From da68c4580cbb087d928f010468c6165aacd6b299 Mon Sep 17 00:00:00 2001
From: Ali Mohammad Pur <ali.mpfard@gmail.com>
Date: Fri, 7 May 2021 09:45:54 +0430
Subject: [PATCH] AK: Make Checked<T> check for division overflow as well

Signed integer overflow can occur with division when the RHS is -1,
as the negative values' range is one larger than the positives.
---
 AK/Checked.h | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/AK/Checked.h b/AK/Checked.h
index 8d5321d5b6..0a92152162 100644
--- a/AK/Checked.h
+++ b/AK/Checked.h
@@ -183,6 +183,13 @@ public:
 
     constexpr void div(T other)
     {
+        if constexpr (IsSigned<T>) {
+            // Ensure that the resulting value won't be out of range, this can only happen when dividing by -1.
+            if (other == -1 && m_value == NumericLimits<T>::min()) {
+                m_overflow = true;
+                return;
+            }
+        }
         m_value /= other;
     }