From f79675563a6bbfc2ff85684bbbaea9ef092664d2 Mon Sep 17 00:00:00 2001 From: Jon Paul Maloy Date: Wed, 23 Nov 2016 21:05:26 -0500 Subject: [PATCH] tipc: fix compatibility bug in link monitoring commit 817298102b0b ("tipc: fix link priority propagation") introduced a compatibility problem between TIPC versions newer than Linux 4.6 and those older than Linux 4.4. In versions later than 4.4, link STATE messages only contain a non-zero link priority value when the sender wants the receiver to change its priority. This has the effect that the receiver resets itself in order to apply the new priority. This works well, and is consistent with the said commit. However, in versions older than 4.4 a valid link priority is present in all sent link STATE messages, leading to cyclic link establishment and reset on the 4.6+ node. We fix this by adding a test that the received value should not only be valid, but also differ from the current value in order to cause the receiving link endpoint to reset. Reported-by: Amar Nv Signed-off-by: Jon Maloy Signed-off-by: David S. Miller --- net/tipc/link.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/net/tipc/link.c b/net/tipc/link.c index 1055164c6232..ecc12411155e 100644 --- a/net/tipc/link.c +++ b/net/tipc/link.c @@ -1492,8 +1492,9 @@ static int tipc_link_proto_rcv(struct tipc_link *l, struct sk_buff *skb, if (in_range(peers_tol, TIPC_MIN_LINK_TOL, TIPC_MAX_LINK_TOL)) l->tolerance = peers_tol; - if (peers_prio && in_range(peers_prio, TIPC_MIN_LINK_PRI, - TIPC_MAX_LINK_PRI)) { + /* Update own prio if peer indicates a different value */ + if ((peers_prio != l->priority) && + in_range(peers_prio, 1, TIPC_MAX_LINK_PRI)) { l->priority = peers_prio; rc = tipc_link_fsm_evt(l, LINK_FAILURE_EVT); } -- 2.34.1