fix regression in SCSI_IOCTL_SEND_COMMAND

blk_rq_set_block_pc() memsets rq->cmd to 0, so it should come immediately after blk_get_request() to avoid overwriting the user-supplied CDB. Also check for failure to allocate rq.

Fixes f27b087b81b7 ("block: add blk_rq_set_block_pc()")

Cc <[email protected]> # 3.16.x

Signed-off-by Tony Battersby <[email protected]>

For inclusion in 3.17 and 3.16.x.

Note: I don't have any programs that use this ioctl, so this patch is compile-tested only.

block/scsi_ioctl.c +7 -3

@@ -448,6 +448,11 @@ int sg_scsi_ioctl(struct request_queue *
  	}
 
  	rq = blk_get_request(q, in_len ? WRITE : READ, __GFP_WAIT);
+	if (!rq) {
+		err = -ENOMEM;
+		goto error;
+	}
+	blk_rq_set_block_pc(rq);
 
  	cmdlen = COMMAND_SIZE(opcode);
 

@@ -501,7 +506,6 @@ int sg_scsi_ioctl(struct request_queue *
  	memset(sense, 0, sizeof(sense));
  	rq->sense = sense;
  	rq->sense_len = 0;
-	blk_rq_set_block_pc(rq);
 
  	blk_execute_rq(q, disk, rq, 0);
 

@@ -521,7 +525,8 @@ out:
 
  error:
  	kfree(buffer);
-	blk_put_request(rq);
+	if (rq)
+		blk_put_request(rq);
  	return err;
  }
  EXPORT_SYMBOL_GPL(sg_scsi_ioctl);
 
--

To test this ioctl one option is to get the sg3_utils package and build scsi_ioctl.c in the examples directory with 'make scsi_ioctl'.

In lk 3.17-rc1, scsi_ioctl indicates that SCSI_IOCTL_SEND_COMMAND is not working. In my test applying this patch fixes the regression.