[PATCH 02/18] bsg: Check private request size before attaching to a queue

[Bart Van Assche <bart.vanassche@sandisk.com>]

Since BSG 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 bd1599d931ca ("scsi_transport_sas: fix BSG ioctl memory corruption")
References: commit 82ed4db499b8 ("block: split scsi_request out of struct request")
Signed-off-by: Bart Van Assche <bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Omar Sandoval <osandov@fb.com>
Cc: Hannes Reinecke <hare@suse.com>
Cc: linux-block@vger.kernel.org
---
 block/bsg.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/block/bsg.c b/block/bsg.c
index 6fd08544d77e..5ccecc9855ac 100644
--- a/block/bsg.c
+++ b/block/bsg.c
@@ -750,6 +750,12 @@ static struct bsg_device *bsg_add_device(struct inode *inode,
 #ifdef BSG_DEBUG
 	unsigned char buf[32];
 #endif
+
+	if (blk_queue_cmd_size(rq) < sizeof(struct scsi_request)) {
+		WARN_ONCE(true, "Attempt to register a non-SCSI queue\n");
+		return ERR_PTR(-EINVAL);
+	}
+
 	if (!blk_get_queue(rq))
 		return ERR_PTR(-ENXIO);
 
-- 
2.12.2