Re: [PATCH net] vsock: Use container_of() to get net namespace in sysctl handlers

[Bobby Eshleman <bobbyeshleman@gmail.com>]

On Mon, Feb 23, 2026 at 06:32:18PM +0100, Greg Kroah-Hartman wrote:
> current->nsproxy is should not be accessed directly as syzbot has found
> that it could be NULL at times, causing crashes.  Fix up the af_vsock
> sysctl handlers to use container_of() to deal with the current net
> namespace instead of attempting to rely on current.
> 
> This is the same type of change done in commit 7f5611cbc487 ("rds:
> sysctl: rds_tcp_{rcv,snd}buf: avoid using current->nsproxy")
> 
> Cc: Stefano Garzarella <sgarzare@redhat.com>
> Cc: stable <stable@kernel.org>
> Assisted-by: gkh_clanker_2000
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> 
> Note, this is compile-tested only.  Some of my scripts found this when
> looking for places that are missing fixes that were applied to other
> parts of the kernel.  I think the af_vsock code uses namespaces, but as
> I don't know the network stack at all I figured I would let you all
> review it to tell me how wrong I got this change and all is fine with
> the original code.
> 
> thanks,
> 
> greg k-h
> 
>  net/vmw_vsock/af_vsock.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
> index 9880756d9eff..f4062c6a1944 100644
> --- a/net/vmw_vsock/af_vsock.c
> +++ b/net/vmw_vsock/af_vsock.c
> @@ -2825,7 +2825,7 @@ static int vsock_net_mode_string(const struct ctl_table *table, int write,
>  	if (write)
>  		return -EPERM;
>  
> -	net = current->nsproxy->net_ns;
> +	net = container_of(table->data, struct net, vsock.mode);
>  
>  	return __vsock_net_mode_string(table, write, buffer, lenp, ppos,
>  				       vsock_net_mode(net), NULL);
> @@ -2838,7 +2838,7 @@ static int vsock_net_child_mode_string(const struct ctl_table *table, int write,
>  	struct net *net;
>  	int ret;
>  
> -	net = current->nsproxy->net_ns;
> +	net = container_of(table->data, struct net, vsock.child_ns_mode);
>  
>  	ret = __vsock_net_mode_string(table, write, buffer, lenp, ppos,
>  				      vsock_net_child_mode(net), &new_mode);
> -- 
> 2.53.0
> 

Thanks Greg. LGTM, and passed all tests on my test setup.

I can't say if nsproxy can be null here in particular but better safe
than sorry.

Reviewed-by: Bobby Eshleman <bobbyeshleman@meta.com>