[PATCH] gpiolib: of: reset name variable in of_gpiochip_add_hog

[PATCH] gpiolib: of: reset name variable in of_gpiochip_add_hog

[trix]

From: Tom Rix <trix@redhat.com>

Clang static analysis reports this error

gpiolib-of.c:664:9: warning: 2nd function call argument
  is an uninitialized value [core.CallAndMessage]
        ret = gpiod_hog(desc, name, lflags, dflags);

name is sometimes set by of_parse_own_gpio
name is always used by gpiod_hog

So it is necessary to reset name so an old value is
not mistakenly used by gpiod_hog.

Fixes: bc21077e084b ("gpio: of: Extract of_gpiochip_add_hog()")

Signed-off-by: Tom Rix <trix@redhat.com>
---
 drivers/gpio/gpiolib-of.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
index bd31dd3b6a75..277ada41d04a 100644
--- a/drivers/gpio/gpiolib-of.c
+++ b/drivers/gpio/gpiolib-of.c
@@ -657,6 +657,7 @@ static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog)
 	int ret;
 
 	for (i = 0;; i++) {
+		name = NULL;
 		desc = of_parse_own_gpio(hog, chip, i, &name, &lflags, &dflags);
 		if (IS_ERR(desc))
 			break;
-- 
2.18.1

Re: [PATCH] gpiolib: of: reset name variable in of_gpiochip_add_hog

[Andy Shevchenko]

On Tue, Jul 28, 2020 at 4:44 PM <trix@redhat.com> wrote:
>
> From: Tom Rix <trix@redhat.com>
>
> Clang static analysis reports this error
>
> gpiolib-of.c:664:9: warning: 2nd function call argument
>   is an uninitialized value [core.CallAndMessage]
>         ret = gpiod_hog(desc, name, lflags, dflags);
>

> name is sometimes set by of_parse_own_gpio
> name is always used by gpiod_hog

It's not clear if it's the output of the analyser.
If so, try to file a bug and fix there how it prints out functions,
should be func().
Otherwise fix in the commit message.

> So it is necessary to reset name so an old value is

the name

> not mistakenly used by gpiod_hog.

gpiod_hog()

> Fixes: bc21077e084b ("gpio: of: Extract of_gpiochip_add_hog()")
>
> Signed-off-by: Tom Rix <trix@redhat.com>

Should be no blank line in between.

> ---
>  drivers/gpio/gpiolib-of.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
> index bd31dd3b6a75..277ada41d04a 100644
> --- a/drivers/gpio/gpiolib-of.c
> +++ b/drivers/gpio/gpiolib-of.c
> @@ -657,6 +657,7 @@ static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog)
>         int ret;
>
>         for (i = 0;; i++) {
> +               name = NULL;
>                 desc = of_parse_own_gpio(hog, chip, i, &name, &lflags, &dflags);
>                 if (IS_ERR(desc))
>                         break;
> --
> 2.18.1
>


-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH] gpiolib: of: reset name variable in of_gpiochip_add_hog

[Geert Uytterhoeven]

Hi Tom,

Thanks for your patch!

On Tue, Jul 28, 2020 at 3:42 PM <trix@redhat.com> wrote:
> From: Tom Rix <trix@redhat.com>
>
> Clang static analysis reports this error
>
> gpiolib-of.c:664:9: warning: 2nd function call argument
>   is an uninitialized value [core.CallAndMessage]
>         ret = gpiod_hog(desc, name, lflags, dflags);
>
> name is sometimes set by of_parse_own_gpio
> name is always used by gpiod_hog

This is a false-positive: gpiod_hog() is only called if
of_parse_own_gpio() returned success, in which case it has filled in the
name output parameter.

> So it is necessary to reset name so an old value is
> not mistakenly used by gpiod_hog.

Hence this is not needed.

> Fixes: bc21077e084b ("gpio: of: Extract of_gpiochip_add_hog()")

This is not the commit that introduced the "bug".

> Signed-off-by: Tom Rix <trix@redhat.com>

> --- a/drivers/gpio/gpiolib-of.c
> +++ b/drivers/gpio/gpiolib-of.c
> @@ -657,6 +657,7 @@ static int of_gpiochip_add_hog(struct gpio_chip *chip, struct device_node *hog)
>         int ret;
>
>         for (i = 0;; i++) {
> +               name = NULL;
>                 desc = of_parse_own_gpio(hog, chip, i, &name, &lflags, &dflags);
>                 if (IS_ERR(desc))
>                         break;

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