* RE: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
@ 2017-05-15 23:32 Long Li
2017-05-16 0:00 ` Bart Van Assche
0 siblings, 1 reply; 12+ messages in thread
From: Long Li @ 2017-05-15 23:32 UTC (permalink / raw)
To: Bart Van Assche, jejb, linux-scsi, linux-kernel, martin.petersen
Cc: KY Srinivasan, Stephen Hemminger
> -----Original Message-----
> From: Bart Van Assche [mailto:Bart.VanAssche@sandisk.com]
> Sent: Monday, May 15, 2017 4:03 PM
> To: jejb@linux.vnet.ibm.com; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org; Long Li <longli@microsoft.com>;
> martin.petersen@oracle.com
> Cc: Long Li <longli@microsoft.com>
> Subject: Re: [Possible Phish Fraud][PATCH] scsi: zero per-cmd driver data for
> each MQ I/O
>
> On Wed, 2017-05-10 at 14:07 -0700, Long Li wrote:
> > From: Long Li <longli@microsoft.com>
> >
> > Lower layer driver may not initialize private data before use. Zero
> > them out to prevent use of stale data.
> >
> > Signed-off-by: Long Li <longli@microsoft.com>
> > ---
> > drivers/scsi/scsi_lib.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index
> > 19125d7..a821593 100644
> > --- a/drivers/scsi/scsi_lib.c
> > +++ b/drivers/scsi/scsi_lib.c
> > @@ -1850,7 +1850,7 @@ static int scsi_mq_prep_fn(struct request *req)
> >
> > /* zero out the cmd, except for the embedded scsi_request */
> > memset((char *)cmd + sizeof(cmd->req), 0,
> > - sizeof(*cmd) - sizeof(cmd->req));
> > + sizeof(*cmd) - sizeof(cmd->req) + shost->hostt->cmd_size);
> >
> > req->special = cmd;
>
> Hello Long,
>
> Sorry but this patch looks wrong to me. Since scsi_mq_prep_fn() is called
> after scsi_req_init(), erasing struct scsi_request from scsi_mq_prep_fn() will
> erase the values that were set by scsi_req_init(). That includes information
> like the pointer to the SCSI CDB and the CDB itself. See e.g.
> scsi_execute().
>
> Did you come up with this patch after source reading or did you come up with
> this patch while chasing a bug?
Thanks for looking! Yes this is for chasing a bug.
Actually scsi_mq_prep_fn() doesn't touch cmd->req (which is the struct scsi_request mentioned in your email).
With the patch, we also zero the private data used by lower layer driver, in addition to the private data in scsi_cmnd.
>
> Thanks,
>
> Bart.
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-15 23:32 [PATCH] scsi: zero per-cmd driver data for each MQ I/O Long Li
@ 2017-05-16 0:00 ` Bart Van Assche
2017-05-16 17:31 ` Long Li
0 siblings, 1 reply; 12+ messages in thread
From: Bart Van Assche @ 2017-05-16 0:00 UTC (permalink / raw)
To: jejb, linux-scsi, linux-kernel, longli, martin.petersen; +Cc: sthemmin, kys
On Mon, 2017-05-15 at 23:32 +0000, Long Li wrote:
> Thanks for looking! Yes this is for chasing a bug.
>
> With the patch, we also zero the private data used by lower layer driver, in
> addition to the private data in scsi_cmnd.
Hello Long,
What bug did you encounter, with which combination of ULP (sd?) and LLD SCSI
driver(s) and for which request type (REQ_OP_*)? You will have to mention that
information in the patch description anyway if you want your patch to get
accepted.
If the bug that you encountered only occurs with a single LLD, would it be
possible to implement a fix by modifying the LLD instead of the SCSI core?
Thanks,
Bart.
^ permalink raw reply [flat|nested] 12+ messages in thread
* RE: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-16 0:00 ` Bart Van Assche
@ 2017-05-16 17:31 ` Long Li
2017-05-17 23:05 ` Bart Van Assche
0 siblings, 1 reply; 12+ messages in thread
From: Long Li @ 2017-05-16 17:31 UTC (permalink / raw)
To: Bart Van Assche, jejb, linux-scsi, linux-kernel, martin.petersen
Cc: Stephen Hemminger, KY Srinivasan
> -----Original Message-----
> From: Bart Van Assche [mailto:Bart.VanAssche@sandisk.com]
> Sent: Monday, May 15, 2017 5:01 PM
> To: jejb@linux.vnet.ibm.com; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org; Long Li <longli@microsoft.com>;
> martin.petersen@oracle.com
> Cc: Stephen Hemminger <sthemmin@microsoft.com>; KY Srinivasan
> <kys@microsoft.com>
> Subject: Re: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
>
> On Mon, 2017-05-15 at 23:32 +0000, Long Li wrote:
> > Thanks for looking! Yes this is for chasing a bug.
> >
> > With the patch, we also zero the private data used by lower layer
> > driver, in addition to the private data in scsi_cmnd.
>
> Hello Long,
>
> What bug did you encounter, with which combination of ULP (sd?) and LLD SCSI
> driver(s) and for which request type (REQ_OP_*)? You will have to mention
> that information in the patch description anyway if you want your patch to get
> accepted.
>
> If the bug that you encountered only occurs with a single LLD, would it be
> possible to implement a fix by modifying the LLD instead of the SCSI core?
The bug I encounter is that in hv_storvsc (a LLD), sometime we are getting stale data in the private driver data memory allocated by SCSI. As a LLD, we expect the memory allocated by SCSI to be zeroed. If not we may send unexpected commands to the device.
A little background on private data: In LLD's scsi_host_template, the driver may optionally ask SCSI to allocate its private driver memory for each command, by specifying cmd_size. This memory is allocated at the end of scsi_cmnd by SCSI. Later when SCSI queues a command, the LLD can use scsi_cmd_priv to get its private data.
hv_storvsc doesn't clear its private data before use. I'm not sure about other LLD drivers. Although it's possible to fix it in LLD not SCSI core, I think that is not the ideal place to do it. Whoever is allocating the SCSI command should also zero it.
There is a similar patch that fixed a similar issue for non-MQ case:
commit ee5242360424b9b967454e9183767323d10cf985
I'm sorry I should have put more details in the patch.
>
> Thanks,
>
> Bart.
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-16 17:31 ` Long Li
@ 2017-05-17 23:05 ` Bart Van Assche
2017-05-18 6:54 ` Christoph Hellwig
0 siblings, 1 reply; 12+ messages in thread
From: Bart Van Assche @ 2017-05-17 23:05 UTC (permalink / raw)
To: jejb, linux-scsi, linux-kernel, longli, martin.petersen; +Cc: sthemmin, kys
On Tue, 2017-05-16 at 17:31 +0000, Long Li wrote:
> > -----Original Message-----
> > From: Bart Van Assche [mailto:Bart.VanAssche@sandisk.com]
> > Sent: Monday, May 15, 2017 5:01 PM
> > To: jejb@linux.vnet.ibm.com; linux-scsi@vger.kernel.org; linux-
> > kernel@vger.kernel.org; Long Li <longli@microsoft.com>;
> > martin.petersen@oracle.com
> > Cc: Stephen Hemminger <sthemmin@microsoft.com>; KY Srinivasan
> > <kys@microsoft.com>
> > Subject: Re: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
> >
> > On Mon, 2017-05-15 at 23:32 +0000, Long Li wrote:
> > > Thanks for looking! Yes this is for chasing a bug.
> > >
> > > With the patch, we also zero the private data used by lower layer
> > > driver, in addition to the private data in scsi_cmnd.
> >
> > Hello Long,
> >
> > What bug did you encounter, with which combination of ULP (sd?) and LLD SCSI
> > driver(s) and for which request type (REQ_OP_*)? You will have to mention
> > that information in the patch description anyway if you want your patch to get
> > accepted.
> >
> > If the bug that you encountered only occurs with a single LLD, would it be
> > possible to implement a fix by modifying the LLD instead of the SCSI core?
>
> The bug I encounter is that in hv_storvsc (a LLD), sometime we are getting stale data in the private driver data memory allocated by SCSI. As a LLD, we expect the memory allocated by SCSI to be zeroed. If not we may send unexpected commands to the device.
>
> A little background on private data: In LLD's scsi_host_template, the driver may optionally ask SCSI to allocate its private driver memory for each command, by specifying cmd_size. This memory is allocated at the end of scsi_cmnd by SCSI. Later when SCSI queues a command, the LLD can use scsi_cmd_priv to get its private data.
>
> hv_storvsc doesn't clear its private data before use. I'm not sure about other LLD drivers. Although it's possible to fix it in LLD not SCSI core, I think that is not the ideal place to do it. Whoever is allocating the SCSI command should also zero it.
>
> There is a similar patch that fixed a similar issue for non-MQ case:
> commit ee5242360424b9b967454e9183767323d10cf985
>
> I'm sorry I should have put more details in the patch.
Hello Long,
Thank you for the feedback. I'm working on a patch series that merges the scsi-sq
and scsi-mq code paths for command initialization and that should fix the bug you
encountered.
Bart.
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-17 23:05 ` Bart Van Assche
@ 2017-05-18 6:54 ` Christoph Hellwig
2017-05-18 13:29 ` KY Srinivasan
2017-05-18 15:52 ` Bart Van Assche
0 siblings, 2 replies; 12+ messages in thread
From: Christoph Hellwig @ 2017-05-18 6:54 UTC (permalink / raw)
To: Bart Van Assche
Cc: jejb, linux-scsi, linux-kernel, longli, martin.petersen, sthemmin, kys
On Wed, May 17, 2017 at 11:05:18PM +0000, Bart Van Assche wrote:
> Thank you for the feedback. I'm working on a patch series that merges the scsi-sq
> and scsi-mq code paths for command initialization and that should fix the bug you
> encountered.
While that sounds great (I tried it a while ago but gave up due to
priorities) I think we should merge this patch as-is and backport it
to stable for now and rebase your series on top of it.
^ permalink raw reply [flat|nested] 12+ messages in thread
* RE: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-18 6:54 ` Christoph Hellwig
@ 2017-05-18 13:29 ` KY Srinivasan
2017-05-18 15:52 ` Bart Van Assche
1 sibling, 0 replies; 12+ messages in thread
From: KY Srinivasan @ 2017-05-18 13:29 UTC (permalink / raw)
To: Christoph Hellwig, Bart Van Assche
Cc: jejb, linux-scsi, linux-kernel, Long Li, martin.petersen,
Stephen Hemminger
> -----Original Message-----
> From: Christoph Hellwig [mailto:hch@infradead.org]
> Sent: Wednesday, May 17, 2017 11:55 PM
> To: Bart Van Assche <Bart.VanAssche@sandisk.com>
> Cc: jejb@linux.vnet.ibm.com; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org; Long Li <longli@microsoft.com>;
> martin.petersen@oracle.com; Stephen Hemminger
> <sthemmin@microsoft.com>; KY Srinivasan <kys@microsoft.com>
> Subject: Re: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
>
> On Wed, May 17, 2017 at 11:05:18PM +0000, Bart Van Assche wrote:
> > Thank you for the feedback. I'm working on a patch series that merges the
> scsi-sq
> > and scsi-mq code paths for command initialization and that should fix the
> bug you
> > encountered.
>
> While that sounds great (I tried it a while ago but gave up due to
> priorities) I think we should merge this patch as-is and backport it
> to stable for now and rebase your series on top of it.
Thanks Christoph.
K. Y
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-18 6:54 ` Christoph Hellwig
2017-05-18 13:29 ` KY Srinivasan
@ 2017-05-18 15:52 ` Bart Van Assche
2017-05-18 16:47 ` Long Li
1 sibling, 1 reply; 12+ messages in thread
From: Bart Van Assche @ 2017-05-18 15:52 UTC (permalink / raw)
To: hch
Cc: jejb, linux-scsi, linux-kernel, sthemmin, kys, longli, martin.petersen
On Wed, 2017-05-17 at 23:54 -0700, Christoph Hellwig wrote:
> On Wed, May 17, 2017 at 11:05:18PM +0000, Bart Van Assche wrote:
> > Thank you for the feedback. I'm working on a patch series that merges the scsi-sq
> > and scsi-mq code paths for command initialization and that should fix the bug you
> > encountered.
>
> While that sounds great (I tried it a while ago but gave up due to
> priorities) I think we should merge this patch as-is and backport it
> to stable for now and rebase your series on top of it.
Hello Christoph,
I will rebase my patch series on top of Long Li's patch. Long, please
repost your patch with a more detailed description and with the Reviewed-by
and Cc: stable tags added.
Thanks,
Bart.
^ permalink raw reply [flat|nested] 12+ messages in thread
* RE: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-18 15:52 ` Bart Van Assche
@ 2017-05-18 16:47 ` Long Li
0 siblings, 0 replies; 12+ messages in thread
From: Long Li @ 2017-05-18 16:47 UTC (permalink / raw)
To: Bart Van Assche, hch
Cc: jejb, linux-scsi, linux-kernel, Stephen Hemminger, KY Srinivasan,
martin.petersen
> -----Original Message-----
> From: Bart Van Assche [mailto:Bart.VanAssche@sandisk.com]
> Sent: Thursday, May 18, 2017 8:52 AM
> To: hch@infradead.org
> Cc: jejb@linux.vnet.ibm.com; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org; Stephen Hemminger <sthemmin@microsoft.com>; KY
> Srinivasan <kys@microsoft.com>; Long Li <longli@microsoft.com>;
> martin.petersen@oracle.com
> Subject: Re: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
>
> On Wed, 2017-05-17 at 23:54 -0700, Christoph Hellwig wrote:
> > On Wed, May 17, 2017 at 11:05:18PM +0000, Bart Van Assche wrote:
> > > Thank you for the feedback. I'm working on a patch series that
> > > merges the scsi-sq and scsi-mq code paths for command initialization
> > > and that should fix the bug you encountered.
> >
> > While that sounds great (I tried it a while ago but gave up due to
> > priorities) I think we should merge this patch as-is and backport it
> > to stable for now and rebase your series on top of it.
>
> Hello Christoph,
>
> I will rebase my patch series on top of Long Li's patch. Long, please repost your
> patch with a more detailed description and with the Reviewed-by and Cc:
> stable tags added.
Will do that.
>
> Thanks,
>
> Bart.
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-10 21:07 Long Li
2017-05-15 22:48 ` Long Li
@ 2017-05-18 6:55 ` Christoph Hellwig
1 sibling, 0 replies; 12+ messages in thread
From: Christoph Hellwig @ 2017-05-18 6:55 UTC (permalink / raw)
To: Long Li
Cc: James E.J. Bottomley, Martin K. Petersen, linux-scsi,
linux-kernel, Long Li
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
^ permalink raw reply [flat|nested] 12+ messages in thread
* RE: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-15 22:48 ` Long Li
@ 2017-05-15 23:20 ` KY Srinivasan
0 siblings, 0 replies; 12+ messages in thread
From: KY Srinivasan @ 2017-05-15 23:20 UTC (permalink / raw)
To: Long Li, James E.J. Bottomley, Martin K. Petersen, linux-scsi,
linux-kernel
Cc: Stephen Hemminger
> -----Original Message-----
> From: Long Li
> Sent: Monday, May 15, 2017 3:48 PM
> To: Long Li <longli@microsoft.com>; James E.J. Bottomley
> <jejb@linux.vnet.ibm.com>; Martin K. Petersen
> <martin.petersen@oracle.com>; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org
> Cc: KY Srinivasan <kys@microsoft.com>; Stephen Hemminger
> <sthemmin@microsoft.com>
> Subject: RE: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
>
> > -----Original Message-----
> > From: Long Li [mailto:longli@exchange.microsoft.com]
> > Sent: Wednesday, May 10, 2017 2:07 PM
> > To: James E.J. Bottomley <jejb@linux.vnet.ibm.com>; Martin K. Petersen
> > <martin.petersen@oracle.com>; linux-scsi@vger.kernel.org; linux-
> > kernel@vger.kernel.org
> > Cc: Long Li <longli@microsoft.com>
> > Subject: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
> >
> > From: Long Li <longli@microsoft.com>
> >
> > Lower layer driver may not initialize private data before use. Zero them out
> > to prevent use of stale data.
> >
> > Signed-off-by: Long Li <longli@microsoft.com>
>
> Can someone help review this patch?
Reviewed-by: K. Y. Srinivasan <kys@microsoft.com>
>
> > ---
> > drivers/scsi/scsi_lib.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index
> > 19125d7..a821593 100644
> > --- a/drivers/scsi/scsi_lib.c
> > +++ b/drivers/scsi/scsi_lib.c
> > @@ -1850,7 +1850,7 @@ static int scsi_mq_prep_fn(struct request *req)
> >
> > /* zero out the cmd, except for the embedded scsi_request */
> > memset((char *)cmd + sizeof(cmd->req), 0,
> > - sizeof(*cmd) - sizeof(cmd->req));
> > + sizeof(*cmd) - sizeof(cmd->req) +
> > + shost->hostt->cmd_size);
> >
> > req->special = cmd;
> >
> > --
> > 2.7.4
^ permalink raw reply [flat|nested] 12+ messages in thread
* RE: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
2017-05-10 21:07 Long Li
@ 2017-05-15 22:48 ` Long Li
2017-05-15 23:20 ` KY Srinivasan
2017-05-18 6:55 ` Christoph Hellwig
1 sibling, 1 reply; 12+ messages in thread
From: Long Li @ 2017-05-15 22:48 UTC (permalink / raw)
To: Long Li, James E.J. Bottomley, Martin K. Petersen, linux-scsi,
linux-kernel
Cc: KY Srinivasan, Stephen Hemminger
> -----Original Message-----
> From: Long Li [mailto:longli@exchange.microsoft.com]
> Sent: Wednesday, May 10, 2017 2:07 PM
> To: James E.J. Bottomley <jejb@linux.vnet.ibm.com>; Martin K. Petersen
> <martin.petersen@oracle.com>; linux-scsi@vger.kernel.org; linux-
> kernel@vger.kernel.org
> Cc: Long Li <longli@microsoft.com>
> Subject: [PATCH] scsi: zero per-cmd driver data for each MQ I/O
>
> From: Long Li <longli@microsoft.com>
>
> Lower layer driver may not initialize private data before use. Zero them out
> to prevent use of stale data.
>
> Signed-off-by: Long Li <longli@microsoft.com>
Can someone help review this patch?
> ---
> drivers/scsi/scsi_lib.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index
> 19125d7..a821593 100644
> --- a/drivers/scsi/scsi_lib.c
> +++ b/drivers/scsi/scsi_lib.c
> @@ -1850,7 +1850,7 @@ static int scsi_mq_prep_fn(struct request *req)
>
> /* zero out the cmd, except for the embedded scsi_request */
> memset((char *)cmd + sizeof(cmd->req), 0,
> - sizeof(*cmd) - sizeof(cmd->req));
> + sizeof(*cmd) - sizeof(cmd->req) +
> + shost->hostt->cmd_size);
>
> req->special = cmd;
>
> --
> 2.7.4
^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH] scsi: zero per-cmd driver data for each MQ I/O
@ 2017-05-10 21:07 Long Li
2017-05-15 22:48 ` Long Li
2017-05-18 6:55 ` Christoph Hellwig
0 siblings, 2 replies; 12+ messages in thread
From: Long Li @ 2017-05-10 21:07 UTC (permalink / raw)
To: James E.J. Bottomley, Martin K. Petersen, linux-scsi, linux-kernel
Cc: Long Li
From: Long Li <longli@microsoft.com>
Lower layer driver may not initialize private data before use. Zero them
out to prevent use of stale data.
Signed-off-by: Long Li <longli@microsoft.com>
---
drivers/scsi/scsi_lib.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 19125d7..a821593 100644
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1850,7 +1850,7 @@ static int scsi_mq_prep_fn(struct request *req)
/* zero out the cmd, except for the embedded scsi_request */
memset((char *)cmd + sizeof(cmd->req), 0,
- sizeof(*cmd) - sizeof(cmd->req));
+ sizeof(*cmd) - sizeof(cmd->req) + shost->hostt->cmd_size);
req->special = cmd;
--
2.7.4
^ permalink raw reply related [flat|nested] 12+ messages in thread
end of thread, other threads:[~2017-05-18 16:47 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
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2017-05-15 23:32 [PATCH] scsi: zero per-cmd driver data for each MQ I/O Long Li
2017-05-16 0:00 ` Bart Van Assche
2017-05-16 17:31 ` Long Li
2017-05-17 23:05 ` Bart Van Assche
2017-05-18 6:54 ` Christoph Hellwig
2017-05-18 13:29 ` KY Srinivasan
2017-05-18 15:52 ` Bart Van Assche
2017-05-18 16:47 ` Long Li
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2017-05-15 22:48 ` Long Li
2017-05-15 23:20 ` KY Srinivasan
2017-05-18 6:55 ` Christoph Hellwig
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