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 i2c_atr.

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

Cc: Wolfram Sang <wsa@kernel.org>
Cc: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Cc: Luca Ceresoli <luca.ceresoli@bootlin.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Tom Rix <trix@redhat.com>
Cc: linux-i2c@vger.kernel.org
Cc: llvm@lists.linux.dev
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/i2c/i2c-atr.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/i2c/i2c-atr.c b/drivers/i2c/i2c-atr.c
index 8ca1daadec93..f21475ae5921 100644
--- a/drivers/i2c/i2c-atr.c
+++ b/drivers/i2c/i2c-atr.c
@@ -94,7 +94,7 @@ struct i2c_atr {
 
 	struct notifier_block i2c_nb;
 
-	struct i2c_adapter *adapter[];
+	struct i2c_adapter *adapter[] __counted_by(max_adapters);
 };
 
 static struct i2c_atr_alias_pair *
-- 
2.34.1

On Fri, Sep 22, 2023 at 10:54:25AM -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 i2c_atr.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Wolfram Sang <wsa@kernel.org>
> Cc: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> Cc: Luca Ceresoli <luca.ceresoli@bootlin.com>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Tom Rix <trix@redhat.com>
> Cc: linux-i2c@vger.kernel.org
> Cc: llvm@lists.linux.dev
> Signed-off-by: Kees Cook <keescook@chromium.org>

Removed "media: " from $subject and applied to for-next, thanks!

On Fri, Sep 22, 2023 at 10:54:25AM -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 i2c_atr.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Wolfram Sang <wsa@kernel.org>
> Cc: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> Cc: Luca Ceresoli <luca.ceresoli@bootlin.com>
> Cc: Nathan Chancellor <nathan@kernel.org>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Tom Rix <trix@redhat.com>
> Cc: linux-i2c@vger.kernel.org
> Cc: llvm@lists.linux.dev
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
--
Gustavo

> ---
>  drivers/i2c/i2c-atr.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/i2c/i2c-atr.c b/drivers/i2c/i2c-atr.c
> index 8ca1daadec93..f21475ae5921 100644
> --- a/drivers/i2c/i2c-atr.c
> +++ b/drivers/i2c/i2c-atr.c
> @@ -94,7 +94,7 @@ struct i2c_atr {
>  
>  	struct notifier_block i2c_nb;
>  
> -	struct i2c_adapter *adapter[];
> +	struct i2c_adapter *adapter[] __counted_by(max_adapters);
>  };
>  
>  static struct i2c_atr_alias_pair *
> -- 
> 2.34.1
> 
>