From 108c2022d9102c187bf153210551d1615e877419 Mon Sep 17 00:00:00 2001
From: Maksim Kita <kitaetoya@gmail.com>
Date: Sat, 8 May 2021 17:01:30 +0300
Subject: [PATCH] Function arrayDifference decimal math overflow

---
 src/Functions/array/arrayDifference.cpp       | 19 ++++++++++++++++++-
 ...ifference_decimal_overflow_ubsan.reference |  0
 ...rray_difference_decimal_overflow_ubsan.sql |  1 +
 3 files changed, 19 insertions(+), 1 deletion(-)
 create mode 100644 tests/queries/0_stateless/01851_array_difference_decimal_overflow_ubsan.reference
 create mode 100644 tests/queries/0_stateless/01851_array_difference_decimal_overflow_ubsan.sql

diff --git a/src/Functions/array/arrayDifference.cpp b/src/Functions/array/arrayDifference.cpp
index b4b30079a4e..45ff117bfdf 100644
--- a/src/Functions/array/arrayDifference.cpp
+++ b/src/Functions/array/arrayDifference.cpp
@@ -13,6 +13,7 @@ namespace ErrorCodes
 {
     extern const int ILLEGAL_TYPE_OF_ARGUMENT;
     extern const int ILLEGAL_COLUMN;
+    extern const int DECIMAL_OVERFLOW;
 }
 
 /** arrayDifference() - returns an array with the difference between all pairs of neighboring elements.
@@ -63,7 +64,23 @@ struct ArrayDifferenceImpl
             else
             {
                 Element curr = src[pos];
-                dst[pos] = curr - prev;
+
+                if constexpr (IsDecimalNumber<Element>)
+                {
+                    using ResultNativeType = typename Result::NativeType;
+
+                    ResultNativeType result_value;
+                    bool overflow = common::subOverflow(static_cast<ResultNativeType>(curr.value), static_cast<ResultNativeType>(prev), result_value);
+                    if (overflow)
+                        throw Exception(ErrorCodes::DECIMAL_OVERFLOW, "Decimal math overflow");
+
+                    dst[pos] = Result(result_value);
+                }
+                else
+                {
+                    dst[pos] = curr - prev;
+                }
+
                 prev = curr;
             }
         }
diff --git a/tests/queries/0_stateless/01851_array_difference_decimal_overflow_ubsan.reference b/tests/queries/0_stateless/01851_array_difference_decimal_overflow_ubsan.reference
new file mode 100644
index 00000000000..e69de29bb2d
diff --git a/tests/queries/0_stateless/01851_array_difference_decimal_overflow_ubsan.sql b/tests/queries/0_stateless/01851_array_difference_decimal_overflow_ubsan.sql
new file mode 100644
index 00000000000..ebf2efda4f1
--- /dev/null
+++ b/tests/queries/0_stateless/01851_array_difference_decimal_overflow_ubsan.sql
@@ -0,0 +1 @@
+SELECT arrayDifference([toDecimal32(100.0000991821289, 0), -2147483647]) AS x; --{serverError 407}