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

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Message-ID: <90ca44b5-52d0-be74-f36c-55d6f4a9bf25@redhat.com>
Date:   Wed, 28 Mar 2018 10:27:09 -0700
From:   Laura Abbott <labbott@...hat.com>
To:     Geert Uytterhoeven <geert@...ux-m68k.org>
Cc:     Linus Walleij <linus.walleij@...aro.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 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?

Thanks,
Laura