Subject: Re: [PATCH] net: qrtr: Allocate workqueue before kernel_bind

From: Bjorn Andersson <[email-masked]>
Date: Thu, 28 May 2020 18:19:03 -0700

On Thu 28 May 16:05 PDT 2020, Chris Lew wrote:

> A null pointer dereference in qrtr_ns_data_ready() is seen if a client
> opens a qrtr socket before qrtr_ns_init() can bind to the control port.
> When the control port is bound, the ENETRESET error will be broadcasted
> and clients will close their sockets. This results in DEL_CLIENT
> packets being sent to the ns and qrtr_ns_data_ready() being called
> without the workqueue being allocated.
> 
> Allocate the workqueue before setting sk_data_ready and binding to the
> control port. This ensures that the work and workqueue structs are
> allocated and initialized before qrtr_ns_data_ready can be called.
> 

Reviewed-by: Bjorn Andersson <[email-masked]>

Regards,
Bjorn

> Fixes: 0c2204a4ad71 ("net: qrtr: Migrate nameservice to kernel from userspace")
> Signed-off-by: Chris Lew <[email-masked]>
> ---
>  net/qrtr/ns.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/net/qrtr/ns.c b/net/qrtr/ns.c
> index e7d0fe3f4330..c5b3202a14ca 100644
> --- a/net/qrtr/ns.c
> +++ b/net/qrtr/ns.c
> @@ -712,6 +712,10 @@ void qrtr_ns_init(void)
>  		goto err_sock;
>  	}
>  
> +	qrtr_ns.workqueue = alloc_workqueue("qrtr_ns_handler", WQ_UNBOUND, 1);
> +	if (!qrtr_ns.workqueue)
> +		goto err_sock;
> +
>  	qrtr_ns.sock->sk->sk_data_ready = qrtr_ns_data_ready;
>  
>  	sq.sq_port = QRTR_PORT_CTRL;
> @@ -720,17 +724,13 @@ void qrtr_ns_init(void)
>  	ret = kernel_bind(qrtr_ns.sock, (struct sockaddr *)&sq, sizeof(sq));
>  	if (ret < 0) {
>  		pr_err("failed to bind to socket\n");
> -		goto err_sock;
> +		goto err_wq;
>  	}
>  
>  	qrtr_ns.bcast_sq.sq_family = AF_QIPCRTR;
>  	qrtr_ns.bcast_sq.sq_node = QRTR_NODE_BCAST;
>  	qrtr_ns.bcast_sq.sq_port = QRTR_PORT_CTRL;
>  
> -	qrtr_ns.workqueue = alloc_workqueue("qrtr_ns_handler", WQ_UNBOUND, 1);
> -	if (!qrtr_ns.workqueue)
> -		goto err_sock;
> -
>  	ret = say_hello(&qrtr_ns.bcast_sq);
>  	if (ret < 0)
>  		goto err_wq;
> -- 
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>