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bugfix(replay): Stop dereferencing a null slot when a replay has no local player #3240

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bugfix(replay): Stop dereferencing a null slot when a replay has no local player #3240

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50b3329
bugfix(replay): Derive the replay CRC queue from the recorded game mode
bobtista Aug 29, 2026
c1bc7ac
bugfix(replay): Replicate replay CRC queue mode derivation to Generals
bobtista Aug 30, 2026
598b1c9
bugfix(replay): Guard the local slot lookup when a replay has no loca…
bobtista Aug 30, 2026
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11 changes: 8 additions & 3 deletions Generals/Code/GameEngine/Source/Common/Recorder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1149,16 +1149,21 @@ Bool RecorderClass::playbackFile(AsciiString filename)
}
#endif

Bool isMultiplayer = m_gameInfo.getSlot(header.localPlayerIndex)->getIP() != 0;
m_crcInfo = CRCInfo(header.localPlayerIndex, isMultiplayer);
REPLAY_CRC_INTERVAL = m_gameInfo.getCRCInterval();
DEBUG_LOG(("Player index is %d, replay CRC interval is %d", m_crcInfo.getLocalPlayer(), REPLAY_CRC_INTERVAL));

Int difficulty = 0;
m_file->read(&difficulty, sizeof(difficulty));

m_file->read(&m_originalGameMode, sizeof(m_originalGameMode));

// TheSuperHackers @bugfix bobtista 30/08/2026 A replay header is allowed to carry a local player
// index of -1 and getSlot returns NULL for it, so reading the slot to tell a network game from a
// local one dereferenced NULL. The recorded game mode answers the same question directly, so the
// crc queue is now primed from the mode and the local slot is no longer read here.

@xezon xezon Sep 15, 2026

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This comment tells what the code did before, which no one cares for. It is also too verbose.

const Bool isMultiplayer = m_originalGameMode == GAME_LAN || m_originalGameMode == GAME_INTERNET;
m_crcInfo = CRCInfo(header.localPlayerIndex, isMultiplayer);
DEBUG_LOG(("Player index is %d, replay CRC interval is %d", m_crcInfo.getLocalPlayer(), REPLAY_CRC_INTERVAL));

Int rankPoints = 0;
m_file->read(&rankPoints, sizeof(rankPoints));

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6 changes: 5 additions & 1 deletion Generals/Code/GameEngine/Source/GameLogic/System/GameLogic.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1315,7 +1315,11 @@ void GameLogic::tryStartNewGame( Bool loadingSaveGame )
d.setInt(TheKey_multiplayerStartIndex, slot->getStartPos());
// d.setBool(TheKey_multiplayerIsLocal, slot->isLocalPlayer());
// d.setBool(TheKey_multiplayerIsLocal, slot->getIP() == game->getLocalIP());
d.setBool(TheKey_multiplayerIsLocal, slot->isHuman() && (slot->getName().compare(TheGameInfo->getSlot(TheGameInfo->getLocalSlotNum())->getName().str()) == 0));
// TheSuperHackers @bugfix bobtista 30/08/2026 A replay recorded without a local player has no
// local slot number and getSlot returns NULL for it, so no slot can be the local one.

@xezon xezon Sep 15, 2026

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This comment is too verbose.

const Int localSlotNum = TheGameInfo->getLocalSlotNum();
const GameSlot *localGameSlot = localSlotNum >= 0 ? TheGameInfo->getSlot(localSlotNum) : nullptr;

@xezon xezon Sep 15, 2026

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&& localSlotNum < MAX_SLOTS

d.setBool(TheKey_multiplayerIsLocal, slot->isHuman() && localGameSlot != nullptr && (slot->getName().compare(localGameSlot->getName().str()) == 0));
Comment on lines +1320 to +1322

@qodo-free-for-open-source-projects qodo-free-for-open-source-projects Bot Sep 14, 2026

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Remediation recommended

1. No-player replays inherit old viewpoints 🐞 Bug ≡ Correctness

tryStartNewGame trusts getLocalSlotNum() even though replay loading does not clear or replace
m_localIP when the recorded index is -1. After an earlier replay leaves a matching IP behind,
the affected replay marks that human as local and uses their starting position and player state
instead of taking the deterministic no-local fallback.
Agent Prompt 
## Issue description
Replay-local player lookup remains IP-based when the replay header explicitly records no local player. Because replay resets preserve the prior local IP, a subsequent replay can resolve an unrelated slot as local.

## Fix Focus Areas
- Generals/Code/GameEngine/Include/Common/Recorder.h[36-47]
- Generals/Code/GameEngine/Source/Common/Recorder.cpp[916-931]
- Generals/Code/GameEngine/Source/GameLogic/System/GameLogic.cpp[1320-1347]
- GeneralsMD/Code/GameEngine/Source/Common/Recorder.cpp[918-933]
- GeneralsMD/Code/GameEngine/Source/GameLogic/System/GameLogic.cpp[1481-1508]

## Recommended Fix
Store the replay header's local slot index explicitly in `ReplayGameInfo` and override its local-slot lookup to return that index, including `-1`, rather than deriving replay locality from retained IP state. Apply the same implementation to both game variants and use the explicit result for local-player flags and the later `localSlot` assignment.

ⓘ Copy this prompt and use it to remediate the issue with your preferred AI generation tools

@xezon xezon Sep 15, 2026

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This line is very long. Can be broken into 2.


/*
if (slot->getIP() == game->getLocalIP())
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11 changes: 8 additions & 3 deletions GeneralsMD/Code/GameEngine/Source/Common/Recorder.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1152,16 +1152,21 @@ Bool RecorderClass::playbackFile(AsciiString filename)
}
#endif

Bool isMultiplayer = m_gameInfo.getSlot(header.localPlayerIndex)->getIP() != 0;
m_crcInfo = CRCInfo(header.localPlayerIndex, isMultiplayer);
REPLAY_CRC_INTERVAL = m_gameInfo.getCRCInterval();
DEBUG_LOG(("Player index is %d, replay CRC interval is %d", m_crcInfo.getLocalPlayer(), REPLAY_CRC_INTERVAL));

Int difficulty = 0;
m_file->read(&difficulty, sizeof(difficulty));

m_file->read(&m_originalGameMode, sizeof(m_originalGameMode));

// TheSuperHackers @bugfix bobtista 30/08/2026 A replay header is allowed to carry a local player
// index of -1 and getSlot returns NULL for it, so reading the slot to tell a network game from a
// local one dereferenced NULL. The recorded game mode answers the same question directly, so the
// crc queue is now primed from the mode and the local slot is no longer read here.
const Bool isMultiplayer = m_originalGameMode == GAME_LAN || m_originalGameMode == GAME_INTERNET;
m_crcInfo = CRCInfo(header.localPlayerIndex, isMultiplayer);
DEBUG_LOG(("Player index is %d, replay CRC interval is %d", m_crcInfo.getLocalPlayer(), REPLAY_CRC_INTERVAL));

Int rankPoints = 0;
m_file->read(&rankPoints, sizeof(rankPoints));

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6 changes: 5 additions & 1 deletion GeneralsMD/Code/GameEngine/Source/GameLogic/System/GameLogic.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1476,7 +1476,11 @@ void GameLogic::tryStartNewGame( Bool loadingSaveGame )
d.setInt(TheKey_multiplayerStartIndex, slot->getStartPos());
// d.setBool(TheKey_multiplayerIsLocal, slot->isLocalPlayer());
// d.setBool(TheKey_multiplayerIsLocal, slot->getIP() == game->getLocalIP());
d.setBool(TheKey_multiplayerIsLocal, slot->isHuman() && (slot->getName().compare(TheGameInfo->getSlot(TheGameInfo->getLocalSlotNum())->getName().str()) == 0));
// TheSuperHackers @bugfix bobtista 30/08/2026 A replay recorded without a local player has no
// local slot number and getSlot returns NULL for it, so no slot can be the local one.
const Int localSlotNum = TheGameInfo->getLocalSlotNum();
const GameSlot *localGameSlot = localSlotNum >= 0 ? TheGameInfo->getSlot(localSlotNum) : nullptr;
d.setBool(TheKey_multiplayerIsLocal, slot->isHuman() && localGameSlot != nullptr && (slot->getName().compare(localGameSlot->getName().str()) == 0));

/*
if (slot->getIP() == game->getLocalIP())
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