Re: [PATCH 2/8] qla2xxx: klocwork - Fix potential null pointer dereference

[Bart Van Assche <bvanassche@acm.org>]

On 5/18/23 00:58, Nilesh Javali wrote:
> From: Bikash Hazarika <bhazarika@marvell.com>
> 
> Klocwork tool reported 'cur_dsd' may be dereferenced.
> Add fix to validate pointer before dereferencing
> the pointer.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Bikash Hazarika <bhazarika@marvell.com>
> Signed-off-by: Nilesh Javali <njavali@marvell.com>
> ---
>   drivers/scsi/qla2xxx/qla_iocb.c | 8 +++++---
>   1 file changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/scsi/qla2xxx/qla_iocb.c b/drivers/scsi/qla2xxx/qla_iocb.c
> index 6acfdcc48b16..a092151aef77 100644
> --- a/drivers/scsi/qla2xxx/qla_iocb.c
> +++ b/drivers/scsi/qla2xxx/qla_iocb.c
> @@ -664,9 +664,11 @@ qla24xx_build_scsi_type_6_iocbs(srb_t *sp, struct cmd_type_6 *cmd_pkt,
>   	}
>   
>   	/* Null termination */
> -	cur_dsd->address = 0;
> -	cur_dsd->length = 0;
> -	cur_dsd++;
> +	if (cur_dsd) {
> +		cur_dsd->address = 0;
> +		cur_dsd->length = 0;
> +		cur_dsd++;
> +	}
>   	cmd_pkt->control_flags |= cpu_to_le16(CF_DATA_SEG_DESCR_ENABLE);
>   	return 0;
>   }

Please add BUG_ON(!cur_dsd) above the first cur_dsd dereference instead 
of making the above change. The above change hides a bug. Hiding bugs 
doesn't help anyone.

Bart.