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Subject: Re: [PATCH] scsi: lpfc: Check queue pointer before use
To:     Daniel Wagner <dwagner@suse.de>, linux-scsi@vger.kernel.org
Cc:     linux-kernel@vger.kernel.org,
        Dick Kennedy <dick.kennedy@broadcom.com>,
        James Smart <jsmart2021@gmail.com>
References: <20191018162111.8798-1-dwagner@suse.de>
From:   James Smart <james.smart@broadcom.com>
Message-ID: <3624b42a-712a-bab5-c325-7171f71a51e1@broadcom.com>
Date:   Fri, 18 Oct 2019 14:40:27 -0700
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On 10/18/2019 9:21 AM, Daniel Wagner wrote:
> The queue pointer might not be valid. The rest of the code checks the
> pointer before accessing it. lpfc_sli4_process_missed_mbox_completions
> is the only place where the check is missing.
>
> Fixes: 657add4e5e15 ("scsi: lpfc: Fix poor use of hardware queues if fewer irq vectors")
> Cc: James Smart <jsmart2021@gmail.com>
> Signed-off-by: Daniel Wagner <dwagner@suse.de>
> ---
> Hi,
>
> Not entirely sure if this correct. I tried to understand the logic of
> the mentioned patch but failed to grasps all the details. Anyway, we
> observe a crash in lpfc_sli4_process_missed_mbox_completions() while
> iterating the array. All but the last one entry has a valid pointer.
>
> Thanks,
> Daniel
>
>   drivers/scsi/lpfc/lpfc_sli.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/lpfc/lpfc_sli.c b/drivers/scsi/lpfc/lpfc_sli.c
> index 379c37451645..149966ba8a17 100644
> --- a/drivers/scsi/lpfc/lpfc_sli.c
> +++ b/drivers/scsi/lpfc/lpfc_sli.c
> @@ -7906,7 +7906,7 @@ lpfc_sli4_process_missed_mbox_completions(struct lpfc_hba *phba)
>   	if (sli4_hba->hdwq) {
>   		for (eqidx = 0; eqidx < phba->cfg_irq_chann; eqidx++) {
>   			eq = phba->sli4_hba.hba_eq_hdl[eqidx].eq;
> -			if (eq->queue_id == sli4_hba->mbx_cq->assoc_qid) {
> +			if (eq && eq->queue_id == sli4_hba->mbx_cq->assoc_qid) {
>   				fpeq = eq;
>   				break;
>   			}

looks fine. Thanks!

Reviewed by: James Smart <james.smart@broadcom.com>

-- james