Prepare for the coming implementation by GCC and Clang of the __counted_by
attribute. Flexible array members annotated with __counted_by can have
their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
(for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
functions).

As found with Coccinelle[1], add __counted_by for struct input_leds.

[1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Cc: linux-input@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/input/input-leds.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/input/input-leds.c b/drivers/input/input-leds.c
index 0b11990ade46..0e935914bc3a 100644
--- a/drivers/input/input-leds.c
+++ b/drivers/input/input-leds.c
@@ -44,7 +44,7 @@ struct input_led {
 struct input_leds {
 	struct input_handle handle;
 	unsigned int num_leds;
-	struct input_led leds[];
+	struct input_led leds[] __counted_by(num_leds);
 };
 
 static enum led_brightness input_leds_brightness_get(struct led_classdev *cdev)
-- 
2.34.1

On Fri, Sep 22, 2023 at 10:50:32AM -0700, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct input_leds.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: linux-input@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Applied, thank you.

-- 
Dmitry

On 9/22/23 11:50, Kees Cook wrote:
> Prepare for the coming implementation by GCC and Clang of the __counted_by
> attribute. Flexible array members annotated with __counted_by can have
> their accesses bounds-checked at run-time checking via CONFIG_UBSAN_BOUNDS
> (for array indexing) and CONFIG_FORTIFY_SOURCE (for strcpy/memcpy-family
> functions).
> 
> As found with Coccinelle[1], add __counted_by for struct input_leds.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: linux-input@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
-- 
Gustavo

> ---
>   drivers/input/input-leds.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/input-leds.c b/drivers/input/input-leds.c
> index 0b11990ade46..0e935914bc3a 100644
> --- a/drivers/input/input-leds.c
> +++ b/drivers/input/input-leds.c
> @@ -44,7 +44,7 @@ struct input_led {
>   struct input_leds {
>   	struct input_handle handle;
>   	unsigned int num_leds;
> -	struct input_led leds[];
> +	struct input_led leds[] __counted_by(num_leds);
>   };
>   
>   static enum led_brightness input_leds_brightness_get(struct led_classdev *cdev)