Re: [PATCH][SCSI] fix regression in SCSI_IOCTL_SEND_COMMAND

[Douglas Gilbert <dgilbert@interlog.com>]

On 14-08-22 03:53 PM, Tony Battersby wrote:
> blk_rq_set_block_pc() memsets rq->cmd to 0, so it should come
> immediately after blk_get_request() to avoid overwriting the
> user-supplied CDB.  Also check for failure to allocate rq.
>
> Fixes: f27b087b81b7 ("block: add blk_rq_set_block_pc()")
> Cc: <stable@vger.kernel.org> # 3.16.x
> Signed-off-by: Tony Battersby <tonyb@cybernetics.com>

Tested-by: Douglas Gilbert <dgilbert@interlog.com>

> For inclusion in 3.17 and 3.16.x.
>
> Note: I don't have any programs that use this ioctl, so this patch is
> compile-tested only.

To test this ioctl one option is to get the sg3_utils
package and build scsi_ioctl.c in the examples
directory with 'make scsi_ioctl'.

In lk 3.17-rc1, scsi_ioctl indicates that
SCSI_IOCTL_SEND_COMMAND is not working. In my test applying
this patch fixes the regression.

> --- linux-3.17.0-rc1-a/block/scsi_ioctl.c	2014-08-16 12:40:26.000000000 -0400
> +++ linux-3.17.0-rc1-b/block/scsi_ioctl.c	2014-08-22 14:15:34.000000000 -0400
> @@ -448,6 +448,11 @@ int sg_scsi_ioctl(struct request_queue *
>   	}
>
>   	rq = blk_get_request(q, in_len ? WRITE : READ, __GFP_WAIT);
> +	if (!rq) {
> +		err = -ENOMEM;
> +		goto error;
> +	}
> +	blk_rq_set_block_pc(rq);
>
>   	cmdlen = COMMAND_SIZE(opcode);
>
> @@ -501,7 +506,6 @@ int sg_scsi_ioctl(struct request_queue *
>   	memset(sense, 0, sizeof(sense));
>   	rq->sense = sense;
>   	rq->sense_len = 0;
> -	blk_rq_set_block_pc(rq);
>
>   	blk_execute_rq(q, disk, rq, 0);
>
> @@ -521,7 +525,8 @@ out:
>   	
>   error:
>   	kfree(buffer);
> -	blk_put_request(rq);
> +	if (rq)
> +		blk_put_request(rq);
>   	return err;
>   }
>   EXPORT_SYMBOL_GPL(sg_scsi_ioctl);
>
> --