Re: [PATCH 18/22] gpio: acpi: fix string overflow for large pin numbers
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Date: 2017-07-14 12:52:40
Also in:
linux-acpi, linux-gpio, linux-scsi, lkml
On Fri, 2017-07-14 at 14:07 +0200, Arnd Bergmann wrote:
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 is obviously a false positive warning. Here we have int pin = u16 pin_table[0] <= 255 (implying >= 0). I see few options how to make it more clear 1) your proposal; 2) use "%02hhX" instead; 3) use if (ret >= 0 && ret <= 255) condition. I would choose one of the 2-3. In case gcc will complain about 3), file a bug to gcc crazy warning.
quoted hunk ↗ jump to hunk
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@arndb.de> --- 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_statusacpi_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; }
-- Andy Shevchenko [off-list ref] Intel Finland Oy