[PATCH] scsi: clear garbage after CDBs on SG_IO

ATAPI devices transfer fixed number of bytes for CDBs (12 or 16).  Some
ATAPI devices choke when shorter CDB is used and the left bytes contain
garbage.  Block SG_IO cleared left bytes but SCSI SG_IO didn't.  This patch
makes SCSI SG_IO clear it and simplify CDB clearing in block SG_IO.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Mathieu Fluhr <mfluhr@nero.com>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Douglas Gilbert <dougg@torque.net>
Acked-by: Jens Axboe <jens.axboe@oracle.com>
Cc: <stable@kernel.org>
Acked-by: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 1 insertions, 2 deletions

diff --git a/block/scsi_ioctl.c b/block/scsi_ioctl.c
index a19338e6215d..e55a75621437 100644
--- a/block/scsi_ioctl.c
+++ b/block/scsi_ioctl.c
@@ -286,9 +286,8 @@ static int sg_io(struct file *file, request_queue_t *q,
          * fill in request structure
          */
         rq->cmd_len = hdr->cmd_len;
+        memset(rq->cmd, 0, BLK_MAX_CDB); /* ATAPI hates garbage after CDB */
         memcpy(rq->cmd, cmd, hdr->cmd_len);
-        if (sizeof(rq->cmd) != hdr->cmd_len)
-                memset(rq->cmd + hdr->cmd_len, 0, sizeof(rq->cmd) - hdr->cmd_len);
 
         memset(sense, 0, sizeof(sense));
         rq->sense = sense;