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

Gustavo A. R. Silva
2023-08-18T03:32:07Z

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@kernel.org>
> Cc: Yu Kuai <yukuai3@huawei.com>
> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> Cc: Jordy Zomer <jordy@pwning.systems>
> Cc: Jernej Skrabec <jernej.skrabec@gmail.com>
> Cc: Tudor Ambarus <tudor.ambarus@linaro.org>
> Cc: dmaengine@vger.kernel.org
> Signed-off-by: Kees Cook <keescook@chromium.org>

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

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)