From d34b100c137ac931379ae5e1b888f16a9c8d6c72 Mon Sep 17 00:00:00 2001
From: Charles Schlosser <cs.schlosser@gmail.com>
Date: Wed, 27 Nov 2024 19:32:14 +0000
Subject: [PATCH] Fix UB in setZero

---
 Eigen/src/Core/Fill.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/Eigen/src/Core/Fill.h b/Eigen/src/Core/Fill.h
index 048b51d98..e7ddf7f1a 100644
--- a/Eigen/src/Core/Fill.h
+++ b/Eigen/src/Core/Fill.h
@@ -80,11 +80,14 @@ struct eigen_zero_impl<Xpr, /*use_memset*/ true> {
   static constexpr size_t max_bytes = (std::numeric_limits<std::ptrdiff_t>::max)();
   static EIGEN_DEVICE_FUNC EIGEN_STRONG_INLINE void run(Xpr& dst) {
     const size_t num_bytes = dst.size() * sizeof(Scalar);
+    if (num_bytes == 0) return;
+    void* dst_ptr = static_cast<void*>(dst.data());
 #ifndef EIGEN_NO_DEBUG
     if (num_bytes > max_bytes) throw_std_bad_alloc();
+    eigen_assert((dst_ptr != nullptr) && "null pointer dereference error!");
 #endif
     EIGEN_USING_STD(memset);
-    memset(dst.data(), 0, num_bytes);
+    memset(dst_ptr, 0, num_bytes);
   }
 };