scsi: sd: don't crash the host on invalid commands

Johannes Thumshirn · martinkpetersen · commit f1f1fadacaf0 · 2018-09-21T12:42:57.000-04:00
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 &lt;jthumshirn@suse.de&gt;
Cc: Hannes Reinecke &lt;hare@suse.de&gt;
Cc: Bart Van Assche &lt;bvanassche@acm.org&gt;
Cc: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Christoph Hellwig &lt;hch@lst.de&gt;
Reviewed-by: Bart Van Assche &lt;bvanassche@acm.org&gt;
Signed-off-by: Martin K. Petersen &lt;martin.petersen@oracle.com&gt;
diff --git 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;
 	}
 }
 

Original file line number	Diff line number	Diff line change
`@@ -1276,7 +1276,8 @@ static int sd_init_command(struct scsi_cmnd *cmd)`
`1276`	`1276`	`case REQ_OP_ZONE_RESET:`
`1277`	`1277`	`return sd_zbc_setup_reset_cmnd(cmd);`
`1278`	`1278`	`default:`
`1279`		`- BUG();`
	`1279`	`+ WARN_ON_ONCE(1);`
	`1280`	`+ return BLKPREP_KILL;`
`1280`	`1281`	`}`
`1281`	`1282`	`}`
`1282`	`1283`