From 9011baa3ebe342c56746ba7c6f5bb99e78d7a230 Mon Sep 17 00:00:00 2001
From: nightjoker7 <mattdeering7@gmail.com>
Date: Wed, 22 Apr 2026 19:08:32 -0500
Subject: [PATCH] StreamInterface: prevent socket/reader-thread leak on
 handshake failure in __init__
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If connect() or waitForConfig() raises during __init__ (handshake timeout,
bad stream, config error), the reader thread started by connect() keeps
running and the underlying stream/socket stays open — but the caller never
receives a reference to the half-initialized instance, so they cannot call
close() themselves. The leak compounds on every retry from a caller's
reconnect loop.

Fix: wrap connect() + waitForConfig() in try/except; call self.close() on
any exception before re-raising. Also guard close() against RuntimeError
from joining an unstarted reader thread (happens when close() runs from
a failed __init__ before connect() could spawn it).

Discovered while debugging a real-world Meshtastic firmware crash where
a passive logger's retrying TCPInterface() calls against a node with
250-entry NodeDB produced a reconnect storm — every retry triggered a
full config+NodeDB dump on the node, compounding heap pressure, which
then exposed null-deref bugs in Router::perhapsDecode / MeshService
(firmware side fixed in meshtastic/firmware#10226 and #10229). The
client-side leak is independent of those firmware bugs and worth fixing
on its own.
---
 meshtastic/stream_interface.py | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/meshtastic/stream_interface.py b/meshtastic/stream_interface.py
index 06ee28a3a..1e7d34038 100644
--- a/meshtastic/stream_interface.py
+++ b/meshtastic/stream_interface.py
@@ -1,5 +1,6 @@
 """Stream Interface base class
 """
+import contextlib
 import io
 import logging
 import threading
@@ -61,9 +62,20 @@ def __init__( # pylint: disable=R0917
 
         # Start the reader thread after superclass constructor completes init
         if connectNow:
-            self.connect()
-            if not noProto:
-                self.waitForConfig()
+            try:
+                self.connect()
+                if not noProto:
+                    self.waitForConfig()
+            except Exception:
+                # Handshake failed (timeout, config error, bad stream). The caller
+                # never receives a reference to this half-initialized instance, so
+                # they cannot call close() themselves. If we don't clean up here,
+                # the reader thread (already started by connect()) keeps running
+                # and the underlying stream/socket leaks — the leak compounds on
+                # every retry from the caller's reconnect loop.
+                with contextlib.suppress(Exception):
+                    self.close()
+                raise
 
     def connect(self) -> None:
         """Connect to our radio
@@ -136,7 +148,13 @@ def close(self) -> None:
         # reader thread to close things for us
         self._wantExit = True
         if self._rxThread != threading.current_thread():
-            self._rxThread.join()  # wait for it to exit
+            try:
+                self._rxThread.join()  # wait for it to exit
+            except RuntimeError:
+                # Thread was never started — happens when close() is invoked
+                # from a failed __init__ before connect() could spawn it.
+                # Nothing to join; safe to ignore.
+                pass
 
     def _handleLogByte(self, b):
         """Handle a byte that is part of a log message from the device."""