ImDrawList: Fixed OOB access in _CalcCircleAutoSegmentCount when passing excessively large radius to AddCircle(). (#6657, #5317)

docs/CHANGELOG.txt

@@ -46,6 +46,8 @@ Other changes:
 
 - Sliders: Fixed an integer overflow and div-by-zero in SliderInt() when
   v_max=INT_MAX (#6675, #6679) [@jbarthelmes]
+- ImDrawList: Fixed OOB access in _CalcCircleAutoSegmentCount when passing excessively
+  large radius to AddCircle(). (#6657, #5317) [@EggsyCRO, @jdpatdiscord]
 
 
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imgui_draw.cpp

@@ -561,7 +561,7 @@ int ImDrawList::_CalcCircleAutoSegmentCount(float radius) const
 {
     // Automatic segment count
     const int radius_idx = (int)(radius + 0.999999f); // ceil to never reduce accuracy
-    if (radius_idx < IM_ARRAYSIZE(_Data->CircleSegmentCounts))
+    if (radius_idx >= 0 && radius_idx < IM_ARRAYSIZE(_Data->CircleSegmentCounts))
         return _Data->CircleSegmentCounts[radius_idx]; // Use cached value
     else
         return IM_DRAWLIST_CIRCLE_AUTO_SEGMENT_CALC(radius, _Data->CircleSegmentMaxError);