A userspace triggerable infinite loop could happen in
mlx5_cvq_kick_handler() if userspace keeps sending a huge amount of
cvq requests.
Fixing this by introducing a quota and re-queue the work if we're out
of the budget (currently the implicit budget is one) . While at it,
using a per device work struct to avoid on demand memory allocation
for cvq.
Fixes: 5262912ef3cfc ("vdpa/mlx5: Add support for control VQ and MAC setting")
Signed-off-by: Jason Wang <jasowang@xxxxxxxxxx>
---
Changes since V1:
- Using 1 as the budget
---
drivers/vdpa/mlx5/net/mlx5_vnet.c | 21 +++++++++------------
1 file changed, 9 insertions(+), 12 deletions(-)
diff --git a/drivers/vdpa/mlx5/net/mlx5_vnet.c b/drivers/vdpa/mlx5/net/mlx5_vnet.c
index d0f91078600e..b2afd2b6fbca 100644
--- a/drivers/vdpa/mlx5/net/mlx5_vnet.c
+++ b/drivers/vdpa/mlx5/net/mlx5_vnet.c
@@ -163,6 +163,7 @@ struct mlx5_vdpa_net {
u32 cur_num_vqs;
struct notifier_block nb;
struct vdpa_callback config_cb;
+ struct mlx5_vdpa_wq_ent cvq_ent;
};
static void free_resources(struct mlx5_vdpa_net *ndev);
@@ -1616,10 +1617,10 @@ static void mlx5_cvq_kick_handler(struct work_struct *work)
ndev = to_mlx5_vdpa_ndev(mvdev);
cvq = &mvdev->cvq;
if (!(ndev->mvdev.actual_features & BIT_ULL(VIRTIO_NET_F_CTRL_VQ)))
- goto out;
+ return;
if (!cvq->ready)
- goto out;
+ return;
while (true) {
err = vringh_getdesc_iotlb(&cvq->vring, &cvq->riov, &cvq->wiov, &cvq->head,
@@ -1653,9 +1654,10 @@ static void mlx5_cvq_kick_handler(struct work_struct *work)
if (vringh_need_notify_iotlb(&cvq->vring))
vringh_notify(&cvq->vring);
+
+ queue_work(mvdev->wq, &wqent->work);
+ break;
}
-out:
- kfree(wqent);
}
static void mlx5_vdpa_kick_vq(struct vdpa_device *vdev, u16 idx)
@@ -1663,7 +1665,6 @@ static void mlx5_vdpa_kick_vq(struct vdpa_device *vdev, u16 idx)
struct mlx5_vdpa_dev *mvdev = to_mvdev(vdev);
struct mlx5_vdpa_net *ndev = to_mlx5_vdpa_ndev(mvdev);
struct mlx5_vdpa_virtqueue *mvq;
- struct mlx5_vdpa_wq_ent *wqent;
if (!is_index_valid(mvdev, idx))
return;
@@ -1672,13 +1673,7 @@ static void mlx5_vdpa_kick_vq(struct vdpa_device *vdev, u16 idx)
if (!mvdev->cvq.ready)
return;
- wqent = kzalloc(sizeof(*wqent), GFP_ATOMIC);
- if (!wqent)
- return;
-
- wqent->mvdev = mvdev;
- INIT_WORK(&wqent->work, mlx5_cvq_kick_handler);
- queue_work(mvdev->wq, &wqent->work);
+ queue_work(mvdev->wq, &ndev->cvq_ent.work);
return;
}
@@ -2668,6 +2663,8 @@ static int mlx5_vdpa_dev_add(struct vdpa_mgmt_dev *v_mdev, const char *name,
if (err)
goto err_mr;
+ ndev->cvq_ent.mvdev = mvdev;
+ INIT_WORK(&ndev->cvq_ent.work, mlx5_cvq_kick_handler);
mvdev->wq = create_singlethread_workqueue("mlx5_vdpa_wq");
if (!mvdev->wq) {
err = -ENOMEM;
--
2.18.1
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