Re: [PATCH] input: mt: Annotate struct input_mt with __counted_by

[Gustavo A. R. Silva]

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_mt.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
> Cc: linux-input@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

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

Thanks
--
Gustavo

> ---
>   include/linux/input/mt.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/linux/input/mt.h b/include/linux/input/mt.h
> index 3b8580bd33c1..2cf89a538b18 100644
> --- a/include/linux/input/mt.h
> +++ b/include/linux/input/mt.h
> @@ -47,7 +47,7 @@ struct input_mt {
>   	unsigned int flags;
>   	unsigned int frame;
>   	int *red;
> -	struct input_mt_slot slots[];
> +	struct input_mt_slot slots[] __counted_by(num_slots);
>   };
>   
>   static inline void input_mt_set_value(struct input_mt_slot *slot,