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[PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning

Started byArnd Bergmann <arnd@arndb.de>
First post2017-09-06 17:50 +0200
Last post2017-09-07 09:00 +0200
Articles 5 — 3 participants

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  [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-09-06 17:50 +0200
    Re: [PATCH] gpio: acpi: work around false-positive  -Wstring-overflow warning Joe Perches <joe@perches.com> - 2017-09-06 18:00 +0200
      Re: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning Arnd Bergmann <arnd@arndb.de> - 2017-09-06 22:00 +0200
        Re: [PATCH] gpio: acpi: work around false-positive  -Wstring-overflow warning Joe Perches <joe@perches.com> - 2017-09-07 01:50 +0200
    Re: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow  warning Mika Westerberg <mika.westerberg@linux.intel.com> - 2017-09-07 09:00 +0200

#1727613 — [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning

FromArnd Bergmann <arnd@arndb.de>
Date2017-09-06 17:50 +0200
Subject[PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning
Message-ID<umKKt-3MF-11@gated-at.bofh.it>
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.

Fixes: 0d1c28a449c6 ("gpiolib-acpi: Add ACPI5 event model support to gpio.")
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://patchwork.kernel.org/patch/9840801/
Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82123
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 4d2113530735..eb4528c87c0b 100644
--- 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)))
-- 
2.9.0

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#1727621 — Re: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning

FromJoe Perches <joe@perches.com>
Date2017-09-06 18:00 +0200
SubjectRe: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning
Message-ID<umKU9-3Qp-11@gated-at.bofh.it>
In reply to#1727613
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)))

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#1727694

FromArnd Bergmann <arnd@arndb.de>
Date2017-09-06 22:00 +0200
Message-ID<umOEq-6jL-3@gated-at.bofh.it>
In reply to#1727621
On Wed, Sep 6, 2017 at 5:52 PM, Joe Perches <joe@perches.com> wrote:
> On Wed, 2017-09-06 at 17:47 +0200, Arnd Bergmann wrote:

>> 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?

No difference, see also the gcc bugzilla report.

        Arnd

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#1727825 — Re: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning

FromJoe Perches <joe@perches.com>
Date2017-09-07 01:50 +0200
SubjectRe: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning
Message-ID<umSeZ-dZ-7@gated-at.bofh.it>
In reply to#1727694
On Wed, 2017-09-06 at 21:53 +0200, Arnd Bergmann wrote:
> On Wed, Sep 6, 2017 at 5:52 PM, Joe Perches <joe@perches.com> wrote:
> > On Wed, 2017-09-06 at 17:47 +0200, Arnd Bergmann wrote:
> > > 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?
> 
> No difference, see also the gcc bugzilla report.

Perhaps the bug report does not apply here as the
function is casting a unsigned int to an int through
a pointer when the int could now be negative, the int
is tested for < 256 and is then printed.

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#1727955 — Re: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning

FromMika Westerberg <mika.westerberg@linux.intel.com>
Date2017-09-07 09:00 +0200
SubjectRe: [PATCH] gpio: acpi: work around false-positive -Wstring-overflow warning
Message-ID<umYX8-4NP-17@gated-at.bofh.it>
In reply to#1727613
On Wed, Sep 06, 2017 at 05:47:45PM +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.
> 
> Fixes: 0d1c28a449c6 ("gpiolib-acpi: Add ACPI5 event model support to gpio.")
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Link: https://patchwork.kernel.org/patch/9840801/
> Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82123
> Signed-off-by: Arnd Bergmann <arnd@arndb.de>

Acked-by: Mika Westerberg <mika.westerberg@linux.intel.com>

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