From: Jon Maloy <jon.ma...@ericsson.com> Date: Wed, 26 Sep 2018 22:28:52 +0200
> From: LUU Duc Canh <canh.d....@dektech.com.au> > > The initial session number when a link is created is based on a random > value, taken from struct tipc_net->random. It is then incremented for > each link reset to avoid mixing protocol messages from different link > sessions. > > However, when a bearer is reset all its links are deleted, and will > later be re-created using the same random value as the first time. > This means that if the link never went down between creation and > deletion we will still sometimes have two subsequent sessions with > the same session number. In virtual environments with potentially > long transmission times this has turned out to be a real problem. > > We now fix this by randomizing the session number each time a link > is created. > > With a session number size of 16 bits this gives a risk of session > collision of 1/64k. To reduce this further, we also introduce a sanity > check on the very first STATE message arriving at a link. If this has > an acknowledge value differing from 0, which is logically impossible, > we ignore the message. The final risk for session collision is hence > reduced to 1/4G, which should be sufficient. > > Signed-off-by: LUU Duc Canh <canh.d....@dektech.com.au> > Signed-off-by: Jon Maloy <jon.ma...@ericsson.com> Applied.
