4.13-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bart Van Assche <bart.vanass...@wdc.com>

commit efea2abcb03215f2efadfe994ff7f652aaff196b upstream.

Avoid that submitting an SG_IO ioctl triggers a kernel oops that
is preceded by:

usercopy: kernel memory overwrite attempt detected to (null) (<null>) (6 bytes)
kernel BUG at mm/usercopy.c:72!

Reported-by: Dann Frazier <dann.fraz...@canonical.com>
Fixes: commit ca18d6f769d2 ("block: Make most scsi_req_init() calls implicit")
Signed-off-by: Bart Van Assche <bart.vanass...@wdc.com>
Cc: Michael S. Tsirkin <m...@redhat.com>
Cc: Dann Frazier <dann.fraz...@canonical.com>
Reviewed-by: Christoph Hellwig <h...@lst.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

Moved virtblk_initialize_rq() inside CONFIG_VIRTIO_BLK_SCSI.

Signed-off-by: Jens Axboe <ax...@kernel.dk>

---
 drivers/block/virtio_blk.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

--- a/drivers/block/virtio_blk.c
+++ b/drivers/block/virtio_blk.c
@@ -593,10 +593,22 @@ static int virtblk_map_queues(struct blk
        return blk_mq_virtio_map_queues(set, vblk->vdev, 0);
 }
 
+#ifdef CONFIG_VIRTIO_BLK_SCSI
+static void virtblk_initialize_rq(struct request *req)
+{
+       struct virtblk_req *vbr = blk_mq_rq_to_pdu(req);
+
+       scsi_req_init(&vbr->sreq);
+}
+#endif
+
 static const struct blk_mq_ops virtio_mq_ops = {
        .queue_rq       = virtio_queue_rq,
        .complete       = virtblk_request_done,
        .init_request   = virtblk_init_request,
+#ifdef CONFIG_VIRTIO_BLK_SCSI
+       .initialize_rq_fn = virtblk_initialize_rq,
+#endif
        .map_queues     = virtblk_map_queues,
 };
 


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