linux-kernel - Re: [PATCH] KVM: Use previously computed array

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Message-ID: <cbf8741e-ede4-af17-309c-666b52883b17@redhat.com>
Date:   Mon, 1 Jun 2020 10:46:47 +0200
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Denis Efremov <efremov@...ux.com>, Joe Perches <joe@...ches.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>
Cc:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] KVM: Use previously computed array_size()

On 30/05/20 19:28, Denis Efremov wrote:
>> On Sat, 2020-05-30 at 17:35 +0300, Denis Efremov wrote:
>>> array_size() is used in alloc calls to compute the allocation
>>> size. Next, "raw" multiplication is used to compute the size
>>> for copy_from_user(). The patch removes duplicated computation
>>> by saving the size in a var. No security concerns, just a small
>>> optimization.
>>>
>>> Signed-off-by: Denis Efremov <efremov@...ux.com>
>> Perhaps use vmemdup_user?
> vmemdup_user() uses kvmalloc internally. I think it will also require
> changing vfree to kvfree.
> 

Yes, it would be a good idea.

Paolo