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From:   Geert Uytterhoeven <geert@linux-m68k.org>
Date:   Wed, 31 Jul 2019 11:27:02 +0200
Message-ID: <CAMuHMdWhA2xxKKEmmobZDDKGnWNfO4xDb6m6gM16CCFX-1UyTQ@mail.gmail.com>
Subject: Re: [PATCH] phy: renesas: rcar-gen3-usb2: Fix sysfs interface of "role"
To:     Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc:     Kishon Vijay Abraham I <kishon@ti.com>,
        Pavel Machek <pavel@denx.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Linux-Renesas <linux-renesas-soc@vger.kernel.org>,
        stable <stable@vger.kernel.org>
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Hi Shimoda-san,

On Wed, Jul 31, 2019 at 11:04 AM Yoshihiro Shimoda
<yoshihiro.shimoda.uh@renesas.com> wrote:
> Since the role_store() uses strncmp(), it's possible to refer
> out-of-memory if the sysfs data size is smaller than strlen("host").
> This patch fixes it by using sysfs_streq() instead of strncmp().
>
> Reported-by: Pavel Machek <pavel@denx.de>
> Fixes: 9bb86777fb71 ("phy: rcar-gen3-usb2: add sysfs for usb role swap")
> Cc: <stable@vger.kernel.org> # v4.10+
> Signed-off-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

> ---
>  Just a record. The role_store() doesn't need to check the count because
>  the sysfs_streq() checks the first argument is NULL or not.

Is that wat you mean? sysfs_streq() doesn't seem to check for NULL pointers.

Isn't the real reason that sysfs (kernfs) guarantees that the passed buffer
is NUL-terminated?

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds