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Subject[PATCH] virtio/vsock: fix the transport to work with VMADDR_CID_ANY
The VMADDR_CID_ANY flag used by a socket means that the socket isn't bound
to any specific CID. For example, a host vsock server may want to be bound
with VMADDR_CID_ANY, so that a guest vsock client can connect to the host
server with CID=VMADDR_CID_HOST (i.e. 2), and meanwhile, a host vsock
client can connect to the same local server with CID=VMADDR_CID_LOCAL
(i.e. 1).

The current implementation sets the destination socket's svm_cid to a
fixed CID value after the first client's connection, which isn't an
expected operation. For example, if the guest client first connects to the
host server, the server's svm_cid gets set to VMADDR_CID_HOST, then other
host clients won't be able to connect to the server anymore.

Reproduce steps:
1. Run the host server:
socat VSOCK-LISTEN:1234,fork -
2. Run a guest client to connect to the host server:
socat - VSOCK-CONNECT:2:1234
3. Run a host client to connect to the host server:
socat - VSOCK-CONNECT:1:1234

Without this patch, step 3. above fails to connect, and socat complains
"socat[1720] E connect(5, AF=40 cid:1 port:1234, 16): Connection
reset by peer".
With this patch, the above works well.

Signed-off-by: Wei Wang <>
net/vmw_vsock/virtio_transport_common.c | 3 ---
1 file changed, 3 deletions(-)

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index 59ee1be5a6dd..5c60fae10569 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -1298,9 +1298,6 @@ void virtio_transport_recv_pkt(struct virtio_transport *t,

space_available = virtio_transport_space_update(sk, pkt);

- /* Update CID in case it has changed after a transport reset event */
- vsk->local_addr.svm_cid = dst.svm_cid;
if (space_available)

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