scsi: Avoid crashing if device uses DIX but adapter does not support it

This can happen if a multipathed device uses DIX and another path is
added via an adapter that does not support it.  Multipath should not
allow this path to be added, but we should not depend upon that to avoid
crashing.

Signed-off-by: Ewan D. Milne <emilne@redhat.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c
index 6d5c0b8cb0bb47a040d7aec986dbcbae68ffa2b5..17bb541f7cc259a8a3f52c65ec1cae5636e87f65 100644 (file)
--- a/drivers/scsi/scsi_lib.c
+++ b/drivers/scsi/scsi_lib.c
@@ -1143,7 +1143,17 @@ int scsi_init_io(struct scsi_cmnd *cmd)
                struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
                int ivecs, count;
 
-               BUG_ON(prot_sdb == NULL);
+               if (prot_sdb == NULL) {
+                       /*
+                        * This can happen if someone (e.g. multipath)
+                        * queues a command to a device on an adapter
+                        * that does not support DIX.
+                        */
+                       WARN_ON_ONCE(1);
+                       error = BLKPREP_KILL;
+                       goto err_exit;
+               }
+
                ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
 
                if (scsi_alloc_sgtable(prot_sdb, ivecs, is_mq)) {