* [PATCH] gpiolib: fix the size of the ngpios variable
@ 2022-03-05 15:42 Bartosz Golaszewski
2022-03-05 21:26 ` Andy Shevchenko
0 siblings, 1 reply; 3+ messages in thread
From: Bartosz Golaszewski @ 2022-03-05 15:42 UTC (permalink / raw)
To: Linus Walleij, Andy Shevchenko
Cc: linux-gpio, linux-kernel, Bartosz Golaszewski
The ngpio fields both in struct gpio_device as well as gpio_chip are
16 bit unsigned integers. Let's not risk an overflow and use the correct
size when reading the device property.
Fixes: 9dbd1ab20509 ("gpiolib: check the 'ngpios' property in core gpiolib code")
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
---
drivers/gpio/gpiolib.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index a3d14277f17c..147b86db16aa 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -607,7 +607,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
int base = gc->base;
unsigned int i;
int ret = 0;
- u32 ngpios;
+ u16 ngpios;
if (gc->fwnode)
fwnode = gc->fwnode;
@@ -665,7 +665,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data,
* of GPIO lines.
*/
if (gc->ngpio == 0) {
- ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);
+ ret = device_property_read_u16(&gdev->dev, "ngpios", &ngpios);
if (ret == -ENODATA)
/*
* -ENODATA means that there is no property found and
--
2.30.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] gpiolib: fix the size of the ngpios variable
2022-03-05 15:42 [PATCH] gpiolib: fix the size of the ngpios variable Bartosz Golaszewski
@ 2022-03-05 21:26 ` Andy Shevchenko
2022-03-06 19:22 ` Bartosz Golaszewski
0 siblings, 1 reply; 3+ messages in thread
From: Andy Shevchenko @ 2022-03-05 21:26 UTC (permalink / raw)
To: Bartosz Golaszewski
Cc: Linus Walleij, Andy Shevchenko, open list:GPIO SUBSYSTEM,
Linux Kernel Mailing List
On Sat, Mar 5, 2022 at 10:14 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
>
> The ngpio fields both in struct gpio_device as well as gpio_chip are
> 16 bit unsigned integers. Let's not risk an overflow and use the correct
> size when reading the device property.
...
> - ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);
> + ret = device_property_read_u16(&gdev->dev, "ngpios", &ngpios);
AFAIU DT format you may not do this. The property is ABI-like and it's
32-bit (BE!). Reading as u16 will bring you 2 MSB (bytes) out of 4
from the 32-bit value.
--
With Best Regards,
Andy Shevchenko
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] gpiolib: fix the size of the ngpios variable
2022-03-05 21:26 ` Andy Shevchenko
@ 2022-03-06 19:22 ` Bartosz Golaszewski
0 siblings, 0 replies; 3+ messages in thread
From: Bartosz Golaszewski @ 2022-03-06 19:22 UTC (permalink / raw)
To: Andy Shevchenko
Cc: Linus Walleij, Andy Shevchenko, open list:GPIO SUBSYSTEM,
Linux Kernel Mailing List
On Sat, Mar 5, 2022 at 10:27 PM Andy Shevchenko
<andy.shevchenko@gmail.com> wrote:
>
> On Sat, Mar 5, 2022 at 10:14 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:
> >
> > The ngpio fields both in struct gpio_device as well as gpio_chip are
> > 16 bit unsigned integers. Let's not risk an overflow and use the correct
> > size when reading the device property.
>
> ...
>
> > - ret = device_property_read_u32(&gdev->dev, "ngpios", &ngpios);
> > + ret = device_property_read_u16(&gdev->dev, "ngpios", &ngpios);
>
> AFAIU DT format you may not do this. The property is ABI-like and it's
> 32-bit (BE!). Reading as u16 will bring you 2 MSB (bytes) out of 4
> from the 32-bit value.
>
Ah right. It's not very obvious from the docs but the DT syntax must
be different for 16 bits. In that case our best shot is to read a
32-bit unsigned integer and check if its value doesn't exceed
UINT16_MAX.
Bart
^ permalink raw reply [flat|nested] 3+ messages in thread
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2022-03-05 15:42 [PATCH] gpiolib: fix the size of the ngpios variable Bartosz Golaszewski
2022-03-05 21:26 ` Andy Shevchenko
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