snow/wireguard-go
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device: call wg.Add outside the goroutine

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One of the first rules of WaitGroups is that you call wg.Add
outside of a goroutine, not inside it. Fix this embarrassing mistake.

This prevents an extremely rare race condition (2 per 100,000 runs)
which could occur when attempting to start a new peer
concurrently with shutting down a device.

Signed-off-by: Josh Bleecher Snyder <josh@tailscale.com>
This commit is contained in:
Josh Bleecher Snyder 2020-12-18 16:32:46 -08:00 committed by Jason A. Donenfeld
parent b5f966ac24
commit b42e32047d
2 changed files with 2 additions and 3 deletions
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2
device/peer.go
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@ -213,6 +213,8 @@ func (peer *Peer) Start() {
// wait for routines to start
// RoutineNonce writes to the encryption queue; keep it alive until we are done.
device.queue.encryption.wg.Add(1)
go peer.RoutineNonce()
go peer.RoutineSequentialSender()
go peer.RoutineSequentialReceiver()

3
device/send.go
View file

@ -352,9 +352,6 @@ func (peer *Peer) RoutineNonce() {
device := peer.device
logDebug := device.log.Debug
// We write to the encryption queue; keep it alive until we are done.
device.queue.encryption.wg.Add(1)
flush := func() {
for {
select {