1 files changed, 4 insertions, 1 deletions

diff --git a/drivers/ata/libata-scsi.c b/drivers/ata/libata-scsi.c
index a89172c100f5..7bb6787de550 100644
--- a/drivers/ata/libata-scsi.c
+++ b/drivers/ata/libata-scsi.c
@@ -2577,8 +2577,11 @@ static void atapi_qc_complete(struct ata_queued_cmd *qc)
                  *
                  * If door lock fails, always clear sdev->locked to
                  * avoid this infinite loop.
+                 *
+                 * This may happen before SCSI scan is complete.  Make
+                 * sure qc->dev->sdev isn't NULL before dereferencing.
                  */
-                if (qc->cdb[0] == ALLOW_MEDIUM_REMOVAL)
+                if (qc->cdb[0] == ALLOW_MEDIUM_REMOVAL && qc->dev->sdev)
                         qc->dev->sdev->locked = 0;
 
                 qc->scsicmd->result = SAM_STAT_CHECK_CONDITION;