On Tue, Nov 8, 2022 at 6:19 PM Yuan Can <yuancan@xxxxxxxxxx> wrote:
>
> A problem about modprobe vhost_vsock failed is triggered with the
> following log given:
>
> modprobe: ERROR: could not insert 'vhost_vsock': Device or resource busy
>
> The reason is that vhost_vsock_init() returns misc_register() directly
> without checking its return value, if misc_register() failed, it returns
> without calling vsock_core_unregister() on vhost_transport, resulting the
> vhost_vsock can never be installed later.
> A simple call graph is shown as below:
>
> vhost_vsock_init()
> vsock_core_register() # register vhost_transport
> misc_register()
> device_create_with_groups()
> device_create_groups_vargs()
> dev = kzalloc(...) # OOM happened
> # return without unregister vhost_transport
>
> Fix by calling vsock_core_unregister() when misc_register() returns error.
>
> Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko")
> Signed-off-by: Yuan Can <yuancan@xxxxxxxxxx>
Acked-by: Jason Wang <jasowang@xxxxxxxxxx>
> ---
> Changes in v2:
> - change to the correct Fixes: tag
>
> drivers/vhost/vsock.c | 9 ++++++++-
> 1 file changed, 8 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
> index 5703775af129..10a7d23731fe 100644
> --- a/drivers/vhost/vsock.c
> +++ b/drivers/vhost/vsock.c
> @@ -959,7 +959,14 @@ static int __init vhost_vsock_init(void)
> VSOCK_TRANSPORT_F_H2G);
> if (ret < 0)
> return ret;
> - return misc_register(&vhost_vsock_misc);
> +
> + ret = misc_register(&vhost_vsock_misc);
> + if (ret) {
> + vsock_core_unregister(&vhost_transport.transport);
> + return ret;
> + }
> +
> + return 0;
> };
>
> static void __exit vhost_vsock_exit(void)
> --
> 2.17.1
>
