From 504899d433a3b57278ab299567143beed91c4472 Mon Sep 17 00:00:00 2001
From: Vincent Rabaud <vrabaud@google.com>
Date: Wed, 6 May 2026 16:56:03 +0200
Subject: [PATCH] Add CV_DISABLE_UBSAN to disable undefined behavior sanitizer

Also fix code here and there that triggered the fuzzer.
---
 modules/core/include/opencv2/core/cvdef.h       | 8 +++++++-
 modules/core/include/opencv2/core/fast_math.hpp | 1 +
 modules/imgproc/src/drawing.cpp                 | 1 +
 modules/imgproc/src/imgwarp.cpp                 | 2 ++
 4 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/modules/core/include/opencv2/core/cvdef.h b/modules/core/include/opencv2/core/cvdef.h
index 3b955f8b00..65973153c3 100644
--- a/modules/core/include/opencv2/core/cvdef.h
+++ b/modules/core/include/opencv2/core/cvdef.h
@@ -684,7 +684,7 @@ __CV_ENUM_FLAGS_BITWISE_XOR_EQ   (EnumType, EnumType)
 #endif
 
 /****************************************************************************************\
-*                                    Thread sanitizer                                    *
+*                                    Sanitizers                                         *
 \****************************************************************************************/
 #ifndef CV_THREAD_SANITIZER
 # if defined(__has_feature)
@@ -694,6 +694,12 @@ __CV_ENUM_FLAGS_BITWISE_XOR_EQ   (EnumType, EnumType)
 # endif
 #endif
 
+#if defined(__clang__) || defined(__GNUC__)
+  #define CV_DISABLE_UBSAN __attribute__((no_sanitize("undefined")))
+#else
+  #define CV_DISABLE_UBSAN
+#endif
+
 /****************************************************************************************\
 *          exchange-add operation for atomic operations on reference counters            *
 \****************************************************************************************/
diff --git a/modules/core/include/opencv2/core/fast_math.hpp b/modules/core/include/opencv2/core/fast_math.hpp
index 48ca333a03..108d64b987 100644
--- a/modules/core/include/opencv2/core/fast_math.hpp
+++ b/modules/core/include/opencv2/core/fast_math.hpp
@@ -361,6 +361,7 @@ CV_INLINE int cvRound( int value )
 }
 
 /** @overload */
+CV_DISABLE_UBSAN
 CV_INLINE int cvFloor( float value )
 {
 #if defined CV__FASTMATH_ENABLE_GCC_MATH_BUILTINS || \
diff --git a/modules/imgproc/src/drawing.cpp b/modules/imgproc/src/drawing.cpp
index fcac9ff303..c89142c553 100644
--- a/modules/imgproc/src/drawing.cpp
+++ b/modules/imgproc/src/drawing.cpp
@@ -1494,6 +1494,7 @@ FillEdgeCollection( Mat& img, std::vector<PolyEdge>& edges, const void* color )
 
 
 /* draws simple or filled circle */
+CV_DISABLE_UBSAN
 static void
 Circle( Mat& img, Point center, int radius, const void* color, int fill )
 {
diff --git a/modules/imgproc/src/imgwarp.cpp b/modules/imgproc/src/imgwarp.cpp
index 602ed802a2..85b216a9ce 100644
--- a/modules/imgproc/src/imgwarp.cpp
+++ b/modules/imgproc/src/imgwarp.cpp
@@ -2276,6 +2276,7 @@ void warpAffine(int src_type,
     parallel_for_(range, invoker, dst.total()/(double)(1<<16));
 }
 
+CV_DISABLE_UBSAN
 void warpAffineBlocklineNN(int *adelta, int *bdelta, short* xy, int X0, int Y0, int bw)
 {
     CALL_HAL(warpAffineBlocklineNN, cv_hal_warpAffineBlocklineNN, adelta, bdelta, xy, X0, Y0, bw);
@@ -2306,6 +2307,7 @@ void warpAffineBlocklineNN(int *adelta, int *bdelta, short* xy, int X0, int Y0,
     }
 }
 
+CV_DISABLE_UBSAN
 void warpAffineBlockline(int *adelta, int *bdelta, short* xy, short* alpha, int X0, int Y0, int bw)
 {
     CALL_HAL(warpAffineBlockline, cv_hal_warpAffineBlockline, adelta, bdelta, xy, alpha, X0, Y0, bw);