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]>
---
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
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
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]>
Acked-by: Michael S. Tsirkin <[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