On Fri, Oct 25, 2013 at 06:07:16PM +0000, Nicholas A. Bellinger wrote: > From: Nicholas Bellinger <[email protected]> > > This patch addresses a long-standing bug where the get_user_pages_fast() > write parameter used for setting the underlying page table entry permission > bits was incorrectly set to write=1 for data_direction=DMA_TO_DEVICE, and > passed into get_user_pages_fast() via vhost_scsi_map_iov_to_sgl(). > > However, this parameter is intended to signal WRITEs to pinned userspace > PTEs for the virtio-scsi DMA_FROM_DEVICE -> READ payload case, and *not* > for the virtio-scsi DMA_TO_DEVICE -> WRITE payload case. > > This bug would manifest itself as random process segmentation faults on > KVM host after repeated vhost starts + stops and/or with lots of vhost > endpoints + LUNs. > > Cc: Stefan Hajnoczi <[email protected]> > Cc: Michael S. Tsirkin <[email protected]> > Cc: Asias He <[email protected]> > Cc: <[email protected]> # 3.6+ > Signed-off-by: Nicholas Bellinger <[email protected]>
Reviewed-by: Asias He <[email protected]> > --- > drivers/vhost/scsi.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c > index ce5221f..e663921 100644 > --- a/drivers/vhost/scsi.c > +++ b/drivers/vhost/scsi.c > @@ -1056,7 +1056,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct > vhost_virtqueue *vq) > if (data_direction != DMA_NONE) { > ret = vhost_scsi_map_iov_to_sgl(cmd, > &vq->iov[data_first], data_num, > - data_direction == DMA_TO_DEVICE); > + data_direction == DMA_FROM_DEVICE); > if (unlikely(ret)) { > vq_err(vq, "Failed to map iov to sgl\n"); > goto err_free; > -- > 1.7.2.5 > -- Asias _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
