* [PATCH] gpiolib: Fix return value of gpio_to_desc() stub if !GPIOLIB
@ 2018-12-06 9:45 Krzysztof Kozlowski
2018-12-06 11:54 ` Linus Walleij
2018-12-14 15:06 ` Linus Walleij
0 siblings, 2 replies; 4+ messages in thread
From: Krzysztof Kozlowski @ 2018-12-06 9:45 UTC (permalink / raw)
To: Linus Walleij, Bartosz Golaszewski, Geert Uytterhoeven,
Janusz Krzysztofik, linux-gpio, linux-kernel
Cc: Krzysztof Kozlowski, stable
If CONFIG_GPOILIB is not set, the stub of gpio_to_desc() should return
the same type of error as regular version: NULL. All the callers
compare the return value of gpio_to_desc() against NULL, so returned
ERR_PTR would be treated as non-error case leading to dereferencing of
error value.
Fixes: 79a9becda894 ("gpiolib: export descriptor-based GPIO interface")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
---
include/linux/gpio/consumer.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
index ed070512b40e..3b01fbcafc94 100644
--- a/include/linux/gpio/consumer.h
+++ b/include/linux/gpio/consumer.h
@@ -505,7 +505,7 @@ static inline int gpiod_set_consumer_name(struct gpio_desc *desc,
static inline struct gpio_desc *gpio_to_desc(unsigned gpio)
{
- return ERR_PTR(-EINVAL);
+ return NULL;
}
static inline int desc_to_gpio(const struct gpio_desc *desc)
--
2.7.4
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH] gpiolib: Fix return value of gpio_to_desc() stub if !GPIOLIB
2018-12-06 9:45 [PATCH] gpiolib: Fix return value of gpio_to_desc() stub if !GPIOLIB Krzysztof Kozlowski
@ 2018-12-06 11:54 ` Linus Walleij
2018-12-06 11:59 ` Krzysztof Kozlowski
2018-12-14 15:06 ` Linus Walleij
1 sibling, 1 reply; 4+ messages in thread
From: Linus Walleij @ 2018-12-06 11:54 UTC (permalink / raw)
To: Krzysztof Kozlowski, Dmitry Torokhov
Cc: Bartosz Golaszewski, Geert Uytterhoeven, Janusz Krzysztofik,
open list:GPIO SUBSYSTEM, linux-kernel, stable
On Thu, Dec 6, 2018 at 10:45 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> If CONFIG_GPOILIB is not set, the stub of gpio_to_desc() should return
> the same type of error as regular version: NULL. All the callers
> compare the return value of gpio_to_desc() against NULL, so returned
> ERR_PTR would be treated as non-error case leading to dereferencing of
> error value.
>
> Fixes: 79a9becda894 ("gpiolib: export descriptor-based GPIO interface")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
> ---
> include/linux/gpio/consumer.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
> index ed070512b40e..3b01fbcafc94 100644
> --- a/include/linux/gpio/consumer.h
> +++ b/include/linux/gpio/consumer.h
> @@ -505,7 +505,7 @@ static inline int gpiod_set_consumer_name(struct gpio_desc *desc,
>
> static inline struct gpio_desc *gpio_to_desc(unsigned gpio)
> {
> - return ERR_PTR(-EINVAL);
> + return NULL;
I suppose this is consistent with comitt:
22c403676dbbb7c6f186099527af7f065498ef45
"gpio: return NULL from gpiod_get_optional when GPIOLIB is disabled"
So in that way it should be fine.
I'm just wondering where you see this problem, because IMO
a driver that is using GPIO should either
depends on GPIOLIB or
select GPIOLIB
it is extremely uncommon for a GPIO line to actually be optional at
compile time (as opposed to optional at runtime) so I would very
much like to look closer at this.
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] gpiolib: Fix return value of gpio_to_desc() stub if !GPIOLIB
2018-12-06 11:54 ` Linus Walleij
@ 2018-12-06 11:59 ` Krzysztof Kozlowski
0 siblings, 0 replies; 4+ messages in thread
From: Krzysztof Kozlowski @ 2018-12-06 11:59 UTC (permalink / raw)
To: linus.walleij
Cc: dmitry.torokhov, bgolaszewski, geert+renesas, jmkrzyszt,
linux-gpio, linux-kernel, stable
On Thu, 6 Dec 2018 at 12:55, Linus Walleij <linus.walleij@linaro.org> wrote:
>
> On Thu, Dec 6, 2018 at 10:45 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
>
> > If CONFIG_GPOILIB is not set, the stub of gpio_to_desc() should return
> > the same type of error as regular version: NULL. All the callers
> > compare the return value of gpio_to_desc() against NULL, so returned
> > ERR_PTR would be treated as non-error case leading to dereferencing of
> > error value.
> >
> > Fixes: 79a9becda894 ("gpiolib: export descriptor-based GPIO interface")
> > Cc: <stable@vger.kernel.org>
> > Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
> > ---
> > include/linux/gpio/consumer.h | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/include/linux/gpio/consumer.h b/include/linux/gpio/consumer.h
> > index ed070512b40e..3b01fbcafc94 100644
> > --- a/include/linux/gpio/consumer.h
> > +++ b/include/linux/gpio/consumer.h
> > @@ -505,7 +505,7 @@ static inline int gpiod_set_consumer_name(struct gpio_desc *desc,
> >
> > static inline struct gpio_desc *gpio_to_desc(unsigned gpio)
> > {
> > - return ERR_PTR(-EINVAL);
> > + return NULL;
>
> I suppose this is consistent with comitt:
> 22c403676dbbb7c6f186099527af7f065498ef45
> "gpio: return NULL from gpiod_get_optional when GPIOLIB is disabled"
>
> So in that way it should be fine.
>
> I'm just wondering where you see this problem, because IMO
> a driver that is using GPIO should either
> depends on GPIOLIB or
> select GPIOLIB
> it is extremely uncommon for a GPIO line to actually be optional at
> compile time (as opposed to optional at runtime) so I would very
> much like to look closer at this.
No, I did not hit this error. Maybe I should mention this explicitly
that this case is rather theoretical (feel free to change the commit
msg respectively). What is however important, it misleads developers
which test for ERR_PTR, like before this fix:
2d88a331e48095cf60ad9bdf3177bd401bf99727 ("leds: leds-gpio: Fix return
value check in create_gpio_led()")
Best regards,
Krzysztof
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH] gpiolib: Fix return value of gpio_to_desc() stub if !GPIOLIB
2018-12-06 9:45 [PATCH] gpiolib: Fix return value of gpio_to_desc() stub if !GPIOLIB Krzysztof Kozlowski
2018-12-06 11:54 ` Linus Walleij
@ 2018-12-14 15:06 ` Linus Walleij
1 sibling, 0 replies; 4+ messages in thread
From: Linus Walleij @ 2018-12-14 15:06 UTC (permalink / raw)
To: Krzysztof Kozlowski
Cc: Bartosz Golaszewski, Geert Uytterhoeven, Janusz Krzysztofik,
open list:GPIO SUBSYSTEM, linux-kernel, stable
On Thu, Dec 6, 2018 at 10:45 AM Krzysztof Kozlowski <krzk@kernel.org> wrote:
> If CONFIG_GPOILIB is not set, the stub of gpio_to_desc() should return
> the same type of error as regular version: NULL. All the callers
> compare the return value of gpio_to_desc() against NULL, so returned
> ERR_PTR would be treated as non-error case leading to dereferencing of
> error value.
>
> Fixes: 79a9becda894 ("gpiolib: export descriptor-based GPIO interface")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Patch applied. I kept the Fixes but removed stable, I do not know
of any regression it is fixing.
Yours,
Linus Walleij
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2018-12-14 15:06 UTC | newest]
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2018-12-06 9:45 [PATCH] gpiolib: Fix return value of gpio_to_desc() stub if !GPIOLIB Krzysztof Kozlowski
2018-12-06 11:54 ` Linus Walleij
2018-12-06 11:59 ` Krzysztof Kozlowski
2018-12-14 15:06 ` Linus Walleij
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