Re: [PATCH] virtio_console: Annotate struct port_buffer with __counted_by

["Gustavo A. R. Silva" <gustavo@embeddedor.com>]

On 9/22/23 11:51, 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 port_buffer.
> 
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
> 
> Cc: Amit Shah <amit@kernel.org>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: virtualization@lists.linux-foundation.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

Thanks
-- 
Gustavo

> ---
>   drivers/char/virtio_console.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/char/virtio_console.c b/drivers/char/virtio_console.c
> index 680d1ef2a217..431e9e5bf9c1 100644
> --- a/drivers/char/virtio_console.c
> +++ b/drivers/char/virtio_console.c
> @@ -106,7 +106,7 @@ struct port_buffer {
>   	unsigned int sgpages;
>   
>   	/* sg is used if spages > 0. sg must be the last in is struct */
> -	struct scatterlist sg[];
> +	struct scatterlist sg[] __counted_by(sgpages);
>   };
>   
>   /*