From 33a47b9e768a3349ee0fff75fd4346157e0e0d1d Mon Sep 17 00:00:00 2001 From: Karsten Graul Date: Wed, 30 Jan 2019 18:51:02 +0100 Subject: [PATCH] net/smc: prevent races between smc_lgr_terminate() and smc_conn_free() BugLink: https://bugs.launchpad.net/bugs/1855787 [ 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 Signed-off-by: Ursula Braun Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Kamal Mostafa Signed-off-by: Kleber Sacilotto de Souza --- net/smc/smc_core.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/smc/smc_core.c b/net/smc/smc_core.c index 852a55a8eb62..dc062dea7c87 100644 --- a/net/smc/smc_core.c +++ b/net/smc/smc_core.c @@ -103,6 +103,8 @@ static void smc_lgr_unregister_conn(struct smc_connection *conn) struct smc_link_group *lgr = conn->lgr; int reduced = 0; + if (!lgr) + return; write_lock_bh(&lgr->conns_lock); if (conn->alert_token_local) { reduced = 1; @@ -435,6 +437,8 @@ int smc_conn_create(struct smc_sock *smc, __be32 peer_in_addr, 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; } -- 2.39.2