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 icc_path.

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

Cc: Georgi Djakov <djakov@kernel.org>
Cc: linux-pm@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/interconnect/internal.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/interconnect/internal.h b/drivers/interconnect/internal.h
index f5f82a5c939e..b30856db523d 100644
--- a/drivers/interconnect/internal.h
+++ b/drivers/interconnect/internal.h
@@ -38,7 +38,7 @@ struct icc_req {
 struct icc_path {
 	const char *name;
 	size_t num_nodes;
-	struct icc_req reqs[];
+	struct icc_req reqs[] __counted_by(num_nodes);
 };
 
 #endif
-- 
2.34.1

On 8/17/23 14:41, 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 icc_path.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Georgi Djakov <djakov@kernel.org>
> Cc: linux-pm@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
--
Gustavo

> ---
>   drivers/interconnect/internal.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/interconnect/internal.h b/drivers/interconnect/internal.h
> index f5f82a5c939e..b30856db523d 100644
> --- a/drivers/interconnect/internal.h
> +++ b/drivers/interconnect/internal.h
> @@ -38,7 +38,7 @@ struct icc_req {
>   struct icc_path {
>   	const char *name;
>   	size_t num_nodes;
> -	struct icc_req reqs[];
> +	struct icc_req reqs[] __counted_by(num_nodes);
>   };
>   
>   #endif