[PATCH 4.16 53/55] net/smc: keep clcsock reference in smc_tcp_listen_work()

[Greg Kroah-Hartman]

4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ursula Braun <ubraun@xxxxxxxxxxxxx>

[ Upstream commit 070204a34884110ac5e19c1e2e036fcfd033f8e3 ]

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@xxxxxxxxxxxxx>
Reported-by: syzbot+9045fc589fcd196ef522@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: syzbot+28a2c86cf19c81d871fa@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: syzbot+9605e6cace1b5efd4a0a@xxxxxxxxxxxxxxxxxxxxxxxxx
Reported-by: syzbot+cf9012c597c8379d535c@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/smc/af_smc.c |    4 ----
 1 file changed, 4 deletions(-)

--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -973,10 +973,6 @@ static void smc_tcp_listen_work(struct w
 	}
 
 out:
-	if (lsmc->clcsock) {
-		sock_release(lsmc->clcsock);
-		lsmc->clcsock = NULL;
-	}
 	release_sock(lsk);
 	sock_put(&lsmc->sk); /* sock_hold in smc_listen */
 }