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 vexpress_syscfg_func.

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

Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Sudeep Holla <sudeep.holla@arm.com>
Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Yangtao Li <frank.li@vivo.com>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/bus/vexpress-config.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c
index c4e1becbb2d2..d2c7ada90186 100644
--- a/drivers/bus/vexpress-config.c
+++ b/drivers/bus/vexpress-config.c
@@ -54,7 +54,7 @@ struct vexpress_syscfg_func {
 	struct vexpress_syscfg *syscfg;
 	struct regmap *regmap;
 	int num_templates;
-	u32 template[]; /* Keep it last! */
+	u32 template[] __counted_by(num_templates); /* Keep it last! */
 };
 
 struct vexpress_config_bridge_ops {
-- 
2.34.1

On Fri, 22 Sep 2023 10:52:35 -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 vexpress_syscfg_func.
>
> [...]

Applied to sudeep.holla/linux (for-next/vexpress/updates), thanks!

[1/1] bus: vexpress-config: Annotate struct vexpress_syscfg_func with __counted_by
      https://git.kernel.org/sudeep.holla/c/cb289ce6e2ce
--
Regards,
Sudeep

On 9/22/23 11:52, 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 vexpress_syscfg_func.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Liviu Dudau <liviu.dudau@arm.com>
> Cc: Sudeep Holla <sudeep.holla@arm.com>
> Cc: Lorenzo Pieralisi <lpieralisi@kernel.org>
> Cc: Rob Herring <robh@kernel.org>
> Cc: Yangtao Li <frank.li@vivo.com>
> Cc: linux-arm-kernel@lists.infradead.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
-- 
Gustavo

> ---
>   drivers/bus/vexpress-config.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/bus/vexpress-config.c b/drivers/bus/vexpress-config.c
> index c4e1becbb2d2..d2c7ada90186 100644
> --- a/drivers/bus/vexpress-config.c
> +++ b/drivers/bus/vexpress-config.c
> @@ -54,7 +54,7 @@ struct vexpress_syscfg_func {
>   	struct vexpress_syscfg *syscfg;
>   	struct regmap *regmap;
>   	int num_templates;
> -	u32 template[]; /* Keep it last! */
> +	u32 template[] __counted_by(num_templates); /* Keep it last! */
>   };
>   
>   struct vexpress_config_bridge_ops {