[PATCH] scsi: Fix more error handling in SCSI_IOCTL_SEND_COMMAND

[Tony Battersby <tonyb@cybernetics.com>]

Fix an error path in SCSI_IOCTL_SEND_COMMAND that calls
blk_put_request(rq) on an invalid IS_ERR(rq) pointer.

Fixes: a492f075450f ("block,scsi: fixup blk_get_request dead queue scenarios")
Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
---

(resending, since no one picked it up last time)

For inclusion in 3.18 only.  This fixes a problem
introduced in 3.18.

Note: this fixes a *different* problem from Jan Kara's
patch with a similar subject line, which has already
been applied to mainline.

--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -458,7 +458,7 @@ int sg_scsi_ioctl(struct request_queue *q, struct gendisk *disk, fmode_t mode,
 	rq = blk_get_request(q, in_len ? WRITE : READ, __GFP_WAIT);
 	if (IS_ERR(rq)) {
 		err = PTR_ERR(rq);
-		goto error;
+		goto error_free_buffer;
 	}
 	blk_rq_set_block_pc(rq);
 
@@ -531,9 +531,11 @@ out:
 	}
 	
 error:
+	blk_put_request(rq);
+
+error_free_buffer:
 	kfree(buffer);
-	if (rq)
-		blk_put_request(rq);
+
 	return err;
 }
 EXPORT_SYMBOL_GPL(sg_scsi_ioctl);