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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Ursula Braun <ubraun@linux.vnet.ibm.com>,
        Stephen Hemminger <stephen@networkplumber.org>,
        "David S. Miller" <davem@davemloft.net>
Subject: [PATCH 4.16 19/81] net/smc: fix shutdown in state SMC_LISTEN
Date:   Fri, 27 Apr 2018 15:58:21 +0200
Message-Id: <20180427135744.381601356@linuxfoundation.org>
In-Reply-To: <20180427135743.216853156@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

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

From: Ursula Braun <ubraun@linux.vnet.ibm.com>


[ Upstream commit 1255fcb2a655f05e02f3a74675a6d6525f187afd ]

Calling shutdown with SHUT_RD and SHUT_RDWR for a listening SMC socket
crashes, because
   commit 127f49705823 ("net/smc: release clcsock from tcp_listen_worker")
releases the internal clcsock in smc_close_active() and sets smc->clcsock
to NULL.
For SHUT_RD the smc_close_active() call is removed.
For SHUT_RDWR the kernel_sock_shutdown() call is omitted, since the
clcsock is already released.

Fixes: 127f49705823 ("net/smc: release clcsock from tcp_listen_worker")
Signed-off-by: Ursula Braun <ubraun@linux.vnet.ibm.com>
Reported-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/smc/af_smc.c |   10 ++++------
 1 file changed, 4 insertions(+), 6 deletions(-)

--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -1254,14 +1254,12 @@ static int smc_shutdown(struct socket *s
 		rc = smc_close_shutdown_write(smc);
 		break;
 	case SHUT_RD:
-		if (sk->sk_state == SMC_LISTEN)
-			rc = smc_close_active(smc);
-		else
-			rc = 0;
-			/* nothing more to do because peer is not involved */
+		rc = 0;
+		/* nothing more to do because peer is not involved */
 		break;
 	}
-	rc1 = kernel_sock_shutdown(smc->clcsock, how);
+	if (smc->clcsock)
+		rc1 = kernel_sock_shutdown(smc->clcsock, how);
 	/* map sock_shutdown_cmd constants to sk_shutdown value range */
 	sk->sk_shutdown |= how + 1;