The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.4.y git checkout FETCH_HEAD git cherry-pick -x 53b08c4985158430fd6d035fb49443bada535210 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2023102739-channel-upstream-7bca@gregkh' --subject-prefix 'PATCH 5.4.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 53b08c4985158430fd6d035fb49443bada535210 Mon Sep 17 00:00:00 2001 From: Alexandru Matei alexandru.matei@uipath.com Date: Tue, 24 Oct 2023 22:17:42 +0300 Subject: [PATCH] vsock/virtio: initialize the_virtio_vsock before using VQs

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.

virtio_transport_send_pkt() can queue packets once the_virtio_vsock is set, but they won't be processed until vsock->tx_run is set to true. We queue vsock->send_pkt_work when initialization finishes to send those packets queued earlier.

Fixes: 0deab087b16a ("vsock/virtio: use RCU to avoid use-after-free on the_virtio_vsock") Signed-off-by: Alexandru Matei alexandru.matei@uipath.com Reviewed-by: Stefano Garzarella sgarzare@redhat.com Link: https://lore.kernel.org/r/20231024191742.14259-1-alexandru.matei@uipath.com Signed-off-by: Jakub Kicinski kuba@kernel.org

diff --git a/net/vmw_vsock/virtio_transport.c b/net/vmw_vsock/virtio_transport.c index e95df847176b..b80bf681327b 100644 --- a/net/vmw_vsock/virtio_transport.c +++ b/net/vmw_vsock/virtio_transport.c @@ -555,6 +555,11 @@ static int virtio_vsock_vqs_init(struct virtio_vsock *vsock)

virtio_device_ready(vdev);

+ return 0; +} + +static void virtio_vsock_vqs_start(struct virtio_vsock *vsock) +{ mutex_lock(&vsock->tx_lock); vsock->tx_run = true; mutex_unlock(&vsock->tx_lock); @@ -569,7 +574,16 @@ static int virtio_vsock_vqs_init(struct virtio_vsock *vsock) vsock->event_run = true; mutex_unlock(&vsock->event_lock);

- return 0; + /* virtio_transport_send_pkt() can queue packets once + * the_virtio_vsock is set, but they won't be processed until + * vsock->tx_run is set to true. We queue vsock->send_pkt_work + * when initialization finishes to send those packets queued + * earlier. + * We don't need to queue the other workers (rx, event) because + * as long as we don't fill the queues with empty buffers, the + * host can't send us any notification. + */ + queue_work(virtio_vsock_workqueue, &vsock->send_pkt_work); }

static void virtio_vsock_vqs_del(struct virtio_vsock *vsock) @@ -664,6 +678,7 @@ static int virtio_vsock_probe(struct virtio_device *vdev) goto out;

rcu_assign_pointer(the_virtio_vsock, vsock); + virtio_vsock_vqs_start(vsock);

mutex_unlock(&the_virtio_vsock_mutex);

@@ -736,6 +751,7 @@ static int virtio_vsock_restore(struct virtio_device *vdev) goto out;

rcu_assign_pointer(the_virtio_vsock, vsock); + virtio_vsock_vqs_start(vsock);

out: mutex_unlock(&the_virtio_vsock_mutex);