From: Jason Wang jasowang@redhat.com
commit c1ea02f15ab5efb3e93fc3144d895410bf79fcf2 upstream
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 pbonzini@redhat.com Cc: Stefan Hajnoczi stefanha@redhat.com Fixes: 057cbf49a1f0 ("tcm_vhost: Initial merge for vhost level target fabric driver") Signed-off-by: Jason Wang jasowang@redhat.com Reviewed-by: Stefan Hajnoczi stefanha@redhat.com Signed-off-by: Michael S. Tsirkin mst@redhat.com Reviewed-by: Stefan Hajnoczi stefanha@redhat.com [jwang: backport to 4.19] Signed-off-by: Jack Wang jinpu.wang@cloud.ionos.com --- drivers/vhost/scsi.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/drivers/vhost/scsi.c b/drivers/vhost/scsi.c index 087ce17b0c39..5e298d9287f1 100644 --- a/drivers/vhost/scsi.c +++ b/drivers/vhost/scsi.c @@ -817,7 +817,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq) u64 tag; u32 exp_data_len, data_direction; unsigned int out = 0, in = 0; - int head, ret, prot_bytes; + int head, ret, prot_bytes, c = 0; size_t req_size, rsp_size = sizeof(struct virtio_scsi_cmd_resp); size_t out_size, in_size; u16 lun; @@ -836,7 +836,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq)
vhost_disable_notify(&vs->dev, vq);
- for (;;) { + do { head = vhost_get_vq_desc(vq, vq->iov, ARRAY_SIZE(vq->iov), &out, &in, NULL, NULL); @@ -1051,7 +1051,7 @@ vhost_scsi_handle_vq(struct vhost_scsi *vs, struct vhost_virtqueue *vq) */ INIT_WORK(&cmd->work, vhost_scsi_submission_work); queue_work(vhost_scsi_workqueue, &cmd->work); - } + } while (likely(!vhost_exceeds_weight(vq, ++c, 0))); out: mutex_unlock(&vq->mutex); }