Re: [PATCH 20/20] scsi: pm8001: fix abort all task initialization

From: John Garry <john.garry@huawei.com>
To: Damien Le Moal <damien.lemoal@opensource.wdc.com>,
	<linux-scsi@vger.kernel.org>,
	"Martin K . Petersen" <martin.petersen@oracle.com>,
	Xiang Chen <chenxiang66@hisilicon.com>,
	"Jason Yan" <yanaijie@huawei.com>,
	Luo Jiaxing <luojiaxing@huawei.com>
Subject: Re: [PATCH 20/20] scsi: pm8001: fix abort all task initialization
Date: Thu, 10 Feb 2022 14:28:00 +0000	[thread overview]
Message-ID: <f3606f3e-43ea-8c98-58f7-3572bbbf816c@huawei.com> (raw)
In-Reply-To: <20220210114218.632725-21-damien.lemoal@opensource.wdc.com>

On 10/02/2022 11:42, Damien Le Moal wrote:
> In pm80xx_send_abort_all(), the n_elem field of the ccb used is not
> initialized to 0. This missing initialization sometimes lead to the
> task completion path seeing the ccb with a non-zero n_elem resulting in
> the execution of invalid dma_unmap_sg() calls in pm8001_ccb_task_free(),
> causing a crash such as:
> 
> [  197.676341] RIP: 0010:iommu_dma_unmap_sg+0x6d/0x280
> [  197.700204] RSP: 0018:ffff889bbcf89c88 EFLAGS: 00010012
> [  197.705485] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff83d0bda0
> [  197.712687] RDX: 0000000000000002 RSI: 0000000000000000 RDI: ffff88810dffc0d0
> [  197.719887] RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881c790098b
> [  197.727089] R10: ffffed1038f20131 R11: 0000000000000001 R12: 0000000000000000
> [  197.734296] R13: ffff88810dffc0d0 R14: 0000000000000010 R15: 0000000000000000
> [  197.741493] FS:  0000000000000000(0000) GS:ffff889bbcf80000(0000) knlGS:0000000000000000
> [  197.749659] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [  197.755459] CR2: 00007f16c1b42734 CR3: 0000000004814000 CR4: 0000000000350ee0
> [  197.762656] Call Trace:
> [  197.765127]  <IRQ>
> [  197.767162]  pm8001_ccb_task_free+0x5f1/0x820 [pm80xx]
> [  197.772364]  ? do_raw_spin_unlock+0x54/0x220
> [  197.776680]  pm8001_mpi_task_abort_resp+0x2ce/0x4f0 [pm80xx]
> [  197.782406]  process_oq+0xe85/0x7890 [pm80xx]
> [  197.786817]  ? lock_acquire+0x194/0x490
> [  197.790697]  ? handle_irq_event+0x10e/0x1b0
> [  197.794920]  ? mpi_sata_completion+0x2d70/0x2d70 [pm80xx]
> [  197.800378]  ? __wake_up_bit+0x100/0x100
> [  197.804340]  ? lock_is_held_type+0x98/0x110
> [  197.808565]  pm80xx_chip_isr+0x94/0x130 [pm80xx]
> [  197.813243]  tasklet_action_common.constprop.0+0x24b/0x2f0
> [  197.818785]  __do_softirq+0x1b5/0x82d
> [  197.822485]  ? do_raw_spin_unlock+0x54/0x220
> [  197.826799]  __irq_exit_rcu+0x17e/0x1e0
> [  197.830678]  irq_exit_rcu+0xa/0x20
> [  197.834114]  common_interrupt+0x78/0x90
> [  197.840051]  </IRQ>
> [  197.844236]  <TASK>
> [  197.848397]  asm_common_interrupt+0x1e/0x40
> 

That's nasty.

> Avoid this issue by always initializing the ccb n_elem field to 0 in
> pm8001_send_abort_all(), pm8001_send_read_log() and
> pm80xx_send_abort_all().
> 
> Fixes: c6b9ef5779c3 ("[SCSI] pm80xx: NCQ error handling changes")
> Signed-off-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
> ---
>   drivers/scsi/pm8001/pm8001_hwi.c | 2 ++
>   drivers/scsi/pm8001/pm80xx_hwi.c | 1 +
>   2 files changed, 3 insertions(+)
> 
> diff --git a/drivers/scsi/pm8001/pm8001_hwi.c b/drivers/scsi/pm8001/pm8001_hwi.c
> index 8095eb0b04f7..d853e8d0195a 100644
> --- a/drivers/scsi/pm8001/pm8001_hwi.c
> +++ b/drivers/scsi/pm8001/pm8001_hwi.c
> @@ -1788,6 +1788,7 @@ static void pm8001_send_abort_all(struct pm8001_hba_info *pm8001_ha,
>   	ccb->device = pm8001_ha_dev;
>   	ccb->ccb_tag = ccb_tag;
>   	ccb->task = task;
> +	ccb->n_elem = 0;

Do you think that it would be better to clear this field when we free 
the tag/ccb in pm8001_ccb_task_free()? I will note that there are error 
paths whch only free the tag (not ccb), so need to be careful there.

BTW, I see that this never landed:
https://lore.kernel.org/lkml/20211214090337.29156-1-niejianglei2021@163.com/

Though alloc'ing a domain_device in pm8001_send_read_log() is questionable.

Thanks,
John

>   
>   	circularQ = &pm8001_ha->inbnd_q_tbl[0];
>   
> @@ -1849,6 +1850,7 @@ static void pm8001_send_read_log(struct pm8001_hba_info *pm8001_ha,
>   	ccb->device = pm8001_ha_dev;
>   	ccb->ccb_tag = ccb_tag;
>   	ccb->task = task;
> +	ccb->n_elem = 0;
>   	pm8001_ha_dev->id |= NCQ_READ_LOG_FLAG;
>   	pm8001_ha_dev->id |= NCQ_2ND_RLE_FLAG;
>   
> diff --git a/drivers/scsi/pm8001/pm80xx_hwi.c b/drivers/scsi/pm8001/pm80xx_hwi.c
> index 4d88c0dbcefc..902af4eefa26 100644
> --- a/drivers/scsi/pm8001/pm80xx_hwi.c
> +++ b/drivers/scsi/pm8001/pm80xx_hwi.c
> @@ -1801,6 +1801,7 @@ static void pm80xx_send_abort_all(struct pm8001_hba_info *pm8001_ha,
>   	ccb->device = pm8001_ha_dev;
>   	ccb->ccb_tag = ccb_tag;
>   	ccb->task = task;
> +	ccb->n_elem = 0;
>   
>   	circularQ = &pm8001_ha->inbnd_q_tbl[0];
>   