2019-02-16 10:44:14

by Jason Yan

Subject: [PATCH] ata: fix a race condition when internal cmd time out

For internal cmds, we will unmap DMA memory associated with the cmd
before we abort the cmd. If DMA transfering data before the aborting,
bus error will occured.

ata_exec_internal_sg
->ata_port_freeze if timeout
->ata_qc_complete
->ata_sg_clean
dma transfering data = bus error
->ap->ops->post_internal_cmd
->sas_ata_post_internal
->sas_ata_internal_abort
->abort the cmd

Fix this by move post_internal_cmd() before unmapping the DMA memory
when time out. Notice that we have to set ATA_QCFLAG_FAILED flag before
calling post_internal_cmd() so that the aborting will work.

Reported-by: luojian <[email protected]>
Signed-off-by: Jason Yan <[email protected]>
---
drivers/ata/libata-core.c | 14 +++++++++++---
1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index adf28788cab5..d0ff5711e805 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1665,6 +1665,13 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
*/
if (qc->flags & ATA_QCFLAG_ACTIVE) {
qc->err_mask |= AC_ERR_TIMEOUT;
+ qc->flags |= ATA_QCFLAG_FAILED;
+
+ spin_unlock_irqrestore(ap->lock, flags);
+ /* do post_internal_cmd */
+ if (ap->ops->post_internal_cmd)
+ ap->ops->post_internal_cmd(qc);
+ spin_lock_irqsave(ap->lock, flags);

if (ap->ops->error_handler)
ata_port_freeze(ap);
@@ -1679,9 +1686,10 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
spin_unlock_irqrestore(ap->lock, flags);
}

- /* do post_internal_cmd */
- if (ap->ops->post_internal_cmd)
- ap->ops->post_internal_cmd(qc);
+ if (!(qc->err_mask & AC_ERR_TIMEOUT))
+ /* do post_internal_cmd */
+ if (ap->ops->post_internal_cmd)
+ ap->ops->post_internal_cmd(qc);

/* perform minimal error analysis */
if (qc->flags & ATA_QCFLAG_FAILED) {
--
2.14.4

2019-02-16 11:29:28

by Sergei Shtylyov

Subject: Re: [PATCH] ata: fix a race condition when internal cmd time out

Hello!

On 16.02.2019 6:42, Jason Yan wrote:

> For internal cmds, we will unmap DMA memory associated with the cmd
> before we abort the cmd. If DMA transfering data before the aborting,

Transferring.

> bus error will occured.

Occur.

> ata_exec_internal_sg
> ->ata_port_freeze if timeout
> ->ata_qc_complete
> ->ata_sg_clean
> dma transfering data = bus error
> ->ap->ops->post_internal_cmd
> ->sas_ata_post_internal
> ->sas_ata_internal_abort
> ->abort the cmd
>
> Fix this by move post_internal_cmd() before unmapping the DMA memory

Moving.

> when time out. Notice that we have to set ATA_QCFLAG_FAILED flag before
> calling post_internal_cmd() so that the aborting will work.
>
> Reported-by: luojian <[email protected]>
> Signed-off-by: Jason Yan <[email protected]>
[...]

MBR, Sergei

2019-02-16 12:12:06

by Jason Yan

Subject: Re: [PATCH] ata: fix a race condition when internal cmd time out

Hi, Sergei

Thanks for the review.

On 2019/2/16 15:45, Sergei Shtylyov wrote:
> Hello!
>
> On 16.02.2019 6:42, Jason Yan wrote:
>
>> For internal cmds, we will unmap DMA memory associated with the cmd
>> before we abort the cmd. If DMA transfering data before the aborting,
>
>    Transferring.
>
>> bus error will occured.
>
>    Occur.
>
>> ata_exec_internal_sg
>>    ->ata_port_freeze if timeout
>>      ->ata_qc_complete
>>        ->ata_sg_clean
>>                                        dma transfering data = bus error
>>    ->ap->ops->post_internal_cmd
>>      ->sas_ata_post_internal
>>        ->sas_ata_internal_abort
>>          ->abort the cmd
>>
>> Fix this by move post_internal_cmd() before unmapping the DMA memory
>
>    Moving.
>
>> when time out. Notice that we have to set ATA_QCFLAG_FAILED flag before
>> calling post_internal_cmd() so that the aborting will work.
>>
>> Reported-by: luojian <[email protected]>
>> Signed-off-by: Jason Yan <[email protected]>
> [...]
>
> MBR, Sergei
>
>