linux-kernel - Re: [PATCH v2] [BUGFIX] gpio: reject invalid gpio before getting gpio

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Date:   Tue, 1 Aug 2017 17:35:50 +0900
From:   Masami Hiramatsu <mhiramat@...nel.org>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     "linux-gpio@...r.kernel.org" <linux-gpio@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andy Shevchenko <andy.shevchenko@...il.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Masami Hiramatsu <masami.hiramatsu@...aro.org>,
        Jassi Brar <jaswinder.singh@...aro.org>
Subject: Re: [PATCH v2] [BUGFIX] gpio: reject invalid gpio before getting
 gpio_desc

On Tue, 1 Aug 2017 10:09:09 +0200
Linus Walleij <linus.walleij@...aro.org> wrote:

> On Mon, Jul 31, 2017 at 3:57 AM, Masami Hiramatsu <mhiramat@...nel.org> wrote:
> 
> > Check user-given gpio number and reject it before
> > calling gpio_to_desc() because gpio_to_desc() is
> > for kernel driver and it expects given gpio number
> > is valid (means 0 to 511).
> > If given number is invalid, gpio_to_desc() calls
> > WARN() and dump registers and stack for debug.
> > This means user can easily kick WARN() just by
> > writing invalid gpio number (e.g. 512) to
> > /sys/class/gpio/export.
> >
> > Fixes: 0e9a5edf5d01 ("gpio: fix deferred probe detection for legacy API")
> > Signed-off-by: Masami Hiramatsu <mhiramat@...nel.org>
> > ---
> >   Changes in v2:
> >    - Add gpio_to_valid_desc() according to Andy's comment (Thanks!).
> >    - Fix patch description.
> 
> I hate the old sysfs ABI sigh. Thanks for fixing it anyways!
> 
> Should this be tagged for stable?

Yes, I think so. Since this has been introduced 3 years ago,
it would be nice to go to older stable trees too.

Thanks,

> 
> Waiting for Andy's review before applying.
> 
> Yours,
> Linus Walleij


-- 
Masami Hiramatsu <mhiramat@...nel.org>