diff mbox series

[v2] vhost/vsock: Fix error handling in vhost_vsock_init()

Message ID 20221108101705.45981-1-yuancan@huawei.com (mailing list archive)
State Not Applicable
Headers show
Series [v2] vhost/vsock: Fix error handling in vhost_vsock_init() | expand

Checks

Context Check Description
netdev/tree_selection success Not a local patch

Commit Message

Yuan Can Nov. 8, 2022, 10:17 a.m. UTC
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@huawei.com>
---
Changes in v2:
- change to the correct Fixes: tag

 drivers/vhost/vsock.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

Comments

Stefano Garzarella Nov. 8, 2022, 10:24 a.m. UTC | #1
On Tue, Nov 08, 2022 at 10:17:05AM +0000, Yuan Can 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@huawei.com>
>---
>Changes in v2:
>- change to the correct Fixes: tag

I forgot to mention that anyway the patch was okay for me :-) and so:

Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>

Thanks,
Stefano

>
> 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
>
Jason Wang Nov. 9, 2022, 3:32 a.m. UTC | #2
On Tue, Nov 8, 2022 at 6:19 PM Yuan Can <yuancan@huawei.com> 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@huawei.com>

Acked-by: Jason Wang <jasowang@redhat.com>

> ---
> 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
>
diff mbox series

Patch

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)