Re: [Patch net v2] tipc: fix a null pointer deref on error path

[David Miller <davem@davemloft.net>]

From: Cong Wang <xiyou.wangcong@gmail.com>
Date: Mon,  4 Dec 2017 10:31:43 -0800

> In tipc_topsrv_kern_subscr() when s->tipc_conn_new() fails
> we call tipc_close_conn() to clean up, but in this case
> calling conn_put() is just enough.
> 
> This fixes the folllowing crash:
 ...
> Fixes: 14c04493cb77 ("tipc: add ability to order and receive topology events in driver")
> Reported-by: syzbot <syzkaller@googlegroups.com>
> Cc: Jon Maloy <jon.maloy@ericsson.com>
> Cc: Ying Xue <ying.xue@windriver.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
 ...
> @@ -511,7 +511,7 @@ bool tipc_topsrv_kern_subscr(struct net *net, u32 port, u32 type,
>  	s = con->server;
>  	scbr = s->tipc_conn_new(*conid);
>  	if (!scbr) {
> -		tipc_close_conn(con);
> +		conn_put(con);
>  		return false;
>  	}
>  
> -- 
> 2.13.0
> 

It looks like tipc_accept_from_sock() has a similar problem?  The
tipc_close_conn() will get invoked indirectly from the sock_release()
path right?