From 59a361bc6f6e91d57f25ff0aebb0e646beb3b41d Mon Sep 17 00:00:00 2001 From: Jon Paul Maloy Date: Mon, 14 Aug 2017 18:28:49 +0200 Subject: [PATCH] tipc: avoid inheriting msg_non_seq flag when message is returned In the function msg_reverse(), we reverse the header while trying to reuse the original buffer whenever possible. Those rejected/returned messages are always transmitted as unicast, but the msg_non_seq field is not explicitly set to zero as it should be. We have seen cases where multicast senders set the message type to "NOT dest_droppable", meaning that a multicast message shorter than one MTU will be returned, e.g., during receive buffer overflow, by reusing the original buffer. This has the effect that even the 'msg_non_seq' field is inadvertently inherited by the rejected message, although it is now sent as a unicast message. This again leads the receiving unicast link endpoint to steer the packet toward the broadcast link receive function, where it is dropped. The affected unicast link is thereafter (after 100 failed retransmissions) declared 'stale' and reset. We fix this by unconditionally setting the 'msg_non_seq' flag to zero for all rejected/returned messages. Reported-by: Canh Duc Luu Signed-off-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/msg.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/tipc/msg.c b/net/tipc/msg.c index ab3087687a32..dcd90e6fa7c3 100644 --- a/net/tipc/msg.c +++ b/net/tipc/msg.c @@ -513,6 +513,7 @@ bool tipc_msg_reverse(u32 own_node, struct sk_buff **skb, int err) /* Now reverse the concerned fields */ msg_set_errcode(hdr, err); + msg_set_non_seq(hdr, 0); msg_set_origport(hdr, msg_destport(&ohdr)); msg_set_destport(hdr, msg_origport(&ohdr)); msg_set_destnode(hdr, msg_prevnode(&ohdr)); -- 2.20.1