virtio-net: only delete bh that existed

We delete without check whether it existed during exit. This will lead NULL
pointer deference since it was created conditionally depends on guest driver
status and features. So add a check of existence before trying to delete it.

Cc: qemu-stable@nongnu.org
Signed-off-by: Jason Wang <jasowang@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

1 files changed, 1 insertions, 1 deletions

diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c
index 22dbd053d4..ae51d96a7a 100644
--- a/hw/net/virtio-net.c
+++ b/hw/net/virtio-net.c
@@ -1601,7 +1601,7 @@ static int virtio_net_device_exit(DeviceState *qdev)
         if (q->tx_timer) {
             timer_del(q->tx_timer);
             timer_free(q->tx_timer);
-        } else {
+        } else if (q->tx_bh) {
             qemu_bh_delete(q->tx_bh);
         }
     }