12 Jul 2022 21:27:53 +0200
From:   Heiko Carstens <hca@linux.ibm.com>
To:     Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc:     Steffen Eiden <seiden@linux.ibm.com>,
        Alexander Gordeev <agordeev@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Janosch Frank <frankja@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>, linux-s390@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org, nrb@linux.ibm.com
Subject: Re: [PATCH 1/3] s390/cpufeature: rework to allow more than only
 hwcap bits
Message-ID: <Ys3LOT/fGcGo+4Eh@osiris>
References: <20220712105220.325010-1-seiden@linux.ibm.com>
 <20220712105220.325010-2-seiden@linux.ibm.com>
 <20220712184619.45edd420@p-imbrenda>
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On Tue, Jul 12, 2022 at 06:46:19PM +0200, Claudio Imbrenda wrote:
> > +int cpu_have_feature(unsigned int num)
> > +{
> > +	struct s390_cpu_feature *feature;
> > +
> > +	feature = &s390_cpu_features[num];
> 
> I would put some check to make sure you are going past the end of the
> array. 
> 
> Maybe something like
> 
> if (num >= MAX_CPU_FEATURES) {
> 	WARN(1, "Invalid feature %d", num);
> 	return 0;

That makes sense. I would go for a simple

	if (WARN_ON_ONCE(num >= MAX_CPU_FEATURES))
		return 0;