Commit f8e7423f authored Jan 30, 2019 by Karsten Graul Committed by Greg Kroah-Hartman Dec 05, 2019

net/smc: prevent races between smc_lgr_terminate() and smc_conn_free()



[ Upstream commit 77f838ace755d2f466536c44dac6c856f62cd901 ]

To prevent races between smc_lgr_terminate() and smc_conn_free() add an
extra check of the lgr field before accessing it, and cancel a delayed
free_work when a new smc connection is created.
This fixes the problem that free_work cleared the lgr variable but
smc_lgr_terminate() or smc_conn_free() still access it in parallel.

Signed-off-by: Karsten Graul <kgraul@linux.ibm.com>
Signed-off-by: Ursula Braun <ubraun@linux.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent dcb901ce

net/smc/smc_core.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -128,6 +128,8 @@ static void smc_lgr_unregister_conn(struct smc_connection *conn)
		{
		struct smc_link_group *lgr = conn->lgr;

		if (!lgr)
		return;
		write_lock_bh(&lgr->conns_lock);
		if (conn->alert_token_local) {
		__smc_lgr_unregister_conn(conn);
		@@ -612,6 +614,8 @@ int smc_conn_create(struct smc_sock *smc, bool is_smcd, int srv_first_contact,
		local_contact = SMC_REUSE_CONTACT;
		conn->lgr = lgr;
		smc_lgr_register_conn(conn); /* add smc conn to lgr */
		if (delayed_work_pending(&lgr->free_work))
		cancel_delayed_work(&lgr->free_work);
		write_unlock_bh(&lgr->conns_lock);
		break;
		}