Re: [PATCH 3/6] block: Create scsi_sense.h for SCSI and ATAPI

[Christoph Hellwig <hch@infradead.org>]

On Wed, May 23, 2018 at 02:17:14PM -0700, Kees Cook wrote:
> 
> True, though I'm finding other robustness issues in the CDROM code.
> They're probably all insane corner cases, but it seems like it'd be
> nice to just fix them:
> 
> diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
> index 3522d2cae1b6..7726c8618c30 100644
> --- a/drivers/cdrom/cdrom.c
> +++ b/drivers/cdrom/cdrom.c
> @@ -2222,9 +2223,12 @@ static int cdrom_read_cdda_bpc(struct
> cdrom_device_info *cdi, __u8 __user *ubuf,
> 
>                 blk_execute_rq(q, cdi->disk, rq, 0);
>                 if (scsi_req(rq)->result) {
> -                       struct request_sense *s = req->sense;
> +                       struct scsi_sense_hdr sshdr;
> +
>                         ret = -EIO;
> -                       cdi->last_sense = s->sense_key;
> +                       scsi_normalize_sense(req->sense, req->sense_len,
> +                                            &sshdr);
> +                       cdi->last_sense = sshdr.sense_key;
>                 }
> 
>                 if (blk_rq_unmap_user(bio))

The proper fix here is to rewrite this function to use the the
->generic_packet cdrom_device_ops method.  Is is the only caller
going straight to the scsi passthrough requests, which is a layering
violation.