linux-hardening - Re: [PATCH] nvmet: prefer flex_array_size and struct

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Date:   Mon, 25 Oct 2021 16:05:03 -0500
From:   "Gustavo A. R. Silva" <gustavoars@...nel.org>
To:     Len Baker <len.baker@....com>
Cc:     Keith Busch <kbusch@...nel.org>, Jens Axboe <axboe@...com>,
        Christoph Hellwig <hch@....de>,
        Sagi Grimberg <sagi@...mberg.me>,
        Chaitanya Kulkarni <kch@...dia.com>,
        Kees Cook <keescook@...omium.org>,
        linux-hardening@...r.kernel.org, linux-nvme@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] nvmet: prefer flex_array_size and struct_size over open
 coded arithmetic

On Sun, Oct 24, 2021 at 07:29:21PM +0200, Len Baker wrote:
> In an effort to avoid open-coded arithmetic in the kernel [1], use the
> flex_array_size() and struct_size() helpers instead of an open-coded
> calculation.
> 
> [1] https://github.com/KSPP/linux/issues/160
> 
> Signed-off-by: Len Baker <len.baker@....com>

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

Thanks
--
Gustavo

> ---
>  drivers/nvme/host/multipath.c   | 2 +-
>  drivers/nvme/target/admin-cmd.c | 2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c
> index 954e84df6eb7..7f2071f2460c 100644
> --- a/drivers/nvme/host/multipath.c
> +++ b/drivers/nvme/host/multipath.c
> @@ -562,7 +562,7 @@ static int nvme_parse_ana_log(struct nvme_ctrl *ctrl, void *data,
>  			return -EINVAL;
> 
>  		nr_nsids = le32_to_cpu(desc->nnsids);
> -		nsid_buf_size = nr_nsids * sizeof(__le32);
> +		nsid_buf_size = flex_array_size(desc, nsids, nr_nsids);
> 
>  		if (WARN_ON_ONCE(desc->grpid == 0))
>  			return -EINVAL;
> diff --git a/drivers/nvme/target/admin-cmd.c b/drivers/nvme/target/admin-cmd.c
> index 403de678fd06..6fb24746de06 100644
> --- a/drivers/nvme/target/admin-cmd.c
> +++ b/drivers/nvme/target/admin-cmd.c
> @@ -264,7 +264,7 @@ static u32 nvmet_format_ana_group(struct nvmet_req *req, u32 grpid,
>  	desc->chgcnt = cpu_to_le64(nvmet_ana_chgcnt);
>  	desc->state = req->port->ana_state[grpid];
>  	memset(desc->rsvd17, 0, sizeof(desc->rsvd17));
> -	return sizeof(struct nvme_ana_group_desc) + count * sizeof(__le32);
> +	return struct_size(desc, nsids, count);
>  }
> 
>  static void nvmet_execute_get_log_page_ana(struct nvmet_req *req)
> --
> 2.25.1
>