linux-kernel - Re: [PATCH 2/2][next] scsi: lpfc: Use struct

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Message-ID: <202305171601.B3FF9D0BB@keescook>
Date:   Wed, 17 May 2023 16:01:47 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Gustavo A. R. Silva" <gustavoars@...nel.org>
Cc:     "Martin K. Petersen" <martin.petersen@...cle.com>,
        "James E.J. Bottomley" <jejb@...ux.ibm.com>,
        Dick Kennedy <dick.kennedy@...adcom.com>,
        James Smart <james.smart@...adcom.com>,
        linux-scsi@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH 2/2][next] scsi: lpfc: Use struct_size() helper

On Wed, May 17, 2023 at 03:23:01PM -0600, Gustavo A. R. Silva wrote:
> Prefer struct_size() over open-coded versions of idiom:
> 
> sizeof(struct-with-flex-array) + sizeof(typeof-flex-array-elements) * count
> 
> where count is the max number of items the flexible array is supposed to
> contain.
> 
> Link: https://github.com/KSPP/linux/issues/160
> Signed-off-by: Gustavo A. R. Silva <gustavoars@...nel.org>
> ---
>  drivers/scsi/lpfc/lpfc_ct.c | 6 ++----
>  1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/scsi/lpfc/lpfc_ct.c b/drivers/scsi/lpfc/lpfc_ct.c
> index e880d127d7f5..3b95c56023bf 100644
> --- a/drivers/scsi/lpfc/lpfc_ct.c
> +++ b/drivers/scsi/lpfc/lpfc_ct.c
> @@ -3748,8 +3748,7 @@ lpfc_vmid_cmd(struct lpfc_vport *vport,
>  		rap->obj[0].entity_id_len = vmid->vmid_len;
>  		memcpy(rap->obj[0].entity_id, vmid->host_vmid, vmid->vmid_len);
>  		size = RAPP_IDENT_OFFSET +
> -			sizeof(struct lpfc_vmid_rapp_ident_list) +
> -			sizeof(struct entity_id_object);
> +			struct_size(rap, obj, rap->no_of_objects);

Has rap->no_of_objects always been "1"? (i.e. there was a prior
multiplication here before...

-- 
Kees Cook