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 mxser_board.

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

Cc: Jiri Slaby <jirislaby@kernel.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
Cc: Fabio Estevam <festevam@gmail.com>
Cc: NXP Linux Team <linux-imx@nxp.com>
Cc: linux-serial@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 drivers/tty/mxser.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index 10aa4ed38793..6ce7f259968f 100644
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -288,7 +288,7 @@ struct mxser_board {
 	enum mxser_must_hwid must_hwid;
 	speed_t max_baud;
 
-	struct mxser_port ports[];
+	struct mxser_port ports[] __counted_by(nports);
 };
 
 static DECLARE_BITMAP(mxser_boards, MXSER_BOARDS);
-- 
2.34.1

On 22. 09. 23, 19:52, 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 mxser_board.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci

Reviewed-by: Jiri Slaby <jirislaby@kernel.org>

thanks,
-- 
js
suse labs

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 mxser_board.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Jiri Slaby <jirislaby@kernel.org>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Shawn Guo <shawnguo@kernel.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> Cc: Pengutronix Kernel Team <kernel@pengutronix.de>
> Cc: Fabio Estevam <festevam@gmail.com>
> Cc: NXP Linux Team <linux-imx@nxp.com>
> Cc: linux-serial@vger.kernel.org
> 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/tty/mxser.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
> index 10aa4ed38793..6ce7f259968f 100644
> --- a/drivers/tty/mxser.c
> +++ b/drivers/tty/mxser.c
> @@ -288,7 +288,7 @@ struct mxser_board {
>   	enum mxser_must_hwid must_hwid;
>   	speed_t max_baud;
>   
> -	struct mxser_port ports[];
> +	struct mxser_port ports[] __counted_by(nports);
>   };
>   
>   static DECLARE_BITMAP(mxser_boards, MXSER_BOARDS);