From 4028606bd9128058a6ab2e957abe966d5778634f Mon Sep 17 00:00:00 2001
From: BruebachL <44814898+BruebachL@users.noreply.github.com>
Date: Sat, 24 Oct 2026 10:28:24 +0200
Subject: [PATCH] [CardDB] Clear CardInfo relations before deferred deletion
 (#7615)
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removeCard() and swapInDatabaseData() schedule CardRelation deletion with deleteLater(), but the owning CardInfo could outlive them through an external shared pointer and kept returning the freed pointers from getAllRelatedCards(). Add CardInfo::clearDirectRelations() and call it after scheduling deletion so the UI can no longer dereference dangling relations.

Co-authored-by: Lukas Brübach <Bruebach.Lukas@bdosecurity.de>
---
 .../libcockatrice/card/card_info.cpp          |  7 +++++
 .../libcockatrice/card/card_info.h            |  8 ++++++
 .../card/database/card_database.cpp           |  7 +++++
 tests/carddatabase/carddatabase_test.cpp      | 27 +++++++++++++++++++
 4 files changed, 49 insertions(+)

diff --git a/libcockatrice_card/libcockatrice/card/card_info.cpp b/libcockatrice_card/libcockatrice/card/card_info.cpp
index c90027442..388c9ab57 100644
--- a/libcockatrice_card/libcockatrice/card/card_info.cpp
+++ b/libcockatrice_card/libcockatrice/card/card_info.cpp
@@ -270,6 +270,13 @@ void CardInfo::resetReverseRelatedCards2Me()
     reverseRelatedCardsToMe = QList<CardRelation *>();
 }
 
+void CardInfo::clearDirectRelations()
+{
+    relatedCards = QList<CardRelation *>();
+    reverseRelatedCards = QList<CardRelation *>();
+    reverseRelatedCardsToMe = QList<CardRelation *>();
+}
+
 // Back-compatibility methods. Remove ASAP
 QString CardInfo::getCardType() const
 {
diff --git a/libcockatrice_card/libcockatrice/card/card_info.h b/libcockatrice_card/libcockatrice/card/card_info.h
index 77ddce5ce..eb1250a1c 100644
--- a/libcockatrice_card/libcockatrice/card/card_info.h
+++ b/libcockatrice_card/libcockatrice/card/card_info.h
@@ -453,6 +453,14 @@ public:
         return result;
     }
     void resetReverseRelatedCards2Me();
+    /**
+     * @brief Clears the raw relation lists without deleting the CardRelation objects.
+     *
+     * Callers that schedule the relations for deletion (e.g. CardDatabase::removeCard())
+     * must use this to drop the now-dangling pointers from this CardInfo, which may
+     * outlive them through external shared pointers.
+     */
+    void clearDirectRelations();
     void addReverseRelatedCards2Me(CardRelation *cardRelation)
     {
         reverseRelatedCardsToMe.append(cardRelation);
diff --git a/libcockatrice_card/libcockatrice/card/database/card_database.cpp b/libcockatrice_card/libcockatrice/card/database/card_database.cpp
index 7b0d5b2f9..946412606 100644
--- a/libcockatrice_card/libcockatrice/card/database/card_database.cpp
+++ b/libcockatrice_card/libcockatrice/card/database/card_database.cpp
@@ -168,6 +168,10 @@ void CardDatabase::removeCard(const CardInfoPtr &card)
         cardRelation->deleteLater();
     }
 
+    // The relations are only scheduled for deletion; the CardInfo may outlive
+    // them through an external shared pointer, so drop the raw pointers now.
+    card->clearDirectRelations();
+
     QMutexLocker locker(removeCardMutex);
     cards.remove(card->getName());
     simpleNameCards.remove(card->getSimpleName());
@@ -271,6 +275,9 @@ void CardDatabase::swapInDatabaseData(CardDatabaseData data)
         for (auto *rel : card->getReverseRelatedCards2Me()) {
             rel->deleteLater();
         }
+        // Replacement cards take over the database; old CardInfo objects may
+        // still be referenced by the UI, so clear their dangling relations.
+        card->clearDirectRelations();
     }
 
     cards = std::move(data.cards);
diff --git a/tests/carddatabase/carddatabase_test.cpp b/tests/carddatabase/carddatabase_test.cpp
index 1b68b8166..eb522434d 100644
--- a/tests/carddatabase/carddatabase_test.cpp
+++ b/tests/carddatabase/carddatabase_test.cpp
@@ -26,6 +26,7 @@
 #include <libcockatrice/card/database/parser/cockatrice_xml_4.h>
 #include <libcockatrice/card/lazy_properties_hash.h>
 #include <libcockatrice/card/printing/printing_info.h>
+#include <libcockatrice/card/relation/card_relation.h>
 #include <libcockatrice/interfaces/interface_card_database_path_provider.h>
 #include <libcockatrice/interfaces/interface_card_set_priority_controller.h>
 #include <libcockatrice/interfaces/noop_card_preference_provider.h>
@@ -124,6 +125,32 @@ TEST(CardDatabaseTest, FindPrintingWithIdOnNullCardInfoReturnsEmpty)
     EXPECT_TRUE(db.query()->findPrintingWithId(nullptr, "card_Not a Card_fixture").isEmpty());
 }
 
+TEST(CardInfoTest, ClearDirectRelationsDropsRawPointers)
+{
+    auto *forward = new CardRelation("Child");
+    auto *reverse = new CardRelation("Parent");
+    auto *toMe = new CardRelation("Child");
+
+    auto card = CardInfo::newInstance("Parent", "", false, QHash<QString, QString>(), {forward}, {reverse},
+                                      SetToPrintingsMap(), CardInfo::UiAttributes());
+    card->addReverseRelatedCards2Me(toMe);
+    ASSERT_EQ(1, card->getRelatedCards().size());
+    ASSERT_EQ(1, card->getReverseRelatedCards().size());
+    ASSERT_EQ(1, card->getReverseRelatedCards2Me().size());
+    ASSERT_EQ(2, card->getAllRelatedCards().size());
+
+    card->clearDirectRelations();
+
+    EXPECT_TRUE(card->getRelatedCards().isEmpty());
+    EXPECT_TRUE(card->getReverseRelatedCards().isEmpty());
+    EXPECT_TRUE(card->getReverseRelatedCards2Me().isEmpty());
+    EXPECT_TRUE(card->getAllRelatedCards().isEmpty());
+
+    delete forward;
+    delete reverse;
+    delete toMe;
+}
+
 TEST(CardDatabaseTest, Xml4LocalizedDataRoundTrip)
 {
     NoopCardSetPriorityController controller;