linux-kernel - Re: [PATCH v3 net-next] mdio-mux-gpio: Remove VLA usage

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Message-ID: <CAGXu5j+Y0gJydvqtb0mo8oZPgtWYzqwm+5fYudiUw9V5nMqwqw@mail.gmail.com>
Date:   Mon, 25 Jun 2018 15:39:23 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Joe Perches <joe@...ches.com>
Cc:     "David S. Miller" <davem@...emloft.net>,
        LKML <linux-kernel@...r.kernel.org>,
        Andrew Lunn <andrew@...n.ch>,
        Network Development <netdev@...r.kernel.org>
Subject: Re: [PATCH v3 net-next] mdio-mux-gpio: Remove VLA usage

On Mon, Jun 25, 2018 at 3:23 PM, Joe Perches <joe@...ches.com> wrote:
> On Mon, 2018-06-25 at 15:09 -0700, Kees Cook wrote:
>> In the quest to remove all stack VLA usage from the kernel[1], this
>> allocates the values buffer during the callback instead of putting it
>> on the stack.
>
> []
>
>> diff --git a/drivers/net/phy/mdio-mux-gpio.c b/drivers/net/phy/mdio-mux-gpio.c
> []
>> @@ -44,15 +44,21 @@ static int mdio_mux_gpio_switch_fn(int current_child, int desired_child,
>>  static int mdio_mux_gpio_probe(struct platform_device *pdev)
>>  {
> []
>> +     s = devm_kzalloc(&pdev->dev, sizeof(*s->values) * gpios->ndescs +
>> +                                  sizeof(*s), GFP_KERNEL);
>
> Isn't this supposed to use your new struct_size()

Why yes. Yes it is. :) When treewide changes meet in the night! :)
I'll send a v4.

-Kees

-- 
Kees Cook
Pixel Security