linux-kernel - Re: [PATCH v2] vsock/virtio: initialize the_virtio

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Date:   Mon, 23 Oct 2023 16:29:48 +0200
From:   Stefano Garzarella <sgarzare@...hat.com>
To:     Alexandru Matei <alexandru.matei@...ath.com>
Cc:     Stefan Hajnoczi <stefanha@...hat.com>,
        "David S . Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, kvm@...r.kernel.org,
        virtualization@...ts.linux-foundation.org, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        Mihai Petrisor <mihai.petrisor@...ath.com>,
        Viorel Canja <viorel.canja@...ath.com>
Subject: Re: [PATCH v2] vsock/virtio: initialize the_virtio_vsock before
 using VQs

On Mon, Oct 23, 2023 at 05:08:33PM +0300, Alexandru Matei wrote:
>Once VQs are filled with empty buffers and we kick the host,
>it can send connection requests.  If 'the_virtio_vsock' is not
>initialized before, replies are silently dropped and do not reach the host.
>
>Fixes: 0deab087b16a ("vsock/virtio: use RCU to avoid use-after-free on the_virtio_vsock")
>Signed-off-by: Alexandru Matei <alexandru.matei@...ath.com>
>---
>v2:
>- split virtio_vsock_vqs_init in vqs_init and vqs_fill and moved
>  the_virtio_vsock initialization after vqs_init
>
> net/vmw_vsock/virtio_transport.c | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
>diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c
>index e95df847176b..92738d1697c1 100644
>--- a/net/vmw_vsock/virtio_transport.c
>+++ b/net/vmw_vsock/virtio_transport.c
>@@ -559,6 +559,11 @@ static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
> 	vsock->tx_run = true;
> 	mutex_unlock(&vsock->tx_lock);
>
>+	return 0;
>+}
>+
>+static void virtio_vsock_vqs_fill(struct virtio_vsock *vsock)

What about renaming this function in virtio_vsock_vqs_start() and move 
also the setting of `tx_run` here?

Thanks,
Stefano

>+{
> 	mutex_lock(&vsock->rx_lock);
> 	virtio_vsock_rx_fill(vsock);
> 	vsock->rx_run = true;
>@@ -568,8 +573,6 @@ static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)
> 	virtio_vsock_event_fill(vsock);
> 	vsock->event_run = true;
> 	mutex_unlock(&vsock->event_lock);
>-
>-	return 0;
> }
>
> static void virtio_vsock_vqs_del(struct virtio_vsock *vsock)
>@@ -664,6 +667,7 @@ static int virtio_vsock_probe(struct virtio_device *vdev)
> 		goto out;
>
> 	rcu_assign_pointer(the_virtio_vsock, vsock);
>+	virtio_vsock_vqs_fill(vsock);
>
> 	mutex_unlock(&the_virtio_vsock_mutex);
>
>@@ -736,6 +740,7 @@ static int virtio_vsock_restore(struct virtio_device *vdev)
> 		goto out;
>
> 	rcu_assign_pointer(the_virtio_vsock, vsock);
>+	virtio_vsock_vqs_fill(vsock);
>
> out:
> 	mutex_unlock(&the_virtio_vsock_mutex);
>-- 
>2.34.1
>