From: Xin Long lucien.xin@gmail.com
commit 6ca328e985cd995dfd1d5de44046e6074f853fbb upstream.
When doing plpmtu probe, the probe size is growing every time when it receives the ACK during the Search state until the probe fails. When the failure occurs, pl.probe_high is set and it goes to the Complete state.
However, if the link pmtu is huge, like 65535 in loopback_dev, the probe eventually keeps using SCTP_MAX_PLPMTU as the probe size and never fails. Because of that, pl.probe_high can not be set, and the plpmtu probe can never go to the Complete state.
Fix it by setting pl.probe_high to SCTP_MAX_PLPMTU when the probe size grows to SCTP_MAX_PLPMTU in sctp_transport_pl_recv(). Also, not allow the probe size greater than SCTP_MAX_PLPMTU in the Complete state.
Fixes: b87641aff9e7 ("sctp: do state transition when a probe succeeds on HB ACK recv path") Signed-off-by: Xin Long lucien.xin@gmail.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/sctp/transport.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/net/sctp/transport.c +++ b/net/sctp/transport.c @@ -324,9 +324,12 @@ bool sctp_transport_pl_recv(struct sctp_ t->pl.probe_size += SCTP_PL_BIG_STEP; } else if (t->pl.state == SCTP_PL_SEARCH) { if (!t->pl.probe_high) { - t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP, - SCTP_MAX_PLPMTU); - return false; + if (t->pl.probe_size < SCTP_MAX_PLPMTU) { + t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_BIG_STEP, + SCTP_MAX_PLPMTU); + return false; + } + t->pl.probe_high = SCTP_MAX_PLPMTU; } t->pl.probe_size += SCTP_PL_MIN_STEP; if (t->pl.probe_size >= t->pl.probe_high) { @@ -341,7 +344,7 @@ bool sctp_transport_pl_recv(struct sctp_ } else if (t->pl.state == SCTP_PL_COMPLETE) { /* Raise probe_size again after 30 * interval in Search Complete */ t->pl.state = SCTP_PL_SEARCH; /* Search Complete -> Search */ - t->pl.probe_size += SCTP_PL_MIN_STEP; + t->pl.probe_size = min(t->pl.probe_size + SCTP_PL_MIN_STEP, SCTP_MAX_PLPMTU); }
return t->pl.state == SCTP_PL_COMPLETE;