linux-kernel - [PATCH] gpio / ACPI: Prevent potential wrap of GPIO value on OpRegion read

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Date:	Tue,  1 Apr 2014 13:03:00 +0300
From:	Mika Westerberg <mika.westerberg@...ux.intel.com>
To:	Linus Walleij <linus.walleij@...aro.org>
Cc:	Alexandre Courbot <gnurou@...il.com>,
	Dan Carpenter <dan.carpenter@...cle.com>,
	linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
	Mika Westerberg <mika.westerberg@...ux.intel.com>
Subject: [PATCH] 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@...cle.com>
Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
---
 drivers/gpio/gpiolib-acpi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
index d5be56fe689e..401add28933f 100644
--- 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:
-- 
1.9.1

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