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Fix ExchangeContext leak in chip_im_initiator (Fix: #6915) #6918

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Fix ExchangeContext leak in chip_im_initiator (Fix: #6915) #6918

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11 changes: 11 additions & 0 deletions src/messaging/ExchangeMgr.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -43,6 +43,10 @@
#include <support/RandUtils.h>
#include <support/logging/CHIPLogging.h>

#if CONFIG_DEVICE_LAYER
#include <platform/CHIPDeviceLayer.h>
#endif

using namespace chip::Encoding;
using namespace chip::Inet;
using namespace chip::System;
Expand Down Expand Up @@ -94,6 +98,10 @@ CHIP_ERROR ExchangeManager::Init(SecureSessionMgr * sessionMgr)

CHIP_ERROR ExchangeManager::Shutdown()
{
// TODO(#6931): Lock guard is a temporary solution. Proper solution should be post chip shutdown function into chip thread
#if CONFIG_DEVICE_LAYER
DeviceLayer::PlatformMgr().LockChipStack();
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Wouldn't the real solution be to have this called in the main event loop task of the stack? Seems like the stack shutting itself down should be done from within the stack task itself, rather than being called from outside with a lock.

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The stack lock was introduced to protect CHIP event processing. Putting a chip lock here can only prevent CHIP from operating, but the problem here is the exchange is also released from the client thread.

How this change can prevent leaking?

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For IM, maybe it is ok, we just moved the logic to close the exchange in OnMessageReceived, but if the exchange closing also occurs in client thread, how this locking helps?

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@yufengwangca yufengwangca May 18, 2021 •
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I would suggest moving DeviceLayer::PlatformMgr().LockChipStack() to the place where shutdown is called from the client thread, instead of within ExchangeManager::Shutdown() itself.

You are trying to fix the problem in the case which Shutdown is called from a client thread, for the cases Shutdown() are called from CHIP main thread event loop(Which it should be), it will crash since chip lock is not recursive.

#endif
mReliableMessageMgr.Shutdown();

mContextPool.ForEachActiveObject([](auto * ec) {
Expand All @@ -109,6 +117,9 @@ CHIP_ERROR ExchangeManager::Shutdown()
}

mState = State::kState_NotInitialized;
#if CONFIG_DEVICE_LAYER
DeviceLayer::PlatformMgr().UnlockChipStack();
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Same as above, move DeviceLayer::PlatformMgr().UnlockChipStack(); to the place Shutdown is called from the client thread

#endif

return CHIP_NO_ERROR;
}
Expand Down