Re: [PATCH] vfio-user: disconnect container when device info query fails

[John Levon <john.levon@nutanix.com>]

On Fri, May 22, 2026 at 02:56:37PM +0800, zhaoguohan@kylinos.cn wrote:

> vfio_user_device_attach() connects the vfio-user container before querying
> VFIO_USER_DEVICE_GET_INFO.  If the device info query fails,
> vfio_device_prepare() has not run yet, so vbasedev->bcontainer is still
> NULL and the later vfio_device_detach() cleanup path cannot reach the new
> container.
> 
> Disconnect the container before returning the attach failure so the listener,
> RAM discard state, object reference and address space reference are released
> on this error path.
> 
> Signed-off-by: GuoHan Zhao <zhaoguohan@kylinos.cn>
> ---
>  hw/vfio-user/container.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
> diff --git a/hw/vfio-user/container.c b/hw/vfio-user/container.c
> index 796289a46903..dc23b06eebf1 100644
> --- a/hw/vfio-user/container.c
> +++ b/hw/vfio-user/container.c
> @@ -309,7 +309,12 @@ static bool vfio_user_device_attach(const char *name, VFIODevice *vbasedev,
>          return false;
>      }
>  
> -    return vfio_user_device_get(container, vbasedev, errp);
> +    if (!vfio_user_device_get(container, vbasedev, errp)) {
> +        vfio_user_container_disconnect(container);
> +        return false;
> +    }
> +
> +    return true;
>  }
>  
>  static void vfio_user_device_detach(VFIODevice *vbasedev)

Reviewed-by: John Levon <john.levon@nutanix.com>