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🛡️ Sentinel: [HIGH] Fix DoS pipe deadlock #85

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Merged
NSEvent merged 3 commits into from
Jul 13, 2026
Merged

🛡️ Sentinel: [HIGH] Fix DoS pipe deadlock #85

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🛡️ Sentinel: [HIGH] Fix DoS deadlock by draining Process pipes before…
google-labs-jules[bot] Jul 13, 2026
ae2da76
🛡️ Sentinel: [HIGH] Fix DoS deadlock by draining Process pipes before…
google-labs-jules[bot] Jul 13, 2026
ee3218b
🛡️ Sentinel: [HIGH] Fix DoS deadlock by draining Process pipes before…
google-labs-jules[bot] Jul 13, 2026
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4 changes: 4 additions & 0 deletions .Jules/sentinel.md
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Original file line number Diff line number Diff line change
Expand Up @@ -18,3 +18,7 @@
**Vulnerability:** The application was falling back to storing OBS passwords as plaintext strings inside exported/saved JSON models (`Macro.swift` and `SystemCommand.swift`) if saving to the macOS Keychain failed.
**Learning:** Saving secrets to unencrypted formats simply because secure storage fails is a critical anti-pattern known as "failing open" that results in data exposure.
**Prevention:** Always fail securely. If secure storage operations fail, discard the sensitive credential in memory rather than writing it insecurely to disk, even if it requires the user to re-authenticate later.
## 2026-06-26 - [Denial of Service via Pipe Deadlock]
**Vulnerability:** The application executed `Foundation.Process` shell commands and waited for them to exit (`process.waitUntilExit()`) before attempting to read the standard output and error pipes.
**Learning:** If a child process writes more data than the operating system's pipe buffer can hold (typically ~64KB), the child process will block waiting for the parent to read the data. If the parent is blocked on `waitUntilExit()`, a deadlock occurs, resulting in a Denial of Service.
**Prevention:** Always read data from process pipes (e.g., using `fileHandleForReading.readDataToEndOfFile()`) *before* calling `process.waitUntilExit()` to ensure the pipe buffer is drained and the child process can finish executing. However, ensure that this fix does not introduce deadlocks when used with handlers like `readabilityHandler` or processes that don't close their streams until parent exit.
3 changes: 1 addition & 2 deletions XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift
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Expand Up @@ -1405,10 +1405,9 @@ final class UniversalControlMouseRelay: @unchecked Sendable {
NSLog("[UCMouseRelay] Could not run tailscale status: %@", String(describing: error))
return []
}
let data = pipe.fileHandleForReading.readDataToEndOfFile()
process.waitUntilExit()
guard process.terminationStatus == 0 else { return [] }
Comment on lines +1408 to 1410

@coderabbitai coderabbitai Bot Jul 13, 2026

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🩺 Stability & Availability | 🟠 Major | ⚡ Quick win

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

# Map the relevant file and locate the target area
ast-grep outline XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift --view expanded || true

# Show the nearby lines around the cited snippet
sed -n '1365,1435p' XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift

# Find the method / helper that contains the process handling
rg -n "standardError|readDataToEndOfFile|waitUntilExit|terminationStatus" XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift

Repository: NSEvent/xbox-controller-mapper

Length of output: 13092

Drain or discard standardError here too. readDataToEndOfFile() only consumes stdout; if tailscale status --json writes enough to stderr, the child can block on the unread error pipe and this call can hang indefinitely. Use FileHandle.nullDevice for standardError or read both pipes concurrently.

🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In
`@XboxControllerMapper/XboxControllerMapper/Services/Input/UniversalControlMouseRelay.swift`
around lines 1408 - 1410, Update the process setup surrounding the
`readDataToEndOfFile()` call to drain or discard `standardError` as well as
stdout, preferably by assigning `FileHandle.nullDevice` before waiting for the
process. Preserve the existing termination-status check and empty-array
behavior.


let data = pipe.fileHandleForReading.readDataToEndOfFile()
guard let object = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
let peers = object["Peer"] as? [String: Any] else {
return []
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