gdiplus: Reject linear gradients where the start and end points are equal.

dlls/gdiplus/brush.c

@@ -325,6 +325,9 @@ GpStatus WINGDIPAPI GdipCreateLineBrush(GDIPCONST GpPointF* startpoint,
     if(!line || !startpoint || !endpoint || wrap == WrapModeClamp)
         return InvalidParameter;
 
+    if (startpoint->X == endpoint->X && startpoint->Y == endpoint->Y)
+        return OutOfMemory;
+
     *line = GdipAlloc(sizeof(GpLineGradient));
     if(!*line)  return OutOfMemory;
 

dlls/gdiplus/tests/brush.c

@@ -356,6 +356,20 @@ static void test_gradientgetrect(void)
     expectf(100.0, rectf.Width);
     expectf(1.0, rectf.Height);
     status = GdipDeleteBrush((GpBrush*)brush);
+    /* zero height rect */
+    rectf.X = rectf.Y = 10.0;
+    rectf.Width = 100.0;
+    rectf.Height = 0.0;
+    status = GdipCreateLineBrushFromRect(&rectf, 0, 0, LinearGradientModeVertical,
+        WrapModeTile, &brush);
+    expect(OutOfMemory, status);
+    /* zero width rect */
+    rectf.X = rectf.Y = 10.0;
+    rectf.Width = 0.0;
+    rectf.Height = 100.0;
+    status = GdipCreateLineBrushFromRect(&rectf, 0, 0, LinearGradientModeHorizontal,
+        WrapModeTile, &brush);
+    expect(OutOfMemory, status);
     /* from rect with LinearGradientModeHorizontal */
     rectf.X = rectf.Y = 10.0;
     rectf.Width = rectf.Height = 100.0;
@@ -401,6 +415,10 @@ static void test_lineblend(void)
     REAL res_positions[6] = {0.3f, 0.0f, 0.0f, 0.0f, 0.0f};
     ARGB res_colors[6] = {0xdeadbeef, 0, 0, 0, 0};
 
+    pt1.X = pt1.Y = pt2.Y = pt2.X = 1.0;
+    status = GdipCreateLineBrush(&pt1, &pt2, 0, 0, WrapModeTile, &brush);
+    expect(OutOfMemory, status);
+
     pt1.X = pt1.Y = 1.0;
     pt2.X = pt2.Y = 100.0;
     status = GdipCreateLineBrush(&pt1, &pt2, 0, 0, WrapModeTile, &brush);