Coverity-scan recently found a possible NULL pointer dereference in
fc_block_scsi_eh() as starget_to_rport() either returns the rport for
the startget or NULL.
While it is rather unlikely to have fc_block_scsi_eh() called without
an rport associated it's a good idea to catch potential misuses of the
API gracefully.
Signed-off-by: Johannes Thumshirn <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
---
Changes since v1:
- s/WARN_ON/WARN_ON_ONCE/ (Bart)
---
drivers/scsi/scsi_transport_fc.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
index ba9d70f8a6a1..38abff7b5dbc 100644
--- a/drivers/scsi/scsi_transport_fc.c
+++ b/drivers/scsi/scsi_transport_fc.c
@@ -3328,6 +3328,9 @@ int fc_block_scsi_eh(struct scsi_cmnd *cmnd)
{
struct fc_rport *rport = starget_to_rport(scsi_target(cmnd->device));
+ if (WARN_ON_ONCE(!rport))
+ return 0;
+
return fc_block_rport(rport);
}
EXPORT_SYMBOL(fc_block_scsi_eh);
--
2.13.5
On 09/26/2017 08:58 AM, Johannes Thumshirn wrote:
> Coverity-scan recently found a possible NULL pointer dereference in
> fc_block_scsi_eh() as starget_to_rport() either returns the rport for
> the startget or NULL.
>
> While it is rather unlikely to have fc_block_scsi_eh() called without
> an rport associated it's a good idea to catch potential misuses of the
> API gracefully.
>
> Signed-off-by: Johannes Thumshirn <[email protected]>
> Reviewed-by: Bart Van Assche <[email protected]>
> ---
>
> Changes since v1:
> - s/WARN_ON/WARN_ON_ONCE/ (Bart)
>
> ---
> drivers/scsi/scsi_transport_fc.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
> index ba9d70f8a6a1..38abff7b5dbc 100644
> --- a/drivers/scsi/scsi_transport_fc.c
> +++ b/drivers/scsi/scsi_transport_fc.c
> @@ -3328,6 +3328,9 @@ int fc_block_scsi_eh(struct scsi_cmnd *cmnd)
> {
> struct fc_rport *rport = starget_to_rport(scsi_target(cmnd->device));
>
> + if (WARN_ON_ONCE(!rport))
> + return 0;
> +
> return fc_block_rport(rport);
> }
> EXPORT_SYMBOL(fc_block_scsi_eh);
>
Reviewed-by: Hannes Reinecke <[email protected]>
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
[email protected] +49 911 74053 688
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: F. Imendörffer, J. Smithard, J. Guild, D. Upmanyu, G. Norton
HRB 21284 (AG Nürnberg)
On 09/26/2017 08:58 AM, Johannes Thumshirn wrote:
> Coverity-scan recently found a possible NULL pointer dereference in
> fc_block_scsi_eh() as starget_to_rport() either returns the rport for
> the startget or NULL.
>
> While it is rather unlikely to have fc_block_scsi_eh() called without
> an rport associated it's a good idea to catch potential misuses of the
> API gracefully.
>
> Signed-off-by: Johannes Thumshirn <[email protected]>
> Reviewed-by: Bart Van Assche <[email protected]>
> ---
>
> Changes since v1:
> - s/WARN_ON/WARN_ON_ONCE/ (Bart)
>
> ---
> drivers/scsi/scsi_transport_fc.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/scsi/scsi_transport_fc.c b/drivers/scsi/scsi_transport_fc.c
> index ba9d70f8a6a1..38abff7b5dbc 100644
> --- a/drivers/scsi/scsi_transport_fc.c
> +++ b/drivers/scsi/scsi_transport_fc.c
> @@ -3328,6 +3328,9 @@ int fc_block_scsi_eh(struct scsi_cmnd *cmnd)
> {
> struct fc_rport *rport = starget_to_rport(scsi_target(cmnd->device));
>
> + if (WARN_ON_ONCE(!rport))
> + return 0;
Good idea.
However, return 0 or FAST_IO_FAIL?
I mean the callchains to this function (and of fc_block_rport()) react
differently depending on the return value.
Returning 0 means that the rport left the blocked state, i.e. is usable
for traffic again.
If there is no rport at all, I suppose one cannot use it for traffic.
If there is any I/O pending on this scope and we return 0, scsi_eh
escalates; and if this happens for a host_reset we end up with offlined
scsi_devices.
I wonder if returning FAST_IO_FAIL would be more appropriate here in
this case, in order to have scsi_eh let the pending I/O bubble up for a
timely path failover?
--
Mit freundlichen Grüßen / Kind regards
Steffen Maier
Linux on z Systems Development
IBM Deutschland Research & Development GmbH
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