Re: [PATCH 21/21] dmaengine: usb-dmac: Annotate struct usb_dmac_desc with __counted_by

[Gustavo A. R. Silva]

On 8/17/23 17:58, 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 usb_dmac_desc.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Vinod Koul <vkoul@xxxxxxxxxx>
> Cc: Yu Kuai <yukuai3@xxxxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Jordy Zomer <jordy@pwning.systems>
> Cc: Jernej Skrabec <jernej.skrabec@xxxxxxxxx>
> Cc: Tudor Ambarus <tudor.ambarus@xxxxxxxxxx>
> Cc: dmaengine@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

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

Thanks
--
Gustavo

> ---
>   drivers/dma/sh/usb-dmac.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/dma/sh/usb-dmac.c b/drivers/dma/sh/usb-dmac.c
> index b14cf350b669..4cfcd23e3268 100644
> --- a/drivers/dma/sh/usb-dmac.c
> +++ b/drivers/dma/sh/usb-dmac.c
> @@ -57,7 +57,7 @@ struct usb_dmac_desc {
>   	u32 residue;
>   	struct list_head node;
>   	dma_cookie_t done_cookie;
> -	struct usb_dmac_sg sg[];
> +	struct usb_dmac_sg sg[] __counted_by(sg_allocated_len);
>   };
>   
>   #define to_usb_dmac_desc(vd)	container_of(vd, struct usb_dmac_desc, vd)