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[Qemu-devel] [PULL 20/25] clean up callback when del virtqueue

From: Jason Wang
Subject: [Qemu-devel] [PULL 20/25] clean up callback when del virtqueue
Date: Wed, 26 Sep 2018 11:16:45 +0800

From: liujunjie <address@hidden>

Before, we did not clear callback like handle_output when delete
the virtqueue which may result be segmentfault.
The scene is as follows:
1. Start a vm with multiqueue vhost-net,
2. then we write VIRTIO_PCI_GUEST_FEATURES in PCI configuration to
triger multiqueue disable in this vm which will delete the virtqueue.
In this step, the tx_bh is deleted but the callback virtio_net_handle_tx_bh
still exist.
3. Finally, we write VIRTIO_PCI_QUEUE_NOTIFY in PCI configuration to
notify the deleted virtqueue. In this way, virtio_net_handle_tx_bh
will be called and qemu will be crashed.

Although the way described above is uncommon, we had better reinforce it.

CC: address@hidden
Signed-off-by: liujunjie <address@hidden>
Signed-off-by: Jason Wang <address@hidden>
 hw/virtio/virtio.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/hw/virtio/virtio.c b/hw/virtio/virtio.c
index f6a588ab57..57a603a65b 100644
--- a/hw/virtio/virtio.c
+++ b/hw/virtio/virtio.c
@@ -1604,6 +1604,8 @@ void virtio_del_queue(VirtIODevice *vdev, int n)
     vdev->vq[n].vring.num = 0;
     vdev->vq[n].vring.num_default = 0;
+    vdev->vq[n].handle_output = NULL;
+    vdev->vq[n].handle_aio_output = NULL;
 static void virtio_set_isr(VirtIODevice *vdev, int value)

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