[SCSI] ses: Avoid kernel panic when lun 0 is not mapped

During device discovery, scsi mid layer sends INQUIRY command to LUN
0. If the LUN 0 is not mapped to host, it creates a temporary
scsi_device with LUN id 0 and sends REPORT_LUNS command to it. After
the REPORT_LUNS succeeds, it walks through the LUN table and adds each
LUN found to sysfs. At the end of REPORT_LUNS lun table scan, it will
delete the temporary scsi_device of LUN 0.

When scsi devices are added to sysfs, it calls add_dev function of all
the registered class interfaces. If ses driver has been registered,
ses_intf_add() of ses module will be called. This function calls
scsi_device_enclosure() to check the inquiry data for EncServ
bit. Since inquiry was not allocated for temporary LUN 0 scsi_device,
it will cause NULL pointer exception.

To fix the problem, sdev->inquiry is checked for NULL before reading it.
Signed-off-by: NSomasundaram Krishnasamy <Somasundaram.Krishnasamy@lsi.com>
Signed-off-by: NBabu Moger <babu.moger@lsi.com>
Cc: stable@kernel.org
Signed-off-by: NJames Bottomley <James.Bottomley@suse.de>

include/scsi/scsi_device.h

@@ -462,7 +462,7 @@ static inline int scsi_device_qas(struct scsi_device *sdev)
 }
 static inline int scsi_device_enclosure(struct scsi_device *sdev)
 {
-	return sdev->inquiry[6] & (1<<6);
+	return sdev->inquiry ? (sdev->inquiry[6] & (1<<6)) : 1;
 }
 
 static inline int scsi_device_protection(struct scsi_device *sdev)