linux-kernel - [PATCH v2] scsi: sd: don't crash the host on invalid commands

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Date:   Fri, 21 Sep 2018 09:01:01 +0200
From:   Johannes Thumshirn <jthumshirn@...e.de>
To:     "Martin K . Petersen" <martin.petersen@...cle.com>
Cc:     Linux Kernel Mailinglist <linux-kernel@...r.kernel.org>,
        Linux SCSI Mailinglist <linux-scsi@...r.kernel.org>,
        Johannes Thumshirn <jthumshirn@...e.de>,
        Hannes Reinecke <hare@...e.de>,
        Bart Van Assche <bvanassche@....org>,
        Christoph Hellwig <hch@....de>
Subject: [PATCH v2] scsi: sd: don't crash the host on invalid commands

When sd_init_command() get's a 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@...e.de>
Cc: Hannes Reinecke <hare@...e.de>
Cc: Bart Van Assche <bvanassche@....org>
Cc: Christoph Hellwig <hch@....de>
Reviewed-by: Christoph Hellwig <hch@....de>

---
Changes since v1:
- Use WARN_ON_ONCE() (Bart)
---
 drivers/scsi/sd.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/scsi/sd.c b/drivers/scsi/sd.c
index b79b366a94f7..f2e41f04e40b 100644
--- a/drivers/scsi/sd.c
+++ b/drivers/scsi/sd.c
@@ -1276,7 +1276,8 @@ static int sd_init_command(struct scsi_cmnd *cmd)
 	case REQ_OP_ZONE_RESET:
 		return sd_zbc_setup_reset_cmnd(cmd);
 	default:
-		BUG();
+		WARN_ON_ONCE(1);
+		return BLKPREP_KILL;
 	}
 }
 
-- 
2.16.4