Merge branch 'win-fix-network-event-race'

3 files changed, 15 insertions, 1 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index d270f254db..a14a9d99fc 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -31,6 +31,8 @@ Line wrap the file at 100 chars.                                              Th
 - Fix WireGuard key status events being lost by the UI, causing stale information to be shown.
 - Fix time left in account not showing in settings screen.
 
+#### Windows
+- Fix race in network adapter monitor that could result in data corruption and crashes.
 
 ## [2020.5-beta1] - 2020-05-18
 ### Added
diff --git a/windows/winnet/src/winnet/networkadaptermonitor.cpp b/windows/winnet/src/winnet/networkadaptermonitor.cpp
index 92eab84932..2cbffd1198 100644
--- a/windows/winnet/src/winnet/networkadaptermonitor.cpp
+++ b/windows/winnet/src/winnet/networkadaptermonitor.cpp
@@ -276,6 +276,16 @@ void __stdcall NetworkAdapterMonitor::Callback(void *context, MIB_IPINTERFACE_RO
 {
 	auto inst = reinterpret_cast<NetworkAdapterMonitor *>(context);
 
+	//
+	// Calls into this function are supposed to be serialized by Windows.
+	// That's not true on Windows 10 :-(
+	//
+	// This can be easily reproduced by changing the callback to never return,
+	// and observing more events being delivered.
+	//
+
+	std::scoped_lock<std::mutex> lock(inst->m_callbackLock);
+
 	try
 	{
 		inst->callback(hint, updateType);
diff --git a/windows/winnet/src/winnet/networkadaptermonitor.h b/windows/winnet/src/winnet/networkadaptermonitor.h
index fe78bb7e2d..044fa62d54 100644
--- a/windows/winnet/src/winnet/networkadaptermonitor.h
+++ b/windows/winnet/src/winnet/networkadaptermonitor.h
@@ -9,7 +9,7 @@
 #include <windows.h>
 #include <functional>
 #include <vector>
-
+#include <mutex>
 
 class NetworkAdapterMonitor
 {
@@ -59,6 +59,8 @@ private:
 
 	std::shared_ptr<IDataProvider> m_dataProvider;
 
+	std::mutex m_callbackLock;
+
 	MIB_IF_ROW2 getAdapter(NET_LUID luid) const;
 
 	bool hasIPv4Interface(NET_LUID luid) const;