netdev - [net 1/1] tipc: fix memory leak of group member when peer node is lost

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Date:   Thu, 21 Dec 2017 14:36:34 +0100
From:   Jon Maloy <jon.maloy@...csson.com>
To:     <davem@...emloft.net>, <netdev@...r.kernel.org>
CC:     <mohan.krishna.ghanta.krishnamurthy@...csson.com>,
        <tung.q.nguyen@...tech.com.au>, <hoang.h.le@...tech.com.au>,
        <jon.maloy@...csson.com>, <canh.d.luu@...tech.com.au>,
        <ying.xue@...driver.com>, <tipc-discussion@...ts.sourceforge.net>
Subject: [net  1/1] tipc: fix memory leak of group member when peer node is lost

When a group member receives a member WITHDRAW event, this might have
two reasons: either the peer member is leaving the group, or the link
to the member's node has been lost.

In the latter case we need to issue a DOWN event to the user right away,
and let function tipc_group_filter_msg() perform delete of the member
item. However, in this case we miss to change the state of the member
item to MBR_LEAVING, so the member item is not deleted, and we have a
memory leak.

We now separate better between the four sub-cases of a WITHRAW event
and make sure that each case is handled correctly.

Signed-off-by: Jon Maloy <jon.maloy@...csson.com>
---
 net/tipc/group.c | 27 ++++++++++++++++++---------
 1 file changed, 18 insertions(+), 9 deletions(-)

diff --git a/net/tipc/group.c b/net/tipc/group.c
index e5b03f0..8e12ab5 100644
--- a/net/tipc/group.c
+++ b/net/tipc/group.c
@@ -850,17 +850,26 @@ void tipc_group_member_evt(struct tipc_group *grp,
 		*usr_wakeup = true;
 		m->usr_pending = false;
 		node_up = tipc_node_is_up(net, node);
-
-		/* Hold back event if more messages might be expected */
-		if (m->state != MBR_LEAVING && node_up) {
-			m->event_msg = skb;
-			tipc_group_decr_active(grp, m);
-			m->state = MBR_LEAVING;
-		} else {
-			if (node_up)
+		m->event_msg = NULL;
+
+		if (node_up) {
+			/* Hold back event if a LEAVE msg should be expected */
+			if (m->state != MBR_LEAVING) {
+				m->event_msg = skb;
+				tipc_group_decr_active(grp, m);
+				m->state = MBR_LEAVING;
+			} else {
 				msg_set_grp_bc_seqno(hdr, m->bc_syncpt);
-			else
+				__skb_queue_tail(inputq, skb);
+			}
+		} else {
+			if (m->state != MBR_LEAVING) {
+				tipc_group_decr_active(grp, m);
+				m->state = MBR_LEAVING;
 				msg_set_grp_bc_seqno(hdr, m->bc_rcv_nxt);
+			} else {
+				msg_set_grp_bc_seqno(hdr, m->bc_syncpt);
+			}
 			__skb_queue_tail(inputq, skb);
 		}
 		list_del_init(&m->list);
-- 
2.1.4