From 0a9155777333ff89fdc39a5ffdd30653e38874f2 Mon Sep 17 00:00:00 2001
From: Dan Dees <dand@appsmiths.com>
Date: Fri, 6 Mar 2026 20:23:32 +0700
Subject: [PATCH] Fixed: UBSAN reports from empty memory copies

Skip zero-length memcpy/memmove calls in AbstractString construction and Array copy, insert, and capacity growth operations. Assert that nonempty Array storage is valid before copying during capacity growth.
---
 src/common/classes/array.h       | 24 +++++++++++++++++-------
 src/common/classes/fb_string.cpp |  3 ++-
 2 files changed, 19 insertions(+), 8 deletions(-)

diff --git a/src/common/classes/array.h b/src/common/classes/array.h
index 897474fbb27..51af8bb29cb 100644
--- a/src/common/classes/array.h
+++ b/src/common/classes/array.h
@@ -193,7 +193,8 @@ class Array : public Storage
 	void copyFrom(const Array<T, Storage>& source)
 	{
 		ensureCapacity(source.count, false);
-		memcpy(static_cast<void*>(data), source.data, sizeof(T) * source.count);
+		if (source.count)
+			memcpy(static_cast<void*>(data), source.data, sizeof(T) * source.count);
 		count = source.count;
 	}
 
@@ -260,8 +261,10 @@ class Array : public Storage
 		fb_assert(index <= count);
 		fb_assert(count < FB_MAX_SIZEOF);
 		ensureCapacity(count + 1);
-		memmove(static_cast<void*>(data + index + 1), data + index, sizeof(T) * (count++ - index));
+		if (count - index)
+			memmove(static_cast<void*>(data + index + 1), data + index, sizeof(T) * (count - index));
 		data[index] = item;
+		++count;
 	}
 
 	void insert(const size_type index, const Array<T, Storage>& items)
@@ -269,8 +272,10 @@ class Array : public Storage
 		fb_assert(index <= count);
 		fb_assert(count <= FB_MAX_SIZEOF - items.count);
 		ensureCapacity(count + items.count);
-		memmove(static_cast<void*>(data + index + items.count), data + index, sizeof(T) * (count - index));
-		memcpy(static_cast<void*>(data + index), items.data, items.count);
+		if (count - index)
+			memmove(static_cast<void*>(data + index + items.count), data + index, sizeof(T) * (count - index));
+		if (items.count)
+			memcpy(static_cast<void*>(data + index), items.data, items.count);
 		count += items.count;
 	}
 
@@ -279,8 +284,10 @@ class Array : public Storage
 		fb_assert(index <= count);
 		fb_assert(count <= FB_MAX_SIZEOF - itemsCount);
 		ensureCapacity(count + itemsCount);
-		memmove(static_cast<void*>(data + index + itemsCount), data + index, sizeof(T) * (count - index));
-		memcpy(static_cast<void*>(data + index), items, sizeof(T) * itemsCount);
+		if (count - index)
+			memmove(static_cast<void*>(data + index + itemsCount), data + index, sizeof(T) * (count - index));
+		if (itemsCount)
+			memcpy(static_cast<void*>(data + index), items, sizeof(T) * itemsCount);
 		count += itemsCount;
 	}
 
@@ -574,8 +581,11 @@ class Array : public Storage
 
 			T* newdata = static_cast<T*>
 				(this->getPool().allocate(sizeof(T) * newcapacity));
-			if (preserve)
+			if (preserve && count != 0)
+			{
+				fb_assert(data != nullptr);
 				memcpy(static_cast<void*>(newdata), data, sizeof(T) * count);
+			}
 			freeData();
 			data = newdata;
 			capacity = newcapacity;
diff --git a/src/common/classes/fb_string.cpp b/src/common/classes/fb_string.cpp
index 616996553d7..b4f26ac8689 100644
--- a/src/common/classes/fb_string.cpp
+++ b/src/common/classes/fb_string.cpp
@@ -100,7 +100,8 @@ namespace Firebird
 		: max_length(static_cast<internal_size_type>(limit))
 	{
 		initialize(sizeL);
-		memcpy(stringBuffer, dataL, sizeL);
+		if (sizeL)
+			memcpy(stringBuffer, dataL, sizeL);
 	}
 
 	AbstractString::AbstractString(const size_type limit, const_pointer p1, const size_type n1,