From: Ursula Braun <ubraun@linux.ibm.com>
Date: Wed, 23 Oct 2019 15:44:05 +0200
Subject: net/smc: fix closing of fallback SMC sockets
Git-commit: f536dffc0b79738c3104af999318279dccbaa261
Patch-mainline: v5.4-rc6
References: git-fixes

For SMC sockets forced to fallback to TCP, the file is propagated
from the outer SMC to the internal TCP socket. When closing the SMC
socket, the internal TCP socket file pointer must be restored to the
original NULL value, otherwise memory leaks may show up (found with
CONFIG_DEBUG_KMEMLEAK).

The internal TCP socket is released in smc_clcsock_release(), which
calls __sock_release() function in net/socket.c. This calls the
needed iput(SOCK_INODE(sock)) only, if the file pointer has been reset
to the original NULL-value.

Fixes: 07603b230895 ("net/smc: propagate file from SMC to TCP socket")
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 net/smc/af_smc.c |    7 +++++++
 1 file changed, 7 insertions(+)

--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -122,6 +122,12 @@ struct proto smc_proto6 = {
 };
 EXPORT_SYMBOL_GPL(smc_proto6);
 
+static void smc_restore_fallback_changes(struct smc_sock *smc)
+{
+	smc->clcsock->file->private_data = smc->sk.sk_socket;
+	smc->clcsock->file = NULL;
+}
+
 static int smc_release(struct socket *sock)
 {
 	struct sock *sk = sock->sk;
@@ -159,6 +165,7 @@ static int smc_release(struct socket *so
 		}
 		sk->sk_state = SMC_CLOSED;
 		sk->sk_state_change(sk);
+		smc_restore_fallback_changes(smc);
 	}
 
 	sk->sk_prot->unhash(sk);