From: Maciej Kwiecien maciej.kwiecien@nokia.com
[ Upstream commit d1f20c03f48102e52eb98b8651d129b83134cae4 ]
hb_timer might not start at all for a particular transport because its start is conditional. In a result a node is not sending heartbeats.
Function sctp_transport_reset_hb_timer has two roles: - initial start of hb_timer for a given transport, - update expire date of hb_timer for a given transport. The function is optimized to update timer's expire only if it is before a new calculated one but this comparison is invalid for a timer which has not yet started. Such a timer has expire == 0 and if a new expire value is bigger than (MAX_JIFFIES / 2 + 2) then "time_before" macro will fail and timer will not start resulting in no heartbeat packets send by the node.
This was found when association was initialized within first 5 mins after system boot due to jiffies init value which is near to MAX_JIFFIES.
Test kernel version: 4.9.154 (ARCH=arm) hb_timer.expire = 0; //initialized, not started timer new_expire = MAX_JIFFIES / 2 + 2; //or more time_before(hb_timer.expire, new_expire) == false
Fixes: ba6f5e33bdbb ("sctp: avoid refreshing heartbeat timer too often") Reported-by: Marcin Stojek marcin.stojek@nokia.com Tested-by: Marcin Stojek marcin.stojek@nokia.com Signed-off-by: Maciej Kwiecien maciej.kwiecien@nokia.com Reviewed-by: Alexander Sverdlin alexander.sverdlin@nokia.com Acked-by: Marcelo Ricardo Leitner marcelo.leitner@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/sctp/transport.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/sctp/transport.c b/net/sctp/transport.c index 033696e6f74fb..ad158d311ffae 100644 --- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -207,7 +207,8 @@ void sctp_transport_reset_hb_timer(struct sctp_transport *transport)
/* When a data chunk is sent, reset the heartbeat interval. */ expires = jiffies + sctp_transport_timeout(transport); - if (time_before(transport->hb_timer.expires, expires) && + if ((time_before(transport->hb_timer.expires, expires) || + !timer_pending(&transport->hb_timer)) && !mod_timer(&transport->hb_timer, expires + prandom_u32_max(transport->rto))) sctp_transport_hold(transport);