Fix GDI handle leak in Icon.DrawImage

src/libraries/Common/src/Interop/Windows/Gdi32/Interop.SelectClipRgn.cs

@@ -11,13 +11,6 @@ internal static partial class Gdi32
         [DllImport(Libraries.Gdi32, SetLastError = true, ExactSpelling = true)]
         public static extern RegionType SelectClipRgn(IntPtr hdc, IntPtr hrgn);
 
-        public static RegionType SelectClipRgn(HandleRef hdc, IntPtr hrgn)
-        {
-            RegionType result = SelectClipRgn(hdc.Handle, hrgn);
-            GC.KeepAlive(hdc.Wrapper);
-            return result;
-        }
-
         public static RegionType SelectClipRgn(HandleRef hdc, HandleRef hrgn)
         {
             RegionType result = SelectClipRgn(hdc.Handle, hrgn.Handle);

src/libraries/Common/tests/System/Drawing/Helpers.cs

@@ -182,6 +182,9 @@ private static Rectangle GetRectangle(RECT rect)
         [DllImport("user32.dll", SetLastError = true)]
         public static extern IntPtr GetForegroundWindow();
 
+        [DllImport("user32.dll", ExactSpelling = true, SetLastError = true)]
+        public static extern int GetGuiResources(IntPtr hProcess, uint flags);
+
         [DllImport("user32.dll", SetLastError = true)]
         public static extern IntPtr GetDC(IntPtr hWnd);
 

src/libraries/System.Drawing.Common/src/System/Drawing/Icon.Windows.cs

@@ -379,7 +379,9 @@ private void DrawIcon(IntPtr dc, Rectangle imageRect, Rectangle targetRect, bool
             }
             finally
             {
-                RestoreClipRgn(dc, hSaveRgn);
+                Interop.Gdi32.SelectClipRgn(dc, hSaveRgn);
+                // We need to delete the region handle after restoring the region as GDI+ uses a copy of the handle.
+                Interop.Gdi32.DeleteObject(hSaveRgn);
             }
         }
 
@@ -394,15 +396,15 @@ private static IntPtr SaveClipRgn(IntPtr hDC)
                 hSaveRgn = hTempRgn;
                 hTempRgn = IntPtr.Zero;
             }
+            else
+            {
+                // if we fail to get the clip region delete the handle.
+                Interop.Gdi32.DeleteObject(hTempRgn);
+            }
 
             return hSaveRgn;
         }
 
-        private static void RestoreClipRgn(IntPtr hDC, IntPtr hRgn)
-        {
-            Interop.Gdi32.SelectClipRgn(new HandleRef(null, hDC), new HandleRef(null, hRgn));
-        }
-
         internal void Draw(Graphics graphics, int x, int y)
         {
             Size size = Size;

src/libraries/System.Drawing.Common/tests/GdiPlusHandlesTests.cs

@@ -0,0 +1,59 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Diagnostics;
+using System.Runtime.InteropServices;
+using Microsoft.DotNet.RemoteExecutor;
+using Xunit;
+using Xunit.Sdk;
+
+namespace System.Drawing.Tests
+{
+    [PlatformSpecific(TestPlatforms.Windows)]
+    public static class GdiPlusHandlesTests
+    {
+        public static bool IsDrawingAndRemoteExecutorSupported => Helpers.GetIsDrawingSupported() && RemoteExecutor.IsSupported;
+
+        [ConditionalFact(nameof(IsDrawingAndRemoteExecutorSupported))]
+        public static void GraphicsDrawIconDoesNotLeakHandles()
+        {
+            RemoteExecutor.Invoke(() =>
+            {
+                const int handleTreshold = 1;
+                using Bitmap bmp = new(100, 100);
+                using Icon ico = new(Helpers.GetTestBitmapPath("16x16_one_entry_4bit.ico"));
+
+                IntPtr hdc = Helpers.GetDC(Helpers.GetForegroundWindow());
+                using Graphics graphicsFromHdc = Graphics.FromHdc(hdc);
+
+                using Process currentProcess = Process.GetCurrentProcess();
+                IntPtr processHandle = currentProcess.Handle;
+
+                int initialHandles = Helpers.GetGuiResources(processHandle, 0);
+                ValidateNoWin32Error(initialHandles);
+
+                for (int i = 0; i < 5000; i++)
+                {
+                    graphicsFromHdc.DrawIcon(ico, 100, 100);
+                }
+
+                int finalHandles = Helpers.GetGuiResources(processHandle, 0);
+                ValidateNoWin32Error(finalHandles);
+
+                Assert.InRange(finalHandles, initialHandles, initialHandles + handleTreshold);
+            }).Dispose();
+        }
+
+        private static void ValidateNoWin32Error(int handleCount)
+        {
+            if (handleCount == 0)
+            {
+                int error = Marshal.GetLastWin32Error();
+
+                if (error != 0)
+                    throw new XunitException($"GetGuiResorces failed with win32 error: {error}");
+            }
+        }
+
+    }
+}

src/libraries/System.Drawing.Common/tests/System.Drawing.Common.Tests.csproj

@@ -22,6 +22,7 @@
     <Compile Include="DrawingTest.cs" />
     <Compile Include="FontTests.cs" />
     <Compile Include="FontFamilyTests.cs" />
+    <Compile Include="GdiPlusHandlesTests.cs" />
     <Compile Include="GdiplusTests.cs" />
     <Compile Include="GraphicsTests.cs" />
     <Compile Include="Graphics_DrawBezierTests.cs" />