🛡️ Sentinel: [HIGH] Fix DoS via Pipe Deadlock in UniversalControlMouseRelay

[NSEvent]

🚨 Severity: HIGH
💡 Vulnerability: The tailscale status command executed in UniversalControlMouseRelay created a Pipe() for standardError but never read from it. If the child process output exceeds the OS pipe buffer (~64KB), it blocks, causing a deadlock and DoS.
🎯 Impact: Denial of Service due to deadlock.
🔧 Fix: Changed process.standardError = Pipe() to process.standardError = FileHandle.nullDevice to safely discard unread stderr output and prevent deadlocks.
✅ Verification: Ran a Python syntax validation script to ensure Swift file correctness.

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PR created automatically by Jules for task 11191703040972347591 started by @NSEvent

Summary by CodeRabbit

• Chores
  • Improved background network status handling by suppressing unnecessary diagnostic output while preserving existing functionality.

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Reviewing files that changed from the base of the PR and between 5ad068c and a8436c9.

📒 Files selected for processing (2)

• XboxControllerMapper/XboxControllerMapper/Services/Mapping/MappingEngine.swift
• XboxControllerMapper/XboxControllerMapperTests/OBSWebSocketLiveIntegrationTests.swift

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📥 Commits

Reviewing files that changed from the base of the PR and between a467a5f and 5ad068c.

📒 Files selected for processing (1)

• XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift

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📝 Walkthrough

Walkthrough

The Tailscale status subprocess in tailscalePeerHosts() now discards standard error output. Standard output capture and existing error handling remain unchanged.

Changes

Tailscale subprocess handling

Layer / File(s)	Summary
Discard Tailscale stderr output XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift	Routes Tailscale subprocess stderr to FileHandle.nullDevice instead of capturing it with a pipe.

Priority: ⬇️ Low

Estimated code review effort: 1 (Trivial) | ~2 minutes

Merge Risk: ⚪ Minimal · up to 5ad06

Tailscale status stderr is now discarded instead of being written to an unread pipe, preventing subprocess deadlock while preserving stdout-based peer discovery. No current merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 1 functions across 1 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly identifies the main change: fixing a pipe deadlock that could cause a denial-of-service condition in UniversalControlMouseRelay. The security prefix and emoji do not prevent the titl…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

✨ Finishing Touches 💡 1

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• Commit unit tests in branch sentinel/fix-dos-pipe-deadlock-11191703040972347591

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