netdev - Re: [Patch net] smc: move unhash as early as possible in smc

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Message-Id: <20190107.071250.1939806747054672326.davem@davemloft.net>
Date:   Mon, 07 Jan 2019 07:12:50 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     xiyou.wangcong@...il.com
Cc:     netdev@...r.kernel.org, mhjungk@...il.com,
        syzbot+fbd1e5476e4c94c7b34e@...kaller.appspotmail.com,
        ubraun@...ux.ibm.com
Subject: Re: [Patch net] smc: move unhash as early as possible in
 smc_release()

From: Cong Wang <xiyou.wangcong@...il.com>
Date: Sat,  5 Jan 2019 23:45:26 -0800

> In smc_release() we release smc->clcsock before unhash the smc
> sock, but a parallel smc_diag_dump() may be still reading
> smc->clcsock, therefore this could cause a use-after-free as
> reported by syzbot.
> 
> Reported-and-tested-by: syzbot+fbd1e5476e4c94c7b34e@...kaller.appspotmail.com
> Fixes: 51f1de79ad8e ("net/smc: replace sock_put worker by socket refcounting")
> Cc: Ursula Braun <ubraun@...ux.ibm.com>
> Signed-off-by: Cong Wang <xiyou.wangcong@...il.com>

We have two patches messing around in here, seeming to deal with release
visibility and ordering problems in two different ways.

https://patchwork.ozlabs.org/patch/1020608/
https://patchwork.ozlabs.org/patch/1021044/

Reported-by: syzbot+0bf2e01269f1274b4b03@...kaller.appspotmail.com
Reported-by: syzbot+e3132895630f957306bc@...kaller.appspotmail.com