[PATCH 4.9 17/35] scsi: sd: dont crash the host on invalid commands

[Greg Kroah-Hartman]

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

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

From: Johannes Thumshirn <jthumshirn@xxxxxxx>

[ Upstream commit f1f1fadacaf08b7cf11714c0c29f8fa4d4ef68a9 ]

When sd_init_command() get's a command with a unknown req_op() it crashes the
system via BUG().

This makes debugging the actual reason for the broken request cmd_flags pretty
hard as the system is down before it's able to write out debugging data on the
serial console or the trace buffer.

Change the BUG() to a WARN_ON() and return BLKPREP_KILL to fail gracefully and
return an I/O error to the producer of the request.

Signed-off-by: Johannes Thumshirn <jthumshirn@xxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxx>
Cc: Bart Van Assche <bvanassche@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Bart Van Assche <bvanassche@xxxxxxx>
Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/scsi/sd.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1158,7 +1158,8 @@ static int sd_init_command(struct scsi_c
 	case REQ_OP_WRITE:
 		return sd_setup_read_write_cmnd(cmd);
 	default:
-		BUG();
+		WARN_ON_ONCE(1);
+		return BLKPREP_KILL;
 	}
 }