[PATCH 04/18] cdrom: Check private request size before attaching to a queue

[Bart Van Assche]

Since the cdrom driver only supports request queues for which
struct scsi_request is the first member of their private request
data, refuse to register block layer queues for which the private
data is smaller than struct scsi_request.

References: commit 82ed4db499b8 ("block: split scsi_request out of struct 
request")
Signed-off-by: Bart Van Assche <bart.vanass...@sandisk.com>
Cc: Jens Axboe <ax...@fb.com>
Cc: Christoph Hellwig <h...@lst.de>
Cc: Omar Sandoval <osan...@fb.com>
Cc: Hannes Reinecke <h...@suse.com>
Cc: linux-bl...@vger.kernel.org
---
 drivers/cdrom/cdrom.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 76c952fd9ab9..dc20e4368136 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -594,6 +594,11 @@ int register_cdrom(struct cdrom_device_info *cdi)
 
        if (cdo->open == NULL || cdo->release == NULL)
                return -EINVAL;
+       if (blk_queue_cmd_size(cdi->disk->queue) <
+           sizeof(struct scsi_request)) {
+               WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
+               return -EINVAL;
+       }
        if (!banner_printed) {
                pr_info("Uniform CD-ROM driver " REVISION "\n");
                banner_printed = 1;
-- 
2.12.2