[PATCH] platform/surface: aggregator: Annotate struct ssam_event with __counted_by

[PATCH] platform/surface: aggregator: Annotate struct ssam_event with __counted_by

[Kees Cook]

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 ssam_event.

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

Cc: Maximilian Luz <luzmaximilian@gmail.com>
Cc: platform-driver-x86@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 include/linux/surface_aggregator/controller.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/surface_aggregator/controller.h b/include/linux/surface_aggregator/controller.h
index cb7980805920..5b67f0f47d80 100644
--- a/include/linux/surface_aggregator/controller.h
+++ b/include/linux/surface_aggregator/controller.h
@@ -44,7 +44,7 @@ struct ssam_event {
 	u8 command_id;
 	u8 instance_id;
 	u16 length;
-	u8 data[];
+	u8 data[] __counted_by(length);
 };
 
 /**
-- 
2.34.1

Re: [PATCH] platform/surface: aggregator: Annotate struct ssam_event with __counted_by

[Gustavo A. R. Silva]

On Fri, Sep 22, 2023 at 10:54:37AM -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 ssam_event.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Maximilian Luz <luzmaximilian@gmail.com>
> Cc: platform-driver-x86@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
--
Gustavo

> ---
>  include/linux/surface_aggregator/controller.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/surface_aggregator/controller.h b/include/linux/surface_aggregator/controller.h
> index cb7980805920..5b67f0f47d80 100644
> --- a/include/linux/surface_aggregator/controller.h
> +++ b/include/linux/surface_aggregator/controller.h
> @@ -44,7 +44,7 @@ struct ssam_event {
>  	u8 command_id;
>  	u8 instance_id;
>  	u16 length;
> -	u8 data[];
> +	u8 data[] __counted_by(length);
>  };
>  
>  /**
> -- 
> 2.34.1
> 
> 

Re: [PATCH] platform/surface: aggregator: Annotate struct ssam_event with __counted_by

[Maximilian Luz]

On 9/22/23 19:54, 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 ssam_event.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Maximilian Luz <luzmaximilian@gmail.com>
> Cc: platform-driver-x86@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>
> ---
>   include/linux/surface_aggregator/controller.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/surface_aggregator/controller.h b/include/linux/surface_aggregator/controller.h
> index cb7980805920..5b67f0f47d80 100644
> --- a/include/linux/surface_aggregator/controller.h
> +++ b/include/linux/surface_aggregator/controller.h
> @@ -44,7 +44,7 @@ struct ssam_event {
>   	u8 command_id;
>   	u8 instance_id;
>   	u16 length;
> -	u8 data[];
> +	u8 data[] __counted_by(length);
>   };
>   
>   /**

Thanks!

Reviewed-by: Maximilian Luz <luzmaximilian@gmail.com>

Re: [PATCH] platform/surface: aggregator: Annotate struct ssam_event with __counted_by

[Ilpo Järvinen]

On Fri, 22 Sep 2023 10:54:37 -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 ssam_event.
> 
> [...]


Thank you for your contribution, it has been applied to my local
review-ilpo branch. Note it will show up in the public
platform-drivers-x86/review-ilpo branch only once I've pushed my
local branch there, which might take a while.

Once I've run some tests on the review-ilpo branch the patches
there will be added to the platform-drivers-x86/for-next branch
and eventually will be included in the pdx86 pull-request to
Linus for the next merge-window.

The list of commits applied:
[1/1] platform/surface: aggregator: Annotate struct ssam_event with __counted_by
      commit: 9cf63f3a33e929f7eca36409914b8c12102b9984

--
 i.