vsock: Fix IOCTL_VM_SOCKETS_GET_LOCAL_CID to check also `transport_local`

Support returning VMADDR_CID_LOCAL in case no other vsock transport is
available.

Fixes: 0e12190578d0 ("vsock: add local transport support in the vsock core")
Suggested-by: Stefano Garzarella <sgarzare@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Michal Luczaj <mhal@rbox.co>
Link: https://patch.msgid.link/20250703-vsock-transports-toctou-v4-3-98f0eb530747@rbox.co
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index 66404c06bdaa0dc453a625c08a04c7eb14a95498..1053662725f8f03b78dc6ef80d46c31167ba0055 100644 (file)
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -2581,6 +2581,8 @@ static long vsock_dev_do_ioctl(struct file *filp,
                cid = vsock_registered_transport_cid(&transport_g2h);
                if (cid == VMADDR_CID_ANY)
                        cid = vsock_registered_transport_cid(&transport_h2g);
+               if (cid == VMADDR_CID_ANY)
+                       cid = vsock_registered_transport_cid(&transport_local);
 
                if (put_user(cid, p) != 0)
                        retval = -EFAULT;