From: Jason Wang <jasowang@redhat.com>
Date: Fri, 17 May 2019 00:29:52 -0400
Subject: vhost: scsi: add weight support
Patch-mainline: v5.2-rc4
Git-commit: c1ea02f15ab5efb3e93fc3144d895410bf79fcf2
References: CVE-2019-3900 bsc#1133374
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>
Acked-by: Michal Kubecek <mkubecek@suse.cz>
SLE(4.12 based): omitted part patching code added by mainline commit
0d02dbd68c47 ("vhost/scsi: Respond to control queue operations") which has
not bee backported into any 4.12 based SLE branch.
---
drivers/vhost/scsi.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/vhost/scsi.c
+++ b/drivers/vhost/scsi.c
@@ -851,7 +851,7 @@ 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;
@@ -870,7 +870,7 @@ 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);
@@ -1085,7 +1085,7 @@ 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);
}