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.
mgaillard · May 7, 2021 · da68c45 · da68c45
1 parent df52040
commit da68c45
Showing 1 changed file with 7 additions and 0 deletions.
diff --git a/AK/Checked.h b/AK/Checked.h
@@ -183,6 +183,13 @@ class Checked {
 
  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;
  }