Re: [PATCH] tcm_vhost: Fix tv_cmd leak in vhost_scsi_handle_vq

[Asias He <asias@redhat.com>]

On Tue, Apr 09, 2013 at 08:46:42AM -0700, Nicholas A. Bellinger wrote:
> On Tue, 2013-04-09 at 17:16 +0800, Asias He wrote:
> > If we fail to submit the allocated tv_vmd to tcm_vhost_submission_work,
> > we will leak the tv_vmd. Free tv_vmd on fail path.
> > 
> > Signed-off-by: Asias He <asias@redhat.com>
> > ---
> >  drivers/vhost/tcm_vhost.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/vhost/tcm_vhost.c b/drivers/vhost/tcm_vhost.c
> > index 3351ed3..1f9116c 100644
> > --- a/drivers/vhost/tcm_vhost.c
> > +++ b/drivers/vhost/tcm_vhost.c
> > @@ -860,7 +860,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
> >  			vq_err(vq, "Expecting virtio_scsi_cmd_resp, got %zu"
> >  				" bytes, out: %d, in: %d\n",
> >  				vq->iov[out].iov_len, out, in);
> > -			break;
> > +			goto err;
> >  		}
> >  
> >  		tv_cmd->tvc_resp = vq->iov[out].iov_base;
> > @@ -882,7 +882,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
> >  				" exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d\n",
> >  				scsi_command_size(tv_cmd->tvc_cdb),
> >  				TCM_VHOST_MAX_CDB_SIZE);
> > -			break; /* TODO */
> > +			goto err;
> >  		}
> >  		tv_cmd->tvc_lun = ((v_req.lun[2] << 8) | v_req.lun[3]) & 0x3FFF;
> >  
> > @@ -895,7 +895,7 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
> >  					data_direction == DMA_TO_DEVICE);
> >  			if (unlikely(ret)) {
> >  				vq_err(vq, "Failed to map iov to sgl\n");
> > -				break; /* TODO */
> > +				goto err;
> >  			}
> >  		}
> >  
> 
> Mmmm, I think these cases also require a VIRTIO_SCSI_S_BAD_TARGET +
> __copy_to_user + vhost_add_used_and_signal similar to how !tv_tpg is
> handled..  Otherwise virtio-scsi will end up in scsi timeout -> abort,
> no..?
> 
> Ditto for the vhost_scsi_allocate_cmd failure case..

Sent out new patches.

> vhost-net uses vhost_discard_vq_desc for some failure cases,  is that
> needed here for the failure cases before __copy_from_user is called..?

I don't think it is useful. vhost_discard_vq_desc reverse the effect of
vhost_get_vq_desc. If we put it back in the queue and next time we will
still fail.

> > @@ -916,6 +916,11 @@ static void vhost_scsi_handle_vq(struct vhost_scsi *vs,
> >  	}
> >  
> >  	mutex_unlock(&vq->mutex);
> > +	return;
> > +
> > +err:
> > +	vhost_scsi_free_cmd(tv_cmd);
> > +	mutex_unlock(&vq->mutex);
> >  }
> >  
> >  static void vhost_scsi_ctl_handle_kick(struct vhost_work *work)
> 
> 

-- 
Asias