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 gsc_hwmon_platform_data.

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

Cc: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 include/linux/platform_data/gsc_hwmon.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/platform_data/gsc_hwmon.h b/include/linux/platform_data/gsc_hwmon.h
index f2781aa7eff8..70e8a6bec0f6 100644
--- a/include/linux/platform_data/gsc_hwmon.h
+++ b/include/linux/platform_data/gsc_hwmon.h
@@ -40,6 +40,6 @@ struct gsc_hwmon_platform_data {
 	unsigned int resolution;
 	unsigned int vreference;
 	unsigned int fan_base;
-	struct gsc_hwmon_channel channels[];
+	struct gsc_hwmon_channel channels[] __counted_by(nchannels);
 };
 #endif
-- 
2.34.1

On Fri, 22 Sep 2023 10:50:53 -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 gsc_hwmon_platform_data.
> 
> [...]

Since this is a trivial change and it's been 2 week without further
discussion, I'll snag this patch.

Applied to for-next/hardening, thanks!

[1/1] hwmon: Annotate struct gsc_hwmon_platform_data with __counted_by
      https://git.kernel.org/kees/c/e909028ba701

Take care,

-- 
Kees Cook

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 gsc_hwmon_platform_data.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Tim Harvey <tharvey@gateworks.com>
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
-- 
Gustavo

> ---
>   include/linux/platform_data/gsc_hwmon.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/include/linux/platform_data/gsc_hwmon.h b/include/linux/platform_data/gsc_hwmon.h
> index f2781aa7eff8..70e8a6bec0f6 100644
> --- a/include/linux/platform_data/gsc_hwmon.h
> +++ b/include/linux/platform_data/gsc_hwmon.h
> @@ -40,6 +40,6 @@ struct gsc_hwmon_platform_data {
>   	unsigned int resolution;
>   	unsigned int vreference;
>   	unsigned int fan_base;
> -	struct gsc_hwmon_channel channels[];
> +	struct gsc_hwmon_channel channels[] __counted_by(nchannels);
>   };
>   #endif