linux-kernel - Re: [PATCH v2 1/7] gpio: mockup: improve the debugfs input sanitization

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Message-ID: <CAHp75VeJdqsXJ_ASTABijcj=-6BWkbAy8PofFyFTZ_1rtGVjQg@mail.gmail.com>
Date:   Tue, 30 May 2017 21:52:43 +0300
From:   Andy Shevchenko <andy.shevchenko@...il.com>
To:     Bartosz Golaszewski <brgl@...ev.pl>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Alexandre Courbot <gnurou@...il.com>,
        Bamvor Jian Zhang <bamvor.zhangjian@...aro.org>,
        "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 1/7] gpio: mockup: improve the debugfs input sanitization

On Tue, May 30, 2017 at 11:58 AM, Bartosz Golaszewski <brgl@...ev.pl> wrote:
> We're currently only checking the first character of the input to the
> debugfs event files, so a string like '0sdfdsf' is valid and indicates
> a falling edge event.
>
> Be more strict and only allow '0', '1', '0\n' & '1\n'.
>
> While we're at it: move the sanitization code before the irq_enabled
> check so that we indicate an error on invalid input even if nobody is
> waiting for events.

> -       int val;
> -       char buf;
> +       int rv, val;

> +       rv = kstrtoint_from_user(usr_buf, size, 0, &val);
> +       if (rv)
> +               return rv;

> +       if (val != 0 && val != 1)

Wouldn't be easier to have

u8 rv;

ret = kstrtu8_from_user();
if (ret >= 2)
 return ...;

?

> +               return -EINVAL;

-- 
With Best Regards,
Andy Shevchenko