fix(Core/Common): Container fixes use after free (#21460)

src/common/Utilities/Containers.h

@@ -138,18 +138,28 @@ namespace Acore::Containers
     }
 
     /*
-     * Select a random element from a container.
+     * @brief Selects a random element from a container that matches the given predicate
+     *
+     * @param container Source container to select from
+     * @param predicate Unary predicate to filter elements
+     * @return Iterator to the randomly selected element, or end iterator if no elements match the predicate
      *
      * Note: container cannot be empty
      */
     template<class C, class Predicate>
-    inline auto SelectRandomContainerElementIf(C const& container, Predicate&& predicate) -> typename std::add_const<decltype(*std::begin(container))>::type&
+    inline auto SelectRandomContainerElementIf(C const& container, Predicate&& predicate) -> decltype(std::begin(container))
     {
-        C containerCopy;
+        std::vector<decltype(std::begin(container))> matchingElements;
-        std::copy_if(std::begin(container), std::end(container), std::inserter(containerCopy, std::end(containerCopy)), predicate);
+
-        auto it = std::begin(containerCopy);
+        for (auto it = std::begin(container); it != std::end(container); ++it)
-        std::advance(it, urand(0, uint32(std::size(containerCopy)) - 1));
+            if (predicate(*it))
-        return *it;
+                matchingElements.push_back(it);
+
+        if (matchingElements.empty())
+            return std::end(container);
+
+        auto randomIt = matchingElements[urand(0, matchingElements.size() - 1)];
+        return randomIt;
     }
 
     /*

src/server/game/Entities/Object/Position.h

@@ -64,6 +64,11 @@ struct Position
         return !(operator==(a));
     }
 
+    inline bool operator!=(Position const& a) const
+    {
+        return !(operator==(a));
+    }
+
     operator G3D::Vector3() const
     {
         return { m_positionX, m_positionY, m_positionZ };

src/server/scripts/Kalimdor/CavernsOfTime/TheBlackMorass/instance_the_black_morass.cpp

@@ -205,10 +205,12 @@ public:
                     {
                         if (_availableRiftPositions.size() > 1)
                         {
-                            spawnPos = Acore::Containers::SelectRandomContainerElementIf(_availableRiftPositions, [&](Position pos) -> bool
+                            auto spawnPosItr = Acore::Containers::SelectRandomContainerElementIf(_availableRiftPositions, [&](Position const& pos) -> bool
                             {
                                 return pos != lastPosition;
                             });
+                            if (spawnPosItr != _availableRiftPositions.end())
+                                spawnPos = *spawnPosItr;
                         }
                         else
                         {

src/server/scripts/Outland/TempestKeep/botanica/boss_laj.cpp

@@ -93,10 +93,13 @@ struct boss_laj : public BossAI
 
         ScheduleTimedEvent(30s, [&] {
             me->RemoveAurasDueToSpell(_lastTransform.spellId);
-            _lastTransform = Acore::Containers::SelectRandomContainerElementIf(_transformContainer, [&](LajTransformData data) -> bool
+            auto lastTransformItr = Acore::Containers::SelectRandomContainerElementIf(_transformContainer, [&](LajTransformData const& data) -> bool
             {
                 return data.spellId != _lastTransform.spellId;
             });
+            if (lastTransformItr == _transformContainer.end())
+                return;
+            _lastTransform = *lastTransformItr;
             me->SetDisplayId(_lastTransform.modelId);
             DoCastSelf(_lastTransform.spellId, true);
         }, 35s);