From 3d1811642f1fec12e39119a65aea3c26fc7f3e55 Mon Sep 17 00:00:00 2001
From: "Ricardo Bossan (BEYONDSOFT CONSULTING INC) (from Dev Box)"
 <v-rbossan@microsoft.com>
Date: Wed, 22 Jan 2025 20:43:50 -0300
Subject: [PATCH] Prevents runtime crashes when the `DataGridView` or
 `CurrentCell` are null.

Fixes #12752

## Root Cause

- The issue occurs because the `NotifyMSAAClient` method is called
without checking if the `DataGridView` instance is `null`. This leads to
a potential `NullReferenceException`.

## Proposed changes

- Add a `null` check for the `DataGridView` instance before calling the
`NotifyMSAAClient` method.
- Adds another `null` check for the `CurrentCell` property before
calling the `PaintGrid` method.

## Customer Impact

- Prevents runtime crashes when the `DataGridView` or `CurrentCell` are
null.

## Regression?

- No

## Risk

- Minimal

## Screenshots

### Before

### After

## Test methodology

- Manual testing

## Test environment(s)

- `10.0.100-alpha.1.25064.3`
---
 .../Controls/DataGridView/DataGridView.Methods.cs  |  6 +++++-
 .../DataGridView/DataGridViewCheckBoxCell.cs       | 14 ++++++++++----
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/src/System.Windows.Forms/src/System/Windows/Forms/Controls/DataGridView/DataGridView.Methods.cs b/src/System.Windows.Forms/src/System/Windows/Forms/Controls/DataGridView/DataGridView.Methods.cs
index a56f85becd4..8991873527c 100644
--- a/src/System.Windows.Forms/src/System/Windows/Forms/Controls/DataGridView/DataGridView.Methods.cs
+++ b/src/System.Windows.Forms/src/System/Windows/Forms/Controls/DataGridView/DataGridView.Methods.cs
@@ -16701,7 +16701,11 @@ protected override void OnPaint(PaintEventArgs e)
                 using GraphicsClipScope clipScope = new(g);
                 g.SetClip(gridRect);
                 PaintBackground(g, clipRect, gridRect);
-                PaintGrid(g, gridRect, clipRect, SingleVerticalBorderAdded, SingleHorizontalBorderAdded);
+
+                if (CurrentCell is not null)
+                {
+                    PaintGrid(g, gridRect, clipRect, SingleVerticalBorderAdded, SingleHorizontalBorderAdded);
+                }
             }
 
             PaintBorder(g, clipRect, _layout.ClientRectangle);
diff --git a/src/System.Windows.Forms/src/System/Windows/Forms/Controls/DataGridView/DataGridViewCheckBoxCell.cs b/src/System.Windows.Forms/src/System/Windows/Forms/Controls/DataGridView/DataGridViewCheckBoxCell.cs
index cee95b9b3d1..1e093a1899e 100644
--- a/src/System.Windows.Forms/src/System/Windows/Forms/Controls/DataGridView/DataGridViewCheckBoxCell.cs
+++ b/src/System.Windows.Forms/src/System/Windows/Forms/Controls/DataGridView/DataGridViewCheckBoxCell.cs
@@ -839,7 +839,10 @@ protected override void OnKeyUp(KeyEventArgs e, int rowIndex)
                 e.Handled = true;
             }
 
-            NotifyMSAAClient(ColumnIndex, rowIndex);
+            if (DataGridView is not null)
+            {
+                NotifyMSAAClient(ColumnIndex, rowIndex);
+            }
         }
     }
 
@@ -967,9 +970,12 @@ private void NotifyUiaClient()
 
     private void NotifyMSAAClient(int columnIndex, int rowIndex)
     {
-        Debug.Assert(DataGridView is not null);
-        Debug.Assert((columnIndex >= 0) && (columnIndex < DataGridView.Columns.Count));
-        Debug.Assert((rowIndex >= 0) && (rowIndex < DataGridView.Rows.Count));
+        if (DataGridView is null ||
+            columnIndex < 0 || columnIndex >= DataGridView.Columns.Count ||
+            rowIndex < 0 || rowIndex >= DataGridView.Rows.Count)
+        {
+            return;
+        }
 
         int visibleRowIndex = DataGridView.Rows.GetRowCount(DataGridViewElementStates.Visible, 0, rowIndex);
         int visibleColumnIndex = DataGridView.Columns.ColumnIndexToActualDisplayIndex(columnIndex, DataGridViewElementStates.Visible);