Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
MIME-Version: 1.0
In-Reply-To: <1523366506-19832-4-git-send-email-geert+renesas@glider.be>
References: <1523366506-19832-1-git-send-email-geert+renesas@glider.be> <1523366506-19832-4-git-send-email-geert+renesas@glider.be>
From:   Todd Kjos <tkjos@android.com>
Date:   Wed, 25 Apr 2018 08:56:54 -0700
Message-ID: <CAD0t5oOmch2YG2Gi9X3VSXt2qLKabjRFKO_8fPFo=O8GEE3hWA@mail.gmail.com>
Subject: Re: [PATCH v2 3/4] ARM: amba: Don't read past the end of sysfs
 "driver_override" buffer
To:     Geert Uytterhoeven <geert+renesas@glider.be>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Russell King <linux@armlinux.org.uk>,
        Adrian Salido <salidoa@google.com>,
        Nicolai Stange <nstange@suse.de>,
        Sasha Levin <Alexander.Levin@microsoft.com>,
        LKML <linux-kernel@vger.kernel.org>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Reviewed-by: Todd Kjos <tkjos@android.com>

On Tue, Apr 10, 2018 at 6:21 AM, Geert Uytterhoeven
<geert+renesas@glider.be> wrote:
> When printing the driver_override parameter when it is 4095 and 4094
> bytes long, the printing code would access invalid memory because we
> need count + 1 bytes for printing.
>
> Cfr. commits 4efe874aace57dba ("PCI: Don't read past the end of sysfs
> "driver_override" buffer") and bf563b01c2895a4b ("driver core: platform:
> Don't read past the end of "driver_override" buffer").
>
> Fixes: 3cf385713460eb2b ("ARM: 8256/1: driver coamba: add device binding path 'driver_override'")
> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
>  drivers/amba/bus.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c
> index 36c5653ced5742b7..4a3ac31c07d0ee49 100644
> --- a/drivers/amba/bus.c
> +++ b/drivers/amba/bus.c
> @@ -84,7 +84,8 @@ static ssize_t driver_override_store(struct device *_dev,
>         struct amba_device *dev = to_amba_device(_dev);
>         char *driver_override, *old, *cp;
>
> -       if (count > PATH_MAX)
> +       /* We need to keep extra room for a newline */
> +       if (count >= (PAGE_SIZE - 1))
>                 return -EINVAL;
>
>         driver_override = kstrndup(buf, count, GFP_KERNEL);
> --
> 2.7.4
>