linux-kernel - Re: [PATCH 3/4] gpio: Remove VLA from xra1403 driver

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Date:   Wed, 4 Apr 2018 14:53:42 +0200
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Laura Abbott <labbott@...hat.com>
Cc:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        Kees Cook <keescook@...omium.org>,
        "open list:GPIO SUBSYSTEM" <linux-gpio@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH 3/4] gpio: Remove VLA from xra1403 driver

On Wed, Mar 28, 2018 at 7:27 PM, Laura Abbott <labbott@...hat.com> wrote:
> On 03/28/2018 12:27 AM, Geert Uytterhoeven wrote:
>>
>> Hi Laura,
>>
>> On Sat, Mar 10, 2018 at 1:10 AM, Laura Abbott <labbott@...hat.com> wrote:
>>>
>>> The new challenge is to remove VLAs from the kernel
>>> (see https://lkml.org/lkml/2018/3/7/621)
>>>
>>> This patch replaces a VLA with an appropriate call to kmalloc_array.
>>>
>>> Signed-off-by: Laura Abbott <labbott@...hat.com>
>>
>>
>> Thanks for your patch!
>>
>>> --- a/drivers/gpio/gpio-xra1403.c
>>> +++ b/drivers/gpio/gpio-xra1403.c
>>> @@ -126,11 +126,16 @@ static void xra1403_dbg_show(struct seq_file *s,
>>> struct gpio_chip *chip)
>>>   {
>>>          int reg;
>>>          struct xra1403 *xra = gpiochip_get_data(chip);
>>> -       int value[xra1403_regmap_cfg.max_register];
>>
>>
>> Apparently xra1403_regmap_cfg.max_register is always 0x15?
>>
>> What about adding
>>
>>          #define XRA_LAST 15
>>
>> at the top, and replacing both "XRA_IFR | 0x01" and
>> xra1403_regmap_cfg.max_register by XRA_LAST instead?
>> That would avoid doing yet another memory allocation over and over.
>>
>> Gr{oetje,eeting}s,
>>
>>                          Geert
>>
>
> I'm okay with making the change but I think Linus already picked
> up the patch into his gpio trees. Linus, do you want a patch on
> top of your -devel branch or should I just send a new patch?

Yeah a patch on top is fine, I sent my pull request to Torvalds
today so we can take this as a fix for the -rc cycle simply.

Yours,
Linus Walleij