From e9c6cb98eaa7f3b510061ca4f1e63fd4e3e714d9 Mon Sep 17 00:00:00 2001
From: Vincent Rabaud <vrabaud@google.com>
Date: Tue, 6 Jan 2026 00:48:59 +0100
Subject: [PATCH] Fix potential pointer overflow.

srcY-roi.y is promoted to size_t which creates problems when it is
negative.
---
 modules/imgproc/src/box_filter.simd.hpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/modules/imgproc/src/box_filter.simd.hpp b/modules/imgproc/src/box_filter.simd.hpp
index b7d2a8b214..5fed5f8ff3 100644
--- a/modules/imgproc/src/box_filter.simd.hpp
+++ b/modules/imgproc/src/box_filter.simd.hpp
@@ -44,6 +44,7 @@
 
 #include "precomp.hpp"
 #include "opencv2/core/hal/intrin.hpp"
+#include <cstddef>
 
 namespace cv {
 CV_CPU_OPTIMIZATION_NAMESPACE_BEGIN
@@ -1513,7 +1514,7 @@ void BlockSum(const Mat& _src, Mat& _dst, Size ksize, Point anchor, const Size &
                                       borderLeft*sizeof(T), inplace);
         }
         else
-            ref = (const T*)(src+(srcY-roi.y)*srcStep);
+            ref = (const T*)(src+(srcY-roi.y)*(ptrdiff_t)srcStep);
 
         S = ref;
         R = (T*)alignPtr(border, VEC_ALIGN);