scsi: sd: Fix sshdr use in read_capacity_16

If scsi_execute_cmd returns < 0, it doesn't initialize the sshdr, so we
shouldn't access the sshdr. If it returns 0, then the cmd executed
successfully, so there is no need to check the sshdr. This has us access
the sshdr when we get a return value > 0.

Signed-off-by: Mike Christie <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Reviewed-by: Christoph Hellwig <[email protected]>
Reviewed-by: John Garry <[email protected]>
Reviewed-by: Bart Van Assche <[email protected]>
Reviewed-by: Martin Wilck <[email protected]>
Signed-off-by: Martin K. Petersen <[email protected]>

Author: mikechristie

drivers/scsi/sd.c

@@ -2388,11 +2388,10 @@ static int read_capacity_16(struct scsi_disk *sdkp, struct scsi_device *sdp,
 		the_result = scsi_execute_cmd(sdp, cmd, REQ_OP_DRV_IN,
 					      buffer, RC16_LEN, SD_TIMEOUT,
 					      sdkp->max_retries, &exec_args);
-
-		if (media_not_present(sdkp, &sshdr))
-			return -ENODEV;
-
 		if (the_result > 0) {
+			if (media_not_present(sdkp, &sshdr))
+				return -ENODEV;
+
 			sense_valid = scsi_sense_valid(&sshdr);
 			if (sense_valid &&
 			    sshdr.sense_key == ILLEGAL_REQUEST &&