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authorBhasker Hariharan <bhaskerh@google.com>2019-06-04 16:16:24 -0700
committerShentubot <shentubot@google.com>2019-06-04 16:17:24 -0700
commite0fb921205b79f401375544652e4de8077162292 (patch)
tree10e51ffa7d84894cf360076e4fa839c0f60bdcb7 /pkg
parent7398f013f043cfe43b5fc615bd24b641df17e6bc (diff)
Fix data race in synRcvdState.
When checking the length of the acceptedChan we should hold the endpoint mutex otherwise a syn received while the listening socket is being closed can result in a data race where the cleanupLocked routine sets acceptedChan to nil while a handshake goroutine in progress could try and check it at the same time. PiperOrigin-RevId: 251537697
Diffstat (limited to 'pkg')
-rw-r--r--pkg/tcpip/transport/tcp/connect.go21
1 files changed, 13 insertions, 8 deletions
diff --git a/pkg/tcpip/transport/tcp/connect.go b/pkg/tcpip/transport/tcp/connect.go
index 2aed6f286..371d2ed29 100644
--- a/pkg/tcpip/transport/tcp/connect.go
+++ b/pkg/tcpip/transport/tcp/connect.go
@@ -284,14 +284,19 @@ func (h *handshake) synRcvdState(s *segment) *tcpip.Error {
// listenContext is also used by a tcp.Forwarder and in that
// context we do not have a listening endpoint to check the
// backlog. So skip this check if listenEP is nil.
- if h.listenEP != nil && len(h.listenEP.acceptedChan) == cap(h.listenEP.acceptedChan) {
- // If there is no space in the accept queue to accept
- // this endpoint then silently drop this ACK. The peer
- // will anyway resend the ack and we can complete the
- // connection the next time it's retransmitted.
- h.ep.stack.Stats().TCP.ListenOverflowAckDrop.Increment()
- h.ep.stack.Stats().DroppedPackets.Increment()
- return nil
+ if h.listenEP != nil {
+ h.listenEP.mu.Lock()
+ if len(h.listenEP.acceptedChan) == cap(h.listenEP.acceptedChan) {
+ h.listenEP.mu.Unlock()
+ // If there is no space in the accept queue to accept
+ // this endpoint then silently drop this ACK. The peer
+ // will anyway resend the ack and we can complete the
+ // connection the next time it's retransmitted.
+ h.ep.stack.Stats().TCP.ListenOverflowAckDrop.Increment()
+ h.ep.stack.Stats().DroppedPackets.Increment()
+ return nil
+ }
+ h.listenEP.mu.Unlock()
}
// If the timestamp option is negotiated and the segment does
// not carry a timestamp option then the segment must be dropped