diff mbox series

leds: leds-mt6323: Adjust return/parameter types in wled get/set callbacks

Message ID 20230622-mt6323-wled-wincompatible-function-pointer-types-strict-v1-1-6ad256f220e8@kernel.org (mailing list archive)
State New, archived
Headers show
Series leds: leds-mt6323: Adjust return/parameter types in wled get/set callbacks | expand

Commit Message

Nathan Chancellor June 22, 2023, 4:12 p.m. UTC 
Clang's kernel Control Flow Integrity (kCFI) is a compiler-based
security mitigation that ensures the target of an indirect function call
matches the expected type of the call and trapping if they do not match
exactly. The warning -Wincompatible-function-pointer-types-strict aims
to catch these issues at compile time, which reveals:

 drivers/leds/leds-mt6323.c:598:49: error: incompatible function pointer types assigning to 'int (*)(struct led_classdev *, enum led_brightness)' from 'int (struct led_classdev *, unsigned int)' [-Werror,-Wincompatible-function-pointer-types-strict]
   598 |                         leds->led[reg]->cdev.brightness_set_blocking =
       |                                                                      ^
   599 |                                                 mt6323_wled_set_brightness;
       |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 drivers/leds/leds-mt6323.c:600:40: error: incompatible function pointer types assigning to 'enum led_brightness (*)(struct led_classdev *)' from 'unsigned int (struct led_classdev *)' [-Werror,-Wincompatible-function-pointer-types-strict]
   600 |                         leds->led[reg]->cdev.brightness_get =
       |                                                             ^
   601 |                                                 mt6323_get_wled_brightness;
       |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
 2 errors generated.

While 'unsigned int' is ABI compatible with 'enum led_brightness' (hence
no warning from -Wincompatible-function-pointer-types) and the callers
of these callbacks use/pass the values as 'unsigned int', the mismatch
between the prototype and the called function will trip kCFI at runtime.

Change the types in the implementations to match the prototypes, clearing
up the warning and avoiding kCFI failures.

Fixes: 9bb0a9e0626c ("leds: leds-mt6323: Add support for WLEDs and MT6332")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
---
 drivers/leds/leds-mt6323.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)


---
base-commit: 7bd932d9adbcc5c5370d968bdb0b00385606bf3a
change-id: 20230621-mt6323-wled-wincompatible-function-pointer-types-strict-334f06d92ffb

Best regards,

Comments

Nick Desaulniers June 22, 2023, 4:43 p.m. UTC | #1 
On Thu, Jun 22, 2023 at 9:12 AM Nathan Chancellor <nathan@kernel.org> wrote:
>
> Clang's kernel Control Flow Integrity (kCFI) is a compiler-based
> security mitigation that ensures the target of an indirect function call
> matches the expected type of the call and trapping if they do not match
> exactly. The warning -Wincompatible-function-pointer-types-strict aims
> to catch these issues at compile time, which reveals:
>
>  drivers/leds/leds-mt6323.c:598:49: error: incompatible function pointer types assigning to 'int (*)(struct led_classdev *, enum led_brightness)' from 'int (struct led_classdev *, unsigned int)' [-Werror,-Wincompatible-function-pointer-types-strict]
>    598 |                         leds->led[reg]->cdev.brightness_set_blocking =
>        |                                                                      ^
>    599 |                                                 mt6323_wled_set_brightness;
>        |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
>  drivers/leds/leds-mt6323.c:600:40: error: incompatible function pointer types assigning to 'enum led_brightness (*)(struct led_classdev *)' from 'unsigned int (struct led_classdev *)' [-Werror,-Wincompatible-function-pointer-types-strict]
>    600 |                         leds->led[reg]->cdev.brightness_get =
>        |                                                             ^
>    601 |                                                 mt6323_get_wled_brightness;
>        |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
>  2 errors generated.
>
> While 'unsigned int' is ABI compatible with 'enum led_brightness' (hence
> no warning from -Wincompatible-function-pointer-types) and the callers
> of these callbacks use/pass the values as 'unsigned int', the mismatch
> between the prototype and the called function will trip kCFI at runtime.
>
> Change the types in the implementations to match the prototypes, clearing
> up the warning and avoiding kCFI failures.
>
> Fixes: 9bb0a9e0626c ("leds: leds-mt6323: Add support for WLEDs and MT6332")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

Thanks for the patch! Consider additionally having
mt6323_get_wled_brightness return LED_OFF rather than 0 in its
ternary.
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>


> ---
>  drivers/leds/leds-mt6323.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/leds/leds-mt6323.c b/drivers/leds/leds-mt6323.c
> index e8fecfc2e90a..24f35bdb55fb 100644
> --- a/drivers/leds/leds-mt6323.c
> +++ b/drivers/leds/leds-mt6323.c
> @@ -76,7 +76,7 @@ struct mt6323_led {
>         int                     id;
>         struct mt6323_leds      *parent;
>         struct led_classdev     cdev;
> -       unsigned int            current_brightness;
> +       enum led_brightness     current_brightness;
>  };
>
>  /**
> @@ -451,7 +451,7 @@ static int mtk_wled_hw_off(struct led_classdev *cdev)
>         return 0;
>  }
>
> -static unsigned int mt6323_get_wled_brightness(struct led_classdev *cdev)
> +static enum led_brightness mt6323_get_wled_brightness(struct led_classdev *cdev)
>  {
>         struct mt6323_led *led = container_of(cdev, struct mt6323_led, cdev);
>         struct mt6323_leds *leds = led->parent;
> @@ -471,7 +471,7 @@ static unsigned int mt6323_get_wled_brightness(struct led_classdev *cdev)
>  }
>
>  static int mt6323_wled_set_brightness(struct led_classdev *cdev,
> -                                     unsigned int brightness)
> +                                     enum led_brightness brightness)
>  {
>         struct mt6323_led *led = container_of(cdev, struct mt6323_led, cdev);
>         struct mt6323_leds *leds = led->parent;
>
> ---
> base-commit: 7bd932d9adbcc5c5370d968bdb0b00385606bf3a
> change-id: 20230621-mt6323-wled-wincompatible-function-pointer-types-strict-334f06d92ffb
>
> Best regards,
> --
> Nathan Chancellor <nathan@kernel.org>
>
>
Lee Jones June 22, 2023, 4:54 p.m. UTC | #2 
On Thu, 22 Jun 2023, Nick Desaulniers wrote:

> On Thu, Jun 22, 2023 at 9:12 AM Nathan Chancellor <nathan@kernel.org> wrote:
> >
> > Clang's kernel Control Flow Integrity (kCFI) is a compiler-based
> > security mitigation that ensures the target of an indirect function call
> > matches the expected type of the call and trapping if they do not match
> > exactly. The warning -Wincompatible-function-pointer-types-strict aims
> > to catch these issues at compile time, which reveals:
> >
> >  drivers/leds/leds-mt6323.c:598:49: error: incompatible function pointer types assigning to 'int (*)(struct led_classdev *, enum led_brightness)' from 'int (struct led_classdev *, unsigned int)' [-Werror,-Wincompatible-function-pointer-types-strict]
> >    598 |                         leds->led[reg]->cdev.brightness_set_blocking =
> >        |                                                                      ^
> >    599 |                                                 mt6323_wled_set_brightness;
> >        |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
> >  drivers/leds/leds-mt6323.c:600:40: error: incompatible function pointer types assigning to 'enum led_brightness (*)(struct led_classdev *)' from 'unsigned int (struct led_classdev *)' [-Werror,-Wincompatible-function-pointer-types-strict]
> >    600 |                         leds->led[reg]->cdev.brightness_get =
> >        |                                                             ^
> >    601 |                                                 mt6323_get_wled_brightness;
> >        |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
> >  2 errors generated.
> >
> > While 'unsigned int' is ABI compatible with 'enum led_brightness' (hence
> > no warning from -Wincompatible-function-pointer-types) and the callers
> > of these callbacks use/pass the values as 'unsigned int', the mismatch
> > between the prototype and the called function will trip kCFI at runtime.
> >
> > Change the types in the implementations to match the prototypes, clearing
> > up the warning and avoiding kCFI failures.
> >
> > Fixes: 9bb0a9e0626c ("leds: leds-mt6323: Add support for WLEDs and MT6332")
> > Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> 
> Thanks for the patch! Consider additionally having
> mt6323_get_wled_brightness return LED_OFF rather than 0 in its
> ternary.

https://elixir.bootlin.com/linux/latest/source/include/linux/leds.h#L32

Perhaps this is not relevant for this older driver though?

I'd really like some more information from Pavel on the history.

> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
> 
> 
> > ---
> >  drivers/leds/leds-mt6323.c | 6 +++---
> >  1 file changed, 3 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/leds/leds-mt6323.c b/drivers/leds/leds-mt6323.c
> > index e8fecfc2e90a..24f35bdb55fb 100644
> > --- a/drivers/leds/leds-mt6323.c
> > +++ b/drivers/leds/leds-mt6323.c
> > @@ -76,7 +76,7 @@ struct mt6323_led {
> >         int                     id;
> >         struct mt6323_leds      *parent;
> >         struct led_classdev     cdev;
> > -       unsigned int            current_brightness;
> > +       enum led_brightness     current_brightness;
> >  };
> >
> >  /**
> > @@ -451,7 +451,7 @@ static int mtk_wled_hw_off(struct led_classdev *cdev)
> >         return 0;
> >  }
> >
> > -static unsigned int mt6323_get_wled_brightness(struct led_classdev *cdev)
> > +static enum led_brightness mt6323_get_wled_brightness(struct led_classdev *cdev)
> >  {
> >         struct mt6323_led *led = container_of(cdev, struct mt6323_led, cdev);
> >         struct mt6323_leds *leds = led->parent;
> > @@ -471,7 +471,7 @@ static unsigned int mt6323_get_wled_brightness(struct led_classdev *cdev)
> >  }
> >
> >  static int mt6323_wled_set_brightness(struct led_classdev *cdev,
> > -                                     unsigned int brightness)
> > +                                     enum led_brightness brightness)
> >  {
> >         struct mt6323_led *led = container_of(cdev, struct mt6323_led, cdev);
> >         struct mt6323_leds *leds = led->parent;
> >
> > ---
> > base-commit: 7bd932d9adbcc5c5370d968bdb0b00385606bf3a
> > change-id: 20230621-mt6323-wled-wincompatible-function-pointer-types-strict-334f06d92ffb
> >
> > Best regards,
> > --
> > Nathan Chancellor <nathan@kernel.org>
> >
> >
> 
> 
> -- 
> Thanks,
> ~Nick Desaulniers
AngeloGioacchino Del Regno June 23, 2023, 8:04 a.m. UTC | #3 
Il 22/06/23 18:12, Nathan Chancellor ha scritto:
> Clang's kernel Control Flow Integrity (kCFI) is a compiler-based
> security mitigation that ensures the target of an indirect function call
> matches the expected type of the call and trapping if they do not match
> exactly. The warning -Wincompatible-function-pointer-types-strict aims
> to catch these issues at compile time, which reveals:
> 
>   drivers/leds/leds-mt6323.c:598:49: error: incompatible function pointer types assigning to 'int (*)(struct led_classdev *, enum led_brightness)' from 'int (struct led_classdev *, unsigned int)' [-Werror,-Wincompatible-function-pointer-types-strict]
>     598 |                         leds->led[reg]->cdev.brightness_set_blocking =
>         |                                                                      ^
>     599 |                                                 mt6323_wled_set_brightness;
>         |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
>   drivers/leds/leds-mt6323.c:600:40: error: incompatible function pointer types assigning to 'enum led_brightness (*)(struct led_classdev *)' from 'unsigned int (struct led_classdev *)' [-Werror,-Wincompatible-function-pointer-types-strict]
>     600 |                         leds->led[reg]->cdev.brightness_get =
>         |                                                             ^
>     601 |                                                 mt6323_get_wled_brightness;
>         |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
>   2 errors generated.
> 
> While 'unsigned int' is ABI compatible with 'enum led_brightness' (hence
> no warning from -Wincompatible-function-pointer-types) and the callers
> of these callbacks use/pass the values as 'unsigned int', the mismatch
> between the prototype and the called function will trip kCFI at runtime.
> 
> Change the types in the implementations to match the prototypes, clearing
> up the warning and avoiding kCFI failures.
> 
> Fixes: 9bb0a9e0626c ("leds: leds-mt6323: Add support for WLEDs and MT6332")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>

leds need to deprecate said enumeration for real, since it's marked for
deprecation but, in the meanwhile, we can't have kCFI failures on this driver.

For this reason,

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>

Cheers,
Angelo

> ---
>   drivers/leds/leds-mt6323.c | 6 +++---
>   1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/leds/leds-mt6323.c b/drivers/leds/leds-mt6323.c
> index e8fecfc2e90a..24f35bdb55fb 100644
> --- a/drivers/leds/leds-mt6323.c
> +++ b/drivers/leds/leds-mt6323.c
> @@ -76,7 +76,7 @@ struct mt6323_led {
>   	int			id;
>   	struct mt6323_leds	*parent;
>   	struct led_classdev	cdev;
> -	unsigned int		current_brightness;
> +	enum led_brightness	current_brightness;
>   };
>   
>   /**
> @@ -451,7 +451,7 @@ static int mtk_wled_hw_off(struct led_classdev *cdev)
>   	return 0;
>   }
>   
> -static unsigned int mt6323_get_wled_brightness(struct led_classdev *cdev)
> +static enum led_brightness mt6323_get_wled_brightness(struct led_classdev *cdev)
>   {
>   	struct mt6323_led *led = container_of(cdev, struct mt6323_led, cdev);
>   	struct mt6323_leds *leds = led->parent;
> @@ -471,7 +471,7 @@ static unsigned int mt6323_get_wled_brightness(struct led_classdev *cdev)
>   }
>   
>   static int mt6323_wled_set_brightness(struct led_classdev *cdev,
> -				      unsigned int brightness)
> +				      enum led_brightness brightness)
>   {
>   	struct mt6323_led *led = container_of(cdev, struct mt6323_led, cdev);
>   	struct mt6323_leds *leds = led->parent;
> 
> ---
> base-commit: 7bd932d9adbcc5c5370d968bdb0b00385606bf3a
> change-id: 20230621-mt6323-wled-wincompatible-function-pointer-types-strict-334f06d92ffb
> 
> Best regards,
Lee Jones June 26, 2023, 9:10 a.m. UTC | #4 
On Thu, 22 Jun 2023, Nathan Chancellor wrote:

> Clang's kernel Control Flow Integrity (kCFI) is a compiler-based
> security mitigation that ensures the target of an indirect function call
> matches the expected type of the call and trapping if they do not match
> exactly. The warning -Wincompatible-function-pointer-types-strict aims
> to catch these issues at compile time, which reveals:
> 
>  drivers/leds/leds-mt6323.c:598:49: error: incompatible function pointer types assigning to 'int (*)(struct led_classdev *, enum led_brightness)' from 'int (struct led_classdev *, unsigned int)' [-Werror,-Wincompatible-function-pointer-types-strict]
>    598 |                         leds->led[reg]->cdev.brightness_set_blocking =
>        |                                                                      ^
>    599 |                                                 mt6323_wled_set_brightness;
>        |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
>  drivers/leds/leds-mt6323.c:600:40: error: incompatible function pointer types assigning to 'enum led_brightness (*)(struct led_classdev *)' from 'unsigned int (struct led_classdev *)' [-Werror,-Wincompatible-function-pointer-types-strict]
>    600 |                         leds->led[reg]->cdev.brightness_get =
>        |                                                             ^
>    601 |                                                 mt6323_get_wled_brightness;
>        |                                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~
>  2 errors generated.
> 
> While 'unsigned int' is ABI compatible with 'enum led_brightness' (hence
> no warning from -Wincompatible-function-pointer-types) and the callers
> of these callbacks use/pass the values as 'unsigned int', the mismatch
> between the prototype and the called function will trip kCFI at runtime.
> 
> Change the types in the implementations to match the prototypes, clearing
> up the warning and avoiding kCFI failures.
> 
> Fixes: 9bb0a9e0626c ("leds: leds-mt6323: Add support for WLEDs and MT6332")
> Signed-off-by: Nathan Chancellor <nathan@kernel.org>
> ---
>  drivers/leds/leds-mt6323.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)

Applied, thanks
diff mbox series

Patch

diff --git a/drivers/leds/leds-mt6323.c b/drivers/leds/leds-mt6323.c
index e8fecfc2e90a..24f35bdb55fb 100644
--- a/drivers/leds/leds-mt6323.c
+++ b/drivers/leds/leds-mt6323.c
@@ -76,7 +76,7 @@  struct mt6323_led {
 	int			id;
 	struct mt6323_leds	*parent;
 	struct led_classdev	cdev;
-	unsigned int		current_brightness;
+	enum led_brightness	current_brightness;
 };
 
 /**
@@ -451,7 +451,7 @@  static int mtk_wled_hw_off(struct led_classdev *cdev)
 	return 0;
 }
 
-static unsigned int mt6323_get_wled_brightness(struct led_classdev *cdev)
+static enum led_brightness mt6323_get_wled_brightness(struct led_classdev *cdev)
 {
 	struct mt6323_led *led = container_of(cdev, struct mt6323_led, cdev);
 	struct mt6323_leds *leds = led->parent;
@@ -471,7 +471,7 @@  static unsigned int mt6323_get_wled_brightness(struct led_classdev *cdev)
 }
 
 static int mt6323_wled_set_brightness(struct led_classdev *cdev,
-				      unsigned int brightness)
+				      enum led_brightness brightness)
 {
 	struct mt6323_led *led = container_of(cdev, struct mt6323_led, cdev);
 	struct mt6323_leds *leds = led->parent;