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

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

[Johannes Thumshirn]

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@suse.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Bart Van Assche <bvanassche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>
---
Fixed Typo in Bart's mail, sorry for this.

 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..19f28962d65b 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(1);
+		return BLKPREP_KILL;
 	}
 }
 
-- 
2.16.4

Re: [PATCH] scsi: sd: don't crash the host on invalid commands

[Christoph Hellwig]

Looks good,

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH] scsi: sd: don't crash the host on invalid commands

[Bart Van Assche]

On Thu, 2018-09-20 at 09:19 +0200, Johannes Thumshirn wrote:
> 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@suse.de>
> Cc: Hannes Reinecke <hare@suse.de>
> Cc: Bart Van Assche <bvanassche@acm.org>
> Cc: Christoph Hellwig <hch@lst.de>
> ---
> Fixed Typo in Bart's mail, sorry for this.
> 
>  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..19f28962d65b 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(1);
> +		return BLKPREP_KILL;
>  	}
>  }

Have you considered to use WARN_ON_ONCE() instead of WARN_ON(1)? Otherwise
this patch looks good to me.

Thanks,

Bart.

Re: [PATCH] scsi: sd: don't crash the host on invalid commands

[Johannes Thumshirn]

On Thu, Sep 20, 2018 at 11:18:19AM -0700, Bart Van Assche wrote:
> On Thu, 2018-09-20 at 09:19 +0200, Johannes Thumshirn wrote:
> 
> Have you considered to use WARN_ON_ONCE() instead of WARN_ON(1)? Otherwise
> this patch looks good to me.

Indeed I did and then forgot to 'git commit --amend' it befroe sending it out.
I'll do so now.

	Johannes
-- 
Johannes Thumshirn                                          Storage
jthumshirn@suse.de                                +49 911 74053 689
SUSE LINUX GmbH, Maxfeldstr. 5, 90409 Nürnberg
GF: Felix Imendörffer, Jane Smithard, Graham Norton
HRB 21284 (AG Nürnberg)
Key fingerprint = EC38 9CAB C2C4 F25D 8600 D0D0 0393 969D 2D76 0850

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

[Johannes Thumshirn]

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@suse.de>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Bart Van Asche <bvanasche@acm.org>
Cc: Christoph Hellwig <hch@lst.de>
---
 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..19f28962d65b 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(1);
+		return BLKPREP_KILL;
 	}
 }
 
-- 
2.16.4