[PATCH 4.19 80/88] net/smc: fix dangling sock under state SMC_APPFINCLOSEWAIT

[Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>]

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

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

From: D. Wythe <alibuda@xxxxxxxxxxxxxxxxx>

[ Upstream commit 5211c9729484c923f8d2e06bd29f9322cc42bb8f ]

Considering scenario:

				smc_cdc_rx_handler
__smc_release
				sock_set_flag
smc_close_active()
sock_set_flag

__set_bit(DEAD)			__set_bit(DONE)

Dues to __set_bit is not atomic, the DEAD or DONE might be lost.
if the DEAD flag lost, the state SMC_CLOSED  will be never be reached
in smc_close_passive_work:

if (sock_flag(sk, SOCK_DEAD) &&
	smc_close_sent_any_close(conn)) {
	sk->sk_state = SMC_CLOSED;
} else {
	/* just shutdown, but not yet closed locally */
	sk->sk_state = SMC_APPFINCLOSEWAIT;
}

Replace sock_set_flags or __set_bit to set_bit will fix this problem.
Since set_bit is atomic.

Fixes: b38d732477e4 ("smc: socket closing and linkgroup cleanup")
Signed-off-by: D. Wythe <alibuda@xxxxxxxxxxxxxxxxx>
Reviewed-by: Dust Li <dust.li@xxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 net/smc/af_smc.c    | 4 ++--
 net/smc/smc.h       | 5 +++++
 net/smc/smc_cdc.c   | 2 +-
 net/smc/smc_close.c | 2 +-
 4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/net/smc/af_smc.c b/net/smc/af_smc.c
index 6b30bec54b624..ad0ac657fe12c 100644
--- a/net/smc/af_smc.c
+++ b/net/smc/af_smc.c
@@ -141,7 +141,7 @@ static int smc_release(struct socket *sock)
 
 	if (!smc->use_fallback) {
 		rc = smc_close_active(smc);
-		sock_set_flag(sk, SOCK_DEAD);
+		smc_sock_set_flag(sk, SOCK_DEAD);
 		sk->sk_shutdown |= SHUTDOWN_MASK;
 	} else {
 		if (sk->sk_state != SMC_LISTEN && sk->sk_state != SMC_INIT)
@@ -852,7 +852,7 @@ static int smc_clcsock_accept(struct smc_sock *lsmc, struct smc_sock **new_smc)
 		if (new_clcsock)
 			sock_release(new_clcsock);
 		new_sk->sk_state = SMC_CLOSED;
-		sock_set_flag(new_sk, SOCK_DEAD);
+		smc_sock_set_flag(new_sk, SOCK_DEAD);
 		sock_put(new_sk); /* final */
 		*new_smc = NULL;
 		goto out;
diff --git a/net/smc/smc.h b/net/smc/smc.h
index adbdf195eb085..c3b0e1e3f505d 100644
--- a/net/smc/smc.h
+++ b/net/smc/smc.h
@@ -268,4 +268,9 @@ static inline bool using_ipsec(struct smc_sock *smc)
 struct sock *smc_accept_dequeue(struct sock *parent, struct socket *new_sock);
 void smc_close_non_accepted(struct sock *sk);
 
+static inline void smc_sock_set_flag(struct sock *sk, enum sock_flags flag)
+{
+	set_bit(flag, &sk->sk_flags);
+}
+
 #endif	/* __SMC_H */
diff --git a/net/smc/smc_cdc.c b/net/smc/smc_cdc.c
index 333e4353498f8..c657fd29ff5d0 100644
--- a/net/smc/smc_cdc.c
+++ b/net/smc/smc_cdc.c
@@ -304,7 +304,7 @@ static void smc_cdc_msg_recv_action(struct smc_sock *smc,
 		smc->sk.sk_shutdown |= RCV_SHUTDOWN;
 		if (smc->clcsock && smc->clcsock->sk)
 			smc->clcsock->sk->sk_shutdown |= RCV_SHUTDOWN;
-		sock_set_flag(&smc->sk, SOCK_DONE);
+		smc_sock_set_flag(&smc->sk, SOCK_DONE);
 		sock_hold(&smc->sk); /* sock_put in close_work */
 		if (!schedule_work(&conn->close_work))
 			sock_put(&smc->sk);
diff --git a/net/smc/smc_close.c b/net/smc/smc_close.c
index cac0773f5ebd9..4ea28ec7ad135 100644
--- a/net/smc/smc_close.c
+++ b/net/smc/smc_close.c
@@ -164,7 +164,7 @@ static void smc_close_active_abort(struct smc_sock *smc)
 		break;
 	}
 
-	sock_set_flag(sk, SOCK_DEAD);
+	smc_sock_set_flag(sk, SOCK_DEAD);
 	sk->sk_state_change(sk);
 }
 
-- 
2.42.0