gpio / ACPI: Prevent potential wrap of GPIO value on OpRegion read

Dan Carpenter's static code checker reports:

 The patch 473ed7be0da0: "gpio / ACPI: Add support for ACPI GPIO
 operation regions" from Mar 14, 2014, leads to the following static
 checker warning:

  drivers/gpio/gpiolib-acpi.c:454 acpi_gpio_adr_space_handler()
  warn: should 'gpiod_get_raw_value(desc) << i' be a 64 bit type?

This is due the fact that *value is of type u64 and gpiod_get_raw_value()
returns int. Since i can be larger than 31, it is possible that the value
returned gets wrapped.

Fix this by casting the return of gpiod_get_raw_value() to u64 first before
shift.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index d5be56fe689ee43a01cfde01ca0040d0b9b1afae..401add28933f4f6f39c70b626e081ec39aef554b 100644 (file)
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -451,7 +451,7 @@ acpi_gpio_adr_space_handler(u32 function, acpi_physical_address address,
                if (function == ACPI_WRITE)
                        gpiod_set_raw_value(desc, !!((1 << i) & *value));
                else
-                       *value |= gpiod_get_raw_value(desc) << i;
+                       *value |= (u64)gpiod_get_raw_value(desc) << i;
        }
 
 out: