[3/9] serial: imx: Fix out-of-bounds access through DT alias

Message ID 1519119624-1268-4-git-send-email-geert+renesas@glider.be
State New
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Series
  • serial: Fix out-of-bounds accesses through DT aliases
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Commit Message

Geert Uytterhoeven Feb. 20, 2018, 9:40 a.m.
The imx_ports[] array is indexed using a value derived from the
"serialN" alias in DT, which may lead to an out-of-bounds access.

Fix this by adding a range check.

Fixes: 9206ab8a0350c3da ("serial: imx: Fix out-of-bounds access through DT alias")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/tty/serial/imx.c | 5 +++++
 1 file changed, 5 insertions(+)

Comments

Uwe Kleine-König Feb. 20, 2018, 10:31 a.m. | #1
Hello Geert,

On Tue, Feb 20, 2018 at 10:40:18AM +0100, Geert Uytterhoeven wrote:
> The imx_ports[] array is indexed using a value derived from the
> "serialN" alias in DT, which may lead to an out-of-bounds access.
> 
> Fix this by adding a range check.
> 
> Fixes: 9206ab8a0350c3da ("serial: imx: Fix out-of-bounds access through DT alias")

huh, this patch fixes itself?

> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> ---
>  drivers/tty/serial/imx.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 1d7ca382bc12b238..e89e90ad87d8245c 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -2041,6 +2041,11 @@ static int serial_imx_probe(struct platform_device *pdev)
>  		serial_imx_probe_pdata(sport, pdev);
>  	else if (ret < 0)
>  		return ret;

I'd prefer an empty line here.

> +	if (sport->port.line >= UART_NR) {

I would have used:

	if (sport->port.line >= ARRAY_SIZE(imx_ports))

which IMHO is better understandable
> +		dev_err(&pdev->dev, "serial%d out of range\n",
> +			sport->port.line);

Note that the same overflow can happen when a device is probed using
platform data (and your commit fixes that, too). Maybe worth to point
out in the commit log?

Other than that: Good catch, thanks for your patch.

Best regards
Uwe
Geert Uytterhoeven Feb. 20, 2018, 10:49 a.m. | #2
Hi Uwe,

On Tue, Feb 20, 2018 at 11:31 AM, Uwe Kleine-König
<u.kleine-koenig@pengutronix.de> wrote:
> On Tue, Feb 20, 2018 at 10:40:18AM +0100, Geert Uytterhoeven wrote:
>> The imx_ports[] array is indexed using a value derived from the
>> "serialN" alias in DT, which may lead to an out-of-bounds access.
>>
>> Fix this by adding a range check.
>>
>> Fixes: 9206ab8a0350c3da ("serial: imx: Fix out-of-bounds access through DT alias")
>
> huh, this patch fixes itself?

Oops

    Fixes: ff05967a07225ab6 ("serial/imx: add of_alias_get_id() reference back")

>
>> Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
>> ---
>>  drivers/tty/serial/imx.c | 5 +++++
>>  1 file changed, 5 insertions(+)
>>
>> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
>> index 1d7ca382bc12b238..e89e90ad87d8245c 100644
>> --- a/drivers/tty/serial/imx.c
>> +++ b/drivers/tty/serial/imx.c
>> @@ -2041,6 +2041,11 @@ static int serial_imx_probe(struct platform_device *pdev)
>>               serial_imx_probe_pdata(sport, pdev);
>>       else if (ret < 0)
>>               return ret;
>
> I'd prefer an empty line here.

OK

>> +     if (sport->port.line >= UART_NR) {
>
> I would have used:
>
>         if (sport->port.line >= ARRAY_SIZE(imx_ports))
>
> which IMHO is better understandable

OK.

>> +             dev_err(&pdev->dev, "serial%d out of range\n",
>> +                     sport->port.line);
>
> Note that the same overflow can happen when a device is probed using
> platform data (and your commit fixes that, too). Maybe worth to point
> out in the commit log?

That's correct. But board code is tied more intimate to the kernel.
Will update.

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

Patch

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 1d7ca382bc12b238..e89e90ad87d8245c 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -2041,6 +2041,11 @@  static int serial_imx_probe(struct platform_device *pdev)
 		serial_imx_probe_pdata(sport, pdev);
 	else if (ret < 0)
 		return ret;
+	if (sport->port.line >= UART_NR) {
+		dev_err(&pdev->dev, "serial%d out of range\n",
+			sport->port.line);
+		return -EINVAL;
+	}
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	base = devm_ioremap_resource(&pdev->dev, res);