[PATCH 18/22] gpio: acpi: fix string overflow for large pin numbers

[Arnd Bergmann]

gcc-7 notices that the pin_table is an array of 16-bit numbers,
but we assume it can be printed as a two-character hexadecimal
string:

drivers/gpio/gpiolib-acpi.c: In function 'acpi_gpiochip_request_interrupt':
drivers/gpio/gpiolib-acpi.c:206:24: warning: '%02X' directive writing between 2 and 4 bytes into a region of size 3 [-Wformat-overflow=]
   sprintf(ev_name, "_%c%02X",
                        ^~~~
drivers/gpio/gpiolib-acpi.c:206:20: note: directive argument in the range [0, 65535]
   sprintf(ev_name, "_%c%02X",
                    ^~~~~~~~~
drivers/gpio/gpiolib-acpi.c:206:3: note: 'sprintf' output between 5 and 7 bytes into a destination of size 5
   sprintf(ev_name, "_%c%02X",
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~
    agpio->triggering == ACPI_EDGE_SENSITIVE ? 'E' : 'L',
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    pin);
    ~~~~

This can't be right, so this changes it to truncate the number to
an 8-bit pin number.

Fixes: 0d1c28a449c6 ("gpiolib-acpi: Add ACPI5 event model support to gpio.")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
---
 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 c9b42dd12dfa..c3faea724af8 100644
--- a/drivers/gpio/gpiolib-acpi.c
+++ b/drivers/gpio/gpiolib-acpi.c
@@ -205,7 +205,7 @@ static acpi_status acpi_gpiochip_request_interrupt(struct acpi_resource *ares,
 		char ev_name[5];
 		sprintf(ev_name, "_%c%02X",
 			agpio->triggering == ACPI_EDGE_SENSITIVE ? 'E' : 'L',
-			pin);
+			(u8)pin);
 		if (ACPI_SUCCESS(acpi_get_handle(handle, ev_name, &evt_handle)))
 			handler = acpi_gpio_irq_handler;
 	}
-- 
2.9.0