Brad Fitzpatrick ec5d51098a derp/derpserver: bound dup client sendHistory growth
When two connections share a node key, they form a dup client set and
noteClientActivity records each sending connection in the set's
sendHistory. It appended on every frame whenever the sender was not the
immediately previous one, and nothing trimmed the slice while both
connections stayed alive. Two connections taking turns sending therefore
grew sendHistory by one *sclient per frame without bound.

Under the default lastWriterIsActive policy nothing ever stops that
growth, so a malicious client (which controls its own node key) or a
buggy one that keeps two connections alive and both sending could leak
server memory, roughly 8 bytes per frame, for the life of the
connection pair.

Record the sender by moving it to the end of sendHistory and dropping any
earlier occurrence, so each connection appears at most once and the slice
stays bounded by the number of connections in the set. This preserves the
existing behavior: the fighting check under disableFighters still runs
before the move and still disables everyone on the first repeat, and
removeClient still promotes the previous speaker from the slice tail.

Fixes tailscale/corp#48884

Change-Id: I06198178e6ab0d7e2f04c1dc4c09eafcb16ace46
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
2026-09-25 09:51:11 -07:00
2026-09-16 10:08:11 -04:00
2026-09-23 18:02:11 -07:00
2026-07-10 17:39:16 -07:00
2026-01-27 16:15:17 -08:00
2026-06-02 10:59:29 -07:00
2026-08-28 12:47:04 -07:00
2026-09-17 16:55:23 -07:00

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 1.27. (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.

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