Re: [PATCH] io_uring/rsrc: Annotate struct io_mapped_ubuf with __counted_by

[Gustavo A. R. Silva]

On 8/17/23 15:21, 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 io_mapped_ubuf.
>
> [1] https://github.com/kees/kernel-tools/blob/trunk/coccinelle/examples/counted_by.cocci
>
> Cc: Jens Axboe <axboe@xxxxxxxxx>
> Cc: Pavel Begunkov <asml.silence@xxxxxxxxx>
> Cc: io-uring@xxxxxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>

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

Thanks
--
Gustavo

> ---
>   io_uring/rsrc.h | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/io_uring/rsrc.h b/io_uring/rsrc.h
> index 8afa9ec66a55..8625181fb87a 100644
> --- a/io_uring/rsrc.h
> +++ b/io_uring/rsrc.h
> @@ -54,7 +54,7 @@ struct io_mapped_ubuf {
>   	u64		ubuf_end;
>   	unsigned int	nr_bvecs;
>   	unsigned long	acct_pages;
> -	struct bio_vec	bvec[];
> +	struct bio_vec	bvec[] __counted_by(nr_bvecs);
>   };
>   
>   void io_rsrc_node_ref_zero(struct io_rsrc_node *node);