Re: [PATCH] scsi: fc: check for rport presence in fc_block_scsi_eh

[Bart Van Assche <Bart.VanAssche@wdc.com>]

On Mon, 2017-09-25 at 14:00 +0200, 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 <jthumshirn@suse.de>
> ---
>  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..830ce53f30fb 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(!rport))
> +		return 0;
> +
>  	return fc_block_rport(rport);
>  }
>  EXPORT_SYMBOL(fc_block_scsi_eh);

Did you perhaps intend to use WARN_ON_ONCE() instead of WARN_ON()? Anyway:

Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>