From 6517b2d2acedb7226802b423e2131f83a693d3be Mon Sep 17 00:00:00 2001
From: Max Kellermann <max@musicpd.org>
Date: Mon, 6 Jul 2020 16:09:17 +0200
Subject: [PATCH] neighbor/upnp: remove D-Bus filter and match in Close()

Fixes use-after-free crash bug during MPD shutdown.
---
 NEWS                                          |  2 ++
 src/neighbor/plugins/UdisksNeighborPlugin.cxx | 17 ++++++++++-------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/NEWS b/NEWS
index d4e05e837..a515aeaad 100644
--- a/NEWS
+++ b/NEWS
@@ -12,6 +12,8 @@ ver 0.21.25 (not yet released)
 * output
   - osx: improve sample rate selection
   - osx: fix noise while stopping
+* neighbor
+  - upnp: fix crash during shutdown
 * Windows/Android:
   - fix Boost detection after breaking change in Meson 0.54
 
diff --git a/src/neighbor/plugins/UdisksNeighborPlugin.cxx b/src/neighbor/plugins/UdisksNeighborPlugin.cxx
index cb5d422f2..359d16ef3 100644
--- a/src/neighbor/plugins/UdisksNeighborPlugin.cxx
+++ b/src/neighbor/plugins/UdisksNeighborPlugin.cxx
@@ -47,6 +47,11 @@ ToNeighborInfo(const UDisks2::Object &o) noexcept
 	return {o.GetUri(), o.path};
 }
 
+static constexpr char udisks_neighbor_match[] =
+	"type='signal',sender='" UDISKS2_INTERFACE "',"
+	"interface='" DBUS_OM_INTERFACE "',"
+	"path='" UDISKS2_PATH "'";
+
 class UdisksNeighborExplorer final
 	: public NeighborExplorer {
 
@@ -110,11 +115,7 @@ UdisksNeighborExplorer::DoOpen()
 
 	try {
 		Error error;
-		dbus_bus_add_match(connection,
-				   "type='signal',sender='" UDISKS2_INTERFACE "',"
-				   "interface='" DBUS_OM_INTERFACE "',"
-				   "path='" UDISKS2_PATH "'",
-				   error);
+		dbus_bus_add_match(connection, udisks_neighbor_match, error);
 		error.CheckThrow("DBus AddMatch error");
 
 		dbus_connection_add_filter(connection,
@@ -147,8 +148,10 @@ UdisksNeighborExplorer::DoClose() noexcept
 		list_request.Cancel();
 	}
 
-	// TODO: remove_match
-	// TODO: remove_filter
+	auto &connection = GetConnection();
+
+	dbus_connection_remove_filter(connection, HandleMessage, this);
+	dbus_bus_remove_match(connection, udisks_neighbor_match, nullptr);
 
 	dbus_glue.Destruct();
 }