Re: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning
From: Joe Perches <joe@perches.com>
Date: 2017-09-06 15:53:01
Also in:
linux-acpi, lkml
On Wed, 2017-09-06 at 17:47 +0200, Arnd Bergmann wrote:
gcc-7 notices that the pin_table is an array of 16-bit numbers,
but fails to take the following range check into account:
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);
~~~~
As suggested by Andy, this changes the format string to have a fixed length.
Since modifying the range check did not help, I also opened a bug against
gcc, see link below.The code has int pin does changing pin to unsigned int matter?
quoted hunk ↗ jump to hunk
diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c
[]
quoted hunk ↗ jump to hunk
@@ -203,7 +203,7 @@ static acpi_status acpi_gpiochip_request_interrupt(struct acpi_resource *ares, if (pin <= 255) { char ev_name[5]; - sprintf(ev_name, "_%c%02X", + sprintf(ev_name, "_%c%02hhX", agpio->triggering == ACPI_EDGE_SENSITIVE ? 'E' : 'L', pin); if (ACPI_SUCCESS(acpi_get_handle(handle, ev_name, &evt_handle)))