Re: [PATCH v2] vhost/vsock: don't check owner in vhost_vsock_stop() while releasing

[Stefan Hajnoczi]

On Tue, Feb 22, 2022 at 10:47:42AM +0100, Stefano Garzarella wrote:
> vhost_vsock_stop() calls vhost_dev_check_owner() to check the device
> ownership. It expects current->mm to be valid.
> 
> vhost_vsock_stop() is also called by vhost_vsock_dev_release() when
> the user has not done close(), so when we are in do_exit(). In this
> case current->mm is invalid and we're releasing the device, so we
> should clean it anyway.
> 
> Let's check the owner only when vhost_vsock_stop() is called
> by an ioctl.
> 
> When invoked from release we can not fail so we don't check return
> code of vhost_vsock_stop(). We need to stop vsock even if it's not
> the owner.
> 
> Fixes: 433fc58e6bf2 ("VSOCK: Introduce vhost_vsock.ko")
> Cc: stable@xxxxxxxxxxxxxxx
> Reported-by: syzbot+1e3ea63db39f2b4440e0@xxxxxxxxxxxxxxxxxxxxxxxxx
> Reported-and-tested-by: syzbot+3140b17cb44a7b174008@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Stefano Garzarella <sgarzare@xxxxxxxxxx>
> ---
> v2:
> - initialized `ret` in vhost_vsock_stop [Dan]
> - added comment about vhost_vsock_stop() calling in the code and an explanation
>   in the commit message [MST]
> 
> v1: https://lore.kernel.org/virtualization/20220221114916.107045-1-sgarzare@xxxxxxxxxx
> ---
>  drivers/vhost/vsock.c | 21 ++++++++++++++-------
>  1 file changed, 14 insertions(+), 7 deletions(-)

Reviewed-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx>

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