gdiplus: Fix a string buffer overflow.
diff --git a/dlls/gdiplus/graphics.c b/dlls/gdiplus/graphics.c
index c1e63f6..3689fd3 100644
--- a/dlls/gdiplus/graphics.c
+++ b/dlls/gdiplus/graphics.c
@@ -2625,7 +2625,7 @@
 
     if(length == -1) length = lstrlenW(string);
 
-    stringdup = GdipAlloc(length * sizeof(WCHAR));
+    stringdup = GdipAlloc((length + 1) * sizeof(WCHAR));
     if(!stringdup) return OutOfMemory;
 
     oldfont = SelectObject(graphics->hdc, CreateFontIndirectW(&font->lfw));