[net 1/1] tipc: fix lost member events bug

[net 1/1] tipc: fix lost member events bug

[Jon Maloy]

Group messages are not supposed to be returned to sender when the
destination socket disappears. This is done correctly for regular
traffic messages, by setting the 'dest_droppable' bit in the header.
But we forget to do that in group protocol messages. This has the effect
that such messages may sometimes bounce back to the sender, be perceived
as a legitimate peer message, and wreak general havoc for the rest of
the session. In particular, we have seen that a member in state LEAVING
may go back to state RECLAIMED or REMITTED, hence causing suppression
of an otherwise expected 'member down' event to the user.

We fix this by setting the 'dest_droppable' bit even in group protocol
messages.

Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
---
 net/tipc/group.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/tipc/group.c b/net/tipc/group.c
index 95fec2c..efb5714 100644
--- a/net/tipc/group.c
+++ b/net/tipc/group.c
@@ -648,6 +648,7 @@ static void tipc_group_proto_xmit(struct tipc_group *grp, struct tipc_member *m,
 	} else if (mtyp == GRP_REMIT_MSG) {
 		msg_set_grp_remitted(hdr, m->window);
 	}
+	msg_set_dest_droppable(hdr, true);
 	__skb_queue_tail(xmitq, skb);
 }
 
-- 
2.1.4


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Re: [net 1/1] tipc: fix lost member events bug

[David Miller]

From: Jon Maloy <jon.maloy@ericsson.com>
Date: Mon, 18 Dec 2017 17:34:16 +0100

> Group messages are not supposed to be returned to sender when the
> destination socket disappears. This is done correctly for regular
> traffic messages, by setting the 'dest_droppable' bit in the header.
> But we forget to do that in group protocol messages. This has the effect
> that such messages may sometimes bounce back to the sender, be perceived
> as a legitimate peer message, and wreak general havoc for the rest of
> the session. In particular, we have seen that a member in state LEAVING
> may go back to state RECLAIMED or REMITTED, hence causing suppression
> of an otherwise expected 'member down' event to the user.
> 
> We fix this by setting the 'dest_droppable' bit even in group protocol
> messages.
> 
> Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>

Applied.