From: Jason Wang jasowang@redhat.com
commit e79b431fb901ba1106670bcc80b9b617b25def7d upstream.
This patch will check the weight and exit the loop if we exceeds the weight. This is useful for preventing vsock kthread from hogging cpu which is guest triggerable. The weight can help to avoid starving the request from on direction while another direction is being processed.
The value of weight is picked from vhost-net.
This addresses CVE-2019-3900.
Cc: Stefan Hajnoczi stefanha@redhat.com Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko") Signed-off-by: Jason Wang jasowang@redhat.com Reviewed-by: Stefan Hajnoczi stefanha@redhat.com Signed-off-by: Michael S. Tsirkin mst@redhat.com Signed-off-by: Balbir Singh sblbir@amzn.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/vhost/vsock.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)
--- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -86,6 +86,7 @@ vhost_transport_do_send_pkt(struct vhost struct vhost_virtqueue *vq) { struct vhost_virtqueue *tx_vq = &vsock->vqs[VSOCK_VQ_TX]; + int pkts = 0, total_len = 0; bool added = false; bool restart_tx = false;
@@ -97,7 +98,7 @@ vhost_transport_do_send_pkt(struct vhost /* Avoid further vmexits, we're already processing the virtqueue */ vhost_disable_notify(&vsock->dev, vq);
- for (;;) { + do { struct virtio_vsock_pkt *pkt; struct iov_iter iov_iter; unsigned out, in; @@ -182,8 +183,9 @@ vhost_transport_do_send_pkt(struct vhost */ virtio_transport_deliver_tap_pkt(pkt);
+ total_len += pkt->len; virtio_transport_free_pkt(pkt); - } + } while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len))); if (added) vhost_signal(&vsock->dev, vq);
@@ -358,7 +360,7 @@ static void vhost_vsock_handle_tx_kick(s struct vhost_vsock *vsock = container_of(vq->dev, struct vhost_vsock, dev); struct virtio_vsock_pkt *pkt; - int head; + int head, pkts = 0, total_len = 0; unsigned int out, in; bool added = false;
@@ -368,7 +370,7 @@ static void vhost_vsock_handle_tx_kick(s goto out;
vhost_disable_notify(&vsock->dev, vq); - for (;;) { + do { u32 len;
if (!vhost_vsock_more_replies(vsock)) { @@ -409,9 +411,11 @@ static void vhost_vsock_handle_tx_kick(s else virtio_transport_free_pkt(pkt);
- vhost_add_used(vq, head, sizeof(pkt->hdr) + len); + len += sizeof(pkt->hdr); + vhost_add_used(vq, head, len); + total_len += len; added = true; - } + } while(likely(!vhost_exceeds_weight(vq, ++pkts, total_len)));
no_more_replies: if (added)