netdev - Re: RFC: sk leak in sock

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Message-ID: <20170627195921.GA9171@oracle.com>
Date:   Tue, 27 Jun 2017 15:59:21 -0400
From:   Sowmini Varadhan <sowmini.varadhan@...cle.com>
To:     David Miller <davem@...emloft.net>
Cc:     netdev@...r.kernel.org
Subject: Re: RFC: sk leak in sock_graft?

On (06/27/17 15:38), David Miller wrote:
> 
> It could simply be the case that rds-tcp is the first setup that
> created that situation where there is a parent->sk already.

Possibly, I noticed that other callers call sock_create_lite()
and I dont know the history here - this seems to have been
the case from day-1 of rds-tcp. (and I dread changing 
rds_tcp_accept_kern() to do this, because then every module unload
would need to go and check if sock->sk is non-null first, before
cleaning it up

> Why does rds-tcp need to call sock_graft() without those invariants
> met?

It would certainly help to declare "dont use sock_creeate_kern()
if you are going to accept on this socket"- I dont see that being 
mandated anywhere.

It would also help to have a BUG_ON(parent->sk) or at least a
WARN_ON(parent->sk) in sock_graft, before unilaterally assigning 
it to the new sk. 

--Sowmini