netdev - Re: [PATCH net] net/smc: fix fastopen for non-blocking connect()

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Message-Id: <20191116.130422.2084572901433723641.davem@davemloft.net>
Date:   Sat, 16 Nov 2019 13:04:22 -0800 (PST)
From:   David Miller <davem@...emloft.net>
To:     kgraul@...ux.ibm.com
Cc:     netdev@...r.kernel.org, linux-s390@...r.kernel.org,
        heiko.carstens@...ibm.com, raspl@...ux.ibm.com,
        ubraun@...ux.ibm.com
Subject: Re: [PATCH net] net/smc: fix fastopen for non-blocking connect()

From: Karsten Graul <kgraul@...ux.ibm.com>
Date: Fri, 15 Nov 2019 12:39:30 +0100

> From: Ursula Braun <ubraun@...ux.ibm.com>
> 
> FASTOPEN does not work with SMC-sockets. Since SMC allows fallback to
> TCP native during connection start, the FASTOPEN setsockopts trigger
> this fallback, if the SMC-socket is still in state SMC_INIT.
> But if a FASTOPEN setsockopt is called after a non-blocking connect(),
> this is broken, and fallback does not make sense.
> This change complements
> commit cd2063604ea6 ("net/smc: avoid fallback in case of non-blocking connect")
> and fixes the syzbot reported problem "WARNING in smc_unhash_sk".
> 
> Reported-by: syzbot+8488cc4cf1c9e09b8b86@...kaller.appspotmail.com
> Fixes: e1bbdd570474 ("net/smc: reduce sock_put() for fallback sockets")
> Signed-off-by: Ursula Braun <ubraun@...ux.ibm.com>
> Signed-off-by: Karsten Graul <kgraul@...ux.ibm.com>

Applied and queued up for -stable, thanks.