On 12/21/2021 9:19 AM, Eli Cohen wrote:
Avoid reading device configuration during feature negotiation. Read
device status and verify that VIRTIO_CONFIG_S_FEATURES_OK is set.

Otherwise, return -EAGAIN.

Signed-off-by: Eli Cohen <[email protected]>
---
  drivers/vdpa/vdpa.c | 10 ++++++++++
  1 file changed, 10 insertions(+)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index 5134c83c4a22..3285cebd89c0 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -838,8 +838,18 @@ vdpa_dev_config_fill(struct vdpa_device *vdev, struct 
sk_buff *msg, u32 portid,
  {
        u32 device_id;
        void *hdr;
+       u8 status;
        int err;
+ mutex_lock(&vdev->cf_mutex);
+       status = vdev->config->get_status(vdev);
Atomicity and data consistency not guaranteed against vdpa_get_config and get_features in vdpa_dev_net_config_fill(). Need to use coarse locking.

-Siwei
+       if (!(status & VIRTIO_CONFIG_S_FEATURES_OK)) {
+               NL_SET_ERR_MSG_MOD(extack, "Features negotiation not 
completed");
+               mutex_unlock(&vdev->cf_mutex);
+               return -EAGAIN;
+       }
+       mutex_unlock(&vdev->cf_mutex);
+
        hdr = genlmsg_put(msg, portid, seq, &vdpa_nl_family, flags,
                          VDPA_CMD_DEV_CONFIG_GET);
        if (!hdr)

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