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: NCanh Duc Luu <canh.d.luu@dektech.com.au> Signed-off-by: NJon Maloy <jon.maloy@ericsson.com> Signed-off-by: NDavid S. Miller <davem@davemloft.net>
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