This is a note to let you know that I've just added the patch titled virtio/vsock: fix the transport to work with VMADDR_CID_ANY to the 5.10-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: virtio-vsock-fix-the-transport-to-work-with-vmaddr_c.patch and it can be found in the queue-5.10 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 42d968e41a83b5ad0e85ccb82e532355dad0b847 Author: Wei Wang <wei.w.wang@xxxxxxxxx> Date: Thu Nov 25 20:18:23 2021 -0500 virtio/vsock: fix the transport to work with VMADDR_CID_ANY [ Upstream commit 1db8f5fc2e5c66a5c51e1f6488e0ba7d45c29ae4 ] 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. Fixes: c0cfa2d8a788 ("vsock: add multi-transports support") Signed-off-by: Wei Wang <wei.w.wang@xxxxxxxxx> Link: https://lore.kernel.org/r/20211126011823.1760-1-wei.w.wang@xxxxxxxxx Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx> Reviewed-by: Stefano Garzarella <sgarzare@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c index 902cb6dd710bd..d6d3a05c008a4 100644 --- a/net/vmw_vsock/virtio_transport_common.c +++ b/net/vmw_vsock/virtio_transport_common.c @@ -1153,7 +1153,8 @@ 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 (vsk->local_addr.svm_cid != VMADDR_CID_ANY) + vsk->local_addr.svm_cid = dst.svm_cid; if (space_available) sk->sk_write_space(sk);