From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joe Perches Subject: Re: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning Date: Wed, 06 Sep 2017 08:52:53 -0700 Message-ID: <1504713173.7546.3.camel@perches.com> References: <20170906154756.2133726-1-arnd@arndb.de> Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170906154756.2133726-1-arnd@arndb.de> Sender: linux-kernel-owner@vger.kernel.org To: Arnd Bergmann , Mika Westerberg , Andy Shevchenko , Linus Walleij Cc: Dmitry Torokhov , Hans de Goede , Wei Yongjun , linux-gpio@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: linux-gpio@vger.kernel.org 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? > diff --git a/drivers/gpio/gpiolib-acpi.c b/drivers/gpio/gpiolib-acpi.c [] > @@ -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)))