Nick Khyl fd7dd6433f ipn/ipnlocal: fix LocalBackend deadlock when packet arrives during profile switch (#18126)
If a packet arrives while WireGuard is being reconfigured with b.mu held, such as during a profile switch,
calling back into (*LocalBackend).GetPeerAPIPort from (*Wrapper).filterPacketInboundFromWireGuard
may deadlock when it tries to acquire b.mu.

This occurs because a peer cannot be removed while an inbound packet is being processed.
The reconfig and profile switch wait for (*Peer).RoutineSequentialReceiver to return, but it never finishes
because GetPeerAPIPort needs b.mu, which the waiting goroutine already holds.

In this PR, we make peerAPIPorts a new syncs.AtomicValue field that is written with b.mu held
but can be read by GetPeerAPIPort without holding the mutex, which fixes the deadlock.

There might be other long-term ways to address the issue, such as moving peer API listeners
from LocalBackend to nodeBackend so they can be accessed without holding b.mu,
but these changes are too large and risky at this stage in the v1.92 release cycle.

Updates #18124

Signed-off-by: Nick Khyl <nickk@tailscale.com>
(cherry picked from commit 557457f3c2e896a41c123e72278194d9f9f60663)
2025-12-04 10:13:58 -05:00
2025-11-18 10:46:28 -08:00
2025-11-19 07:06:18 -08:00
2025-10-29 21:15:46 +00:00
2025-11-26 15:35:58 -05:00

Tailscale

https://tailscale.com

Private WireGuard® networks made easy

Overview

This repository contains the majority of Tailscale's open source code. Notably, it includes the tailscaled daemon and the tailscale CLI tool. The tailscaled daemon runs on Linux, Windows, macOS, and to varying degrees on FreeBSD and OpenBSD. The Tailscale iOS and Android apps use this repo's code, but this repo doesn't contain the mobile GUI code.

Other Tailscale repos of note:

For background on which parts of Tailscale are open source and why, see https://tailscale.com/opensource/.

Using

We serve packages for a variety of distros and platforms at https://pkgs.tailscale.com.

Other clients

The macOS, iOS, and Windows clients use the code in this repository but additionally include small GUI wrappers. The GUI wrappers on non-open source platforms are themselves not open source.

Building

We always require the latest Go release, currently Go 1.25. (While we build releases with our Go fork, its use is not required.)

go install tailscale.com/cmd/tailscale{,d}

If you're packaging Tailscale for distribution, use build_dist.sh instead, to burn commit IDs and version info into the binaries:

./build_dist.sh tailscale.com/cmd/tailscale
./build_dist.sh tailscale.com/cmd/tailscaled

If your distro has conventions that preclude the use of build_dist.sh, please do the equivalent of what it does in your distro's way, so that bug reports contain useful version information.

Bugs

Please file any issues about this code or the hosted service on the issue tracker.

Contributing

PRs welcome! But please file bugs. Commit messages should reference bugs.

We require Developer Certificate of Origin Signed-off-by lines in commits.

See commit-messages.md (or skim git log) for our commit message style.

About Us

Tailscale is primarily developed by the people at https://github.com/orgs/tailscale/people. For other contributors, see:

WireGuard is a registered trademark of Jason A. Donenfeld.

Description
The easiest, most secure way to use WireGuard and 2FA.
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