From c1ea02f15ab5efb3e93fc3144d895410bf79fcf2 Mon Sep 17 00:00:00 2001 From: Jason Wang Date: Fri, 17 May 2019 00:29:52 -0400 Subject: [PATCH] vhost: scsi: add weight support This patch will check the weight and exit the loop if we exceeds the weight. This is useful for preventing scsi kthread from hogging cpu which is guest triggerable. This addresses CVE-2019-3900. Cc: Paolo Bonzini Cc: Stefan Hajnoczi Fixes: 057cbf49a1f0 ("tcm_vhost: Initial merge for vhost level target fabric driver") Signed-off-by: Jason Wang Reviewed-by: Stefan Hajnoczi Signed-off-by: Michael S. Tsirkin Reviewed-by: Stefan Hajnoczi --- drivers/vhost/scsi.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c index 27c9dac9f518..a9caf1bc3c3e 100644 --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -918,7 +918,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq) struct iov_iter in_iter, prot_iter, data_iter; u64 tag; u32 exp_data_len, data_direction; - int ret, prot_bytes; + int ret, prot_bytes, c = 0; u16 lun; u8 task_attr; bool t10_pi = vhost_has_feature(vq, VIRTIO_SCSI_F_T10_PI); @@ -938,7 +938,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq) vhost_disable_notify(&vs->dev, vq); - for (;;) { + do { ret = vhost_scsi_get_desc(vs, vq, &vc); if (ret) goto err; @@ -1118,7 +1118,7 @@ err: break; else if (ret == -EIO) vhost_scsi_send_bad_target(vs, vq, vc.head, vc.out); - } + } while (likely(!vhost_exceeds_weight(vq, ++c, 0))); out: mutex_unlock(&vq->mutex); } @@ -1177,7 +1177,7 @@ vhost_scsi_ctl_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq) } v_req; struct vhost_scsi_ctx vc; size_t typ_size; - int ret; + int ret, c = 0; mutex_lock(&vq->mutex); /* @@ -1191,7 +1191,7 @@ vhost_scsi_ctl_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq) vhost_disable_notify(&vs->dev, vq); - for (;;) { + do { ret = vhost_scsi_get_desc(vs, vq, &vc); if (ret) goto err; @@ -1270,7 +1270,7 @@ err: break; else if (ret == -EIO) vhost_scsi_send_bad_target(vs, vq, vc.head, vc.out); - } + } while (likely(!vhost_exceeds_weight(vq, ++c, 0))); out: mutex_unlock(&vq->mutex); }