Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933026AbdLVI4I (ORCPT ); Fri, 22 Dec 2017 03:56:08 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:35516 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932928AbdLVI4B (ORCPT ); Fri, 22 Dec 2017 03:56:01 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, John Thompson , Jon Maloy , Ying Xue , Parthasarathy Bhuvaragan , "David S. Miller" , Sasha Levin Subject: [PATCH 4.9 028/104] tipc: fix nametbl deadlock at tipc_nametbl_unsubscribe Date: Fri, 22 Dec 2017 09:45:54 +0100 Message-Id: <20171222084611.747741757@linuxfoundation.org> X-Mailer: git-send-email 2.15.1 In-Reply-To: <20171222084609.262099650@linuxfoundation.org> References: <20171222084609.262099650@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3501 Lines: 102 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ying Xue [ Upstream commit 557d054c01da0337ca81de9e9d9206d57245b57e ] Until now, tipc_nametbl_unsubscribe() is called at subscriptions reference count cleanup. Usually the subscriptions cleanup is called at subscription timeout or at subscription cancel or at subscriber delete. We have ignored the possibility of this being called from other locations, which causes deadlock as we try to grab the tn->nametbl_lock while holding it already. CPU1: CPU2: ---------- ---------------- tipc_nametbl_publish spin_lock_bh(&tn->nametbl_lock) tipc_nametbl_insert_publ tipc_nameseq_insert_publ tipc_subscrp_report_overlap tipc_subscrp_get tipc_subscrp_send_event tipc_close_conn tipc_subscrb_release_cb tipc_subscrb_delete tipc_subscrp_put tipc_subscrp_put tipc_subscrp_kref_release tipc_nametbl_unsubscribe spin_lock_bh(&tn->nametbl_lock) <> CPU1: CPU2: ---------- ---------------- tipc_nametbl_stop spin_lock_bh(&tn->nametbl_lock) tipc_purge_publications tipc_nameseq_remove_publ tipc_subscrp_report_overlap tipc_subscrp_get tipc_subscrp_send_event tipc_close_conn tipc_subscrb_release_cb tipc_subscrb_delete tipc_subscrp_put tipc_subscrp_put tipc_subscrp_kref_release tipc_nametbl_unsubscribe spin_lock_bh(&tn->nametbl_lock) <> In this commit, we advance the calling of tipc_nametbl_unsubscribe() from the refcount cleanup to the intended callers. Fixes: d094c4d5f5c7 ("tipc: add subscription refcount to avoid invalid delete") Reported-by: John Thompson Acked-by: Jon Maloy Signed-off-by: Ying Xue Signed-off-by: Parthasarathy Bhuvaragan Signed-off-by: David S. Miller Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- net/tipc/subscr.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) --- a/net/tipc/subscr.c +++ b/net/tipc/subscr.c @@ -141,6 +141,11 @@ void tipc_subscrp_report_overlap(struct static void tipc_subscrp_timeout(unsigned long data) { struct tipc_subscription *sub = (struct tipc_subscription *)data; + struct tipc_subscriber *subscriber = sub->subscriber; + + spin_lock_bh(&subscriber->lock); + tipc_nametbl_unsubscribe(sub); + spin_unlock_bh(&subscriber->lock); /* Notify subscriber of timeout */ tipc_subscrp_send_event(sub, sub->evt.s.seq.lower, sub->evt.s.seq.upper, @@ -173,7 +178,6 @@ static void tipc_subscrp_kref_release(st struct tipc_subscriber *subscriber = sub->subscriber; spin_lock_bh(&subscriber->lock); - tipc_nametbl_unsubscribe(sub); list_del(&sub->subscrp_list); atomic_dec(&tn->subscription_count); spin_unlock_bh(&subscriber->lock); @@ -205,6 +209,7 @@ static void tipc_subscrb_subscrp_delete( if (s && memcmp(s, &sub->evt.s, sizeof(struct tipc_subscr))) continue; + tipc_nametbl_unsubscribe(sub); tipc_subscrp_get(sub); spin_unlock_bh(&subscriber->lock); tipc_subscrp_delete(sub);