Harden exception handling in RunawayProcessKiller

src/WinSW.Core/Native/Handle.cs

@@ -5,7 +5,7 @@ using static WinSW.Native.HandleApis;
 namespace WinSW.Native
 {
     [StructLayout(LayoutKind.Sequential)]
-    internal readonly ref struct Handle
+    internal readonly struct Handle : IDisposable
     {
         private readonly IntPtr handle;
 

src/WinSW.Core/Native/ProcessApis.cs

@@ -34,12 +34,20 @@ namespace WinSW.Native
             int processInformationLength,
             IntPtr returnLength = default);
 
+        [DllImport(Libraries.Kernel32)]
+        internal static extern Handle OpenProcess(ProcessAccess desiredAccess, bool inheritHandle, int processId);
+
         [DllImport(Libraries.Advapi32, SetLastError = true)]
         internal static extern bool OpenProcessToken(
             IntPtr processHandle,
             TokenAccessLevels desiredAccess,
             out Handle tokenHandle);
 
+        internal enum ProcessAccess : uint
+        {
+            QueryInformation = 0x0400,
+        }
+
         internal enum PROCESSINFOCLASS
         {
             ProcessBasicInformation = 0,

src/WinSW.Core/Util/ProcessHelper.cs

@@ -26,7 +26,11 @@ namespace WinSW.Util
             {
                 foreach (var child in GetChildren(process))
                 {
-                    StopProcessTree(child, stopTimeout, stopParentProcessFirst);
+                    using (child.Key)
+                    using (child.Value)
+                    {
+                        StopProcessTree(child.Key, stopTimeout, stopParentProcessFirst);
+                    }
                 }
             }
 
@@ -36,7 +40,11 @@ namespace WinSW.Util
             {
                 foreach (var child in GetChildren(process))
                 {
-                    StopProcessTree(child, stopTimeout, stopParentProcessFirst);
+                    using (child.Key)
+                    using (child.Value)
+                    {
+                        StopProcessTree(child.Key, stopTimeout, stopParentProcessFirst);
+                    }
                 }
             }
         }
@@ -95,23 +103,33 @@ namespace WinSW.Util
             Logger.Debug($"Process {process.Id} has already exited.");
         }
 
-        private static unsafe List<Process> GetChildren(Process process)
+        // The handle is to keep a reference to the process.
+        private static unsafe List<KeyValuePair<Process, Handle>> GetChildren(Process process)
         {
             var startTime = process.StartTime;
             int processId = process.Id;
 
-            var children = new List<Process>();
+            var children = new List<KeyValuePair<Process, Handle>>();
 
             foreach (var other in Process.GetProcesses())
             {
+                var handle = OpenProcess(ProcessAccess.QueryInformation, false, other.Id);
+                if (handle == IntPtr.Zero)
+                {
+                    goto Next;
+                }
+
                 try
                 {
                     if (other.StartTime <= startTime)
                     {
                         goto Next;
                     }
-
-                    var handle = other.Handle;
+                }
+                catch (Exception e) when (e is InvalidOperationException || e is Win32Exception)
+                {
+                    goto Next;
+                }
 
                 if (NtQueryInformationProcess(
                     handle,
@@ -125,17 +143,13 @@ namespace WinSW.Util
                 if ((int)information.InheritedFromUniqueProcessId == processId)
                 {
                     Logger.Debug($"Found child process {other.Id}.");
-                        children.Add(other);
+                    children.Add(new(other, handle));
                     continue;
                 }
 
             Next:
                 other.Dispose();
-                }
-                catch (Exception e) when (e is InvalidOperationException || e is Win32Exception)
-                {
-                    other.Dispose();
-                }
+                handle.Dispose();
             }
 
             return children;

src/WinSW.Plugins/NativeMethods.cs

@@ -10,6 +10,9 @@ namespace WinSW.Plugins
             private const string Kernel32 = "kernel32.dll";
             private const string NTDll = "ntdll.dll";
 
+            [DllImport(Kernel32)]
+            internal static extern bool CloseHandle(IntPtr objectHandle);
+
             [DllImport(Kernel32)]
             internal static extern int IsWow64Process(IntPtr hProcess, out int Wow64Process);
 
@@ -53,6 +56,14 @@ namespace WinSW.Plugins
                 long BufferSize,
                 long NumberOfBytesRead = default);
 
+            [DllImport(Kernel32)]
+            internal static extern IntPtr OpenProcess(ProcessAccess desiredAccess, bool inheritHandle, int processId);
+
+            internal enum ProcessAccess : uint
+            {
+                QueryInformation = 0x0400,
+            }
+
             internal enum PROCESSINFOCLASS
             {
                 ProcessBasicInformation = 0,

src/WinSW.Plugins/RunawayProcessKillerExtension.cs

@@ -268,7 +268,17 @@ namespace WinSW.Plugins
 
             // Ensure the process references the service
             string expectedEnvVarName = WinSWSystem.EnvVarNameServiceId;
-            string? affiliatedServiceId = ReadEnvironmentVariable(proc.Handle, expectedEnvVarName);
+
+            var processHandle = OpenProcess(ProcessAccess.QueryInformation, false, pid);
+            if (processHandle == IntPtr.Zero)
+            {
+                Logger.Warn("Cannot get process handle of PID=" + pid + ". Assuming that the process has not been started by WinSW.");
+                return;
+            }
+
+            try
+            {
+                string? affiliatedServiceId = ReadEnvironmentVariable(processHandle, expectedEnvVarName);
                 if (affiliatedServiceId is null && this.CheckWinSWEnvironmentVariable)
                 {
                     Logger.Warn("The process " + pid + " has no " + expectedEnvVarName + " environment variable defined. "
@@ -302,6 +312,11 @@ namespace WinSW.Plugins
                 Logger.Warn(bldr.ToString());
                 ProcessHelper.StopProcessTree(proc, this.StopTimeout, this.StopParentProcessFirst);
             }
+            finally
+            {
+                _ = CloseHandle(processHandle);
+            }
+        }
 
         /// <summary>
         /// Records the started process PID for the future use in OnStart() after the restart.