linux-kernel - Re: [PATCH] x86-ksysfs: Use kmalloc_array() in create_setup_data

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Message-ID: <CAGXu5jLSsU+daPP=uX+3T02RkTFguG1rtemOF-7Py_Fi=qYP6A@mail.gmail.com>
Date:   Tue, 6 Sep 2016 17:49:50 -0400
From:   Kees Cook <keescook@...omium.org>
To:     Ingo Molnar <mingo@...hat.com>
Cc:     SF Markus Elfring <elfring@...rs.sourceforge.net>,
        "x86@...nel.org" <x86@...nel.org>, Dave Young <dyoung@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Matt Fleming <matt.fleming@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        Julia Lawall <julia.lawall@...6.fr>,
        Paolo Bonzini <pbonzini@...hat.com>
Subject: Re: [PATCH] x86-ksysfs: Use kmalloc_array() in create_setup_data_nodes()

On Sun, Sep 4, 2016 at 4:23 PM, SF Markus Elfring
<elfring@...rs.sourceforge.net> wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Sun, 4 Sep 2016 22:15:09 +0200
>
> A multiplication for the size determination of a memory allocation
> indicated that an array data structure should be processed.
> Thus use the corresponding function "kmalloc_array".
>
> This issue was detected by using the Coccinelle software.

Which rule-set was used?

>
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>

While probably impossible to overflow in the real world, it's still
better to use the right function here.

Acked-by: Kees Cook <keescook@...omium.org>

> ---
>  arch/x86/kernel/ksysfs.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/ksysfs.c b/arch/x86/kernel/ksysfs.c
> index 4afc67f..cddf3c6 100644
> --- a/arch/x86/kernel/ksysfs.c
> +++ b/arch/x86/kernel/ksysfs.c
> @@ -283,7 +283,7 @@ static int __init create_setup_data_nodes(struct kobject *parent)
>         if (ret)
>                 goto out_setup_data_kobj;
>
> -       kobjp = kmalloc(sizeof(*kobjp) * nr, GFP_KERNEL);
> +       kobjp = kmalloc_array(nr, sizeof(*kobjp), GFP_KERNEL);
>         if (!kobjp) {
>                 ret = -ENOMEM;
>                 goto out_setup_data_kobj;
> --
> 2.9.3
>



-- 
Kees Cook
Nexus Security