netdev - [PATCH net 1/1] net/smc: keep clcsock reference in smc_tcp_listen

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Date:   Wed, 25 Apr 2018 12:48:58 +0200
From:   Ursula Braun <ubraun@...ux.ibm.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, linux-s390@...r.kernel.org,
        schwidefsky@...ibm.com, heiko.carstens@...ibm.com,
        raspl@...ux.vnet.ibm.com, ubraun@...ux.vnet.ibm.com
Subject: [PATCH net 1/1] net/smc: keep clcsock reference in smc_tcp_listen_work()

The internal CLC socket should exist till the SMC-socket is released.
Function tcp_listen_worker() releases the internal CLC socket of a
listen socket, if an smc_close_active() is called. This function
is called for the final release(), but it is called for shutdown
SHUT_RDWR as well. This opens a door for protection faults, if
socket calls using the internal CLC socket are called for a
shutdown listen socket.

With the changes of
commit 3d502067599f ("net/smc: simplify wait when closing listen socket")
there is no need anymore to release the internal CLC socket in
function tcp_listen_worker((). It is sufficient to release it in
smc_release().

Fixes: 127f49705823 ("net/smc: release clcsock from tcp_listen_worker")
Signed-off-by: Ursula Braun <ubraun@...ux.ibm.com>
Reported-by: syzbot+9045fc589fcd196ef522@...kaller.appspotmail.com
Reported-by: syzbot+28a2c86cf19c81d871fa@...kaller.appspotmail.com
Reported-by: syzbot+9605e6cace1b5efd4a0a@...kaller.appspotmail.com
Reported-by: syzbot+cf9012c597c8379d535c@...kaller.appspotmail.com
---
 net/smc/af_smc.c | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index f5d4b69dbabc..4470501374bf 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -978,10 +978,6 @@ static void smc_tcp_listen_work(struct work_struct *work)
 	}

 out:
-	if (lsmc->clcsock) {
-		sock_release(lsmc->clcsock);
-		lsmc->clcsock = NULL;
-	}
 	release_sock(lsk);
 	sock_put(&lsmc->sk); /* sock_hold in smc_listen */
 }
-- 
2.13.5