From 45cd7c1b1174dbeaebc1b52e20cb89927fb115ae Mon Sep 17 00:00:00 2001 From: Kevin Krakauer Date: Mon, 21 Jun 2021 12:34:56 -0700 Subject: netstack: don't ACK SYNs in TIME-WAIT It was possible for a SYN to arrive after the endpoint sent an ACK as part of the transition to TIME-WAIT, but before returning from handleSegmentsLocked(). This caused the SYN to be dequeued and ACK'd despite the change in EndpointState. Deflakes TestTCPTimeWaitNewSyn. Tested with: blaze test --config=gotsan --runs_per_test 10000 \ //third_party/gvisor/pkg/tcpip/transport/tcp:tcp_x_test -j 2000 \ // --test_filter TestTCPTimeWaitNewSyn PiperOrigin-RevId: 380639808 --- pkg/tcpip/transport/tcp/connect.go | 2 +- pkg/tcpip/transport/tcp/rcv.go | 1 - 2 files changed, 1 insertion(+), 2 deletions(-) diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go index 2137ebc25..f86450298 100644 --- a/pkg/tcpip/transport/tcp/connect.go +++ b/pkg/tcpip/transport/tcp/connect.go @@ -1130,7 +1130,7 @@ func (e *endpoint) handleReset(s *segment) (ok bool, err tcpip.Error) { func (e *endpoint) handleSegmentsLocked(fastPath bool) tcpip.Error { checkRequeue := true for i := 0; i < maxSegmentsPerWake; i++ { - if e.EndpointState().closed() { + if state := e.EndpointState(); state.closed() || state == StateTimeWait { return nil } s := e.segmentQueue.dequeue() diff --git a/pkg/tcpip/transport/tcp/rcv.go b/pkg/tcpip/transport/tcp/rcv.go index 661ca604a..9ce8fcae9 100644 --- a/pkg/tcpip/transport/tcp/rcv.go +++ b/pkg/tcpip/transport/tcp/rcv.go @@ -559,7 +559,6 @@ func (r *receiver) handleTimeWaitSegment(s *segment) (resetTimeWait bool, newSyn // (2) returns to TIME-WAIT state if the SYN turns out // to be an old duplicate". if s.flags.Contains(header.TCPFlagSyn) && r.RcvNxt.LessThan(segSeq) { - return false, true } -- cgit v1.2.3